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Purpose Methods Results Conclusions To introduce a novel methodology for subjective refraction based on power vectors with a conventional phoropter.A conventional phoropter was used to measure power vector components of refraction (M, J0 and J45) directly by using the sphere power (for M measurement) and the cylinder power combined with the Jackson cross‐cylinders (for J0 and J45 measurements). Conventional subjective refraction was also performed, and this result was mathematically transformed into power vector notation for comparison purposes. Visual acuities with the conventional prescription and the quasi‐vector‐based prescription were compared.Refractive error from 40 healthy participants was measured by conventional and quasi‐vector‐based subjective refraction. No differences were found between methods for any of the power vector components of refraction (p > 0.21 in all cases). The visual acuity achieved with the prescriptions yielded similar values (p = 0.85).Subjective refraction can be measured directly in power vector notation using a conventional phoropter without any additional adaptation and computation. [ABSTRACT FROM AUTHOR]

Background: During the subjective measurement of astigmatic refractive error, the recommended targets for the Jackson Cross Cylinder (JCC) test are interchanged often depending on availability, convenience, and preference of clinicians. However, reliability of the JCC test becomes uncertain. Methods: A cross-sectional, quantitative research design was used to compare measurements of cylinder power and axis with the JCC test but with three different targets (a cluster of random dots, the letter O, and the letter H). Randomisation of order of targets was applied to prevent biases. Data was captured using SPSS (version 27) and analysed using dependent-samples Wilcoxon signed-rank tests and Bland-Altman plots at a 95% confidence level. Results: A total of 61 left eyes of 72 subjects, with cylinders of at least -0.50 D after subjective refraction, were analysed. The study found no statistically or clinically significant difference in the subjective measurement of cylindrical power and axis with the JCC test irrespective of the target used. Random dots and the letter H were the most and the least preferred targets, respectively. Conclusion: The clinical implication of this study is that random dots, circular letters, and non-circular letters can be used interchangeably to measure the cylinder power and axis of mild astigmatism. [ABSTRACT FROM AUTHOR]

AIM: To evaluate the refractive status through computer refractometer and OPD-Scan III auto refractometer in cataract patients after extended depth of focus(EDOF)intraocular lens implantation.METHODS: Retrospective observational study. A total of 61 cases(76 eyes)that received phacomulsification and implanted with TECNIS® Symfony ZXR00 intraocular lens in Shanghai Eye Diseases Prevention & Treatment Center from May 2022 to May 2023 were collected. Measurements from the computer refractometer, OPD-Scan III auto refractometer, and subjective refraction, were taken from all patients on the same day postoperatively.RESULTS: There were statistical significant difference in sphere(S)and spherical equivalent(SE)readings from the computer refractometer and subjective refraction(all P

Purpose To evaluate the repeatability of a pyramidal wavefront-based refraction (WFR) measurement and its agreement with dry autorefraction (DR), cycloplegic autorefraction (CR), and subjective refraction (SR) in myopic refractive surgery candidates. Methods One hundred eighty-nine eyes from 189 participants were evaluated. PERAMIS aberrometry (PERAMIS; SCHWIND eye-tech-solutions, Kleinostheim, Germany), DR, and CR, as well as SR, were completed for all candidates. The repeatability of PERAMIS measurements was assessed, and the Bland–Altman plots were used to test the agreement between different methods. Results Repeatability of the PERAMIS aberrometer was very high in the measurement of all refractive elements (Sphere, cylinder, spherical equivalent [M], J0, and J45) (interclass correlation coefficient >0.980 for all). A significant myopic shift was found with WFR compared to CR (0.45 diopter [D]) and SR (0.28 D) (P < 0.05). For the M component, there was a significant difference between WFR and CR (P < 0.05). J0 component measured with WFR was significantly different from SR and CR (P < 0.05). For the J45 variable, all three refraction methods were comparable (all, P > 0.05). In M > 5.00 D, a difference of 0.79 D (limit of agreement: −3.50–1.90) was found between WFR and CR. Conclusions In lower degrees of myopia, WFR was in good agreement with the manifest autorefraction. WFR, CR, and SR techniques were comparable in measuring astigmatism, especially in oblique astigmatism.

Purpose: To investigate the impact of accommodation function on the difference between cycloplegic and noncycloplegic subjective and automatic refraction in adult myopes. Methods: Myopic patients between 18 and 50 years old evaluated at Peking University Third Hospital who underwent cycloplegic and noncycloplegic automatic and subjective refraction were enrolled. Accommodation function, including negative and positive relative accommodation (PRA/NRA) and accommodation response (binocular cross cylinder, BCC) was examined. Results: Of the 3268 individuals enrolled, the mean age was 27.3 ± 6.9 years, and 34.8% of participants were male. The noncycloplegic spherical equivalent (SE) was 0.23 ± 0.29 D and 0.64 ± 0.61 D more myopic than cycloplegic subjective and automatic refraction. Adjusting for associated factors, participants with at least 0.50 D of more myopia SE refraction by noncycloplegic subjective refraction were more likely to be older (odds ratio [OR], 1.029; 95% confidence interval [CI], 1.013–1.045) and with insufficient (OR, 1.514; 95% CI, 1.093–2.096) and excessive (OR, 2.196; 95% CI, 1.538–3.137) NRA value. The automatic refraction SE difference of at least 1.00 D more myopia was more likely to be found in individuals with older age (OR, 1.036; 95% CI, 1.022–1.050) and accommodative lead (OR, 1.255; 95% CI, 1.004–1.568). Conclusion: A quarter of adult myopes had at least 0.50 and 1.00 D of subjective and automatic SE difference with cycloplegia. The accommodation function significantly affects the difference between cycloplegic and noncycloplegic refraction. Investigating the differences in refraction measurement guarantees the proper use of cycloplegia in adults for myopia correction. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to assess the inter-examiner repeatability of subjective refraction across diverse age cohorts, an aspect not previously investigated. Methods: A cross-sectional, randomized study enrolled 86 participants (mean age: 37.0 ± 18.0 years), distributed into three groups: youth, non-presbyopic adults, and presbyopic adults. Each participant underwent three subjective refractions by three different optometrists on separate days. Repeatability analysis encompassed all refractive variables (M, J0, and J45). Results: There were no significant differences between optometrists in all refractive variables for either the overall sample or across age groups (p ≥ 0.05). Additionally, no correlation was found between participants' age and the mean difference in refractive variables across optometrists (p ≥ 0.05). The 95% confidence interval of repeatability (r) for the total sample was ±0.70 D for M, ±0.29 for J0, and ±0.21 D for J45. Conclusions: Based on these findings and previous research, it is suggested to establish 95% limits of agreement of ±0.75 D for M, and between ±0.25 D and ±0.50 D for both J0 and J45 when validating new refraction systems compared to subjective refraction as the gold standard, regardless of the age of the subjects evaluated. [ABSTRACT FROM AUTHOR]

