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Clinical Relevance: Myopia has become a public health priority as its prevalence increases worldwide, and in clinical practice, the precise evaluation of refraction errors is necessary., Background: This study aimed to compare objective and subjective refraction measured by a binocular wavefront optometer (BWFOM) in adults with conventional objective and subjective refractions measured by an optometrist., Methods: This cross-sectional study included 119 eyes of 119 participants (34 men and 85 women; mean age:27.5 ± 6.3 years). Refractive errors were measured using BWFOM and conventional methods, with and without cycloplegia. The mean outcome measures were spherical power, cylindrical power, and spherical equivalence (SE). The agreement test was assessed using a two-tailed paired t-test and Bland - Altman plots., Results: Under noncycloplegic conditions, there were no significant differences in the objective SE between BWFOM and Nidek. Significant differences in subjective SE were observed between BWFOM and conventional subjective refraction (-5.79 ± 1.86 vs -5.65 ± 1.75 D, P  < 0.01). Under cycloplegic conditions, the mean objective SE was significantly different between BWFOM and Nidek (-5.70 ± 1.76 vs -5.50 ± 1.83 D, P  < 0.001); the mean subjective SE was significantly different between BWFOM and conventional subjective refractions (-5.52 ± 1.77 vs -5.62 ± 1.79 D, P  < 0.001). The Bland - Altman plots revealed mean percentages of 95.38% and 95.17% for the points within the limits of agreement between BWFOM and conventional measurements and those between noncycloplegic and cycloplegic refractions, respectively., Conclusion: The BWFOM is a new device that measures both objective and subjective refraction. It is more convenient and faster to obtain a proper prescription at a 0.05-D interval. The subjective refraction results of the BWFOM and the conventional subjective refraction were in good agreement.

In monocular see-through augmented reality systems, each eye is stimulated differently by a monocular image that is superimposed on the binocular background. This can impair binocular fusion, due to interocular conflict. As a function of visual characteristics, the latter can have a greater or lesser impact on user comfort and performance. This study tested several visual characteristics of a binocular background and a monocular element during an exposure that reproduced the interocular conflict induced by a monocular see-through near-eye display. The aim was to identify which factors impact the user's performance. Performance was measured as target tracking and event detection, identification, fixation time, and latency. Our results demonstrate that performance is a function of the binocular background. Furthermore, exogenous attentional stimulation, in the form of a pulse with different levels of contrast applied to the monocular display, appears to preserve performance in most background conditions., Competing Interests: This commercial affiliation does not alter our adherence to Plos One policies on sharing data and materials.

Importance: The coronavirus disease 2019 pandemic illustrates the increasingly important role of telemedicine as a method of clinician-patient interaction. However, electronic applications (apps) for the testing of ophthalmology vital signs, such as visual acuity, can be published and used without any verification of accuracy, validity, or reliability., Objective: To reassess the accuracy of visual acuity-testing apps and assess their viability for telehealth., Design, Setting, and Participants: The US Apple App Store was queried for apps for visual acuity testing. Anticipated optotype size for various visual acuity lines were calculated and compared against the actual measured optotype size on 4 different Apple hardware devices. No human participants were part of this study., Main Outcomes and Measures: Mean (SD) errors were calculated per device and across multiple devices., Results: On iPhones, 10 apps met inclusion criteria, with mean errors ranging from 0.2% to 109.9%. On the iPads, 9 apps met inclusion criteria, with mean errors ranging from 0.2% to 398.1%. Six apps met criteria and worked on both iPhone and iPad, with mean errors from 0.2% to 249.5%. Of the 6 apps that worked across devices, the top 3 most accurate apps were Visual Acuity Charts (mean [SD] error, 0.2% [0.0%]), Kay iSight Test Professional (mean [SD] error, 3.5% [0.7%]), and Smart Optometry (mean [SD] error, 15.9% [4.3%]). None of the apps tested were ideal for telemedicine, because some apps displayed accurate optotype size, while others displayed the same letters on separate devices; no apps exhibited both characteristics., Conclusions and Relevance: Both Visual Acuity Charts and Kay iSight Test Professional had low mean (SD) errors and functionality across all tested devices, but no apps were suitable for telemedicine. This suggests that new and/or improved visual acuity-testing apps are necessary for optimal telemedicine use.

Purpose: To assess the performance of an open-view binocular handheld aberrometer (QuickSee) for diagnosing refractive errors in children., Methods: 123 school-age children (9.9 ± 3.3 years) with moderate refractive error underwent autorefraction (AR) with a standard desktop device and subjective refraction (SR), with or without cycloplegia to determine their eyeglass prescription. Measurements with QuickSee (QS) were taken in 62 of these patients without cycloplegia (NC), and in 61 under cycloplegia (C). Differences in refraction values (AR vs SR vs QS) as well as the visual acuity (VA) achieved by the patients with each method (QS vs SR) were used to evaluate the performance of the device in measuring refractive error., Results: The spherical equivalent refraction obtained by QS agreed within 0.5 D of the SR in 71% (NC) and 70% (C) of the cases. Agreement between the desktop autorefractor and SR for the same threshold was of 61% (NC) and 77% (C). VA resulting from QS refractions was equal to or better than that achieved by SR procedure in 77% (NC) and 74% (C) of the patients. Average improvement in VA with the QS refractions was of 8.6 and 13.4 optotypes for the NC and C groups respectively, while the SR procedure provided average improvements of 8.9 (NC) and 14.8 (C) optotypes., Conclusions: The high level of agreement between QuickSee and subjective refraction together with the VA improvement achieved in both study groups using QuickSee refractions suggest that the device is a useful autorefraction tool for school-age children., Competing Interests: E. Lage, S.R. Dave and D. Lim are inventors in patents related to the device presented in this work and have ownership in PlenOptika Inc. A. Gil, C.S. Hernandez, M. Rubio and I. Casares work or have worked in research and development projects funded by PlenOptika Inc. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Purpose: To investigate a new algorithm to perform an automated non-cycloplegic refraction in adults., Methods: Fifty healthy subjects were measured twice (test-retest) with the new automated subjective refraction method and with the conventional clinician subjective refraction procedure. Objective refraction was also measured with the Grand Seiko WAM-5500 autorefractor. The new automated method was inspired on the root finding bisection algorithm and on the Euclidean distances in the power vector domain. The algorithm was implemented in a computer that was synchronized with a customized motorized phoropter. Repeatability was mainly assessed with the within-subject standard deviation (Sw) and accuracy was mainly assessed with the limits of agreement., Results: The within-subject standard deviations of the power vector components (M, J0, J45) obtained for the right eye are (±0.13, ±0.04, ±0.05)D and (±0.17, ±0.03, ±0.07)D, respectively, for the clinical and the automated subjective refraction methods. The limits of agreement (with the clinical method) for the automated and the objective methods are, respectively (±0.56, ±0.18, ±0.31)D and (±0.77, ±0.15, ±0.18)D. Similar results are obtained for the left eye., Conclusions: The proposed automated method is repeatable and more accurate than objective techniques in healthy adults. However, it is not accurate enough to replace the clinical subjective refraction yet and it should be tested in a wider population in terms of age, refraction and different ocular conditions. Despite these important limitations, this method has been shown to be a potentially valuable method to improve the access to primary eye care services in developing countries., (Copyright © 2018 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.)

Purpose: To investigate the influence of trabeculectomy and phacotrabeculectomy on the ocular surface., Design: Retrospective, case-control study., Methods: Eighty-one samples without dry eyes were recruited and divided into three groups, including phacoemulsification group (N = 30) as control group, trabeculectomy group (N = 27) and phacotrabeculectomy group (N = 24) as study groups. Ocular surface parameters, including noninvasive keratograph first (NifBUT) and average (NiaBUT) tear film breakup time, tear meniscus height (TMH) and corneal fluorescein stain (CFS), were estimated preoperatively, at 3 days, 1 month and 3 months postoperatively using oculus keratograph., Results: No significant difference was observed in ocular surface parameters at baseline among three groups (p > 0.05). The magnitude of NifBUT and NiaBUT was reduced at 3 days and 1 month postoperatively in phacotrabeculectomy group, but greater than that in the other two groups (All p < 0.001). In all the groups, both the NifBUT and NiaBUT tended to recover at 1 and 3 months postoperatively, whereas both of them did not recover to baseline at 3 months postoperatively in trabeculectomy (NifBUT, p = 0.001; NiaBUT, p < 0.001) and phacotrabeculectomy group (NifBUT, p < 0.001; NiaBUT, p = 0.020). TMH was raised at 3 days postoperatively and restored to the baseline level at 1 and 3 months postoperatively for three groups (p > 0.05). CFS was elevated at 3 days postoperatively and different in recovery at 1 and 3 months postoperatively for three groups., Conclusions: The influence of phacotrabeculectomy on ocular surface is worse than that of trabeculectomy for the short run and is not distinct different for a long time.

