Age-matched analysis of axial length growth in myopic children wearing defocus incorporated multiple segments spectacle lenses.

BACKGROUND/AIMS: Defocus incorporated multiple segments (DIMS) spectacle lenses are known to be able to inhibit axial length (AL) growth in myopic children compared with single vision (SV) spectacle lenses. However, it is not known whether AL growth is sufficiently inhibited to achieve the treatment goal of physiological AL growth. METHODS: Of the data already collected in 2014-2017 by Lam et al, the AL growth with DIMS and SV spectacle lenses was re-evaluated according to the age-matched myopia control system. The individual AL growth after the first year of treatment of each eye was plotted against the corresponding age of the same time point in a colour-coded scheme. The two treatment groups were further subdivided based on their age and their baseline AL. RESULTS: Overall, 65% (61% of male, 70% of female) of eyes with DIMS spectacle lenses and 16% (16% of male, 16% of female) of eyes with SV spectacle lenses are within range of physiological AL growth rate. Median AL growth rate of eyes with DIMS spectacle lenses is also within the range of physiological growth. In the subgroups, eyes with DIMS spectacle lenses were also superior to the ones with SV spectacle lenses regarding this treatment goal. Of the children with SV spectacle lenses, older children and children with eyes with high baseline AL were least likely to achieve physiological AL growth rate. CONCLUSIONS: DIMS spectacle lenses can bring the AL growth rate of myopic children to the level of physiological AL growth rate, indicating 100% reduction of excessive myopic AL growth, independent of age and baseline AL. Older children and children with eyes with high AL have the risk to have increased AL growth without treatment.

Myopia Control Effect Is Influenced by Baseline Relative Peripheral Refraction in Children Wearing Defocus Incorporated Multiple Segments (DIMS) Spectacle Lenses.

The aim of this study is to investigate if baseline relative peripheral refraction (RPR) influences the myopia control effects in Chinese myopic children wearing Defocus Incorporated Multiple Segments (DIMS) lenses. Peripheral refraction at 10°, 20°, and 30° nasal (10 N, 20 N, 30 N) and temporal (10 T, 20 T, 30 T) retina were measured at six-month intervals for children who participated in a 2-year randomized controlled trial. The relationship between the baseline peripheral refractions and myopia progression and axial length changes were analysed. A total of 79 children and 81 children in the DIMS and single vision (SV) group were investigated, respectively. In the DIMS group, more baseline myopic RPR spherical equivalent (SE) was associated with more myopic progression (10 N: r = 0.36, p = 0.001; 20 N: r = 0.35, p = 0.001) and greater axial elongation (10 N: r = −0.34, p = 0.001; 20 N: r = −0.29, p = 0.006) after adjusting for co-factors. In the SV group, baseline RPR had association with only myopia progression (10 N: r = 0.37, p = 0.001; 20 N: r = 0.36, p = 0.001; 30 N: r = 0.35, p = 0.002) but not with axial elongation after Bonferroni correction (p > 0.008). No statistically significant relationship was found between temporal retina and myopia progression or axial elongation in both groups. Children with baseline myopic RPR had statistically significant more myopia progression (mean difference around −0.40 D) and more axial elongation (mean difference 0.15 mm) when compared with the children having baseline hyperopic RPR in the DIMS group but not in the SV group. In conclusion, the baseline RPR profile may not influence future myopia progression or axial elongation for the SV lens wearers. However, DIMS lenses slowed down myopia progression and was better in myopia control for the children with baseline hyperopic RPR than the children with myopic RPR. This may partially explain why myopia control effects vary among myopic children. Customised myopic defocus for individuals may optimise myopia control effects, and further research to determine the optimal dosage, with consideration of peripheral retinal profile, is warranted.

Adherence to home-based videogame treatment for amblyopia in children and adults.