Myopia has become a public health priority as its prevalence increases worldwide, and in clinical practice, the precise evaluation of refraction errors is necessary. 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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Introduction: Despite the well‐known reproducibility issues of subjective refraction, most studies evaluating autorefractors compared differences between the device and subjective refraction. This work evaluated the performance of a novel handheld Hartmann–Shack‐based autorefractor using an alternative protocol, which considered the inherent variability of subjective refraction. Methods: Participants underwent an initial measurement with a desktop autorefractor, two subjective refractions (SR1 and SR2) and a final measurement with the QuickSee Free (QSFree) portable autorefractor. Autorefractor performance was evaluated by comparing the differences between the QSFree and each of the subjective refractions with the difference between the subjective refractions (SR1 vs. SR2) using Bland–Altman analysis and percentage of agreement. Results: A total of 75 subjects (53 ± 14 years) were enrolled in the study. The average difference in the absolute spherical equivalent (M) between the QSFree and the SR1 and SR2 was ±0.24 and ±0.02 D, respectively, that is, very similar or smaller than the SR1 versus SR2 difference (±0.26 D). Average differences in astigmatic components were found to be negligible. The results demonstrate that differences between QSFree and both subjective refractions in J0 and J45 were within ±0.50 D for at least 96% of the measurements. The limits of agreement (LOAs) of the differences between QSFree and SR1, as well as QSFree and SR2, were higher than those observed between SR1 and SR2 for M, J0 and J45. Conclusions: A protocol was designed and validated for the evaluation of a refractive device to account for the variability of subjective refraction. This protocol was used to evaluate a novel portable autorefractor and observed a smaller difference between the device and subjective refractions than the difference between the two subjective refraction measurements in terms of mean bias error, although the standard deviation was higher. [ABSTRACT FROM AUTHOR]

Abstract Purpose To evaluate objective and subjective refraction differences in healthy young adults. Methods Data concerning candidates for the Israeli Air Force Flight Academy, as well as active air force pilots in all stages of service who underwent a routine health checkup between the years 2018 and 2019 were retrospectively analyzed. Objective refraction measured using a single autorefractometer was compared with subjective refraction measured by an experienced military optometrist during the same visit. The results were converted to power vectors (spherical equivalent [SE], J0, and J45). To interpret astigmatism using power vector values, the cylinder power (Cp) was determined. Results This study included 1,395 young adult participants. The average age was 22.17 years (range, 17–39, 84.8% males). The average SE was − 0.65 ± 1.19 diopter (D) compared with − 0.71 ± 0.91D in the auto- and subjective refraction, respectively (p = 0.001). Cp was 0.91 ± 0.52D and 0.67 ± 0.40D, respectively (p

Purpose: To evaluate objective and subjective refraction differences in healthy young adults. Methods: Data concerning candidates for the Israeli Air Force Flight Academy, as well as active air force pilots in all stages of service who underwent a routine health checkup between the years 2018 and 2019 were retrospectively analyzed. Objective refraction measured using a single autorefractometer was compared with subjective refraction measured by an experienced military optometrist during the same visit. The results were converted to power vectors (spherical equivalent [SE], J0, and J45). To interpret astigmatism using power vector values, the cylinder power (Cp) was determined. Results: This study included 1,395 young adult participants. The average age was 22.17 years (range, 17–39, 84.8% males). The average SE was − 0.65 ± 1.19 diopter (D) compared with − 0.71 ± 0.91D in the auto- and subjective refraction, respectively (p = 0.001). Cp was 0.91 ± 0.52D and 0.67 ± 0.40D, respectively (p < 0.001). This difference was more common in older participants (p < 0.001). J0 and J45 value differences were not significant. The absolute SE value of subjective refraction was lower in the myopic (p < 0.001) and hyperopic (p < 0.001) patients. Conclusions: Young hyperopic participants tended to prefer "less plus" in subjective refraction compared with autorefraction. Young myopic participants tended to prefer "less minus" in subjective refraction compared with autorefraction. All participants, but mainly older participants, preferred slightly "less Cp" than that measured using autorefraction; The astigmatic axis did not differ significantly between the methods. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to assess the inter-examiner repeatability of subjective refraction across diverse age cohorts, an aspect not previously investigated. Methods: A cross-sectional, randomized study enrolled 86 participants (mean age: 37.0 ± 18.0 years), distributed into three groups: youth, non-presbyopic adults, and presbyopic adults. Each participant underwent three subjective refractions by three different optometrists on separate days. Repeatability analysis encompassed all refractive variables (M, J0, and J45). Results: There were no significant differences between optometrists in all refractive variables for either the overall sample or across age groups (p ≥ 0.05). Additionally, no correlation was found between participants’ age and the mean difference in refractive variables across optometrists (p ≥ 0.05). The 95% confidence interval of repeatability (r) for the total sample was ±0.70 D for M, ±0.29 for J0, and ±0.21 D for J45. Conclusions: Based on these findings and previous research, it is suggested to establish 95% limits of agreement of ±0.75 D for M, and between ±0.25 D and ±0.50 D for both J0 and J45 when validating new refraction systems compared to subjective refraction as the gold standard, regardless of the age of the subjects evaluated.

Purpose: To evaluate and compare the objective refractions obtained by autorefraction and aberrometry under different lighting conditions with an isofocal intraocular lens (Isopure, BVI medical, Liége, Belgium) compared to a monofocal control lens (Micropure, BVI medical, Liége, Belgium) with the same platform and material. Methods: Prospective, comparative and randomized study on patients undergoing cataract surgery and bilateral isofocal or monofocal IOL implantation. A total of 44 subjects were randomly assigned to either the isofocal group (n = 22) or the Micropure (n = 22). Manifest refraction (MR) was always performed under the same lighting conditions for all the patients. For objective refraction the autorefractor KR8800 and the aberrometer OPD-Scan III (Nidek Inc., Tokyo, Japan.) were used. For each eye included in the study, six result sets were collected: MR, AR (autorefraction measured with the autorefractor), WF-P and WF-M (Zernike-coefficients-based objective refraction, photopic and mesopic pupil size), OPD-C and OPD-M (autorefraction measured with the aberrometer in photopic and mesopic conditions). Results: The mean sphere for MR was 0.03 ± 0.32D for the Isopure group and 0.24 ± 0.22D for the monofocal group (p = 0.013). For the Isopure group, Friedman analysis showed statistically significant differences for sphere measured with WF-P (p = 0.035), WF-M (p = 0.018) and OPD-M (p = 0.000), and SE measured with OPD-M (p = 0.004). In the Micropure lens group, the Friedman analysis showed differences for all values studied (p < 0.05). Correlation coefficients showed that AR is the objective method with the strongest correlation values for all components of refraction for both groups. Conclusion: The modification of the surfaces of the isofocal lens does not have a negative impact on the refraction obtained by AR compared to a standard monofocal intraocular lens. [ABSTRACT FROM AUTHOR]

