Correction: Impact of visual impairment on balance and visual processing functions in students with special educational needs.

[This corrects the article DOI: 10.1371/journal.pone.0249052.].

Bilberry-containing supplements on severe dry eye disease in young and middle-aged adults: A 3-month pilot analysis.

Purpose: To explore the effect of bilberry and fish oil combination supplement on a small clinical sample patient-base with severe dry eyes. Methods: Twenty-four subjects were recruited with twelve randomly assigned to the intervention and control groups, respectively. Inclusion criteria included severe dry eye symptoms determined by scores >33 from the Ocular Surface Disease Index (OSDI) questionnaire. The intervention group was instructed to take an oral supplement with key ingredients of 600 mg bilberry extract and 240 mg docosahexaenoic acid-refined fish oil once daily for 3 months. The control group did not take any supplements. Mean changes in OSDI score, non-invasive tear break-up time (NITBUT), phenol red thread test (PRT), and percentage of meibomian gland openings were used as outcome measures. Testing was done at baseline, 1-month, and 3-month follow-up. Comparison between the treatment and control groups, and the younger adult and middle-age groups were performed. Results: The mean baseline values for the treatment and control groups were not clinically different. The OSDI score, NITBUT, PRT, and percentage of meibomian gland openings improved after taking the supplements for 3 months. The OSDI score, NITBUT, and PRT showed clinical improvements between the intervention and control groups. These improvements were consistent between the two age groups. Conclusion: This study suggested preliminary improvements in signs and symptoms of severe dry eyes that were independent of age after taking dietary supplementation of bilberry extract and fish oil for 3 months. Further studies using more device-based measures and a placebo supplement are warranted.

Impact of visual impairment on balance and visual processing functions in students with special educational needs.

INTRODUCTION: Vision is critical for children's development. However, prevalence of visual impairment (VI) is high in students with special educational needs (SEN). Other than VI, SEN students are prone to having functional deficits. Whether visual problems relate to these functional deficits is unclear. This study aimed to assess the impact of vision on visual processing functions and balance in SEN students through a community service. METHODS: Visual acuity (VA) and contrast sensitivity were measured in a total of 104 (aged 14.3±4.3) SEN students as the visual outcomes, followed by retinoscopy. Visual processing function assessment included facial expression recognition by card matching examiner's facial expression matching, and visual orientation recognition. Dynamic balance, by Timed Up and Go test, and static standing balance (postural sway in double-legged standing with feet-together and tandem-stance for open-eye and closed-eye conditions) were assessed. Static balance was presented in terms of the maximal medial-lateral and antero-posterior sways. RESULTS: Of the 104 students, 62 (59.6%) were classified as visually impaired according to WHO classification of visual impairment based on presenting distance acuity. Ocular problems (e.g. optic nerve anomaly, uncorrected/ under-corrected refractive errors) and neurological anomalies were the major causes of vision loss. VA was positively associated with visual processing functions (all p ≤ 0.01), as SEN students with better vision tended to perform better in visual orientation and facial expression recognition tasks, as well as dynamic balance function (p = 0.04). For the static balance, postural sway and VA showed a positive relationship under open-eye and tandem stance conditions. However, the relationship between postural sway and VA became negative under closed-eye and tandem stance conditions. CONCLUSION: This study found a high prevalence of SEN students with visual impairment, in which many of them were undetected. Optometric examination is important to improve their visual function to minimize the effect of vision on functional performance. Vision is critical in visual processing as well as playing an important role in maintaining balance in SEN students.

Instant vision assessment device for measuring refraction in low vision.

