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Purpose: Asthenopia is related to near vision activities or visual tasks that dissociate accommodation from vergence. Since the results of previous studies using objective measures to diagnose asthenopia are inconsistent, this study compared optometric tests and objective metrics of accommodation in non‐asthenopic and asthenopic young adults before and after a visual fatigue task. Methods: The accommodative response was recorded objectively for 6 min at a 3.33 D accommodative demand using an autorefractor, before and after a 5‐min non‐congruent visual task. Accommodation was disassociated from vergence with a ±2.00 D accommodative flipper while reading at the same distance. Optometric tests and subjective evaluations of asthenopia were performed before and after the task. Twenty‐six non‐presbyopic adults (23.15 ± 2.56 years) were included and identified as asthenopic (n = 14) or non‐asthenopic (n = 12) based on their score on the Computer Vision Syndrome Questionnaire. Results: A mixed ANOVA found no significant difference between the groups for objective (accommodative response) or subjective metrics (feeling of fatigue, optometric tests), although all participants reported greater visual fatigue after the task. A significant effect of time (before and after the non‐congruent task) was identified for the overall sample for mean accommodative lag (+0.10 D, p = 0.01), subjective visual fatigue (+1.18, p < 0.01), negative relative accommodation (−0.20 D, p = 0.02) and near negative fusional reserve (blur: +2.46Δ, p < 0.01; break: +1.89Δ, p < 0.01; recovery: +3.34Δ, p = 0.02). Conclusions: The task‐induced asthenopia, measured both objectively and subjectively, was accompanied by a change in accommodative lag, greater visual fatigue and a decrease in negative relative accommodation. Conversely, near negative fusional reserves seem to adapt to the task. No significant differences were found between the two groups with respect to accommodative metrics (objective) or subjective and optometric tests. [ABSTRACT FROM AUTHOR]

Purpose: Critical flicker‐fusion frequency (CFF) has been used in clinical studies as a measure of visual fatigue. We examine the correlation between CFF and subjective reports of visual fatigue in a group of symptomatic computer users, to consider whether CFF may be used as a surrogate measure of visual fatigue symptoms. Methods: We analysed data from a previous randomised controlled trial. One hundred and twenty adults, diagnosed with computer vision syndrome, had CFF and visual fatigue symptoms quantified before and after a visually demanding 2‐h computer task. Symptoms were assessed using a questionnaire with nine subcomponents that summed to a total score of 900. CFF was measured using a two‐interval forced‐choice method, with the flicker rate altered by a computer‐controlled staircase procedure. For our primary analysis, we determined Spearman correlation coefficients between post‐task symptom scores and CFF, and between change from baseline symptom scores and CFF. We also used a bootstrap procedure to consider whether symptom score subcomponents were significantly (Bonferroni‐corrected) different from overall scores with regard to their correlations with CFF. Results: Although visual fatigue symptom scores altered significantly post‐task (mean change: 92 units; 95% confidence interval [CI]: 11 to 122), CFF did not (mean change −0.7 Hz; 95% CI: −1.7 to 0.3). There was no significant correlation between overall symptom scores and CFF, either for the post‐task (r = −0.13; 95% CI: −0.31 to 0.05) or the change from baseline (r = −0.18; 95% CI: −0.35 to 0.01) analysis. Subcomponents of the symptom questionnaire did not show a significant correlation with CFF, either for the post‐task or the change from baseline analysis. Conclusions: We find that CFF is not a useful surrogate for symptoms of visual fatigue, given its low correlation with scores on a visual fatigue symptom questionnaire. [ABSTRACT FROM AUTHOR]