Clinical relevance: Home-based videogame treatments are increasingly popular for amblyopia treatment. However, at-home treatments tend to be done in short sessions and with frequent disruptions, which may reduce the effectiveness of binocular visual stimulation. These treatment adherence patterns need to be accounted for when considering dose-response relationships and treatment effectiveness.Background: Home-based videogame treatments are increasingly being used for various sensory conditions, including amblyopia ('lazy eye'), but treatment adherence continues to limit success. To examine detailed behavioural patterns associated with home-based videogame treatment, we analysed in detail the videogame adherence data from the Binocular tReatment of Amblyopia with VideOgames (BRAVO) clinical trial (ACTRN12613001004752).Methods: Children (7-12 years), teenagers (13-17 years) and adults (≥ 18 years) with unilateral amblyopia were loaned iPod Touch devices with either an active treatment or placebo videogame and instructed to play for a total of 1-2 hours/day for six weeks at home. Objectively-recorded adherence data from device software were used to analyse adherence patterns such as session length, daily distribution of gameplay, use of the pause function, and differences between age groups. Objectively-recorded adherence was also compared to subjectively-reported adherence from paper-based diaries.Results: One hundred and five of the 115 randomised participants completed six weeks of videogame training. Average adherence was 65% (SD 37%) of the minimum hours prescribed. Game training was generally performed in short sessions (mean 21.5, SD 11.2 minutes), mostly in the evening, with frequent pauses (median every 4.1 minutes, IQR 6.1). Children played in significantly shorter sessions and paused more frequently than older age groups (p < 0.0001). Participants tended to over-report adherence in subjective diaries compared to objectively-recorded gameplay time.Conclusion: Adherence to home-based videogame treatment was characterised by short sessions interspersed with frequent pauses, suggesting regular disengagement. This complicates dose-response calculations and may interfere with the effectiveness of treatments like binocular treatments for amblyopia, which require sustained visual stimulation.

Effect of dichoptic video game treatment on mild amblyopia - a pilot study.

PURPOSE: The effect of contrast-balanced dichoptic video game training on distance visual acuity (DVA) and stereo acuity has been investigated in severe-to-moderate amblyopia, but its effect on mild amblyopia and fixation stability has not been assessed. This pilot study aimed to evaluate the effect of home-based dichoptic video game on amblyopic eye DVA, stereo acuity and fixation stability in adults with mild amblyopia. METHODS: A randomized single-masked design was adopted. The active 6-week home-based treatment was an anaglyphic, contrast-balanced dichoptic video game, and the placebo was an identical non-dichoptic game. Participants (n = 23) had mild amblyopia (amblyopic DVA ≤ 0.28 log Minimum Angle of Resolution (logMAR)). The primary outcome was change in amblyopic DVA at 6 weeks postrandomization. Near visual acuity, stereo acuity and fixation stability (bivariate contour eclipse area) were also measured. Follow-up occurred at 12 and 24 weeks postrandomization. RESULTS: Mean amblyopic eye DVA was 0.21 ± 0.06 and 0.18 ± 0.06 logMAR for the active (n = 12) and placebo (n = 11) group, respectively. Amblyopic DVA improved significantly more in the active group (0.09 ± 0.05) than in the placebo group (0.03 ± 0.04 logMAR; p < 0.05). The difference between groups remained at 12 weeks postrandomization (p = 0.04) but not at 24 weeks (p = 0.43). Titmus stereo acuities improved significantly more in the active group (0.40 log arcsec) than in the placebo group (0.09 log arcsec) after 6 weeks of gameplay. The between-group difference was still present at 24 weeks postrandomization (p = 0.05). There were no differences between groups on any other secondary outcomes. CONCLUSION: Home-based dichoptic video gameplay may be an effective method to improve amblyopic DVA and stereo acuity in mild amblyopia.

Optical treatment of amblyopia in older children and adults is essential prior to enrolment in a clinical trial.