Clinical relevance: Refracting low vision patients require special procedures and strategies. A device-taking the reduced visual acuity and higher blur tolerance into account-is designed to measure refraction in this group.Background: Instant Vision Assessment Device (IVAD) is a stenopaeic slit refraction system in a binocular telescopic optometer calibrated to measure refraction. This study aims to validate IVAD in measuring refraction of low vision patients.Methods: Refractions were measured with IVAD on the right eyes of 35 normal subjects (ages nine to 69) and on the better eyes of 20 low vision subjects (ages 60 to 90) and compared with subjective refraction (SR). The visual acuities were compared in the low vision group. Paired Student t-test and Bland-Altman analysis were used to test the significance of difference and limits of agreement between methods, respectively.Results: In normal subjects, mean spherical equivalent refraction (M) measured by IVAD and SR was -2.88 ± 2.51 D and -2.72 ± 2.29 D, respectively, and the difference of -0.16 ± 0.47 D was not statistically significant (p = 0.05, t = 2.03). In low vision subjects, M measured by IVAD and SR was-0.66 ± 2.64 D and -0.55 ± 2.61 D, respectively, and the difference of -0.11 ± 0.59 D was also not statistically significant (p = 0.43, t = 2.09). Only the astigmatism J0 in the normal subject group of -0.03 ± 0.24 D by IVAD and 0.07 ± 0.17 D by SR showed a statistically significant difference of -0.10 ± 0.25 D (p = 0.04, t = 2.03). In low vision subjects, mean visual acuities with refraction from IVAD and SR were 0.52 ± 0.32 logMAR and 0.53 ± 0.32 logMAR, respectively, and the difference of 0.01 ± 0.07 logMAR was not statistically significant (p = 0.51, t = 2.09). At least 80% of the IVAD measure of refraction components (M, J0, J45) were within ±0.50 D of SR measure.Conclusion: IVAD is a practical and valid refraction method for low vision patients.

Development of optometry in the People's Republic of China.

The significant economic growth in China has resulted in a better quality of life. In order to cope with the demand for quality eye care, there are plans to increase the number of optometric personnel and to standardise the comprehensive eye-care services. This review aims to update the current educational programs in optometry and the regulations pertaining to the practice of optometry in China. There has been much progress since the publication of a report on the development of optometry in Greater China 15-years ago. China currently has three types of optometry programs: Diploma, Bachelor of Science, and Bachelor of Medicine. Only graduates of the Optometric Medicine program may perform full scope comprehensive eye-care services. Graduates from the other two types of programs may not use diagnostic or therapeutic pharmaceutical agents. The number of practising optometrists in China therefore needs to be planned by the Ministry of Education and the National Health Commission, accordingly.

Prevalence of visual problems among stroke survivors in Hong Kong Chinese.

BACKGROUND: Stroke, a common cerebrovascular accident, usually results in various extents of functional disability. Extensive studies have shown that ocular and visual problems are common in patients with stroke. Unfortunately, current stroke rehabilitation programs rarely address stroke-related ocular and visual problems in Hong Kong. METHODS: To examine how visual impairment (for example, deterioration in visual acuity and restriction in visual field) affects the stroke population in Hong Kong, vision screening was conducted for post-stroke patients attending in-patient and out-patient stroke clinics at two hospitals. RESULTS: One hundred and thirteen stroke patients were recruited. The percentage of various aspects of visual problems in Hong Kong post-stroke patients was generally lower than that reported in Western countries; however, a high percentage of patients had deficits in oculomotor (53.1 per cent) and vergence functions (11.5 per cent), restrictions in binocular visual field (11.5 per cent) and impairment in visual acuity (worse than 0.30 logMAR, 29.8 per cent). Conversely, only a small proportion of patients noticed problems with their vision (for example, diplopia and blurry vision) through subjective reports. This revealed that many post-stroke patients had undetected or undiagnosed ocular and visual problems. Appropriate referral was given to patients with visual problems for further evaluation and treatment. CONCLUSION: Neglecting visual problems may impose deteriorating effect on patients' stroke rehabilitation and functional independence and lead to increased incidents of injury. To address this potential hindrance in rehabilitation, formal screening for visual problems in stroke patients in a rehabilitation setting is essential.

Effect of bifocal and prismatic bifocal spectacles on myopia progression in children: three-year results of a randomized clinical trial.