Purpose: A self‐controlled study to determine the influence of illuminance and correlated colour temperature (CCT) of light‐emitting diode (LED) lighting on asthenopia. Methods: Twenty‐two healthy postgraduates (nine women) were recruited to read under eight LED lighting conditions with four illuminances (300 lx, 500 lx, 750 lx and 1000 lx) and four CCTs (2700, 4000, 5000 and 6500 K) for 2 h. A subjective asthenopia questionnaire, the optical quality analysis system (OQAS) and an inflammatory cytokine assay were used to assess the levels of asthenopia. Results: Increased asthenopia was observed after reading, but the degree varied with lighting conditions. There were significant differences among the groups in terms of subjective symptoms (inattention, eye pain, dry eye and total score), optical performance parameters (modulation transfer function [MTF] cut‐off frequency, Strehl ratio [SR], objective scattering index [OSI], mean OSI and accommodative amplitude [AA]) as well as inflammatory cytokines in the tears (epidermal growth factor [EGF], transforming growth factor [TGF]‐α, interleukin [IL]‐6, IL‐8, macrophage inflammatory protein [MIP]‐1β, tumour necrosis factor [TNF]‐α, TNF‐β and vascular endothelial growth factor [VEGF]‐A). All of the subjective and objective measurements collectively suggested that asthenopia was lessened for the 500 lx–4000 K condition. However, asthenopia was significantly worse for 300 lx–2700 K and 1000 lx–6500 K in terms of subjective symptoms and objective optical performance, respectively. Conclusions: LED illuminance and CCT do have a significant effect on asthenopia during reading. 500 lx–4000 K lighting resulted in the lowest level of asthenopia. Conversely, low illuminance at low CCT (300 lx–2700 K) and high illuminance at high CCT (1000 lx–6500 K) promoted more severe asthenopia. [ABSTRACT FROM AUTHOR]

Purpose: Accommodative support (AS) lenses are a low add progressive addition spectacle lens designed to ease symptoms in computer vision syndrome (CVS). The study aims to investigate if (1) AS lenses improve CVS symptoms; (2) binocular/accommodative functions predict a benefit from AS lenses and (3) wearing AS lenses for six months impacts on binocular/accommodative functions. Methods: Pre‐presbyopic adults with symptoms of CVS (Computer Vision Syndrome Questionnaire, CVS‐Q©, score ≥ 6) were randomly allocated to wear AS lenses or control single vision (SV) lenses. The CVS‐Q© and a battery of optometric tests were applied at baseline and after three and six months. Participants and researchers were masked to participant group. After six months, the SV group were unmasked and changed to AS lenses and one week later asked to choose which they preferred. Results: The change in CVS‐Q© scores from baseline to six months did not differ significantly in the two groups. At the end of the one week period, when the control group wore the AS lenses, control group participants were significantly more likely to prefer AS lenses to SV lenses. No optometric functions correlated with the benefit from AS lenses. AS lenses did not have any adverse effects on binocular or accommodative function. Conclusions: In pre‐presbyopic adults, there was no greater improvement in CVS‐Q© scores in the group wearing AS lenses than in the control group. No adverse effects on optometric function (including accommodation) are associated with wearing AS lenses. [ABSTRACT FROM AUTHOR]

Introduction: The prescription of blue‐blocking (B‐B) filters for the management of visual symptoms and signs associated with the use of electronic devices is routinely performed by eye care specialists. However, the utility of B‐B filters is a matter of debate and discussion by the scientific community due to the lack of evidence supporting their use. Here, we aimed to determine the effects of using B‐B filters on the dynamics of the accommodative response and pupil size and perceived levels of visual discomfort, while performing a 30‐min reading task at a close distance in subjects who routinely use electronic devices. Methods: Nineteen healthy young adults (22.0 ± 2.7 years) read two 30‐min passages on a computer screen placed at 50 cm, either while using a commercially available B‐B filter or without any filter on two different days. The magnitude and variability of both the accommodative response and pupil size were dynamically measured for 60 s using the WAM‐5500 open field autorefractometer at 4–5, 9–10, 14–15, 19–20, 24–25, and 29–30 min into the trial. The perceived levels of visual discomfort were also obtained. Results: The lag and variability of accommodation were insensitive to the blue light level (p = 0.34 and 0.62, respectively). There was a time‐on‐task effect for the variability of accommodation, showing greater instability over time regardless of the blue light level. The use of the B‐B filter was associated with improved reading speed (p = 0.02), with an increase of 16.5 words per minute. However, it was not associated with any significant change in pupil dynamics or the perceived levels of visual discomfort (p> 0.05 in both cases). Conclusions: Our data showed that the use of a B‐B filter had no effect on accommodative dynamics or visual symptomatology. Based on these findings, there is no support for the prescription of B‐B filters to attenuate the visual symptoms and signs associated with the use of electronic devices in healthy young adults. [ABSTRACT FROM AUTHOR]