To assess the agreement between the Eye Refract, an instrument to perform subjective automated refraction, and the traditional subjective refraction, as the gold standard, in young hyperopes under noncycloplegic and cycloplegic conditions. A cross-section and randomized study was carried out, involving 42 participants (18.2 ± 7.7 years, range 6 to 31 years). Only one eye was chosen for the analysis, randomly. An optometrist conducted the refraction with the Eye Refract, while another different optometrist conducted the traditional subjective refraction. Spherical equivalent (M), cylindrical components (J0 and J45), and corrected distance visual acuity (CDVA) were compared between both refraction methods under noncycloplegic and cycloplegic conditions. A Bland-Altman analysis was performed to assess the agreement (accuracy and precision) between both refraction methods. Without cycloplegia, the Eye Refract showed significantly lower values of hyperopia than the traditional subjective refraction (p < 0.009), the mean difference (accuracy) and its 95% limits of agreement (precision) being -0.31 (+0.85, -1.47) D. Conversely, there were no statistical differences between both refraction methods under cycloplegic conditions (p ≥ 0.05). Regarding J0 and J45, both refraction methods manifested no significant differences between them under noncycloplegic and cycloplegic conditions (p ≥ 0.05). Finally, the Eye Refract significantly improved CDVA (0.04 ± 0.01 logMAR) compared with the traditional subjective refraction without cycloplegia (p = 0.01). The Eye Refract is presented as a useful instrument to determine the refractive error in young hyperopes, the use of cycloplegia being necessary to obtain accurate and precise spherical refraction. [ABSTRACT FROM AUTHOR]

Purpose: To implement a pure power vector method for monocular subjective refraction using a regular phoropter with the only modification being the inclusion of a Stokes lens. The proposed methodology was tested with three different Stokes lenses, and the results were compared with conventional clinical refraction procedures. Methods: Power vector subjective refraction was performed by attaching a Stokes lens to the Risley prism holder. Stokes lenses allow for pure astigmatic compensation in the form of the J0, J45 components while the spherical lenses in the phoropter allow determination of the spherical component in the form of M (spherical equivalent). The proposed routine is presented step‐by‐step using three Stokes lenses having different astigmatic powers. Results: Monocular subjective refraction was performed on 26 healthy subjects with a mean age of 44 ± 16 years, mean spherical equivalent of −0.56 D (range −5.50 to +2.38 D) and refractive astigmatism ≤1.50 D. No differences were found between the results obtained with the conventional technique versus the vector‐based procedure for the spherical equivalent (p = 0.28) or astigmatic components (p = 0.34). In addition, visual acuity (VA) was equivalent through the refractions measured with the conventional and vector procedures (p = 0.12). Repeatability coefficients for J0 and J45 with the new vector methodology were <0.38 D. Conclusions: The proposed routine could be helpful for cases where it is difficult to get a valid starting point for conventional refraction (e.g., irregular corneas and media opacities), for testing facilities with limited resources/equipment and/or for motivated clinicians who wish to know about alternative methods of refractive error determination. [ABSTRACT FROM AUTHOR]

Purpose: To compare optical performance, visual performance, and patient‐perceived quality of vision with: (1) spectacles determined using subjective refraction and (2) spectacles determined using an objective optimisation method based on wavefront aberration data for eyes with keratoconus. Methods: Thirty‐seven eyes (20 subjects) with keratoconus underwent both subjective refraction and uncorrected wavefront aberration measurement. Wavefront aberration data were used to objectively identify a sphero‐cylindrical refraction that optimised the visual image quality metric visual Strehl ratio (VSX). The two refractions were assembled in trial frames and worn by the subject in a random order. High‐contrast visual acuity (VA), letter contrast sensitivity (CS), and the patient's short‐term subjective preference were recorded for each prescription. Results: Median magnitude of the dioptric difference (a measure of similarity between the subjective and objective refractions) was 2.77 D (range = 0.21–20.44 D, first quartile = 1.02 D, third quartile = 4.36 D). Sixty‐eight per cent of eyes had better VA with the objective refraction and 32% of eyes gained more than one line of VA. Monocularly, objective refraction was preferred 68% of the time when looking at a distant acuity chart and 76% of the time when viewing a real‐world dynamic scene. Conclusions: Objective refraction based on visual image quality derived from wavefront aberration data can be valuable in the determination of monocular spectacle refractions for individuals with keratoconus. [ABSTRACT FROM AUTHOR]

Abstract Background The increase in the prevalence of myopia has become a matter of serious public health concern, and few studies to date have examined the ocular biometric parameters of myopia in young Chinese adults. This study aimed to investigate the longitudinal ocular biometric and refractive development of first-year university students and the influence of near work. Methods This study included 526 first-year university students from Tianjin Medical University (mean age, 18.34 years; 313 females and 213 males). From 2016 to 2018, participants underwent ocular biometry measurements and subjective refraction annually. Near-work activities such as the use of electronic devices, online games, reading, and writing as well as demographic data were recorded by questionnaires. Results The prevalence of myopia in this population from 2016 to 2018 was 92.40%, 92.59%, and 92.97%, respectively. Importantly, the prevalence of high myopia increased significantly from 20.91% to 28.33% (P

Purpose The aim of this study was to compare subjective refraction under two lighting conditions to understand whether illumination affects the correction of myopia. Patients and methods This is a prospective, comparative study that was carried out on 33 myopic patients with corrected visual acuity of both eyes of 1.0 or better (in decimal unit). The included patients had a refractive error greater than −1.50 D. Examinations were carried out under two levels of lighting conditions. The patients underwent objective refraction followed by subjective refraction, pupil diameter measurement, visual acuity assessment, and intraocular pressure measurement. Results The mean subjective refraction under room illumination at 2, 4, and 6 m was −0.65, −0.48, and +0.29 D, respectively, compared with −0.42, +0.39, and +0.60 D without room illumination, respectively. There was a statistically significant difference between mean value of subjective refractions under the two lighting conditions at 4 m (P=0.00) and 6 m (P=0.00). However, the mean subjective refraction at the distance of 2 m was not statistically significantly different between the two lighting conditions (P=0.25). At 2 m, the pupil size and subjective refraction did not show significant differences under both lighting conditions (with and without room illumination). Conclusion There was a hyperopic refractive shift during subjective refraction in dim illumination, which may cause undercorrection of myopia that may trigger myopia progression.