Background: Accommodation is often recorded at a low sampling rate using devices such as autorefractors that are designed to measure the static refractive error. It is therefore important to determine if that resolution is sufficient to accurately measure the dynamic properties of accommodation. The current study provides both theoretical and empirical evidence on the ideal sampling rate necessary to measure a dynamic response., Methods: Accommodative and disaccommodative step stimuli ranging from 1-3D (1D steps) were presented using a Badal optical system. Responses from 12 children (8-13 years) and 6 adults (20-35 years) were recorded using a dynamic photorefractor (DPR). Fast Fourier transformation was applied to the unsmoothed dynamic responses including position, velocity and acceleration. Also, velocity and acceleration main sequence (MS) characteristics were compared between three photorefractor conditions on 3 subjects., Results: The Nyquist sampling limit necessary to accurately estimate position, velocity and acceleration was at least 5, 10 and 70Hz, respectively. Peak velocity and acceleration were significantly underestimated at a lower rate (p<0.5). However, the slope of MS remained invariant with sampling rate (p>0.5)., Conclusion: Contrary to the previous findings, a dynamic accommodative response exhibited frequencies larger than 10Hz. Stimulus direction and amplitude had no influence on the frequencies present in the dynamic response. Peak velocity and acceleration can be significantly underestimated when sampled at a lower rate. Taken as a whole, low sampling rate instruments can accurately estimate static accommodation, however, caution needs to be exercised when using them for dynamic accommodation., (Copyright © 2018 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.)

Objective: Quantitative saccadic testing is a non-invasive method of evaluating the neural networks involved in the control of eye movements. The aim of this study is to provide a standardized and reproducible protocol for infrared oculography measurements of eye movements and analysis, which can be applied for various diseases in a multicenter setting., Methods: Development of a protocol to Demonstrate Eye Movement Networks with Saccades (DEMoNS) using infrared oculography. Automated analysis methods were used to calculate parameters describing the characteristics of the saccadic eye movements. The two measurements of the subjects were compared with descriptive and reproducibility statistics., Results: Infrared oculography measurements of all subjects were performed using the DEMoNS protocol and various saccadic parameters were calculated automatically from 28 subjects. Saccadic parameters such as: peak velocity, latency and saccade pair ratios showed excellent reproducibility (intra-class correlation coefficients > 0.9). Parameters describing performance of more complex tasks showed moderate to good reproducibility (intra-class correlation coefficients 0.63-0.78)., Conclusions: This study provides a standardized and transparent protocol for measuring and analyzing saccadic eye movements in a multicenter setting. The DEMoNS protocol details outcome measures for treatment trial which are of excellent reproducibility. The DEMoNS protocol can be applied to the study of saccadic eye movements in various neurodegenerative and motor diseases., Competing Interests: The authors have read the journal’s policy and the authors of this manuscript have the following competing interests. Petzold: member of the steering committee for the OCTiMS study (Novartis), no consulting fees. Performs OCT QC for the Passos study (Novartis), receives consulting fees. L.J. Balk: the VUmc MS Center received research support from TEVA. B.M.J Uitdehaag: has received consultancy fees from Biogen Idec, Genzyme, Merck Serono, Novartis, Roche and Teva.

Background: Belmonte Ocular Pain Meter (OPM) air jet aesthesiometry overcomes some of the limitations of the Cochet-Bonnet aesthesiometer. However, for true mechanical corneal sensitivity measurement, the airflow stimulus temperature of the aesthesiometer must equal ocular surface temperature (OST), to avoid additional response from temperature-sensitive nerves. The aim of this study was to determine: (A) the stimulus temperature inducing no or least change in OST; and (B) to evaluate if OST remains unchanged with different stimulus durations and airflow rates., Methods: A total of 14 subjects (mean age 25.14 ± 2.18 years; seven women) participated in this clinical cohort study: (A) OST was recorded using an infrared camera (FLIR A310) during the presentation of airflow stimuli, at five temperatures, ambient temperature (AT) +5°C, +10°C, +15°C, +20°C and +30°C, using the OPM aesthesiometer (duration three seconds; over a four millimetre distance; airflow rate 60 ml/min); and (B) OST measurements were repeated with two stimulus temperatures (AT +10°C and +15°C) while varying stimulus durations (three seconds and five seconds) and airflow rates (30, 60, 80 and 100 ml/min). Inclusion criteria were age <40 years, no contact lens wear, absence of ocular disease including dry eye, and no use of artificial tears. Repeated measures (analysis of variance) and appropriate post-hoc t-tests were applied., Results: (A) Stimulus temperatures of AT +10°C and +15°C induced the least changes in OST (-0.20 ± 0.13°C and 0.08 ± 0.05°C). (B) OST changes were statistically significant with both stimulus temperatures and increased with increasing airflow rates (p < 0.001), and were more marked with stimulus temperature AT +10°C., Conclusion: A true mechanical threshold for corneal sensitivity cannot be established with the air stimulus of the Belmonte OPM because its air jet stimulus with mechanical setting is likely to have a thermal component. Appropriate stimulus selection for an air jet aesthesiometer must incorporate stimulus temperature control that can vary with stimulus duration and airflow rate., (© 2017 Optometry Australia.)

Background: The aim was to analyse the effect of peripheral depth cues on accommodation in Badal optometers., Methods: Monocular refractions at 0.17 and 5.00 D of accommodative stimulus were measured with the PowerRef II autorefractor (Plusoptix Inc., Atlanta, Georgia, USA). Subjects looked (randomly) at four different scenes, one real scene comprising familiar objects at different depth planes (Real) and three virtual scenes comprising different two-dimensional pictures seen through a Badal lens. The first image consisted of a photograph of the real scene taken in conditions that closely mimic a healthy standard human eye performance (out-of-focus [OoF] blur); the second image was the same photograph rendered with a depth of focus to infinity (OoF sharpness); and finally the third image consisted of a fixation target and a even white surrounding (White). In all cases the field of view was 25.0° and the fixation target was a Maltese cross subtending to two degrees., Results: Twenty-eight right eyes from healthy young subjects were measured. The achieved statistical power was 0.9. At 5.00 D of accommodative stimulus, the repeated measures analysis of variance was statistically significant (p < 0.05) and the corresponding Bonferroni post hoc tests showed the following mean accommodative response differences and standard deviation (p-value) between the real and the virtual scenes: real-white =-0.66 ± 0.92 D (p < 0.01); real-OoF sharpness = -0.43 ± 0.88 D (p = 0.07); real-OoF blur =-0.25 ± 0.93 D (p = 0.89)., Conclusions: A stimulus poor in depth cues inaccurately stimulates accommodation in Badal optometers; however, accommodation can be significantly improved in the same Badal optometer, when displaying a realistic image rich in peripheral depth cues, even though these peripheral cues (also referred to as retinal blur cues) are shown in the same plane as the fixation target. These results have important implications in stereoscopic virtual reality systems that fail to represent appropriately retinal blur., (© 2017 Optometry Australia.)