Purpose: There is evidence that attention can modulate ocular dynamics, but its effects on accommodative dynamics have yet to be fully determined. We investigated the effects of manipulating the capacity to focus on task‐relevant stimuli, using two levels of dual‐tasking (arithmetic task) and auditory feedback, on the accommodative dynamics at three different target distances (500, 40 and 20 cm). Methods: The magnitude and variability of the accommodative response were objectively measured in 20 healthy young adults using the Grand Seiko WAM‐5500 autorefractor. In randomised order, participants fixated on a Maltese cross while 1) performing an arithmetic task with two levels of complexity (low and high mental load); 2) being provided with two levels of auditory feedback (low and high feedback); and 3) without performing any mental task or receiving feedback (control). Accommodative and pupil dynamics were monitored for 90 seconds during each of the 15 trials (5 experimental conditions x 3 target distances). Results: The lag of accommodation was sensitive to the attentional state (p = 0.001), where a lower lag of accommodation was observed for the high feedback condition compared to the control (corrected p‐value = 0.009). The imposition of mental load while fixating on a distant target led to a greater accommodative response (corrected p‐value = 0.010), but no effects were found for the near targets. There was a main effect of the experimental manipulation on the accommodative variability (p < 0.001), with the use of auditory feedback improving the accuracy of the accommodative system. Conclusions: Our data show that accommodative dynamics is affected by varying the capacity to focus on task‐relevant stimuli, observing an improvement in accommodative stability and response with auditory feedback. These results highlight an association between attention and ocular dynamics and provide new insight into the control of accommodation. [ABSTRACT FROM AUTHOR]

Purpose To evaluate objectively changes in vergence dynamics following intentional visual fatiguing tasks using congruent (C) and non-congruent ( NC) vergence stimulus demands. Methods Pre- and post-task vergence dynamics to a 10.3° disparity stimulus were recorded objectively in 12 adult, asymptomatic individuals for both convergence and divergence. There were two fatigue-inducing tasks: Congruent or C-task: Subjects altered bifixation (50 cycles) between reduced Snellen charts at 2 m and at 20 cm every 3 s. Non-congruent or NC task: Subjects performed 50 cycles of vergence flipper (7Δ BO/ BI), while bifixating a reduced Snellen chart at 40 cm. Pre- and post-task mean amplitude, time constant, peak velocity, and steady-state response variability were compared. Results There was a significant increase in mean post-task, steady-state response variability for both the C and NC tasks. However, there were no significant group differences for either convergence or divergence between the pre- and post-mean amplitude, time constant, and peak velocity parameters for both the C and NC tasks, although post-task peak velocity was consistently reduced. Conclusions Steady-state vergence response variability was found to be the critical objective parameter to demonstrate significant fatigue effects in the group. Peak velocity was also consistently reduced to a small extent in the NC task. We speculate that these fatigue effects are of a central, and not of peripheral, origin. [ABSTRACT FROM AUTHOR]

Purpose: To compare comfort-related outcomes when wearing rigid gas permeable (RGP) contact lenses made of two different materials and using two cleaning regimes. Methods: In a double-masked lens material cross-over study, subjects (n = 28 who completed the study) were refitted with new lenses made from (A) Boston XO material in one eye and made from (B) ONSI-56 material in the other eye. The lenses made from materials A and B were worn on the right eye and the left eye following the pattern AB–BA–AB (or vice versa) during the first, second, and third 5 week trial periods respectively. Miraflow cleaner (1st and 2nd period) was replaced by Boston Advance cleaner in the 3rd period. Comfortrelated outcomes were assessed by a numerical rating scale (NRS) after each period. Subjects rated six comfort-related factors: satisfaction, sharpness of vision, end of day comfort, maximum comfortable wearing time, maximum wearing time and foreign body feeling. Additionally we obtained subjects’ preferences for type of lens and lens cleaner during an exit interview. The sessile drop method was used to measure static contact angles. Results: The mean of the contact angle measured for the Boston XO material was 93.3° and for the ONSI-56 material was 75.8°. Mean ‘end of the day comfort’, ‘satisfaction’ and ‘lens feeling’ scores reached statistical significance (anova periods 1, 2 and 3, p’s: 0.005, 0.028, 0.046, n = 23) with marginal differences in favour of those eyes that had worn lenses made of the ONSI-56 material (differences in mean scores on a 1–10 NRS never exceeded 0.7, 0.5 and 0.2 points in periods 1, 2, 3 respectively). At the exit interview 60% of the subjects (n = 17) were not able to express a preference for wearing either of the lenses, while 29% reported some preference for lenses made of the ONSI- 56 material (n = 8) and 11% for wearing lenses made of the Boston XO material (n = 3) within one or more periods. Conclusions: The differences in comfort-related outcomes between contact lenses made from two different materials, with sessile contact angles that differed by 17.5°, were small. Although some observed comfort differences reached statistical significance, none of these differences were sufficiently large to support a clinically significant difference in comfort between the two materials. We recommend that both the sessile drop and the captive bubble contact angles, measured according to current standards, are made available to practitioners. [ABSTRACT FROM AUTHOR]