IMPORTANCE: Myopia is a significant public health problem, making it important to determine whether a bifocal spectacle treatment involving near prism slows myopia progression in children. OBJECTIVE: To determine whether bifocal and prismatic bifocal spectacles control myopia in children with high rates of myopia progression and to assess whether the treatment effect is dependent on the lag of accommodation and/or near phoria status. DESIGN, SETTING, AND PARTICIPANTS: This 3-year randomized clinical trial was conducted in a private practice. A total of 135 (73 female and 62 male) Chinese-Canadian children (aged 8-13 years; mean [SE] age, 10.29 [0.15] years; mean [SE] myopia, -3.08 [0.10] D) with myopia progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments. A total of 128 (94.8%) completed the trial. INTERVENTIONS: Single-vision lenses (control, n = 41), +1.50-D executive bifocals (n = 48), and +1.50-D executive bifocals with 3-Δ base-in prism in the near segment of each lens (n = 46). MAIN OUTCOMES AND MEASURES Myopia progression (primary) measured using an automated refractor following cycloplegia and increase in axial length (secondary) measured using ultrasonography at intervals of 6 months for 36 months. RESULTS Myopia progression over 3 years was an average (SE) of -2.06 (0.13) D for the single-vision lens group, -1.25 (0.10) D for the bifocal group, and -1.01 (0.13) D for the prismatic bifocal group. Axial length increased an average (SE) of 0.82 (0.05) mm, 0.57 (0.07) mm, and 0.54 (0.06) mm, respectively. The treatment effect of bifocals (0.81 D) and prismatic bifocals (1.05 D) was significant (P < .001). Both bifocal groups had less axial elongation (0.25 mm and 0.28 mm, respectively) than the single-vision lens group (P < .001). For children with high lags of accommodation (≥ 1.01 D), the treatment effect of both bifocals and prismatic bifocals was similar (1.1 D) (P < .001). For children with low lags (<1.01 D), the treatment effect of prismatic bifocals (0.99 D) was greater than of bifocals (0.50 D) (P = .03). The treatment effect of both bifocals and prismatic bifocals was independent of the near phoria status. CONCLUSIONS AND RELEVANCE: Bifocal spectacles can slow myopia progression in children with an annual progression rate of at least 0.50 D after 3 years. These results suggest that prismatic bifocals are more effective for myopic children with low lags of accommodation. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00787579.

The role of suppression in amblyopia.

PURPOSE: This study had three main goals: to assess the degree of suppression in patients with strabismic, anisometropic, and mixed amblyopia; to establish the relationship between suppression and the degree of amblyopia; and to compare the degree of suppression across the clinical subgroups within the sample. METHODS: Using both standard measures of suppression (Bagolini lenses and neutral density [ND] filters, Worth 4-Dot test) and a new approach involving the measurement of dichoptic motion thresholds under conditions of variable interocular contrast, the degree of suppression in 43 amblyopic patients with strabismus, anisometropia, or a combination of both was quantified. RESULTS: There was good agreement between the quantitative measures of suppression made with the new dichoptic motion threshold technique and measurements made with standard clinical techniques (Bagolini lenses and ND filters, Worth 4-Dot test). The degree of suppression was found to correlate directly with the degree of amblyopia within our clinical sample, whereby stronger suppression was associated with a greater difference in interocular acuity and poorer stereoacuity. Suppression was not related to the type or angle of strabismus when this was present or the previous treatment history. CONCLUSIONS: These results suggest that suppression may have a primary role in the amblyopia syndrome and therefore have implications for the treatment of amblyopia.

Relationships among diabetic retinopathy, antioxidants, and glycemic control.