Purpose: Previous studies of dark focus have found evidence of a propinquity response, in which subjects accommodate to the perceived distance of their surroundings despite being in absolute darkness. Their distance perception in a lighted room allows a spatial representation to persist within the darkened room. This study sought to establish the significance and magnitude of the propinquity response in a large sample of young adults, and to determine whether the propinquity response can be predicted by a subject's initial dark focus in an unknown dark room., Methods: Dark focus was measured with a dynamic infrared optometer (Plusoptix PowerRef 3) in 30 young adult subjects, 26 of whom were naive to the testing room and its dimensions. Dark focus was then measured at varying dioptric wall distances of 0.25-4D. The subject viewed the lighted room before each measurement. For each individual, the dark focus was plotted as a function of dioptric wall distance. The slope of this function was used as a measure of the propinquity response., Results: The mean initial dark focus value was 1.05D (SD 1.04D) for the 26 naive subjects. The mean slope of the plot of dark focus as a function of dioptric wall distance was small (+0.097), yet highly statistically significant (P = .0002). The propinquity response function showed no statistically significant quadratic or cubic trends, and so may be considered linear. No statistically significant correlation was found between naive dark focus and propinquity response (r = +0.246, P = .226)., Conclusions: Propinquity seems to be a small but statistically significant factor in dark focus measurements. Though it is unlikely to contaminate tonic accommodation measurements in large samples under normal laboratory conditions, a minority of individuals exhibit large propinquity responses equal to that of proximal accommodation in lighted conditions.

Purpose: To develop equations for accommodation stimulus and accommodation response with autorefractors when the accommodation stimulus is produced by combinations of object distances and lenses placed in front of eyes, and to give worked examples using these equations., Methods: Simple ray tracing was used to determine stimulus and response equations, taking into account the reference positions for targets, for refraction, and for autorefractor readings., Results: Several examples applying equations are provided. Features of these examples include evaluating approximate calculations that have been used previously, demonstrating which equations should be used in different circumstances, how to substitute numbers into equations, how to deal with discrepancies between subjective and objective refraction, and how to deal with astigmatism. Problems associated with measuring accommodation response by placing lenses in front of the eye are discussed., Conclusions: Accurate equations for accommodation stimulus and accommodation response for a range of accommodation stimuli in different setups have been developed., (© 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.)

Purpose: To study whether the accommodation response to Badal optometer is equivalent to the response for real space targets., Methods: Accommodative responses were measured for 28 young eyes with the WAM-5500 autorefractometer in eight configurations for 0.17 D, 2.0 D and 5.0 D accommodation stimuli. Parameters that might contribute to differences in response were systematically isolated: stimulation method (real space vs Badal targets), field of view, instrument's cover proximity, the looming effect, and the peripheral interposition of objects in depth., Results: Mean accommodative response differences between a natural view configuration and a configuration with a Badal Optometer were 0.50 ± 0.43 D and 0.58 ± 0.53 D for 2.0 D and 5.0 D stimulation, respectively (p < 0.001), with accommodation lags for the latter condition. Of the isolated parameters that might contribute to these differences, varying the interposition of objects in depth affected accommodation response more markedly., Conclusions: It is likely that Badal optometers affect accommodation through a combination of some or all of the studied parameters. We conclude that accommodation response to closed-view Badal optometers is not equivalent to real space target response., (© 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.)

Purpose: Stereoscopic displays challenge the neural cross-coupling between accommodation and vergence by inducing a constant accommodative demand and a varying vergence demand. Stereoscopic viewing calls for a decrease in the gain of vergence accommodation, which is the accommodation caused by vergence, quantified by using the convergence-accommodation to convergence (CA/C) ratio. However, its adaptability is still a subject of debate., Methods: Cross-coupling (CA/C and AC/A ratios) and tonic components of vergence and accommodation were assessed in 12 participants (27.5 ± 5 years, stereoacuity better than 60 arc seconds, 6/6 acuity with corrected refractive error) before and after a 20-minute exposure to stereoscopic viewing. During stimulation, vergence demand oscillated from 1 to 3 meter angles along a virtual sagittal line in sinusoidal movements, while accommodative demand was fixed at 1.5 diopters., Results: Results showed a decreased CA/C ratio (-10.36%, df = 10, t = 2.835, P = 0.018), with no change in the AC/A ratio (P = 0.090), tonic vergence (P = 0.708), and tonic accommodation (P = 0.493)., Conclusions: These findings demonstrated that the CA/C ratio can exhibit adaptive adjustments. The observed nature and amount of the oculomotor modification failed to compensate for the stereoscopic constraint.

Purpose: To evaluate the repeatability of power profiles measured on NIMO TR1504 (Lambda-X, Belgium) and investigate the effects of lens decentration on the power profiles for single vision (SV), bifocal (BF) and multifocal (MF) contact lenses., Methods: Accuracy of the sphere power was evaluated using single vision BK-7 calibration glass lenses of six minus and six plus powers. Three SV and four BF/MF contact lenses - three lenses each, were measured five times to calculate the coefficients of repeatability (COR) of the instrument. The COR was computed for each chord position, lens design, prescription power and operator. One lens from each type was measured with a deliberate decentration up to ±0.5mm in 0.1mm steps., Results: For all lenses, the COR varied across different regions of the half-chord position. In general, SV lenses showed lower COR compared to the BF/MF group lenses. There were no noticeable trends of COR between prescription powers for SV and BF/MF lenses. The shape of the power profiles was not affected when lenses were deliberately decentered for all SV and PureVision MF lenses. However, for Acuvue BF lenses, the peak to trough amplitude of the power profiles flattened up to 1.00D., Conclusion: The COR across the half-chord of the optic zone diameter was mostly within clinical relevance except for the central 0.5mm half-chord position. COR were dependent on the lens type, whereby BF/MF group produced higher COR than SV lenses. The effects of deliberate decentration on the shape of power profiles were pronounced for lenses where the profiles had sharp transitions of power., (Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.)

Objective: To compare the results of the three methods of Suresight handheld autorefractor, table-mounted autorefractor and retinoscopy in examination of juveniles patients with or without cycloplegia.
, Methods: Firstly, 156 eyes of 78 juveniles (5 to 17 years old) were examined by using WelchAllyn Suresight handheld autorefractor and NIDEK ARK-510A table-mounted autorefractor with or without cycloplegia; secondly, retinoscopy was performed with cycloplegia.
, Results: The spherical power measured by methods without cycloplegia were significantly greater than those measured with cycloplegia (P<0.05); without cycloplegia, there was no significant difference in spherical power, cylindrical power and cylindrical axis between Suresight handheld autorefractor and retinoscopy (P>0.05). These results were highly consistent, suggesting a tendency towards a short sight. However, the spherical power and cylindrical power measured by table-mounted autorefractor was significantly different (P<0.05); with cycloplegia, there was significant difference in spherical power between Suresight handheld autorefractor and retinoscopy (P<0.05).
, Conclusion: Cycloplegic retinoscopy is necessary for juvenile refraction examination. Under natural pupil situation, Suresight handheld autorefractor is better than table-mounted autorefractor, though both show a myopia tendency. Nevertheless, table-mounted autorefractor can be taken as a recommendation for the prescription of lens trial. As a strong reference for subjective optometry, retinoscopy should be the gold standard for measuring refractive errors.

The aim of this study is to assess the agreement of IOL power and ocular biometry measurements before and after pupillary dilatation by using the IOLMaster. This was the prospective nonrandomized cohort study. Measurements were taken with the IOLMaster (®) (Carl Zeiss Meditec AG, Jena, Germany) from healthy volunteers at the Department of Ophthalmology, King Chulalongkorn Memorial Hospital. Axial length (AL), keratometry both flattest and steepest (K1, K2), and anterior chamber depth (ACD) were measured before and after the dilatation of the pupil with 1 % tropicamide. The IOL power was calculated using the Sanders-Retzlaff-Kraff/Theoretical (SRK/T) formula. The mean difference of each parameter was assessed by Bland-Altman plot analysis. 384 eyes from 195 healthy volunteers were measured. The mean age of the patients was 52.39 ± 1.02 years (range 21-79). Pupillary dilatation had no significant effect on AL (p = 0.07), keratometry [steepest K (p = 0.95) and flattest K (p = 0.17)], and IOL power (Alcon SN60WF) (p = 0.40) obtained from the IOLMaster. However, ACD was significantly increased post-dilatation (p < 0.05). The Bland-Altman plot indicated good concordance in nearly all parameters except ACD. For ACD measurements, the 95 % limit of agreement between pre-dilatation and post-dilatation was -0.47 to 0.23 mm; therefore, 92.2 % of the measurement differences were with a LoA of -0.47 to 0.23 mm. There were no eyes that could not be measured by the IOLMaster. The dilatation of the pupil had no significant effect on AL, keratometry measurements, and SRK/T calculated IOL power. However, the ACD significantly increased post-dilatation.