The visual stimulus provided by a 3-D stereoscopic display differs from that of the real world because the image provided to each eye is produced on a flat surface. The distance from the screen to the eye remains fixed, providing a single focal distance, but the introduction of disparity between the images allows objects to be located geometrically in front of, or behind, the screen. Unlike in the real world, the stimulus to accommodation and the stimulus to convergence do not match. Although this mismatch is used positively in some forms of Orthoptic treatment, a number of authors have suggested that it could negatively lead to the development of asthenopic symptoms. From knowledge of the zone of clear, comfortable, single binocular vision one can predict that, for people with normal binocular vision, adverse symptoms will not be present if the discrepancy is small, but are likely if it is large, and that what constitutes 'large' and 'small' are idiosyncratic to the individual. The accommodation-convergence mismatch is not, however, the only difference between the natural and the artificial stimuli. In the former case, an object located in front of, or behind, a fixated object will not only be perceived as double if the images fall outside Panum's fusional areas, but it will also be defocused and blurred. In the latter case, however, it is usual for the producers of cinema, TV or computer game content to provide an image that is in focus over the whole of the display, and as a consequence diplopic images will be sharply in focus. The size of Panum's fusional area is spatial frequency-dependent, and because of this the high spatial frequencies present in the diplopic 3-D image will provide a different stimulus to the fusion system from that found naturally. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effect on optometric variables of reading text presented in 2-D and 3-D on two types of stereoscopic display. Methods: This study measured changes in binocular visual acuity, fixation disparity, aligning prism, heterophoria, horizontal fusional reserves, prism facility and accommodation responses for near of subjects after completing ten consecutive reading tasks of 1 minute each. The tasks consisted of reading words on a polarized two-view (n = 39) and an auto-stereoscopic lenticular nine-view display (n = 19) with the text presented without or with stereoscopic disparity at 3 m. Performance was assessed by measuring reading speed and symptoms were rated by the Convergence Insufficiency Symptom Survey (CISS) questionnaire. Results: With both types of display, CISS scores at least doubled immediately after subjects viewed the 3-D text image in an extreme stereoscopic condition compared to the 2-D condition (p < 0.001), while the mean reading speed slowed (p < 0.001). Mean changes in optometric test variables were not clinically or statistically significant (p values > 0.05). After the 3-D task one participant showed consistent clinically meaningful decreases in convergent fusional break and recovery points for both displays. Conclusion: When healthy adult subjects with normal binocular vision viewed text images at 3 m in extreme 3-D display settings for a short period of time there were no clinically significant mean changes in optometric test variables compared with 2-D viewing. [ABSTRACT FROM AUTHOR]

Although visual discomfort symptoms associated with near work have been correlated with clinical measures of accommodation, studies using objective recordings have not found corresponding deficits in accommodative function. One problem with previous studies is that accommodation measures have been too brief to assess accommodative fatigue. This study examined steady state accommodative responses among a college population with visual discomfort, over a 90-s time period. Thirty-one participants were grouped into high ( n = 15) or low visual discomfort groups ( n = 16) based on their scores on the Conlon Visual Discomfort Survey. Using the WAM-5500 autorefractor, accommodation responses were recorded at 5 Hz for two consecutive minutes at five viewing distances. The results showed a significant interaction between the high and low discomfort groups over time in accommodation response. The high discomfort group showed an increase in accommodative lag, whereas the low discomfort group had a stable response. Our study suggests that the high visual discomfort group is characterized by accommodative fatigue, with a higher lag of accommodation developing at a near viewing distance over time. [ABSTRACT FROM AUTHOR]