Purpose: Accurate refraction is arguably the most important parameter for a successful laser vision correction surgery and is based on a combination of manifest and cycloplegic refraction. Wavefront-based objective refraction may be useful in the evaluation of patients. So far, the reliability of objective refraction as measured using the Pentacam® AXL Wave has not been published in the literature. Methods: This was a prospective study including a total of 168 eyes belonging to 84 young non-presbyopic patients evaluated for refractive surgery. Pentacam® AXL Wave full sequence was taken for all patients. Then, a clinician who was unaware of the objective refraction results performed a full physical examination, including manifest refraction starting from an autorefractometer value. All refraction values were transferred to astigmatic power vectors as per the Thibos method. Reliability of the different vectors and a unifying blur value were compared using Spearman correlation, Bland–Altman plot, and intraclass correlation coefficient. Results: The mean age was 28.8 ± 5.4 years, with a female preponderance (60.7%). The correlation between both eyes was high. The difference in M vector between subjective and objective refraction was 0.16 D, while the difference was 0.04 and 0.01 D for the J0 and J45 vectors, respectively. Paired samples Student t was non-significant for all comparisons. Spearman rho correlations were high (0.666–0.924, all P < 0.001). Intraclass correlation coefficients were also high (0.890–0.966). Bland–Altman plots did not demonstrate any systematic errors. Conclusion: Wavefront-based refractive refraction obtained using the Pentacam® AXL Wave is highly agreeable and correlated with measurements obtained by manifest subjective refraction.

To compare Netra smartphone-based and automated refraction with subjective refraction for screening of refractive errors. Cross-sectional study at the University of Malaya Medical Centre, Kuala Lumpur. Subjects underwent subjective refraction, then automated refraction, and finally Netra smartphone-based refraction. All results were converted to power vectors (M, J0 and J45) and were analysed using repeated-measures ANOVA and Bland-Altman plots. Sensitivity and specificity were determined. The best cut-off points were determined from ROC curve analysis. P <.05 was considered statistically significant. Data from the right eyes of 204 subjects were analysed. Mean age was 36.6 ± 15.7 years (range 16–78 years). Spherical equivalent [mean (95% CI)] from Netra and automated refraction were similar, and both more myopic than subjective refraction; −2.87 (−3.23 to −2.51), −2.85 (−3.21 to −2.49) and −2.46 (−2.83 to −2.10) respectively (p <.001). Differences in J0 and J45 between Netra and subjective refraction were not statistically significant (0.10 vs 0.11 and 0.01 vs −0.02 respectively, both p >.05), but those between automated and subjective refraction were (0.06 vs 0.11 and 0.07 vs −0.02, p =.004 and p <.001 respectively). Bland Altman plots showed the 95% limits of agreement with Netra refraction were wider than with automated refraction (−2.21D to 1.42D vs. −1.90D to 1.16D respectively). Netra smartphone-based refraction gives similar readings to automated refraction, and both show myopic overestimation when compared to subjective refraction. However, due to non-insignificant practical usage issues, its use as a screening tool for refractive errors is limited. [ABSTRACT FROM AUTHOR]

Accurate detection of subjective refraction is important to provide patients with the best visual quality. One of the factors affecting detection of subjective refraction is viewing distance. Lack of requirements for optometric office arrangement and required space dimensions leads to smaller optometric offices that provide shorter distance between the patient and the optotype chart. However, the effect of decreased viewing distance on detected subjective refraction remains unknown. The aim of this study was to evaluate the effect of viewing distance on the assessment of subjective refraction. Two types of subjective refraction of the dominant eye were determined in 45 participants at five viewing distances (6 m, 5 m, 4 m, 3 m, and 2.5 m): subjective refraction that ensured visual acuity 1.0 (in decimal units) and maximum subjective refraction that ensured the best corrected visual acuity. The results demonstrated that viewing distance significantly affected the outcome of subjective refraction detection; there were hyperopic shifts in all types of refractions that increased as the viewing distance decreased. To conclude, the most appropriate viewing distance for subjective refraction detection is 5 m or 6 m. If viewing distance is reduced to 4 m or less, a negative spherical lens of the corresponding proximity should be added to the obtained subjective refraction as it cannot be reliably stated that ocular accommodation is fully relaxed. Since this is not always achievable by 0.25 D steps, mirror systems should be used in smaller (3 m and closer viewing distances) optometric offices to provide more appropriate subjective refraction detection.

Abstract Background To evaluate the necessity of cycloplegia for epidemiological studies of refraction in Chinese young adults (aged 17–22 years) with dark irises, and to compare the cycloplegic effects of 1% cyclopentolate and 0.5% tropicamide in them. Methods A total of 300 young adults (108 males and 192 females) aged 17 to 22 years (mean 19.03 ± 1.01) were recruited from Tianjin Medical University from November 2019 to January 2020. Participants were randomly divided into two groups. In the cyclopentolate group, two drops of 1% cyclopentolate eye drop were administrated (one drop every 5 min), followed by autorefraction and subjective refraction 30 to 45 min later. In the tropicamide group, four drops of 1% Mydrin P (Tropicamide 0.5%, phenylephrine HCl 0.5%) eye drop were given (one drop every 5 min), followed by autorefraction and subjective refraction 20 to 30 min later. The participants and the examiners were masked to the medication. Distance visual acuity, intraocular pressure (IOP), non-cycloplegic and cycloplegic autorefraction (Topcon KR-800, Topcon Co. Tokyo, Japan), non-cycloplegic and cycloplegic subjective refraction and ocular biometry (Lenstar LS-900) were performed. Results The values of spherical equivalent (SE) and sphere component were significantly different before and after cycloplegia in the cyclopentolate group and the tropicamide group (p 0.05). In each group, no significant difference was found between autorefraction and subjective refraction after cycloplegia (p > 0.05). We also found that more positive or less negative cycloplegic refraction was associated with the higher difference in SE in each group. Conclusions Cycloplegic refractions were generally more positive or less negative than non-cycloplegic refractions. It is necessary to perform cycloplegia for Chinese young adults with dark irises to obtain accurate refractive errors. We suggest that cycloplegic autorefraction using tropicamide may be considered as a reliable method for epidemiological studies of refraction in Chinese young adults with dark irises. Trial registration The study was registered on September 7, 2019 (Registration number: ChiCTR1900025774 ).