PURPOSE: Optical treatment alone can improve visual acuity (VA) in children with amblyopia, thus clinical trials investigating additional amblyopia therapies (such as patching or videogames) for children require a preceding optical treatment phase. Emerging therapies for adult patients are entering clinical trials. It is unknown whether optical treatment is effective for adults with amblyopia and whether an optical correction phase is required for trials involving adults. METHODS: We examined participants who underwent optical treatment in the Binocular Treatment for Amblyopia using Videogames (BRAVO) clinical trial (ANZCTR ID: ACTRN12613001004752). Participants were recruited in three age groups (7 to 12, 13 to 17, or ≥18 years), and had unilateral amblyopia due to anisometropia and/or strabismus, with amblyopic eye VA of 0.30-1.00 logMAR (6/12 to 6/60, 20/40 to 20/200). Corrective lenses were prescribed based on cycloplegic refraction to fully correct any anisometropia. VA was assessed using the electronic visual acuity testing algorithm (e-ETDRS) test and near stereoacuity was assessed using the Randot Preschool Test. Participants were assessed every four weeks up to 16 weeks, until either VA was stable or until amblyopic eye VA improved to better than 0.30 logMAR, rendering the participant ineligible for the trial. RESULTS: Eighty participants (mean age 24.6 years, range 7.6-55.5 years) completed four to 16 weeks of optical treatment. A small but statistically significant mean improvement in amblyopic eye VA of 0.05 logMAR was observed (S.D. 0.08 logMAR; paired t-test p < 0.0001). Twenty-five participants (31%) improved by ≥1 logMAR line and of these, seven (9%) improved by ≥2 logMAR lines. Stereoacuity improved in 15 participants (19%). Visual improvements were not associated with age, presence of strabismus, or prior occlusion treatment. Two adult participants withdrew due to intolerance to anisometropic correction. Sixteen out of 80 participants (20%) achieved better than 0.30 logMAR VA in the amblyopic eye after optical treatment. Nine of these participants attended additional follow-up and four (44%) showed further VA improvements. CONCLUSIONS: Improvements from optical treatment resulted in one-fifth of participants becoming ineligible for the main clinical trial. Studies investigating additional amblyopia therapies must include an appropriate optical treatment only phase and/or parallel treatment group regardless of patient age. Optical treatment of amblyopia in adult patients warrants further investigation.

Effectiveness of a Binocular Video Game vs Placebo Video Game for Improving Visual Functions in Older Children, Teenagers, and Adults With Amblyopia: A Randomized Clinical Trial.

Importance: Binocular amblyopia treatment using contrast-rebalanced stimuli showed promise in laboratory studies and requires clinical trial investigation in a home-based setting. Objective: To compare the effectiveness of a binocular video game with a placebo video game for improving visual functions in older children and adults. Design, Setting, and Participants: The Binocular Treatment of Amblyopia Using Videogames clinical trial was a multicenter, double-masked, randomized clinical trial. Between March 2014 and June 2016, 115 participants 7 years and older with unilateral amblyopia (amblyopic eye visual acuity, 0.30-1.00 logMAR; Snellen equivalent, 20/40-20/200) due to anisometropia, strabismus, or both were recruited. Eligible participants were allocated with equal chance to receive either the active or the placebo video game, with minimization stratified by age group (child, age 7 to 12 years; teenager, age 13 to 17 years; and adult, 18 years and older). Interventions: Falling-blocks video games played at home on an iPod Touch for 1 hour per day for 6 weeks. The active video game had game elements split between eyes with a dichoptic contrast offset (mean [SD] initial fellow eye contrast, 0.23 [0.14]). The placebo video game presented identical images to both eyes. Main Outcomes and Measures: Change in amblyopic eye visual acuity at 6 weeks. Secondary outcomes included compliance, stereoacuity, and interocular suppression. Participants and clinicians who measured outcomes were masked to treatment allocation. Results: Of the 115 included participants, 65 (56.5%) were male and 83 (72.2%) were white, and the mean (SD) age at randomization was 21.5 (13.6) years. There were 89 participants (77.4%) who had prior occlusion. The mean (SD) amblyopic eye visual acuity improved 0.06 (0.12) logMAR from baseline in the active group (n = 56) and 0.07 (0.10) logMAR in the placebo group (n = 59). The mean treatment difference between groups, adjusted for baseline visual acuity and age group, was -0.02 logMAR (95% CI, -0.06 to 0.02; P = .25). Compliance with more than 25% of prescribed game play was achieved by 36 participants (64%) in the active group and by 49 (83%) in the placebo group. At 6 weeks, 36 participants (64%) in the active group achieved fellow eye contrast greater than 0.9 in the binocular video game. No group differences were observed for any secondary outcomes. Adverse effects included 3 reports of transient asthenopia. Conclusions and Relevance: The specific home-based binocular falling-blocks video game used in this clinical trial did not improve visual outcomes more than the placebo video game despite increases in fellow eye contrast during game play. More engaging video games with considerations for compliance may improve effectiveness. Trial Registration: anzctr.org.au Identifier: ACTRN12613001004752.

Higher-Order Aberrations in Children and Adolescents of Southwest China.