PURPOSE: Type 2 Diabetes Mellitus (DM) is increasing worldwide and affects ∼11% of the Hong Kong population. Diabetic retinopathy (DR) is a common cause of vision loss in type 2 DM. Risk of DR is increased by poor glycemic control, elevated lipids, and blood pressure, but it is not possible to predict the development or progression of DR at an individual level. Increased oxidative stress is thought to play a role. The use of a wider biomarker profile incorporating biomarkers of antioxidant status and oxidative stress may aid identification of individuals at higher risk or at very early stages of developing DR. METHODS: Four hundred twenty type 2 DM subjects without diabetic complications were investigated. Eyes were examined for DR and anterior and posterior ocular segment pathology. DR was graded according to Early Treatment Diabetic Retinopathy Study criteria. Demographic data were collected. Traditional risk factors plus biomarkers of antioxidant status and oxidative stress in fasting blood and urine were determined. RESULTS: Overall DR prevalence was 89%. No significant differences in any demographic measures or biomarkers were found among those subjects with different DR grades, or in those without DR. Significant correlations (p < 0.0001) between HbA1c and DNA damage, (ρ = 0.32) and fasting plasma glucose and DNA damage (ρ = 0.52) were seen. DNA damage was also significantly and inversely correlated (p < 0.0001) with both plasma ascorbic acid (ρ = -0.41) and plasma total antioxidant level (ρ = -0.21). CONCLUSIONS: DR prevalence was very high in this group, but no biomarker differences were seen in those with DR compared to those free of DR, or in those with different degrees of severity of DR. This group of 420 subjects is being followed up to investigate whether the extended biomarker profile at baseline is related to progression of and/or incident DR.

Bifocal lens control of myopic progression in children.

Bifocal spectacle lenses have been used as a strategy to slow myopic progression in children since the 1950s and perhaps earlier. The reported success of this strategy varies greatly, as does the design of studies reporting the outcomes of their use-from earlier retrospective analysis of records to later prospective clinical trials. Collectively, published data support the suggestion that bifocal lenses inhibit myopic development in children but only by a small amount and only in a subset of children. Possible reasons for the greatly varying outcomes include a lack of individualism of the treatment and failure to take the vergence system into account. This review summarises the results of bifocal and multifocal studies, describes how accommodation, convergence and their interaction are linked to myopic development and details how a bifocal treatment that takes this into account may be devised. Also discussed is whether alterations to peripheral retinal blur contribute to bifocal lens effects.

Factors affecting accuracy in the Developmental Eye Movement Test measurement for Cantonese-speaking children.

BACKGROUND: This study aims to determine the factors affecting the accuracy in the Developmental Eye Movement (DEM) test measurement for Cantonese-speaking children. METHOD: The voices of 10 Cantonese-speaking children (aged between six and eight years) undertaking the vertical test (40 numbers) of the DEM test were recorded on a digital audio recorder. These voice clips were assessed by an experienced examiner to give the DEM test times. The examiner repeated the measurement five times for each voice clip and completed all 10 voice clips from the 10 children. The average of a single measurement, the mean of two, the mean of three and the mean of five repeated measurements were then compared. Five experienced and five inexperienced examiners of the DEM test were asked to record the results from five Cantonese-speaking children by listening to the playback of prerecorded audio clips. The deviation of the results from the preset values between the two groups was compared. RESULTS: There is no difference between the single measurement and those obtained by mean of two, three, four or five. Both experienced and inexperienced examiners obtained a higher deviation from the preset values in the adjusted compared with the non-adjusted times in both vertical and horizontal times. Experienced examiners measured the vertical times and adjusted vertical times significantly closer to the preset values than the inexperienced examiners (paired t-test, p < 0.05). CONCLUSION: The DEM test needs to be measured only once for an accurate time measurement. Inaccurate assessment of 'reading errors' in the DEM test can increase the inaccuracy of the adjusted times. It is suggested that an audio recording of the test be made to allow reassessment of reading errors. Experience in using the DEM test yields a more accurate DEM measurement as errors are detected more easily.

Quantifying sensory eye dominance in the normal visual system: a new technique and insights into variation across traditional tests.

PURPOSE: Although eye dominance assessment is used to assist clinical decision-making, current understanding is limited by inconsistencies across the range of available tests. A new psychophysical test of sensory eye dominance has been developed that objectively measures the relative contribution of each eye to a fused suprathreshold binocular percept. METHODS: Six standard tests and the newly developed test were used to measure motor and sensory dominance in a group of 44 binocularly normal individuals (mean age, 29.5 ± 9.10 years). The new test required observers to perform a motion coherence task under dichoptic viewing conditions, wherein a population of moving, luminance-defined signal (coherently moving) and noise (randomly moving) dots were presented separately to each eye. The observers judged the motion direction of the signal dots. Motion coherence thresholds were measured by varying the ratio of signal-to-noise dots, in a staircase procedure. RESULTS: The new dichoptic motion coherence threshold test revealed a clear bimodal distribution of sensory eye dominance strength, wherein the majority of the participants (61%) showed weak dominance, but a significant minority (39%) showed strong dominance. Subsequent analysis revealed that the strong-dominance group showed greater consistency across the range of traditional eye dominance tests used. CONCLUSIONS: This new quantitative dichoptic motion coherence threshold technique suggests that there are two separate sensory eye dominance strength distributions among observers with normal binocular vision: weak and strong eye dominance. This finding may provide a basis for clinical decision-making by indicating whether eye dominance is likely to be an important consideration in a particular patient.