Sabrina N Mukash,1 David L Kayembe,1 Jean-Claude Mwanza1,2 1Department of Ophthalmology, School of Medicine, Kinshasa University Hospital, Kinshasa, Democratic Republic of Congo; 2Department of Ophthalmology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USACorrespondence: Sabrina N MukashDepartment of Ophthalmology, School of Medicine, Kinshasa University Hospital, Kinshasa, Democratic Republic of CongoTel +243 816917089Email mukashsaby@gmail.comObjective: To assess the agreement between retinoscopy and autorefractometry and between subjective refraction and both retinoscopy and autorefractometry in Congolese children.Patients and Methods: Fifty-four children (6– 17 years old) were enrolled consecutively in this cross-sectional study. Refraction was evaluated before and after cycloplegia (1% cyclopentolate) with retinoscopy and autorefractometry. Readings were compared (paired t-test) and agreement assessed with Bland–Altman plots. Subjective refraction was compared with the two methods to determine which one provides better reference estimates for subjective refraction.Results: Under cycloplegia, the spherical power was comparable between retinoscopy and autorefractometry (1.12 ± 1.37 D vs 1.22 ± 1.06D, P = 0.70), cylinder power was significantly more myopic on retinoscopy than autorefractometry (0.80 ± 1.10D vs − 0.62 ± 0.66, P = 0.019), and SE was greater on autorefractometry than retinoscopy (0.91 ± 1.10D vs 0.72 ± 1.00D, P = 0.014). Retinoscopy and autorefractometry overestimated the power of spherical (P = 0.022 and 0.002, respectively) and cylindrical components (all P < 0.001). There was an agreement between retinoscopy and autorefractometry in measuring spherical (bias: 0.09 ± 0.16D; limit of agreement, LoA: − 0.40 to 0.22D) and cylindrical power (bias: − 0.18 ± 0.20D; LoA: − 0.57 to 0.21D). Subjective refraction agreed with cycloplegic retinoscopy for determining SE power (bias: 0.11D; LoA: − 0.51 to 0.73D).Conclusion: Retinoscopy and autorefractometry can be used interchangeably in children for determining the power of spherical and cylindrical components. Cycloplegic retinoscopy is better than autorefractometry to obtain SE reference values for subjective refraction in children.Keywords: retinoscopy, autorefractometry, subjective refraction, agreement

Khulood Muhammad Sayed, Alahmady Hammad Alsmman, Engy Mohammed Mostafa The Department of Ophthalmology, Sohag Faculty of Medicine, Sohag University, Sohag, EgyptCorrespondence: Alahmady Hammad AlsmmanThe Department of Ophthalmology, Sohag Faculty of Medicine, Sohag University, Sohag, 82524, EgyptTel +20-1111-428-635Email alahmady20@yahoo.comObjective: To compare the agreement between commercially available table mounted and a hand-held autorefractors and their agreement with subjective refraction. The effect of different body position with the handheld autorefractometer was also evaluated.Methods: A prospective study was performed on 253 healthy eyes. Refraction was acquired by a table-mounted Huvitz and hand-held Nidek autorefractometer, subjective refraction was acquired. Refractive errors were compared in terms of spherical equivalent (SE), cylinder power, and the J0 and J45. The level of agreement was evaluated by Bland–Altman plots.Results: There was a significant difference in SE measurements between both devices and between them and subjective refraction (P=0.00). The Huvitz SE readings tended to be less myopic. However, limits of agreement (LOA) for SE were narrowest for Nidek sitting vs supine followed by Huvitz vs subjective SE refraction. The LOA for SE for Nidek sitting vs subjective SE were of wider range. For cylinder values, LOA were similar for all devices and positions and between them and subjective cylinder refraction.Conclusion: Table mounted Huvitz and Nidek portable autorefractor cannot be used interchangeably in clinical practice except for estimation of the cylinder power. No difference in refraction between sitting and supine positions for portable Nidek autorefractor but with caution in cylinder axis. High agreement was achieved between subjective refraction and Huvitz readings but not with Nidek hand-held autorefractor. A highly reliable spectacle prescription could be done based on Huvitz readings. Both devices and positions could be used interchangeably in estimation of K-readings.Keywords: Huvitz, Nidek, portable, autorefractometer, subjective refraction

Background: The increase in the prevalence of myopia has become a matter of serious public health concern, and few studies to date have examined the ocular biometric parameters of myopia in young Chinese adults. This study aimed to investigate the longitudinal ocular biometric and refractive development of first-year university students and the influence of near work.Methods: This study included 526 first-year university students from Tianjin Medical University (mean age, 18.34 years; 313 females and 213 males). From 2016 to 2018, participants underwent ocular biometry measurements and subjective refraction annually. Near-work activities such as the use of electronic devices, online games, reading, and writing as well as demographic data were recorded by questionnaires.Results: The prevalence of myopia in this population from 2016 to 2018 was 92.40%, 92.59%, and 92.97%, respectively. Importantly, the prevalence of high myopia increased significantly from 20.91% to 28.33% (P < .001). The spherical equivalent refraction was significantly more myopic by approximately - 0.38 D (from - 4.18 ± 2.44 to - 4.56 ± 2.57 D; P < .001) during the period. The axial length, central corneal thickness, and lens thickness became significantly different (all P < .05), and the axial length significantly increased by 0.12 mm during 2 years (P < .001). Using binary logistic regression analysis, the data indicated that spending more time on online games (odds ratio, 2.09; 95% confidence interval, 1.33-3.29) could speed up the progression of myopia (P < .05).Conclusions: This study showed that the prevalence of high myopia continued to increase in undergraduate students over 2 years. Baseline myopia correlated with myopic shift, the time spent on online games, and parental myopia were significantly associated with an increase in myopia in these young adult populations. [ABSTRACT FROM AUTHOR]

Purpose: Accurate refraction is arguably the most important parameter for a successful laser vision correction surgery and is based on a combination of manifest and cycloplegic refraction. Wavefront-based objective refraction may be useful in the evaluation of patients. So far, the reliability of objective refraction as measured using the Pentacam® AXL Wave has not been published in the literature.Methods: This was a prospective study including a total of 168 eyes belonging to 84 young non-presbyopic patients evaluated for refractive surgery. Pentacam® AXL Wave full sequence was taken for all patients. Then, a clinician who was unaware of the objective refraction results performed a full physical examination, including manifest refraction starting from an autorefractometer value. All refraction values were transferred to astigmatic power vectors as per the Thibos method. Reliability of the different vectors and a unifying blur value were compared using Spearman correlation, Bland-Altman plot, and intraclass correlation coefficient.Results: The mean age was 28.8 ± 5.4 years, with a female preponderance (60.7%). The correlation between both eyes was high. The difference in M vector between subjective and objective refraction was 0.16 D, while the difference was 0.04 and 0.01 D for the J0 and J45 vectors, respectively. Paired samples Student t was non-significant for all comparisons. Spearman rho correlations were high (0.666-0.924, all P < 0.001). Intraclass correlation coefficients were also high (0.890-0.966). Bland-Altman plots did not demonstrate any systematic errors.Conclusion: Wavefront-based refractive refraction obtained using the Pentacam® AXL Wave is highly agreeable and correlated with measurements obtained by manifest subjective refraction. [ABSTRACT FROM AUTHOR]