SIGNIFICANCE: This study provides a descriptive characterization of higher-order optical aberrations for the eyes of a larger number of Chinese children and adolescents. PURPOSE: To determine the distribution of higher-order aberrations (HOAs) of Han Chinese young subjects with normal vision and their relationship to age. METHODS: Children and adolescents, aged from 3 to 17 years, with normal visual acuity were enrolled, and their wavefront aberrations for a 6-mm pupil were evaluated by the Zywave II aberrometer. Their correlations with age were analyzed, and the 95% statistical reference ranges were computed for each Zernike term. RESULTS: A total of 1634 eyes (287 for preschool-age children, 897 for school-age children, and 450 for adolescents) were analyzed. There was a significant correlation with age and the root mean square (RMS) of total HOAs (r = 0.256, P < .0001), third-order aberrations (r = 0.062, P = .029), fourth-order aberrations (r = 0.197, P < .0001), fifth-order aberrations (r = 0.067, P = .017), and trefoil-like aberrations (r = 0.100, P < .0001) in the myopic group. There were significant differences in RMS values (except coma-like aberrations, χ = 4.179, P = .124) as well as the Zernike coefficients among three different age groups. Therefore, the 95% statistical normal reference values were calculated separately for three age groups. CONCLUSIONS: The RMS value of total HOAs, coma-like, trefoil-like, third-order, fourth-order, and fifth-order aberrations are correlated with age, and the RMS values and Zernike coefficients of aberrations were different in different age stages of the subjects. This study described the distribution of HOAs in children and adolescents and established 95% statistical normal values of HOAs for different ages of children and adolescents by analyzing the HOAs in a large number of the Han Chinese clinical population.

Binocular treatment of amblyopia using videogames (BRAVO): study protocol for a randomised controlled trial.

BACKGROUND: Amblyopia is a common neurodevelopmental disorder of vision that is characterised by visual impairment in one eye and compromised binocular visual function. Existing evidence-based treatments for children include patching the nonamblyopic eye to encourage use of the amblyopic eye. Currently there are no widely accepted treatments available for adults with amblyopia. The aim of this trial is to assess the efficacy of a new binocular, videogame-based treatment for amblyopia in older children and adults. We hypothesise that binocular treatment will significantly improve amblyopic eye visual acuity relative to placebo treatment. METHODS/DESIGN: The BRAVO study is a double-blind, randomised, placebo-controlled multicentre trial to assess the effectiveness of a novel videogame-based binocular treatment for amblyopia. One hundred and eight participants aged 7 years or older with anisometropic and/or strabismic amblyopia (defined as ≥0.2 LogMAR interocular visual acuity difference, ≥0.3 LogMAR amblyopic eye visual acuity and no ocular disease) will be recruited via ophthalmologists, optometrists, clinical record searches and public advertisements at five sites in New Zealand, Canada, Hong Kong and Australia. Eligible participants will be randomised by computer in a 1:1 ratio, with stratification by age group: 7-12, 13-17 and 18 years and older. Participants will be randomised to receive 6 weeks of active or placebo home-based binocular treatment. Treatment will be in the form of a modified interactive falling-blocks game, implemented on a 5th generation iPod touch device viewed through red/green anaglyphic glasses. Participants and those assessing outcomes will be blinded to group assignment. The primary outcome is the change in best-corrected distance visual acuity in the amblyopic eye from baseline to 6 weeks post randomisation. Secondary outcomes include distance and near visual acuity, stereopsis, interocular suppression, angle of strabismus (where applicable) measured at baseline, 3, 6, 12 and 24 weeks post randomisation. Treatment compliance and acceptability will also be assessed along with quality of life for adult participants. DISCUSSION: The BRAVO study is the first randomised controlled trial of a home-based videogame treatment for older children and adults with amblyopia. The results will indicate whether a binocular approach to amblyopia treatment conducted at home is effective for patients aged 7 years or older. TRIAL REGISTRATION: This trial was registered in Australia and New Zealand Clinical Trials Registry ( ACTRN12613001004752 ) on 10 September 2013.

How representative is the 'Representative Value' of refraction provided by the Shin-Nippon NVision-K 5001 autorefractor?