The purpose of this work was to characterize contrast sensitivity (CS) under short-wavelength illumination in 20 symptom-free subjects and eight asthenopics: all had normal unaided or corrected visual acuity and no sign of oculomotor disease. Threshold CS was assessed using the von Békésy tracking method from a viewing distance of 2.4 m (0.40 D). Three counterbalanced tasks required central fixation of black-and-white square-wave gratings (1, 5, 10, 14 and 17 c/deg) presented through a low-pass filter blue lens and (1) a +1.50 D lens; (2) a −1.50 D lens and (3) a 0 D lens, while attempting accommodation to minimize blur. Baseline increases in eye strain, which approached high levels at the end of the experiment, did not differentiate between the two groups of volunteers. All the subjects made evident appropriate accommodation during the low blur condition (0 D); the CS curve exhibited the expected characteristics. When the minus lens was placed before the eyes of the observers the distant square-wave gratings were still seen clearly, the eyes presumably had accommodated by an amount equal to the power of the negative lens. Compared with symptom-free subjects, asthenopics exhibited greater CS at the intermediate spatial frequencies both during the low blur and the minus blur conditions. Asthenopics may exhibit an individualized sensory tendency to react more strongly to shorter wavelengths of light and may therefore reflexively ‘drive’ their accommodative system harder than symptom-free subjects. This would explain the presence of their asthenopia in the first place. Blue light may, in addition, induce more arousal and higher alertness in this category of participants. This would boost the oculomotor aspects of their performance. These findings add to the current understanding of individual variability in the level of oculomotor loads following strenuous near work. [ABSTRACT FROM AUTHOR]