Purpose: To expand the SyntEyes keratoconus (KTC) model to assess the Visual Image Quality (VIQ) of sphero‐cylindrical spectacle and rigid contact lens corrections as keratoconus progresses. Methods: The previously published SyntEyes KTC eye model to determine best sphero‐cylindrical spectacle and rigid contact lens correction in keratoconic eyes was expanded to include the natural progression of keratoconus, thus allowing the assessment of corrected VIQ with disease progression. Results: As keratoconus progresses, the pattern of visual Strehl ratio (VSX) in correction space for spectacles alters from a typical hourglass into a shell pattern. The former would guide the subjective refraction towards the optimal correction while the latter is relatively insensitive to large dioptric steps. In 15 out of the 20 SyntEyes, the shell pattern eventually produces two foci on different sides of the correction space separated by a clinically significant dioptric difference with a similar, albeit lower VIQ. Wearing the best possible spectacle corrections provided an average gain of up to 3.5 lines of logMAR visual acuity compared to the uncorrected cases, which increased to 5.5 lines for the best rigid contact lens correction. Continuing to wear a spectacle correction as the disease progresses often leads to a VIQ that is almost as bad as the uncorrected case. Continuing to wear a rigid contact lens correction as the disease progresses maintains a relatively high level of VIQ, albeit in the low range for typically well‐corrected normal eyes. Conclusions: The results reflect the clinical experience that subjective refraction is difficult in highly‐aberrated keratoconic eyes, the benefit of spectacle correction is short lived and that rigid contact lenses provide better and more stable VIQ with disease progression. Other aspects, such as the presence and behaviour of the second focus in some cases, remain to be confirmed clinically. [ABSTRACT FROM AUTHOR]

Abstract Purpose: To evaluate six different premium IOLs retrospectively in respect to both subjective and objective refraction after cataract operation. Methods: Five hundreds and seventy eyes of 285 patients with bilateral cataract who had undergone phacoemulsification and IOL implantation operation between February 2017 and September 2018 were enrolled in this study. The mean age of the patients was 57.78 ± 7.49 (41-71) years. Out of 285 patients 137 were male (48.07%) and 148 were female (51.93%). TheIOLsusedare: RayOne Trifocal (Rayner, Worthing, UK), Lucidis (Swiss Advanced Vision, Neuchâtel, Switzerland), PanOptix (Alcon, Fort Worth, USA), LentisMplus (Oculentis, Berlin, Germany), TecnisSymfony (Abbott, Illinois, USA) and Acriva Trinova (VSY Biotechnology, Istanbul, Turkey). Results: There were no significant differences among the groups regarding age, sex, axial length, the mean preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), the mean preoperative spherical equivalent (SE) and the mean postoperative SE (subjective measurement) (P> .05). The postoperative refractions measured with autorefractometer were more myopic than subjective refractions in all patients except the patients who had PanOptix IOL. In postoperative twelfth month, the mean UCVA arrived 0.00 logMAR in 405 eyes (78.48%) , however, the mean autorefractometric measurement was -1.28 ± 1.02 (0.00_-2.75) D. Conclusion: The autorefractometer measurements of all patients who had premium IOLs except PanOptix IOL were not coherent with their visual acuities postoperatively. The ophthalmologists and/or optometrists should be careful while examining these types of patients.

Background and Objectives: Keratoconus is a non-inflammatory asymmetric corneal degenerative disease characterized by the steepening and distortion of the cornea. In this disease, irregular astigmatism makes the subjective refraction difficult. Using the Pentacam, we aimed to determine the corrective astigmatism of the spectacle. Methods: The subjective refraction and Pentacam imaging were performed for 317 keratoconic patients who referred to the Salouti Eye Clinic, Shiraz, Iran. Then, the astigmatism values obtained with subjective refraction were compared with the values of anterior and posterior corneal surface astigmatism obtained with the Pentacam imaging. Results: The mean age of 317 keratoconic patients was 29.81 years (range: 15 to 45 years). The minimum, maximum, and average astigmatism of the corneal front surface were 0.3, 16.8, and 3.21 diopters, respectively. Also, the minimum, maximum, and average astigmatism of the corneal back surface were 0, 2.8, and 0.67 diopters, respectively. Moreover, the P value was lower than 0.001 in the regression analysis of the subjective refraction for both the power and axis of the cylinder. Conclusion: The regression formulas obtained in this study can accurately (with a probability of 99%) predict refractive astigmatism, using corneal astigmatism.

Accurate detection of subjective refraction is important to provide patients with the best visual quality. One of the factors affecting detection of subjective refraction is viewing distance. Lack of requirements for optometric office arrangement and required space dimensions leads to smaller optometric offices that provide shorter distance between the patient and the optotype chart. However, the effect of decreased viewing distance on detected subjective refraction remains unknown. The aim of this study was to evaluate the effect of viewing distance on the assessment of subjective refraction. Two types of subjective refraction of the dominant eye were determined in 45 participants at five viewing distances (6 m, 5 m, 4 m, 3 m, and 2.5 m): subjective refraction that ensured visual acuity 1.0 (in decimal units) and maximum subjective refraction that ensured the best corrected visual acuity. The results demonstrated that viewing distance significantly affected the outcome of subjective refraction detection; there were hyperopic shifts in all types of refractions that increased as the viewing distance decreased. To conclude, the most appropriate viewing distance for subjective refraction detection is 5 m or 6 m. If viewing distance is reduced to 4 m or less, a negative spherical lens of the corresponding proximity should be added to the obtained subjective refraction as it cannot be reliably stated that ocular accommodation is fully relaxed. Since this is not always achievable by 0.25 D steps, mirror systems should be used in smaller (3 m and closer viewing distances) optometric offices to provide more appropriate subjective refraction detection. [ABSTRACT FROM AUTHOR]