PURPOSE: The aim of the study was to evaluate the level of agreement between the 'Representative Value' (RV) of refraction obtained from the Shin-Nippon NVision-K 5001 instrument with values calculated from individual measurement readings using standard algebraic methods. METHODS: Cycloplegic autorefraction readings for 101 myopic children aged 8-13 years (10.9 ± 1.42 years) were obtained using the Shin-Nippon NVision-K 5001. Ten autorefractor measurements were taken for each eye. The spherical equivalent (SE), sphere (Sph) and cylindrical component (Cyl) power of each eye were calculated, firstly, by averaging the 10 repeated measurements (Mean SE, Mean Sph and Mean Cyl), and secondly, by the vector representation method (Vector SE, Vector Sph and Vector Cyl). These calculated values were then compared with those of RV (RV SE, RV Sph and RV Cyl) provided by the proprietary software of the NVision-K 5001 using one-way analysis of variance (anova). The agreement between the methods was also assessed. RESULTS: The SE of the subjects ranged from -5.37 to -0.62 D (mean ± SD, = -2.89 ± 1.01 D). The Mean SE was in exact agreement with the Vector SE. There were no significant differences between the RV readings and those calculated using non-vectorial or vectorial methods for any of the refractive powers (SE, p = 0.99; Sph, p = 0.93; Cyl, p = 0.24). The (mean ± SD) differences were: RV SE vs Mean SE (and also RV SE vs Vector SE) -0.01 ± 0.06 D; RV Sph vs Mean Sph, -0.01 ± 0.05 D; RV Sph vs Vector Sph, -0.04 ± 0.06 D; RV Cyl vs Mean Cyl, 0.01 ± 0.07 D; RV Cyl vs Vector Cyl, 0.06 ± 0.09 D. Ninety-eight percent of RV reading differed from their non-vectorial or vectorial counterparts by less than 0.25 D. CONCLUSION: The RV values showed good agreement to the results calculated using conventional methods. Although the formula used to calculate RV by the NVision-K 5001 autorefractor is proprietary, our results provide validation for the use of RV measurements in clinical practice and vision science research.

Visual profile of children with handwriting difficulties in Hong Kong Chinese.

The purpose of this study was to find out the visual profiles of children with handwriting difficulties (HWD) in Hong Kong Chinese. Forty-nine children with HWD (mean age 8.4 ± 1.1 years) and 27 controls (mean age 7.7 ± 0.7 years) were recruited. All subjects received eye examination and vision assessment included ocular health, refraction, accommodative functions, binocularity, visual perception (by Gardner reversal frequency test: recognition subtest; Test of visual perceptual skills (non-motor)-revised) and motor skills (by The Beery-Buktenica developmental test of visual motor integration; Detroit test of motor speed and precision). Higher percentages of tropia and phoria (of magnitude >6 prism dioptres) were found in children with HWD of 6.1% and 14.3% respectively. After adjusted for the effect of age, children with HWD showed significantly worse accommodative facility, directionality, visual discrimination, visual spatial relation, visual form constancy, visual sequential memory, visual figure ground, visual closure and visual motor integration. Studies reported the visual functions of children with HWD were mostly concerned with alphabetic languages, while studies concerning Chinese HWD were relatively less. This study provided the visual profiles of children with Chinese HWD. Based on the visual profile, further study is indicated to investigate the effect of optometric interventions on the assessment and remediation for children with HWD.

Prevalence of myopia-related retinal changes among 12-18 year old Hong Kong Chinese high myopes.

PURPOSE: To determine the prevalence and risk factors of myopia-related retinal changes in Hong Kong Chinese adolescents with high myopia. METHODS: A cross-sectional study on Hong Kong Chinese teenage subjects with high myopia was conducted between January 2005 and June 2009. Subjects were recruited via newspaper advertisements, invitation letters to schools, leaflets and posters. Data collected included history related to myopia progression and retinal characteristics. RESULTS: In total, 120 subjects (61 boys and 59 girls) were recruited. The mean age was 14.8 ± 1.6 years (range: 12-18 years). The mean SER of the eyes was -8.41 ± 1.60 D. Ninety four of the 120 adolescents were found to have a retinal change of which 0.8% were sight-threatening, 2.5% were posterior pole changes, and 61.7% were peripheral retinal changes. The five most frequent retinal changes found were optic nerve crescents (52.5%), white-without-pressure (51.7%), lattice degeneration (5.8%), microcystoid degeneration (5%) and pigmentary degeneration (4.2%). After adjusting for myopia over -8 D, age, gender, duration of myopia, family retinal history and intraocular pressure (IOP), binary logistic regressions showed that an axial length longer than 26.5 mm was a significant risk factor for peripheral retinal changes, optic nerve crescents and white-without-pressure. CONCLUSIONS: Peripheral retinal degenerative changes and optic nerve crescent were found in a significant proportion of high myopic teenage subjects. There is increased risk of retinal changes in eyes with an axial length >26.5 mm in 12-18 year-olds.