Purpose: The Shin-Nippon SRW-5000 is an open view autorefractor that superseded the Canon R-1 autorefractor in the mid-1990 s and has been used widely in optometry and vision science laboratories. It has been used to measure refractive error, accommodation responses both statically and dynamically, off-axis refractive error, and adapted to measure pupil size. This paper presents an overview of the original 2001 clinical evaluation of the SRW-5000 in adults (Mallen et al., Ophthal Physiol Opt 2001; 21: 101) and provides an update on the use and modification of the instrument since the original publication., Recent Findings: The SRW-5000 instrument, and the family of devices which followed, have shown excellent validity, repeatability, and utility in clinical and research settings. The instruments have also shown great potential for increased research functionality following a number of modifications., Summary: The SRW-5000 and its derivatives have been, and continue to be, of significant importance in our drive to understand myopia progression, myopia control techniques, and oculomotor function in human vision., (© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists.)

The practice shows that in everyday life we encounter ever-growing demand for better visual acuity at all viewing distances. The presbyopic population needs correction to far, near and intermediate distance with different dioptric powers. PAL lenses seem to be a comfortable solution. The object of the present study is the analysis of the factors determining adaptation to progressive addition lenses (PAL) of the first-time users. Only novice test persons were chosen in order to avoid the bias of previously worn particular lens design. For optimal results with this type of lens, several individual parameters must be considered: correct refraction, precise ocular and facial measures, and proper mounting of lenses into the frame. Nevertheless, first time wearers encounter various difficulties in the process of adapting to this type of glasses and adaptation time differs greatly between individual users. The question that arises is how much the individual parameters really affect the ease of adaptation and comfort when wearing progressive glasses. To clarify this, in the present study, the individual PAL lenses--Rodenstock's Impression FreeSign (with inclusion of all parameters related to the user's eye and spectacle frame: prescription, pupillary distance, fitting height, back vertex distance, pantoscopic angle and curvature of the frame) were compared to power optimized PAL--Rodenstock's Multigressiv MyView (respecting only prescription power and pupillary distance). Adaptation process was monitored over a period of four weeks. The collected results represent scores of user's subjective impressions, where the users themselves rated their adaptation to new progressive glasses and the degree of subjective visual impression. The results show that adaptation time to fully individually fit PAL is easier and quickly. The information obtained from users is valuable in everyday optometry practice because along with the manufacturer's specifications, the user's experience can give us a better insight in design and characteristics of progressive lenses.

Objective: To observe the change of teenagers with short-time and long-time orthokeratology discontinuation, including diopters, corneal curvature, corneal topography, axial length, and central corneal thickness, and to investigate the refractive correction methods after long-time orthokeratology discontinuation., Methods: Retrospective study. A total of 141 patients (257 eyes) with a history of wearing and discontinuing wearing orthokeratology lenses in our center were collected. According to the spherical equivalent diopters, the patients were divided into two groups (< or = -4.00 D for group I and -4.00 D for group II). Each group was further divided into two sub-groups by the discontinuation time (1 to 3 months for sub-group A and more than 3 months for sub-group B). Four sub-groups were named as I A, II A, I B, and II B. Some optical examinations were performed for the patients before orthokeratology lens wearing and after orthokeratology discontinuation, such as refraction, corneal curvature, corneal topography, corneal endothelial cells, axial length, and central corneal thickness measurement. The refractive correction methods used by patients who had long-term orthokeratology discontinuation were recorded. The observed data were analyzed with paired t-test and one-way ANOVA by SPSS16., Results: The statistically significant changes (t = 3.222, 3.404, 3.141, 5.012, P < 0.05) of spherical diopter values were (-0.31 +/- 0.58) D, (-0.48 +/- 0.68) D, (-0.35 +/- 0.65) D, and (-0.57 +/- 0.58) D for groups IA, IB, IIA, and IIB, respectively. astigmatism of the four sub-groups had no significant change (P > 0.05) The average annual spherical growth was (-0.08 +/- 0.17) D, (-0.12 +/- 0.17) D, (-0.07 +/- 0.19) D, and (-0.15 +/- 0.16) D, respectively, for the four sub-groups, and there was no statistically significant difference among them (F = 1.180, P > 0.05). Compared to the state before wearing orthokeratology lenses, the corneal curvature measured by an autorefractor was statistically different for groups I A and I A, but not statistically different for groups I B and II B. For the long-time discontinuation groups, only the SRI of the corneal topography had a statistically significant decrease compared to the value before wearing orthokeratology lenses, and others had no significant change. The average annual increase of axial length was (0.22 +/- 0.16) mm and (0.16 +/- 0.10) mm for groups IA and IB, respectively, and the increase was statistically significant (P < 0.05), but there was no significant difference between the two sub-groups (F = 1.908, P > 0.05). The central corneal thickness had no significant change (t = 1.971, 2.017, P > 0.05). The rates of the refractive correction methods after long-time discontinuation were 36.7%, 22.4%, 22.4%, 12.4%, and 6.1% for spectacles, rigid gas permeable contact lenses, soft contact lenses, either spectacles or soft contact lenses, and refractive operations, respectively., Conclusion: The corneal morphology and central corneal thickness returned to the original after three months of discontinuation of orthokeratology. The myopia had no significant growth after discontinuation, and there was no significant difference between low to moderate and relatively high myopia.

Purpose: To determine the repeatability of ocular surface threshold measurements using the Cochet-Bonnet esthesiometer on the same day and 3 months apart., Methods: Two separate studies were conducted to determine the repeatability of ocular surface threshold measurements made on the same day (n = 20 subjects) and 3 months apart (n = 29 subjects). The Cochet-Bonnet esthesiometer was used to measure corneal and inferior conjunctival thresholds using the ascending method of limits. The pressure exerted by the Cochet-Bonnet esthesiometer was determined using an analytical balance, for both the 0.08- and 0.12-mm-diameter filaments. This calibration was then used to convert filament length measurements to pressure. Repeatability was determined using a Bland and Altman analysis., Results: The pressure exerted at each filament length differed between the two filament diameters. The measured pressure also differed from values provided by the manufacturer. Repeatability of threshold measurements at the central cornea was shown to be good, with better repeatability for same-day measurements (coefficient of repeatability [CoR] = ±0.23 g/mm²) than for those 3 months apart (CoR = ±0.52 g/mm²). Threshold measurements at the inferior conjunctiva, in contrast, were poorly repeatable (CoR = ±12.78 g/mm²)., Conclusions: Cochet-Bonnet esthesiometry is repeatable when performed on the central cornea on the same day and 3 months apart, but this instrument is not recommended for conjunctival threshold measurements.

Objective: To compare the accommodation response (AR) to monochromatic targets in subjects with different color vision statuses, and to investigate the role of color vision in the control of accommodation and emmetropization., Methods: It was a case-control study. Accommodation was measured with a dynamic infrared optometer while subjects [17 protans, 47 deutans, and 23 normals; mean age: (20.0 ± 4.4) years] viewed a (1) red on black or (2) green on black vertical square-wave gratings of iso-luminance (3 cycles/deg; 0.9 contrast) in a Badal optic system. The grating stepped 1.00 D towards the eye from an initial position of 0 D until 5.00 D., Results: With red-black targets, the AR in the protans (AR = 1.98 D) was worse than that in the normals (AR = 2.55 D) when the accommodation stimulus (AS) was 4.00 D (LSD, P = 0.031). The AR in the deutans were worse than that in the normals when the AS was 3.00, 4.00, and 5.00 D (3.00 D: 1.23 D vs. 1.69 D, P = 0.002; 4.00 D: 1.89 D vs. 2.55 D, P = 0.002; 5.00 D: 2.40 D vs. 3.17 D, P = 0.003). With green-black targets, the AR in the protans were worse than that in the normals when the AS was 3.00 and 4.00 D (3.00 D: 1.13 D vs. 1.61 D, P = 0.004; 4.00 D: 1.80 D vs. 2.34 D, P = 0.021). In the deutans, the AR was worse with stimuli of 3.00, 4.00, and 5.00 D (3.00 D: 1.21 D vs. 1.61 D, P = 0.003; 4.00 D: 1.65 D vs. 2.34 D, P < 0.001; 5.00 D: 2.36 D vs. 2.93 D, P = 0.007). No significant differences between the protans and deutans were found for all the stimulus conditions. In the protans, accommodation to red-black targets was better than that to green-black targets when the stimulus was 2.00, 3.00, and 5.00 D (2.00 D: t = -2.81, P = 0.013; 3.00 D: t = -4.55, P < 0.001; 5.00 D: t = -3.15, P = 0.006). In the deutans, accommodation to red-black targets was better than that to green-black targets when the stimulus was 4.00 D (t = -2.19, P = 0.034). In the normals, accommodation to red-black targets were better than that to green-black targets when the stimulus was 2.00, 4.00, and 5.00 D (2.00 D: t = -2.57, P = 0.017; 4.00 D, t = -2.67, P = 0.014; 5.00 D: t = -2.15, P = 0.043)., Conclusions: Individuals with a color vision deficiency tend to have a larger accommodative lag than normals. Red targets tend to induce better accommodation response than green ones. Color vision may play a role in the control of accommodation and emmetropization.