Background: To evaluate the necessity of cycloplegia for epidemiological studies of refraction in Chinese young adults (aged 17-22 years) with dark irises, and to compare the cycloplegic effects of 1% cyclopentolate and 0.5% tropicamide in them.Methods: A total of 300 young adults (108 males and 192 females) aged 17 to 22 years (mean 19.03 ± 1.01) were recruited from Tianjin Medical University from November 2019 to January 2020. Participants were randomly divided into two groups. In the cyclopentolate group, two drops of 1% cyclopentolate eye drop were administrated (one drop every 5 min), followed by autorefraction and subjective refraction 30 to 45 min later. In the tropicamide group, four drops of 1% Mydrin P (Tropicamide 0.5%, phenylephrine HCl 0.5%) eye drop were given (one drop every 5 min), followed by autorefraction and subjective refraction 20 to 30 min later. The participants and the examiners were masked to the medication. Distance visual acuity, intraocular pressure (IOP), non-cycloplegic and cycloplegic autorefraction (Topcon KR-800, Topcon Co. Tokyo, Japan), non-cycloplegic and cycloplegic subjective refraction and ocular biometry (Lenstar LS-900) were performed.Results: The values of spherical equivalent (SE) and sphere component were significantly different before and after cycloplegia in the cyclopentolate group and the tropicamide group (p < 0.05). The mean difference between noncycloplegic and cycloplegic autorefraction SE was 0.39 D (±0.66 D) in the cyclopentolate group and 0.39 D (±0.34 D) in the tropicamide group. There was no significant difference in the change of SE and sphere component after cycloplegia between the cyclopentolate group and the tropicamide group (p > 0.05). In each group, no significant difference was found between autorefraction and subjective refraction after cycloplegia (p > 0.05). We also found that more positive or less negative cycloplegic refraction was associated with the higher difference in SE in each group.Conclusions: Cycloplegic refractions were generally more positive or less negative than non-cycloplegic refractions. It is necessary to perform cycloplegia for Chinese young adults with dark irises to obtain accurate refractive errors. We suggest that cycloplegic autorefraction using tropicamide may be considered as a reliable method for epidemiological studies of refraction in Chinese young adults with dark irises.Trial Registration: The study was registered on September 7, 2019 (Registration number: ChiCTR1900025774 ). [ABSTRACT FROM AUTHOR]

AIM: To evaluate the effect of red-green duochrome test in subjective refraction.METHODS: A randomly-selected sample size of 60 new patients with myopia were measured twice using subjective refraction with and without the red-green duochrome test. Assessments on the effectiveness were made based on comprehensive optometry analysis, accommodation response, accommodation sensitivity, positive and negative relative accommodation.RESULTS: Application of red-green duochrome test on the targeted population did not show any statistical significance to the subjective refraction results. No difference was observed on patients with dilated pupils(P=0.686)and non-dilated pupils(P=0.655). Bland-Altman analysis of displayed good consistency between both subjective refraction measurements on each patient. Multivariate linear regression analysis shows that the results of subjective refraction were independent of age, obliquity, regulation lag, positive relative adjustment, and negative relative adjustment effect(P>0.05).CONCLUSION: The red-green duochrome test does not affect optometric results.

Alan G Kabat,1 Christopher W Lievens,2 Christina M Newman,2 Jacob Weber2 1Pennsylvania College of Optometry, Salus University, Elkins Park, PA, USA; 2Southern College of Optometry, Memphis, TN, USACorrespondence: Alan G KabatPennsylvania College of Optometry, Salus University, 8360 Old York Road, Elkins Park, PA 19027, USATel +1 954 553 1061Fax +1 856 433 8439Email alan.kabat@alankabat.comPurpose: To compare the accuracy, speed and repeatability of the voice assisted subjective refractor (VASR) to traditional refractive methods.Methods: Fifty healthy adult subjects were examined by autorefractor, followed by subjective phoropter refinement. Subjects were then evaluated using the VASR (Vmax Vision) to obtain an objective and subjective result. Three total assessments were performed for each subject using each of the methods described. Corrected visual acuity was recorded for each eye after each procedure. The total time was measured for both the traditional and VASR refraction.Results: A comparison of the results obtained by traditional refraction and VASR revealed no statistically significant difference from the mean in equivalent sphere measurements (P=0.1383), and the datasets were highly correlated (r=0.993). The data comparisons for cylinder power and axis were similar (cylinder: P=0.6377, r=0.864) (axis: P=0.6991, r=0.738). VASR, on average, required 71 additional seconds to complete when compared to traditional phoropter refraction. In terms of repeatability, the average difference noted upon repeat of equivalent sphere power was 0.01 D for the phoropter (P=0.98) and 0.10 D for the VASR (P=0.23). For sphere power, the average difference was 0.02 D for the phoropter (P=0.55) and 0.07 D for the VASR (P=0.58). For cylinder power, the average difference was 0.02 D for the phoropter (P=0.11) and 0.03 D for the VASR (P=0.39). For all refractive methods, the differences between measurements amounted to ≤0.10 diopters, which is neither clinically nor statistically significant.Conclusion: Refractive error results obtained with the VASR were not statistically different from those achieved using traditional phoropter methods. Time elapsed for the VASR was slightly longer than a more traditional refractive sequence. The VASR demonstrated clinically and statistically significant repeatability of measurement, consistent with traditional refraction.Keywords: autorefractor, subjective refraction, wavefront aberrometry, point-spread function, VASR

Purpose: To evaluate six different premium IOLs retrospectively in respect to both subjective and objective refraction after cataract ope-ration. Methods: Five hundreds and seventy eyes of 285 patients with bilateral cataract who had undergone phacoemulsification and IOL implantation operation between February 2017 and September 2018 were enrolled in this study. The mean age of the patients was 57.78 ± 7.49 (41-71) years. Out of 285 patients 137 were male (48.07%) and 148 were female (51.93%). The IOL susedare: RayOne Trifocal (Rayner, Worthing, UK), Lucidis (Swiss Advanced Vision, Neuchâtel, Switzerland), PanOptix (Alcon, Fort Worth, USA), LentisMplus (Oculentis, Berlin, Germany), TecnisSymfony (Abbott, Illinois, USA) and Acriva Trinova (VSY Biotechnology, Istanbul, Turkey). Re-sults: There were no significant differences among the groups regarding age, sex, axial length, the mean preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), the mean preoperative spherical equivalent (SE) and the mean postoperative SE (subjective measurement) (P> .05). The postoperative refractions measured with autorefractometer were more myopic than subjective refractions in all patients except the patients who had PanOptix IOL. In postoperative twelfth month, the mean UCVA arrived 0.00 logMAR in 405 eyes (78.48%), however, the mean autorefractometric measurement was -1.28 ± 1.02 (0.00_-2.75) D. Conclusion: The autorefractometer measurements of all patients who had premium IOLs except PanOptix IOL were not coherent with their visual acuities postoperatively. The ophthalmologists and/or optometrists should be careful while examining these types of patients. [ABSTRACT FROM AUTHOR]

Background: A Dyop (or dynamic optotype) is a spinning visual target which uses the strobic detection of the spinning gaps/segments of the ring to measure visual acuity. Methods: Forty subjects with visual acuity better than 6/12 (20/40) and ages between 20 and 28 years (24.48 ± 2.01 years) were recruited at the University of Benin Optometry Clinic. Snellen and Dyop acuity charts were displayed on a monitor at a distance of 6 meters. The assessment sequence between the two acuity chart formats was alternated for every other patient to reduce potential refractionist bias. Subjective refraction was measured in both eyes, and the duration of testing for each patient and each method was recorded. Results: There was no significant mean Thibos notations difference, M (p = 0.77), J0 (p = 0.27), and J45 (p = 0.57) using the Bland-Altman plot and 95% limits of agreement between the two charts, and there were no differences as to age or gender. There was, however, a disparity in the mean acuity of about 0.25 diopters with the mean Snellen acuity of 1.60 ± 0.21 decimal units and the mean Dyop acuity of 1.17 ± 0.14 decimal units with a linear relationship: y = 0.3121x + 0.6709 (p = 0.00). The refraction with a Dyop acuity chart also typically took half as long (339 ± 122 seconds) as the refraction with a Snellen acuity chart (680 ± 281 seconds), p = 0.00. Conclusions: Subjective refractions with a Dyop chart were comparable to a Snellen chart. The efficiency of a Dyop refraction, however, was typically twice that of the Snellen chart, with a narrower variance in visual acuity measurements and an improved level of acuity of about 0.25 diopters. [ABSTRACT FROM AUTHOR]