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.

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.

Retinal thickness in myopic and non-myopic eyes.

PURPOSE: To investigate the retinal thickness profile in myopic and non-myopic eyes. METHODS: The retinal thickness profile of 30 myopic eyes [spherical equivalent error (SER) between -6.00 and -13.63 D] and 31 non-myopic eyes (SER between +2.75 and -0.50 D) were measured using the Stratus OCT (Carl Zeiss Meditec, Dublin, CA, USA). Two scan types were used: the Macular Thickness Map and the Customized Line Scan for a central 80° horizontal retinal thickness profile. RESULTS: At foveal center and fovea, myopic eyes had a thicker retina than the non-myopic group (p = 0.002 and 0.044, respectively). At other zones of the macula, the retina was significantly thinner in myopic eyes compared to non-myopic eyes (p < 0.01, unpaired t-test). From 40° nasal to 40° temporal retina, a general reduction of retinal thickness was observed across the myopic retina compared to the non-myopic retina except at 20° nasal to fixation. CONCLUSIONS: There was general reduction in retinal thickness within the horizontal central 80° in myopic eyes compared with non-myopic eyes.

Use of the Optomap with lid retraction and its sensitivity and specificity.

BACKGROUND: Optomap uses the ultra-wide field scanning laser ophthalmoscopy to provide retinal examination. It permits fundus examination without the use of a mydriatic, which is more comfortable for the patients. This paper determines the sensitivity and specificity of the Optomap for detecting retinal signs under non-mydriatic conditions. METHODS: Fifty-four eyes identified with retinal/choroidal signs and eight normal eyes were recruited from 31 Hong Kong Chinese subjects. Photo-documentation of fundal changes was obtained with the Optomap under non-mydriatic conditions before a dilated fundus examination by a clinician using standard procedures. The eyelid was retracted using a cotton bud when necessary. Dilated fundus examinations were performed by another clinician using binocular indirect ophthalmoscopy and slitlamp biomicroscopy with a fundus lens. The Optomap images were evaluated by four other investigators under masked condition. The International Classification of Disease, Ninth Revision (ICD-9-CM) was adopted for recording retinal features. Screening results were compared with those obtained using the dilated fundus examination as the gold standard. RESULTS: The cotton bud method for eyelid retraction showed an improvement in the area of retina that could be visualised. The sensitivity and specificity of the Optomap averaged 76.4 and 71.9 per cent, respectively. Some fundal signs were missed by all observers in the Optomap but not with the biomicroscope. These included white-without-pressure, lattice degeneration, paramacular drusen and pigmentary changes at central fundus. CONCLUSION: Optomap serves as a reliable screening tool for fundus examination especially because it covers a much wider area of the peripheral retina than other digital instruments for fundus photography.

Objective real-time measurement of instrument myopia in microscopists under different viewing conditions.

While instrument myopia is known to occur when microscopes are used, little is known about the accommodation response during microscopy, or about the factors which may alter the magnitude of instrument myopia. In addition, there has been no real-time objective measurement of instrument myopia during the microscopy task. Twenty inexperienced subjects and 10 experienced microscopists (average work experience of 4.8 years (SD 3.2 yr)) with mean age of 24.1 years (SD 2.9 yr) and 31.2 years (SD 2.9 yr) respectively were recruited to the study. Instrument myopia was measured using an infrared photorefractor (PowerRefractor) under different viewing conditions and microscope settings (with different forms of refractive error correction, changes in target quality, changes in eyepiece power settings, changes in magnification and changes in illumination of the target). Instrument myopia was greater in inexperienced (1.98 D (SD 0.91 D)) than in experienced (1.38 D (SD 0.75 D)) microscope users. There was no statistically significant change in the level of instrument myopia under the different viewing conditions or different microscope settings, and there were large individual variations. Other factors may play more of a role in determining the degree of instrument myopia during microscopy than the task variables altered here.