Purpose: Recently, a number of lens mappers have become available for measuring the detailed optical properties of progressive addition lenses (PALs). The goal of this study was to compare the results obtained from several different lens mappers for a range of different lenses., Methods: The optical power maps of six lenses-two single-vision lenses, a parallel-sided slide, a flat prism, and two progressive lenses-were measured using four different lens mappers: the Dual Lens Mapper, the Nimo TR4005, the Rotlex Class Plus, and the Visionix VM2500. The repeatability of the instruments was also evaluated., Results: All lens mappers gave very repeatable measurements; however, measurements among the lens mappers varied considerably. Differences appeared to be above the tolerance at the optical center for measurements of single-vision lenses, and these differences increase in the periphery up to 1.00 diopter. Similar differences were observed for the PALs, even increased by prism and base curve effect, with figures greater than 1 diopter in the periphery. The measurements made on the prism and lenses with different base curves suggest that base curve, thickness, and prismatic effect can all contribute to the differences among instruments., Conclusions: Measurements of a given lens taken with different lens mappers can vary substantially. Particular caution should be exercised when interpreting power maps for PALs taken with different instruments.

Purpose: To investigate current and anticipated use of equipment and information technology (IT) in community optometric practice in the UK, and to elicit optometrists' views on adoption of specialist equipment and IT., Methods: An anonymous online questionnaire was developed, covering use of standard and specialist diagnostic equipment, and IT. The survey was distributed to a random sample of 1300 UK College of Optometrists members., Results: Four hundred and thirty-two responses were received (response rate = 35%). Enhanced (locally commissioned) or additional/separately contracted services were provided by 73% of respondents. Services included glaucoma repeat measures (30% of respondents), glaucoma referral refinement (22%), fast-track referral for wet age-related macular degeneration (48%), and direct cataract referral (40%). Most respondents (88%) reported using non-contact/pneumo tonometry for intra-ocular pressure measurement, with 81% using Goldmann or Perkins tonometry. The most widely used item of specialist equipment was the fundus camera (74% of respondents). Optical Coherence Tomography (OCT) was used by 15% of respondents, up from 2% in 2007. Notably, 43% of those anticipating purchasing specialist equipment in the next 12 months planned to buy an OCT. 'Paperless' records were used by 39% of respondents, and almost 80% of practices used an electronic patient record/practice management system. Variations in responses between parts of the UK reflect differences in the provision of the General Ophthalmic Services contract or community enhanced services. There was general agreement that specialised equipment enhances clinical care, permits increased involvement in enhanced services, promotes the practice and can be used as a defence in clinico-legal cases, but initial costs and ongoing maintenance can be a financial burden. Respondents generally agreed that IT facilitates administrative flow and secure exchange of health information, and promotes a state-of-the-art practice image. However, use of IT may not save examination time; its dynamic nature necessitates frequent updates and technical support; the need for adequate training is an issue; and security of data is also a concern., Conclusion: UK optometrists increasingly employ modern equipment and IT services to enhance patient care and for practice management. While the clinical benefits of specialist equipment and IT are appreciated, questions remain as to whether the investment is cost-effective, and how specialist equipment and IT may be used to best advantage in community optometric practice., (© 2014 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

Purpose: Guidelines for the screening, prognosis, diagnosis, management and prevention of glaucoma were released by the Australian National Health and Medical Research Council in 2010. Comparable guidance has been made available by respective bodies in the USA and UK at a similar time. Key to successful translation of guidelines into clinical practice includes clinicians having the necessary skills to perform required tests. Optometrists in Australia and New Zealand were invited to participate in an online survey exploring these aspects. The results provide insights for improving glaucoma diagnosis and management by optometric primary eye care practitioners., Methods: An online questionnaire was developed to investigate glaucoma assessment of optometrists as a function of demographic details, educational background and experience. Key points to ascertain compliance with current guidelines were the availability of equipment, procedural confidence in techniques, and preferences in visual field tests. Chi square statistics was employed to support similarity to national averages and highlight differences between the two countries. Multivariate linear regression analysis identified variables significantly associated with individual tests being available to optometrists and their confidence in applying them., Results: Thirteen per cent of all Australian and 36% of the New Zealand optometrists responded to the survey in 2013, which reflected the demographics/geography of the practising populations. Techniques considered essential or preferred for glaucoma assessment were widely available in both countries with the exception of gonioscopy and pachymetry. After correcting for availability, regression models highlighted therapeutic endorsement and knowledge of glaucoma guidelines as the main variables to maintain high diagnostic confidence. Correlations to number of years in optometric practice mirrored a changed emphasis in teaching and technology over the past 10-15 years., Conclusions: Australian and New Zealand optometrists were well equipped to perform glaucoma assessments with the possible exception of gonioscopy. Advanced imaging modalities were not yet fully integrated into optometric practice, although optical coherence tomography has shown use by 23-32% of optometrists. A marked increase in use, availability and procedural confidence of gonioscopy and other techniques with therapeutically endorsed optometrists demonstrates the advantage and importance of additional training., (© 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.)

Background: The accuracy and precision of any instrument should not be taken for granted. While there is an international standard for checking focimeters, there is no report of any study on their performance., Method: A sample set of 51 focimeters (11 brands), were used to measure the spherical power of a set of lenses and the prismatic power of two lenses complying with ISO 9342-1:2005 and other calibrated prismatic lenses and the spherical power of some grey filters., Results: The mean measured spherical power corresponded very closely with the calibrated values; however, the spread of results was substantial and 10 focimeters did not comply with ISO 8598:1996. The measurement of prism was much more accurate and precise and all the focimeters complied easily. With the grey filters, about one-third of the focimeters either showed erratic reading or an error with the equivalent of category 4 sunglasses. On the other hand, nine focimeters had stable and accurate reading on a filter with a luminous transmittance of 0.5 per cent., Conclusions: These results confirm that, in common with all other measurement instruments, there is a need to ensure that a focimeter is reading accurately and precisely over the range of refractive powers and luminous transmittances. The accurate and precise performance of an automated focimeter over its working life cannot be assumed. Checking before purchase with a set of calibrated lenses and some dark sunglass tints will indicate the suitability of a focimeter. Routine checking with the calibrated lenses will inform the users if a focimeter continues to indicate accurately., (© 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.)

Purpose: Stereoacuity tests used in clinical practice should be repeatable and reproducible. However, it has been observed in a clinical setting that new editions of the TNO stereotest appear to give different values from those obtained using previous versions. The purpose of the present research was to investigate this observation., Methods: One hundred and twenty-one Dutch subjects, 88 (73%) females and 33 (27%) males, with an average age of 34.0 years (range 18-55) had their stereoacuity measured using two different versions of the TNO stereoacuity test (TNO 13 and TNO 15). The TNO was tested in a counterbalanced order so that consecutive subjects started with alternate editions to avoid bias., Results: There was a significant difference (p < 0.001) between the median value for stereoacuity measured with TNO 13 (30 s of arc) and TNO 15 (60 s of arc). The bias between the two test versions was -0.23 Log arcseconds (95% limits of the differences: 0.15 to -0.60 Log arcseconds)., Conclusion: This study reveals that results obtained with two different editions of a commonplace stereoacuity test are not comparable. New versions come on the market at regular intervals and the assumption that they will give the same results as previous versions may not be valid. Besides the statistically significant difference between the TNO 13 and TNO 15, the Bland-Altman plot also showed a considerable bias and the 95% limits of the differences between the TNO 13 and TNO 15 are more than two steps on the Log arcsecond scale. This difference between two editions of the TNO stereotests is not clinically acceptable and therefore it is inappropriate to use the two versions of the test interchangeably. It is important in both research and clinical records to specify the edition of the TNO test used., (© 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.)