The developmental eye movement (DEM) test and Cantonese-speaking children in Hong Kong SAR, China.

BACKGROUND: There is no published norm for the Developmental Eye Movement (DEM) Test for Cantonese-speaking Chinese children. This study aimed to determine the normative values of this test for Cantonese-speaking Chinese children in Hong Kong SAR and to compare the results with the published norms of English-speaking and Spanish-speaking children. METHOD: Cantonese-speaking students aged from 6 to 11 years were tested by the DEM test in Cantonese and a digital recorder was used to record the process. The DEM scores for the 305 students were determined by listening again to the audio records after the test and computed by using the formula from the DEM manual, except that the 'vertical scores' were adjusted by taking the vertical errors into consideration. The results were compared with other norms that have been published. RESULTS: Our subjects made more vertical errors than in other normative studies and adjusted vertical scores were proposed. In both adjusted vertical and horizontal scores, the Cantonese-speaking children completed the tests much faster than the norms for English- and Spanish-speaking children, the differences of the means being significant (p < 0.0001) in all age groups. CONCLUSION: The DEM norms may be affected by differences in languages, cultures and education systems among different ethnicities. The norms of the DEM test are proposed for Cantonese-speaking children in Hong Kong SAR, China.

Randomized trial of effect of bifocal and prismatic bifocal spectacles on myopic progression: two-year results.

OBJECTIVE: To determine whether bifocal and prismatic bifocal spectacles could control myopia in children with high rates of myopic progression. METHODS: This was a randomized controlled clinical trial. One hundred thirty-five (73 girls and 62 boys) myopic Chinese Canadian children (myopia of > or =1.00 diopters [D]) with myopic progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments: (1) single-vision lenses (n = 41), (2) +1.50-D executive bifocals (n = 48), or (3) +1.50-D executive bifocals with a 3-prism diopters base-in prism in the near segment of each lens (n = 46). MAIN OUTCOME MEASURES: Myopic progression measured by an automated refractor under cycloplegia and increase in axial length (secondary) measured by ultrasonography at 6-month intervals for 24 months. Only the data of the right eye were used. RESULTS: Of the 135 children (mean age, 10.29 years [SE, 0.15 years]; mean visual acuity, -3.08 D [SE, 0.10 D]), 131 (97%) completed the trial after 24 months. Myopic progression averaged -1.55 D (SE, 0.12 D) for those who wore single-vision lenses, -0.96 D (SE, 0.09 D) for those who wore bifocals, and -0.70 D (SE, 0.10 D) for those who wore prismatic bifocals. Axial length increased an average of 0.62 mm (SE, 0.04 mm), 0.41 mm (SE, 0.04 mm), and 0.41 mm (SE, 0.05 mm), respectively. The treatment effect of bifocals (0.59 D) and prismatic bifocals (0.85 D) was significant (P < .001) and both bifocal groups had less axial elongation (0.21 mm) than the single-vision lens group (P < .001). CONCLUSIONS: Bifocal lenses can moderately slow myopic progression in children with high rates of progression after 24 months. APPLICATIONS TO CLINICAL PRACTICE: Bifocal spectacles may be considered for slowing myopic progression in children with an annual progression rate of at least 0.50 D.

Thyroid disease induced diplopia.

This report describes a patient who was suffering from incomitant vertical diplopia due to Graves' ophthalmopathy. Previous optical treatment was a diffusing lens for the left eye resulting in monocular vision only. We proceeded to measure the amount of diplopia and prescribed a vertical Fresnel prism to be placed on the left spectacle lens to alleviate his diplopia and resolve his mobility problems. The amount of prism was further reduced by five prism dioptres after extraocular muscle surgery.