Practitioners’ decisions on when to intervene in decompensated heterophoria are often based on symptoms, which are in some cases an unreliable indicator of whether an intervention will be helpful. The aim of our study was to determine when prismatic corrections improve performance at a measure of dynamic visual function: the Wilkins Rate of Reading Test (WRRT). All participants manifested an aligning prism (associated heterophoria) on the near Mallett Unit of 0.5Δ or greater. There were 80 participants, of whom 58 had exophoria, 15 esophoria, and seven hyperphoria. The effect of the aligning prism on the WRRT was compared with a control lens using a double-masked randomised design. For exophoria, an aligning prism of 2Δ and above has a sensitivity of 67% and a specificity of 79% for improving performance at the WRRT by 5% or more. It is not possible from our data to achieve a good compromise between sensitivity and specificity for the other types of heterophoria. Patients in the horizontal (but not vertical) heterophoria groups had significantly more symptoms than a control group. The patients whose visual performance is improved by prismatic correction are not necessarily those who report the most symptoms. Our data suggest that exophoric patients of any age are likely to have improved visual performance with an intervention if they have an aligning prism of 2Δ or more, even in the absence of symptoms. We stress that although the Mallett Unit Fixation Disparity test provides useful information, its results need to be considered in the overall context of the patient's symptoms, lifestyle, and the results of other optometric tests. Although this study evaluated prismatic corrections, we note that interventions for decompensated heterophoria include not only prismatic corrections, but also eye exercises and refractive modification. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the relation between subjective symptoms at near and ocular accommodation in terms of the amplitude of accommodation and the relative accommodation. A secondary aim was to discuss the diagnosis of accommodative insufficiency. The chosen cohort was examined on two occasions with 1.8 years in between. The first examination included 72 children, 43 boys (mean age 8.1 years, ranging from 5.8 to 9.8) and 29 girls (mean age 8.3 years, ranging from 6.2 to 10.0). The second examination included 59 of these children, 34 boys (mean age 9.9 years, ranging from 7.8 to 11.7) and 25 girls (mean age 10.1 ranging from 8.0 to 11.8). Subjective symptoms at near work (headache, asthenopia, floating text, facility problems) were recorded and the amplitude and the relative accommodation, both positive and negative, were measured. The result from the questionnaire showed that at the first examination more than one-third of the children (34.7%) reported at least one subjective symptom when doing near work and 42.4% at the second examination. No symptoms were found among children younger than 7.5 years, but for children between 7.5 and 10 years old at the first examination, the prevalence of at least one symptom was 47.2%. At the second examination, symptoms were reported also for the youngest children, i.e. from the age of 8 years. The discrimination ability for the amplitude of accommodation, both monocular and binocular, was significant. In the first examination the difference between the mean for the two groups (i.e. with and without at least one symptom) was around 2.00 D monocular and 3.00 D binocular. Corresponding figures from the second examination was a difference between the mean for the two groups of around 3.50 D monocular and nearly 4.00 D binocular. We suggest that accommodation measurements should be performed more routinely and regularly, maybe as screening, especially in children over 8 years of age. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine it vision therapy (VT), as practiced within the constraints of UK optometric practice, employing graded routine eye exercises, is as an effective method for treatment of convergence insufficiency (CI) as previously published data suggest. The study also evaluates the associated symptoms before and after therapy. Methods: As many optometrists diagnose CI solely on the basis of near point of convergence (NPC) and treat only when symptoms are present (Letoumeau et al., 1979; Rouse et at., 1997), in this study CI was defined as NPC of 10 cm or greater (either with or without the presence of asthenopic symptoms for near work) accompanied by exophoria greater at near than at distance. The effect of treatment by optometric vision therapy (OVT) on the NPC and number of symptoms was investigated for 92 patients by retrospectively reviewing the clinical records. Success was defined as the restoration of NPC to normal values and significant reduction in the presenting symptoms. Results: The effect of treatment on the NPC was shown to be highly significant (t - 14.61, p < 0.001). Although treatment times were slightly longer, the success rates were higher than reported by other authors. Post-treatment values for NPC were: <10 cm (98.9%), <8.5 cm (95.7%) and <6.5 cm (80.4%). Longer treatment limes were noted for patients who complained that the text appeared to move (χ[SUP2] ρ = 0.007). Conclusion: Vision therapy is an effective method for treatment of CI. [ABSTRACT FROM AUTHOR]

Meares-Irlen Syndrome is characterized by visual stress (visual discomfort) and visual perceptual distortions that can be alleviated by individually prescribed colored filters. The benefit from colored filters can be demonstrated with the Wilkins Rate of Reading Test (WRRT). Previous research using individually prescribed colored overlays (sheets of plastic placed on a page) found that between one-fifth and one-third of unselected school-children show a significant (> 5%) improvement in their rate of reading with their chosen overlay, This 5% cut-off has good sensitivity and specificity for predicting those children who will continue to voluntarily use their overlay for a sustained period. Previous research has concentrated on children, and we sought to investigate the immediate effect of overlays on rate of reading In an adult population. Subjects were 113 unselected university students who answered a symptom questionnaire and were tested with the Wilkins Intuitive Overlays and WRRT. Some symptoms were common: 73% reported sore or tired eyes when reading and 40% reported four to 12 headaches a year. One hundred of the subjects chose an overlay as improving their immediate perception of text. These subjects were significantly more likely to report perceptual distortions and visual discomfort on viewing text than subjects who did not choose an overlay. The 100 subjects read 3.8% faster with the overlay than without any overlay (p < 0.00001 ). whereas the 13 subjects who did not choose an overlay read 1.7% slower with a placebo overlay than without (ρ - 0.37). Of the subjects who chose an overlay, 38% read more than 5% faster with the overlay and 2% read more than 25% faster. These results are comparable with those obtained for children. We conclude that Meares-Irlen Syndrome is likely to be as common in adults as it is in children. [ABSTRACT FROM AUTHOR]