Purpose: The aims of this study were (i) to develop a new portable slit-lamp mounted digital meniscometer (PDM) and (ii) to test its accuracy and repeatability compared to the existing Yokoi et al. videomeniscometer (VM)., Methods: We developed a novel application for an iPod or iPhone, which created an illuminated target of parallel black and white bands. This was used as a portable device with which to perform reflective meniscometry. The medians of three consecutive measurements on five glass capillaries (internal radii, 0.100 to 0.505 mm) were compared between VM and PDM at two different sessions. Also, the central lower tear meniscus radius (TMR) in 20 normal subjects (10 males and 10 females; mean [SD] age, 32.3 [9.3] years) was measured using both techniques. Correlations between the instruments were analyzed using the Pearson coefficient. Differences between sessions and instruments were analyzed using Bland-Altman plots, coefficient of repeatability, and paired t-tests., Results: The PDM and VM were accurate in vitro (95% confidence interval [CI] of difference: PDM -0.0134 to +0.0074 mm, p = 0.468; VM -0.0282 to + 0.0226 mm; p = 0.775) and reproducible between sessions (95% coefficient of repeatability, 0.019 and 0.018, respectively). The mean difference between the PDM and VM in vitro was 0.0002 mm (95% CI, -0.0252 to + 0.0256; p = 0.984). In human subjects, mean (SD) TMR measured with the PDM (0.34 [0.10] mm) and VM (0.36 [0.11] mm) was significantly correlated (r = 0.940; p < 0.001), and there was no statistically significant difference between the measured TMR of the instruments (p = 0.124)., Conclusions: This new slit-lamp mounted digital meniscometer produces accurate and reliable measurements and provides similar values for tear meniscus radius, in human studies, to the existing VM. The instrument is suitable for use in both research and clinical practice.

Purpose: To assess the normal values and the repeatability of the Galilei Dual Scheimpflug Analyzer (GDSA), the biometer IOL Master, and the autokerato/refractometer WAM 5500 in anterior segment examinations., Methods: Eighty-eight eyes from 88 healthy volunteers were prospectively and consecutively recruited. The repeatability was assessed, calculating the intraclass correlation coefficient (ICC)., Results: The correlations among the repeated measurements showed nearly perfect reliability (ICC > 0.81) for all of the parameters, except corneal astigmatism Galilei (0.79) and WAM (0.68). There were statistically significant differences (P < 0.001) between the values of the flat simulated keratometry (SimK) and the steep SimK measured by GDSA and the other methods; however, there were no statistically significant differences for the values obtained with the IOL Master and WAM 5500 (P = 0.302 and P = 0.172, resp.) or between the values of the ACD (P < 0.001) and WTW (P = 0.007) measured by the IOL Master and GDSA., Conclusions: The anterior segment measurements from the IOL Master and WAM 5500 were highly repeatable, comparable, and well correlated. In healthy young persons, the evaluated parameters had very good repeatability, although significant differences were found between the GDSA and IOL Master and between the GDSA and WAM 5500.

Background: The aim was to investigate the effect on the measured amplitude of accommodation and repeatability of using the minus lens technique with the target at distance or near., Methods: Forty-three students (average age: 21.17 ± 1.50 years, 35 female) had their amplitude of accommodation measured with minus lenses on top of their distance correction in a trial frame with the target at far (6.0 m) or near (0.4 m). The minus lens power was gradually added with steps of 0.25 D. Measurements were taken on two occasions at each distance, which were separated by a time interval of at least 24 hours., Results: The measured amplitude at six metres was significantly lower than that with the target at 40 cm, by 1.56 ± 1.17 D (p < 0.001) and this varied between individuals (r = 0.716, intraclass correlation coefficient = 0.439). With either target distance, repeated measurement was highly correlated (r > 0.9) but the agreement was better at 6.0 m (±0.74 D) than at 40 cm (± 0.92 D)., Conclusion: The measurements of the amplitude of accommodation with the minus lens technique using targets at far or near are not comparable and the difference between the target distances may provide clinically relevant information., (© 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.)

Lensometers and keratometers yield powers along perpendicular meridians even if the principal meridians of the lens and the cornea are oblique. From each such instrument, multiple raw data represented on optical crosses require conversion to determine elementary statistics. Calculations for research decisions need to be authentic. Principles common to meridians generalize formulaic methods for oblique meridians. Like a lens or a cornea, matrix latent quantities are represented on a matrix cross. Our problem is to determine the matrix whose cross represents quantities on the optical cross. All measurements on an optical cross that include corneal and lens powers and oblique meridians can be considered. Once determined, a portfolio of matrix calculations applies and is justified for ophthalmic calculation. Matrices can be unique and, like a cornea before it is measured, contain latent observations. Asymmetric power component matrices quantify a deviation of a corneal surface from smoothness and toricity. Entries may identify those measurements causing irregular astigmatism that may stem from surgical or other external intervention. Irregular astigmatism is detected primarily from significant measurements in the paraxial range. Measurements are assimilated with matrix factors in a holistic way in order to support choices with calculations and statistics.

Purpose: To evaluate the effect of pupil dilation on the biometric parameters of the Lenstar LS 900 (Haag Streit AG, Koeniz, Switzerland)., Methods: In this cross-sectional study of 33 eyes with cataracts, axial length (AL), anterior chamber depth, intraocular lens (IOL) power, keratometry, and pupil diameter measurements were performed using Lenstar biometry before and after pupil dilatation. Intraobserver repeatability was assessed by taking 2 consecutive recordings of biometric parameters using Lenstar biometry in the undilated pupils of 30 eyes with cataracts., Results: The mean difference in AL measurements from intraobserver readings was -0.001 ± 0.01 mm. The study group showed a statistically significant change in the first keratometry reading and anterior chamber depth values (P < 0.05); however, the mean difference in AL and IOL power was statistically insignificant between the undilated and dilated pupil Lenstar biometry readings. Three cases in the study group (9.1%) and 1 case in the control group (3.3%) demonstrated changes in IOL power >0.50 diopter., Conclusions: Dilated and undilated pupil size did not affect the measurement of IOL using the Lenstar biometry.

Purpose: To objectively determine the effects of pupil size on optical quality parameters in astigmatic eyes using a double-pass instrument., Methods: We examined twenty-two eyes of 22 healthy volunteers (mean age  ±  standard deviation, 27.1 ± 2.8 years) who had no ophthalmic diseases other than refractive errors (manifest cylinder ≤ 0.25 diopters (D)). After we fully corrected cycloplegic refraction, we created with-the-rule astigmatism of 1, 2, and 3 diopters in these eyes and then quantitatively assessed the modulation transfer function (MTF) cutoff frequency and the Strehl2D ratio with 2-, 4-, and 6-mm pupil sizes using the Optical Quality Analysis System., Results: The MTF cutoff frequency and the Strehl2D ratio decreased significantly as the amount of astigmatism increased at each pupil size (P < 0.001 for 2, 4, and 6 mm, analysis of variance). They also decreased significantly with an increase in pupil size at each diopter of astigmatism (P < 0.001 for 0, 1, 2, and 3 D). Multiple comparisons demonstrated a significant difference between measurements made for a 2-mm pupil and for a 6-mm pupil at each diopter of astigmatism (P < 0.001 for 0, 1, 2, and 3 D, Dunnett test) and those made for a 4-mm pupil and for a 6-mm pupil at each diopter of astigmatism (P < 0.001 for 0 D, P < 0.05 1, 2, and 3 D)., Conclusions: Eyes with larger pupils had lower optical quality even when they were astigmatic. It may be necessary to correct the preexisting astigmatism to acquire excellent visual performance, especially in astigmatic eyes with larger pupils.