Objective: To determine the difference of refraction measured by cycloplegic retinoscopy (CR) and non-cycloplegic subjective refraction (NS). Materials and Methods: The present descriptive study included normal children aged 6 to 15 years with refractive error. The refractive status was measured by CR and cycloplegic autorefractometer (CA) at the initial visit. At 2-week follow-up, the refraction was measured with non-cycloplegic autorefractometer (NA) and NS. The spherical equivalent (SE) from participants' right eye was used in the data analyses. Results: Forty-four participants were included in this study with a mean age of 9±3 years and 22 (50%) were male. Overall, the median (Q1, Q3) of SE by CR, CA, NS, and NA were -1.00 (-2.50, 0.25), -1.63 (-2.63, -0.50), -1.63 (-2.50, -1.00), and -1.88 (-2.88, -1.13) diopters (D), respectively. The SE by CR was 0.56 D more than NS (p<0.001), and 0.38 D more than CA (p<0.001). The SE by NS was 0.25 D more than NA (p=0.008). By using the CR method, 11 (25%) participants were classified in the hyperopic group (positive SE) and 33 (75%) in the myopic group (negative SE). In the hyperopic group, the median (Q1, Q3) of SE by CR and NS were 0.75 (0.50, 1.75) and -0.63 (-1.00, 1.38) D, respectively. The refraction by CR was 1.50 D more than by NS (p=0.003). In the myopic group, the median (Q1, Q3) of SE by CR and NS were -1.50 (-2.50, -0.75) and -2.00 (-3.25, -1.50) D, respectively. The refraction by CR was 0.50 D more than NS (p<0.001). Conclusion: The refraction in children aged 6 to 15 years measured by CR was significantly more than NS in the participants. The authors should decrease the number of refractions obtained from CR when prescribing glasses to hyperopic children. [ABSTRACT FROM AUTHOR]

Purpose: To calculate the mean difference of visual acuity as measured by auto refraction and subjective refraction. Study Design: Descriptive cross-sectional study. Place and Duration of Study: Department of Ophthalmology, Services hospital Lahore from November 2013 to April 2014. Material and Methods: Using non-probability consecutive sampling 300 eyes of 300 patients fulfilling inclusion criteria were recruited through OPD registration slip. Demographic data including age and gender was recorded. Complete ophthalmic examination was performed. This included measurement of refractive error by autorefraction as well as subjective refraction. Detailed anterior segment examination with slit lamp and dilated fundus examination with indirect ophthalmoscopy was performed. The collected data was analyzed by using software SPSS version 17. Results: The mean age of patients was 34.71 ± 7.45 years. There were 156 (52%) males and 144 (48%) females. There were 263 (87.69%) patients who had visual acuity of 6/6 and 37 (12.33%) had 6/9. Mean spherical auto-refraction and subjective refraction was 0.0290 ± 2.58 and -0.2842 ± 2.37 D with mean difference of -0.3133 ± 1.27 D. The mean cylindrical auto and subjective refraction in this study was -.9742 ± 0.78 D and -0.7500 ± 0.81 D and mean difference was 0.2242 ± 0.74 D. The mean cylindrical axis of auto and subjective refraction was 114.88 ± 49.75 and 115.60 ± 49.70 with mean difference as 0.72 ± 3.02 D (p-value < 0.05). Conclusion: Difference of spherical, cylindrical and cylindrical axis in auto and subjective refraction was significantly different. [ABSTRACT FROM AUTHOR]

Purpose: To conduct a clinical validation of a virtual reality-based experimental system that is able to assess the spherical subjective refraction simplifying the methodology of ocular refraction. Methods: For the agreement assessment, spherical refraction measurements were obtained from 104 eyes of 52 subjects using three different methods: subjectively with the experimental prototype (Subj.E) and the classical subjective refraction (Subj.C); and objectively with the WAM-5500 autorefractor (WAM). To evaluate precision (intra- and inter-observer variability) of each refractive tool independently, 26 eyes were measured in four occasions. Results: With regard to agreement, the mean difference (±SD) for the spherical equivalent (M) between the new experimental subjective method (Subj.E) and the classical subjective refraction (Subj.C) was −0.034 D (±0.454 D). The corresponding 95% Limits of Agreement (LoA) were (−0.856 D, 0.924 D). In relation to precision, intra-observer mean difference for the M component was 0.034 ± 0.195 D for the Subj.C, 0.015 ± 0.177 D for the WAM and 0.072 ± 0.197 D for the Subj.E. Inter-observer variability showed worse precision values, although still clinically valid (below 0.25 D) in all instruments. Conclusions: The spherical equivalent obtained with the new experimental system was precise and in good agreement with the classical subjective routine. The algorithm implemented in this new system and its optical configuration has been shown to be a first valid step for spherical error correction in a semiautomated way.

AIM: To evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with both devices and to determine which of these three spherocylindrical corrections allows the subject to achieve the best visual comfort. METHODS: Forty-two non-presbyopic healthy eyes of 42 subjects were enrolled in this prospective study. Refractive values were compared, evaluating the repeatability, the relationship between the methods and the best visual comfort obtained. RESULTS: Sphere, cylinder and axis results showed good intraclass correlation coefficients (ICC); the highest ICC was obtained using the spherical refraction with the autorefractometer and the aberrometer, achieving levels of 0.999 and 0.998, respectively. The power vector (PV) was calculated for each refraction method, and the results indicated that there were no statistically significant differences between them (P>0.05). Direct comparison of PV measurements using the three methods showed that aberrometer refraction gave the highest values, followed by the subjective values; the autorefractometer gave the lowest values. The subjective method correction was most frequently chosen as the first selection. Equal values were found for the autorefractometer and the aberrometer as the second selection. CONCLUSION: The iTrace aberrometer and the WAM-5500 auto-kerato/refractometer showed high levels of repeatability in healthy eyes. Refractive corrections with the aberrometer, the autorefractometer and subjective methods presented similar results, but spherocylindrical subjective correction was the most frequently selected option. These technologies can be used as complements in refractive evaluation, but they should not replace subjective refraction.