Objective: Recording of the dynamic behaviour of the near triad during viewing of a three-dimensional (3-D) display is attempted. This may then be used to identify the possible origin of asthenopia and other ocular problems which occur whilst viewing such displays. Methods: Subjects viewed a 3-D display through an image splitter. Video recordings of ocular responses (pupil diameter, vergence and accommodation) were made with a commercially available video refraction unit at a distance of 1.2 m from the subject. Continuous recordings were made whilst a step-wise disparity of up to 2.6° was introduced between the targets presented to the two eyes, but the accommodative stimulus remained unchanged. Image analysis from the recordings was carried out on a personal computer. Results: Results showed various complex patterns of response, with the accommodation and vergence recorded reflecting the effect of stimulus conflict. Difficulty in fusional convergence was recorded when disparity was large, and the recordings reflected the subjects comments. Conclusion: The video refraction method is a useful tool Ear studying the dynamic behaviour of the near triad. [ABSTRACT FROM AUTHOR]

Visual correlates of specific learning difficulties (SpLD) include: binocular instability, low amplitude of accommodation, and Meares-Irlen Syndrome. Meares-Irlen Syndrome describes asthenopia and perceptual distortions which are alleviated by using individually prescribed coloured filters. Data from 323 consecutive patients seen over a 15 month period in an optometric clinic specialising in SpLD are reviewed. Visual symptoms and headaches were common. 48% of patients were given a conventional optometric intervention (spectacles, orthoptic exercises) and 50% were issued with coloured filters, usually for a trial period. 40% of those who were given orthoptic exercises were later issued with coloured overlays. 32% of those who were issued with coloured overlays were ultimately prescribed Precision Tinted lenses. Approximately half the sample were telephoned more than a year after the last clinical appointment. More than 70% of those who were prescribed Precision Tints were still wearing them daily, and results for this intervention compared favourably with data for non-tinted spectacles. The data suggest that many people with SpLD need optometric care and that the optometrist needs to be skilled in orthoptic techniques and cognisant of recent research on coloured filters. [ABSTRACT FROM AUTHOR]

We evaluated the accommodative and pupillary responses to sinusoidal target depth movement in 10 normal subjects and one patient by analysing frequency responses and associated Bode plots. The phase of the pupillary response significantly lagged behind that of accommodative response, which suggests that they are controlled by separate central nervous systems. We measured the baseline shift of each response trace using a regression line and found that they were larger at higher stimulation frequencies. A patient with severe asthenopia showed a considerable baseline shift in accommodative response. These analyses may be useful for the quantitative assessment of dynamic accommodation and pupillary response. [ABSTRACT FROM AUTHOR]

Measurements of tonic accommodation (TA) were made on 25 subjects using He-Ne laser optometry (HNL), infra-red optometry (IR) and near retinoscopy (NR) under darkroom conditions. All three techniques were shown to produce comparable mean estimates of TA (HNL: 1.10 D; IR: 1.15 D; NR: 1.07 D). Significant correlations were found between HNL and IR (r = 0.88, p < 0.001) and between HNL and NR (r = 0.81. p < 0.001). Control studies under cycloplegia indicate that the estimates are not seriously affected by fluctuations in accommodative state. These findings indicate that ophthalmic practitioners can gain access to refractive data that aids the clinical management of the "anomalous myopias" and asthenopia associated with VDU work. [ABSTRACT FROM AUTHOR]

Orthoptic therapy was instituted in an adult, alternating esotrope with asthenopia who exhibited inaccurate static accommodative responses with adequate, clinically determined, accommodative facility. During and following therapy the patient showed considerable improvement in accommodative accuracy and related visual functions, such as contrast sensitivity, in the absence of any change in strabismic deviation. This case provides the first laboratory documentation of orthoptic effects on accommodation in an adult strabismic. [ABSTRACT FROM AUTHOR]

This paper retrospectively examines the result of the treatment of 18 subjects (11 males, seven females) with divergence excess, using orthoptics. The mean age of the subjects was 15.8 years, which was significantly younger than the population from which this group was referred. Diplopia (89%) and asthenopia (56%) were the most frequently reported symptoms. Seventy-two percent of the subjects had intermittent deviations of the eyes. Over the mean necessary course of treatment of 5.2 weeks, the distance angle of deviation (slightly) and the positive vergences at distance and near were found to have changed significantly. The near angle of deviation, the negative vergences, the near point of convergence, the amplitude of accommodation, and the threshold of stereopsis were found to have remained stable over the treatment period. Further results of the study are presented and the implications of these results with regard to the treatment of divergence excess are briefly discussed. [ABSTRACT FROM AUTHOR]