Aim: To determine the validity and reliability of the measurement of corneal curvature and non-invasive tear break-up time (NITBUT) measures using the Oculus Keratograph., Method: One hundred eyes of 100 patients had their corneal curvature assessed with the Keratograph and the Nidek ARKT TonorefII. NITBUT was then measured objectively with the Keratograph with Tear Film Scan software and subjectively with the Keeler Tearscope. The Keratograph measurements of corneal curvature and NITBUT were repeated to test reliability. The ocular sensitivity disease index questionnaire was completed to quantify ocular comfort., Results: The Keratograph consistently measured significantly flatter corneal curvatures than the ARKT (MSE difference: +1.83 ± 0.44D), but was repeatable (p > 0.05). Keratograph NITBUT measurements were significantly lower than observation using the Tearscope (by 12.35 ± 7.45 s; p < 0.001) and decreased on subsequent measurement (by -1.64 ± 6.03 s; p < 0.01). The Keratograph measures the first time the tears break up anywhere on the cornea with 63% of subjects having NITBUTs <5 s and a further 22% having readings between 5 and 10 s. The Tearscope results were found to correlate better with the patients symptoms (r = -0.32) compared to the Keratograph (r = -0.19)., Conclusions: The Keratograph requires a calibration off-set to be comparable to other keratometry devices. Its current software detects very early tear film changes, recording significantly lower NITBUT values than conventional subjective assessment. Adjustments to instrumentation software have the potential to enhance the value of Keratograph objective measures in clinical practice., (Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Background: The visual system is necessary for reading. Understanding the mechanics of eye movements during reading can give insight into the reading process. The ReadAlyzer is an electronic recording system that measures eye movements while reading. Long passages on the ReadAlyzer of 800 words have recently been introduced as a tool to assess the efficiency of reading eye movements. Previously, short passages of 100 words have been used exclusively. This project was designed to determine if passage length influences the quality of reading eye movements;, Methods: Optometry students (N = 40) at Southern College of Optometry were separated into 2 equal groups (symptomatic vs. asymptomatic) based on the College of Optometrists in Vision Development Quality of Life questionnaire score. Each subject then performed two reading passage recordings with the ReadAlyzer: one short, one long. The order of the passages was alternated to reduce fatigue effects. Data were collected based on the ratio of fixations-to-regressions;, Results: A multivariate analysis of variance indicated that the difference between short and long paragraphs for the symptomatic and asymptomatic groups combined was significant (P = 0.001) but was not significant for the symptomatic group vs. the asymptomatic group ( P = 0. 651) . Post-hoc comparisons using estimated marginal means indicated for asymptomatic, short vs. long, P = .036 and for symptomatic, short vs. long, P = 0.008. Additionally, for short length, symptomatic vs. asymptomatic, P = 0.242 and for long length, symptomatic vs. asymptomatic, P = 0.176;, Conclusion: This information indicates that both symptomatic and asymptomatic patients will have more difficulty on longer reading passages. This finding calls into question the use of shorter length reading tests to determine a diagnosis of ocular motor dysfunction and other visual efficiency problems., (American Optometric Association.)

Background: The aim was to evaluate anterior segment parameters in patients with pseudoexfoliation syndrome (PXS) or pseudoexfoliative glaucoma (PXG) with the Pentacam-Scheimpflug imaging system., Methods: Eighty eyes of 53 patients with PXS (Group 1), 80 eyes of 57 patients with PXG (Group 2) and 80 eyes of 45 control cases (Group 3) were included in the study. Anterior chamber depth, volume (ACV), angle (ACA) width, central corneal thickness (CCT), central 3.0, 5.0 and 7.0 mm corneal volumes and pupil diameters were compared between groups., Results: Although anterior chamber depths in the PXG group were significantly lower than the control group (p < 0.05), there was no statistically significant difference between the PXS group and the control group in means of anterior chamber depth values (p > 0.05). There were no statistically significant differences among PXS, PXG and the control group in mean values of ACV, ACA width, CCT, pupil diameters and central 3.0, 5.0 and 7.0 mm corneal volume (p > 0.05). conclusions: The anterior chamber depths of PXG patients were lower than those of healthy individuals. Although the difference in anterior chamber depth between PXG patients and normal patients was statistically significant, this finding is unlikely to be of clinical significance. The anterior chamber depths of PXS patients were similar to those of healthy individuals. There were no significant differences in the means of ACV, ACA width, CCT, pupil diameter and corneal volume values on central 3.0, 5.0 and 7.0 mm among patients with PXS, PXG and healthy individuals., (© 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.)

Background: Visual acuity is an essential estimate to assess ability of the visual system and is used as an indicator of ocular health status., Aim: The aim of this study is to investigate the consistency of acuity estimates from three different clinical visual acuity charts under two levels of ambient room illumination., Materials and Methods: This study involved thirty Malay university students aged between 19 and 23 years old (7 males, 23 females), with their spherical refractive error ranging between plano and -7.75D, astigmatism ranging from plano to -1.75D, anisometropia less than 1.00D and with no history of ocular injury or pathology. Right eye visual acuity (recorded in logMAR unit) was measured with Snellen letter chart (Snellen), wall mounted letter chart (WM) and projected letter chart (PC) under two ambient room illuminations, room light on and room light off., Results: Visual acuity estimates showed no statistically significant difference when measured with the room light on and with the room light off (F1,372 = 0.26, P = 0.61). Post-hoc analysis with Tukey showed that visual acuity estimates were significantly different between the Snellen and PC (P = 0.009) and between Snellen and WM (P = 0.002)., Conclusions: Different levels of ambient room illumination had no significant effect on visual acuity estimates. However, the discrepancies in estimates of visual acuity noted in this study were purely due to the type of letter chart used.

Background: Single image random dot stereograms (SIRDS) have been used to study diverse visual parameters and skills. The aim of the present study was to identify the main optometric factors involved in the perception of SIRDS and to obtain a discriminant model to categorise our participants in terms of their skill in perceiving SIRDS., Methods: Response time was determined to assess the ability of 69 participants to perceive the hidden three-dimensional shape in an auto-stereogram presented under controlled conditions, whereupon three skill level groups were defined. The same participants were administered a battery of optometric tests to evaluate various aspects of accommodation and convergence, as well as stereopsis and phoria. Linear discriminant analysis, which served to examine the relationship between response times and the evaluated visual parameters and skills, provided a set of discriminant functions (or model), thus allowing for the categorisation of participants according to their skill to perceive SIRDS., Results: Two discriminant functions were obtained, which allowed for an overall predictive accuracy of 66.67 per cent (p = 0.024), with a higher predictive accuracy for groups 1 (minimum time less than 10 seconds, 78.26 per cent) and 2 (minimum time greater than 10 seconds, 75.86 per cent) than for group 3 (SIRDS not perceived, 35.29 per cent). Stereoacuity, negative relative convergence, phoria at near and, to a lesser extent, the accommodative convergence and accommodation ratio were found to be the most relevant discriminant variables, although between-group statistically significant differences were only disclosed for stereoacuity (p = 0.001) and negative relative convergence (p = 0.003)., Conclusion: The ability to perceive SIRDS was related to many visual parameters and skills, including, but not limited to, stereoacuity and negative relative convergence. It is uncertain whether SIRDS might be considered a useful tool in clinical practice., (© 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.)

Purpose: To quantify the change in ocular aberrations due to intraocular lens (IOL) implantation position errors for pseudo-phakic eyes with different refractive errors., Methods: The theoretical part of this work was based on ray-tracing in emmetropic and myopic eye models. The possible misalignments i.e. the decentration, tilt and axial translation, of the IOLs were statistically combined together and analysed using Monte-Carlo simulations. Spherical IOLs with a 3 and 5 mm pupil and an aspheric IOL with a 5 mm pupil were analysed as a function of refractive error. In the experimental part of the work, we built an IOL optical test bench including a model eye. The white light discrete point spread functions of misaligned IOLs were recorded by a CCD and we compared the change of the spread function as a result of misalignments for two spherical IOLs with different optical powers., Results: The Monte-Carlo simulations showed that the average root-mean-square spot size at the retinal plane decreased with increasing myopic refractive error, i.e. lower power IOL. The experiments showed that a lower optical power spherical IOL had a less distributed point spread function than a higher optical power IOL, which supported the results of the simulation., Conclusion: Regarding IOLs designed for myopic patients, low power IOLs (for high myopes) were shown to be less sensitive to the misalignment than high power ones. Aspheric IOLs were more sensitive to position errors than spherical IOLs under the same conditions., (Ophthalmic & Physiological Optics © 2011 The College of Optometrists.)