The effect of positive-lens addition and base-in prism on accommodation accuracy and near horizontal phoria in Chinese myopic children.

The effect of positive-lens addition (0, +0.75, +1.50, +2.25, +3.00 D each eye) and base-in prism power (0, 1.5, 3 Delta each eye) on both near focusing errors and latent horizontal deviations was evaluated in 29 Chinese myopic children (age: 10.3 +/- 1.9 years, refractive error: -2.73 +/- 1.31 D). Accommodation response and phoria were measured by the Shin-Nippon auto-refractor (right eye) and Howell-Dwyer near phoria card at 33 cm with each of the 15 lens/prism combinations in random order. The initial accommodative error was -0.96 +/- 0.67 D (lag) and near phoria was -0.8 +/- 5.0 Delta (exophoria). The positive-lens addition decreased the accommodative lag but increased the exophoria as the power increased (e.g. up to -9.1 +/- 4.1 Delta with +3 D). A 6-Delta base-in prism totally controlled the exophoria induced by a +1.50 D addition (-0.3 +/- 4.3 Delta), but the accommodative lag was still considerable (-0.69 +/- 0.54 D). In the graphical analysis of the data, a lens addition of +2.25 D combined with a 6-Delta base-in prism minimized both the lag and lens-induced exophoria to -0.33 D and -2.4 Delta respectively (regression analysis). This lens and prism combination decreased the lens-induced exophoria by 4.5 Delta compared with that measured with +2.25 D alone (-2.4 Delta vs -6.9 Delta). The results suggest that incorporating near base-in prism when prescribing bifocal lenses for young progressing myopes with exophoria could reduce the positive lens-induced oculomotor imbalance.

Refractive error and visual acuity changes in orthokeratology patients.

PURPOSE: To evaluate the refractive error and visual acuity (VA) at various contrast levels in the two eyes of overnight orthokeratology (ortho-k) subjects, and to compare their postortho-k VA with the best corrected VA of spectacle-wearing control subjects matched for age, gender, and initial refractive error. METHODS: Distance postortho-k uncorrected and best corrected logMAR VA at four different contrast levels of 31 ortho-k (test) subjects (aged 7-35 years old) and the best corrected VA of 31 spectacle-wearing (control) subjects were measured and compared using the Waterloo Four-Contrast LogMAR VA Chart, which incorporated four sets of letters at different contrast levels: 90%, 48%, 21%, and 7%. Noncycloplegic manifest refractive error was measured in both eyes. RESULTS: The mean +/- SD percentage reductions in spherical equivalent achieved in the current study were 92% +/- 11% in the better eye and 84% +/- 14% in the worse eye of the test subjects. Postortho-k uncorrected VAs were significantly correlated with the residual overall blurring strength (length of the vector representing the residual refractive error) in both eyes at all contrast levels. The mean postortho-k uncorrected VA in the better eye were 0.00 +/- 0.11, 0.08 +/- 0.11, 0.21 +/- 0.12, and 0.46 +/- 0.13 with the 90%, 48%, 21%, and 7% contrast charts, respectively. These were comparable to the best corrected VA of the better eye of the control group with the 90% (-0.03 +/- 0.07) and 48% contrast charts (0.03 +/- 0.09), but worse than those of the control group with the 21% (0.13 +/- 0.10) and 7% (0.35 +/- 0.13) contrast charts. Postortho-k VA, with the four different contrast charts, improved by 0.07 to 0.12 log units in the better eye and 0.15 to 0.18 log units in the worse eye after correction of the residual refractive error; the improved VA was comparable to the best corrected VA of the control group. CONCLUSIONS: Postortho-k visual outcomes were compromised primarily due to the presence of residual refractive error. Although the uncorrected postortho-k VA was comparable to the best corrected VA of the spectacle wearers at high-contrast levels, it was worse at low-contrast levels and caused a significant between-eye difference at all contrast levels. Therefore, we suggested that monocular VA at high- and low-contrast levels should be evaluated for ortho-k patients.