Background: The Mallett Unit is a clinical test designed to detect the fixation disparity that is most likely to occur in the presence of a decompensated heterophoria. It measures the associated phoria, which is the "aligning prism" needed to nullify the subjective disparity. The technique has gained widespread acceptance within professions such as optometry, for investigating suspected cases of decompensating heterophoria; it is, however, rarely used by orthoptists and ophthalmologists. The aim of this study was to investigate whether fusional vergence reserves, measured routinely by both orthoptists and ophthalmologists to detect heterophoria decompensation, were correlated with aligning prism (associated phoria) in a normal clinical population., Methodology/principal Findings: Aligning prism (using the Mallett Unit) and fusional vergence reserves (using a prism bar) were measured in 500 participants (mean 41.63 years; standard deviation 11.86 years) at 40 cm and 6 m. At 40 cm a strong correlation (p<0.001) between base in aligning prism (Exo FD) and positive fusional reserves was found. Of the participants with zero aligning prism 30% had reduced fusional reserves. At 6 m a weak correlation between base out aligning prism (Eso FD) and negative fusional reserves was found to break (p = 0.01) and to recovery (p = 0.048). Of the participants with zero aligning prism 12% reported reduced fusional reserves., Conclusions/significance: For near vision testing, the strong inverse correlation between base in aligning prism (Exo FD) and fusional vergence reserves supports the notion that both measures are indicators of decompensation of heterophoria. For distance vision testing and for those patients reporting zero aligning prism further research is required to determine why the relationship appears to be weak/non-existent?

The aim of the article is to present and summarize the current knowledge of wavefront aberrations, methods and applications of aberrations measurement. Ideal optical system is stygmatic, which means that object point is imaged by optical system into the image point without deformation. Optical system of the eye is not ideal, it has aberrations. Aberrations limitate and determine visual quality. Wavefront aberrometers measure manochromatic low and high order aberrations. Wavefront aberrations are described by Zernike polinomials. More important wavefront sensor types are described in the article. In their practice authors use KR1W Topcon aberrometer. Authors also present difficulties in taking aberrometric measurements. In recent years quality of vision becomes the point of interest for vision scientists. Correction of high order aberrations is the future of optics.

Caecanometry was a short-lived visual fields examination technique first described by Ingwold Davidsen, O.D. in 1949. The technique was based upon the unusual premise that the blind spot constricted in size when certain types of infection were present above the level of the shoulder blades. The Davidsen-Wottring caecanometer was patented as a device for plotting blind spot size and shape. Caecanometry was practiced mainly in the southern U.S., dying out in the middle 1970s.

Purpose: Interest in peripheral refraction measurement has grown in recent years in response to the insight it may provide into myopia development. In light of the likely increase in the clinical use of open-field autorefractors for peripheral refraction measurements, the question of instrument alignment and its impact on the accuracy of refraction measurements is raised. The aim of this study was to investigate the accuracy and precision when an open-field device was moved away from alignment with the corneal reflex towards the pupil margins, and to determine the optimum alignment position for peripheral refraction measurements., Methods: Autorefractions were performed on the right eyes of 10 healthy participants using the Shin-Nippon NVision-K 5001 autorefractor. At least five measurements were taken with the subject fixating a distance target in the primary position of gaze, and then four peripheral fixation targets located along the horizontal meridian (10° and 20° eccentricities in the nasal and temporal retina). Measurements were taken at seven alignment positions across the pupil for each fixation angle. Refraction was recorded as the spherical and cylindrical power., Results: The central objective refraction achieved under cycloplegia based on the autorefraction result for the whole sample, ranged between -5.62 D and +1.85 D for the value of sphere, with a maximum astigmatism of -1.00 D. Acceptable alignment position range varied with fixation angle but was -1.0 to +1.0 mm in width across the pupil. Peripheral refraction measurements centred on the entrance pupil were as reliable as those centred on the corneal reflex., Conclusions: Our data suggest that for peripheral refraction measurements, there is a range of acceptable positions and operators can be confident of the validity of results obtained if aligned half way between the pupil centre and corneal reflex. The alignment becomes more critical at greater eccentricities., (Ophthalmic & Physiological Optics © 2011 The College of Optometrists.)

To assess the inter-session repeatability of the Goldmann-Weekers adaptometer for the measurement of cone dark adaptation in a population of healthy subjects. Data were obtained from 31 healthy adults (mean age 21.5 ± 2.5) on 2 days. At each visit, pupils were dilated and a 96% bleach of cone photopigment was administered to the test eye before threshold was monitored continuously for 5 min in the dark using the Goldmann-Weekers adaptometer. A single exponential function was fitted to the threshold recovery data on a least squares basis. The coefficient of repeatability (CoR) was calculated to assess the repeatability of the time constant of recovery (τ), initial threshold and final threshold. Cone dark adaptation functions were successfully recorded from all subjects on both visits. The CoR was 79.48 s for τ, 0.71 log cdm(-2) for the initial threshold, and 0.58 log cdm(-2) for the final threshold. Paired samples t-tests showed that there were no significant differences between visits for any of the parameters assesed. Although the Goldmann-Weekers adaptometer was capable of monitoring the rapid changes in threshold that occur during cone dark adaptation, the CoR for τ was relatively large compared to the mean recovery time constants (126.48 ± 40.33 and 119.94 ± 33.25 s at the first and second visits, respectively). This indicates that the Goldmann-Weekers adaptometer is unlikely to be a useful instrument to chart changes in an individual's vision over time.

Purpose: To validate a novel ultrasonic sensor for logging reading distances. In addition, this device was used to compare the habitual reading distances between low and high myopes., Methods: First, the stability and sensitivity of the ultrasonic device were determined by repeated measures using artificial targets. Then, thirty Hong Kong Chinese (20-30 years) were recruited, of whom fifteen were considered to be high myopes (mean ± S.D. = -8.7 ± 0.5 D) and 15 to be low to non-myopes (mean ± S.D. = -2.0 ± 0.2 D). Each subject read a newspaper with their habitual visual aid continuously for 10 min in two sessions at their preferred working distance(s). The reading distances were recorded continuously using a novel nearwork analyzer. The modal working distance was considered as the 'habitual' reading distance. In addition, habitual reading distance was reported orally by each subject., Results: The nearwork analyzer gave accurate and repeatable measurements over a range of distances and angles. Using this instrument, high myopes were found to have a significantly shorter reading distance than low myopes or non-myopes (mean ± S.D. = 35.9 ± 9.8 cm vs 50.9 ± 24.8 cm; two-sample t-test, p = 0.04, df = 18). The reading distances reported orally by the subjects were not correlated with those recorded by the nearwork analyzer., Conclusions: The nearwork analyzer was found to be an effective tool for measuring nearwork reading distance in a small group of emmetropic and myopic adults over a 10 min interval. Differences between the reading distance between high myopes and low/non-myopes was detected by the device. Further study is needed to determine if a closer working distance is a cause or effect of myopia development., (© 2011 The College of Optometrists.)

The theory of wavefront analysis of a noncircular wavefront is given and applied for a systematic comparison of the use of annular and Zernike circle polynomials for the analysis of an annular wavefront. It is shown that, unlike the annular coefficients, the circle coefficients generally change as the number of polynomials used in the expansion changes. Although the wavefront fit with a certain number of circle polynomials is identically the same as that with the corresponding annular polynomials, the piston circle coefficient does not represent the mean value of the aberration function, and the sum of the squares of the other coefficients does not yield its variance. The interferometer setting errors of tip, tilt, and defocus from a four-circle-polynomial expansion are the same as those from the annular-polynomial expansion. However, if these errors are obtained from, say, an 11-circle-polynomial expansion, and are removed from the aberration function, wrong polishing will result by zeroing out the residual aberration function. If the common practice of defining the center of an interferogram and drawing a circle around it is followed, then the circle coefficients of a noncircular interferogram do not yield a correct representation of the aberration function. Moreover, in this case, some of the higher-order coefficients of aberrations that are nonexistent in the aberration function are also nonzero. Finally, the circle coefficients, however obtained, do not represent coefficients of the balanced aberrations for an annular pupil. The various results are illustrated analytically and numerically by considering an annular Seidel aberration function.