Optimal Refractive Correction Research Articles

Refractive blur’s influence on discomfort glare perception from white LED headlights at night

This study examined the effects of refractive blur on discomfort perception caused by peripheral glare from white LED passing (low)-beam headlights at night. The study compared two levels of binocular blur (+0.50 diopter [D] and +1.00D) against a baseline of optimal refractive correction. Thirty participants (mean age 21.3±1.6 years; range 20–24 years) simulating a driving position assessed discomfort from glare sources (headlights of oncoming vehicles) located at 40 and 20 m distances using the de Boer scale. The study found that, with a blur of +0.50D, discomfort glare from white LED headlights did not significantly differ from the baseline regarding de Boer scores. However, with a blur of +1.00D, de Boer scores significantly decreased, indicating increased discomfort glare compared with the baseline for all distances (P=0.004). These results suggest that refractive blur may contribute to an increased perception of discomfort glare during nighttime driving.

Surgical management of non-syndromic ectopia lentis.

To compare whether aphakic contact lenses or secondary iris-claw intraocular lenses are superior in the refractive management post-pars plana vitreolensectomy in a pedigree with an FBN1 mutation causing non-syndromic ectopia lentis (NSEL) with retinal detachment (RD). Eight affected individuals had pars plana vitreolensectomy for bilateral ectopia lentis (EL). Twelve eyes of 6 patients had secondary iris-claw intraocular lenses inserted and 4 eyes of 2 patients were managed with contact lenses. Rhegmatogenous retinal detachment (RRD) was treated when necessary. Pre- and post-operative assessment included visual acuity, endothelial cell count and dilated fundal examination. Macula-on RRD was present in all individuals >18y, 64% (7/11 eyes) presenting post-vitreolensectomy with 57% having bilateral non-synchronous RRD. Surgical aphakia was managed with iris-fixated intraocular lenses (IOL group, n=6), or contact lenses (CL group, n=2). Visual acuity ≥0.3 logMAR (driving standard) was achieved in 75% of IOL group eyes and 25% of the CL group eyes. Mean loss of corneal endothelial cell count in the IOL group was 4% at 2y post-operative. In this cohort, refractive management with iris-claw IOLs provided superior outcomes to contact lenses and the authors recommend this as the optimal refractive correction in EL patients.

Feasibility of monitoring compliance with intermittent occlusion therapy glasses for amblyopia treatment

Liquid crystal glasses use an intermittent occlusion technique and may improve compliance compared to adhesive patches. Previous studies support the effectiveness of intermittent occlusion therapy (IO therapy) glasses for amblyopia treatment. However, objective compliance for these glasses has not been measured. The purpose of this study was to investigate the feasibility of using a microsensor to monitor objective compliance with IO therapy glasses. Children 3 to ≤8years of age with unilateral amblyopia were enrolled. All subjects had optimal refractive correction (if needed) for at least 5weeks without improvement. Subjects were prescribed IO therapy glasses, set at 30-second opaque/transparent intervals (ie, occluded 50% of wear time). Wear time was prescribed according to amblyopia severity. For each patient, objective compliance with the IO therapy glasses was monitored by means of a microsensor. A total of 13 subjects returned with microsensor data. Compliance varied among and within individuals. General compliance averaged 51.6% (range, 10%-97%). Mean daily compliance decreased slightly over time. On average, patients' visual acuity improved 0.14±0.15 logMAR (range, -0.1 to 0.5 logMAR). No parents reported that their child had social concerns related to the attached microsensor. Objective compliance with IO therapy glasses can be monitored by a simple microsensor reliably. In our study cohort, objective compliance with IO therapy glasses varied among individuals, but on average it declined slightly over time.

Contrast Sensitivity in Eyes with Central Scotoma: Effect of Stimulus Drift.

In the field of visual rehabilitation of patients with central visual field loss (CFL), knowledge on how peripheral visual function can be improved is essential. This study presents measurements of peripheral dynamic contrast sensitivity (with optical correction) for off-axis viewing angles in subjects with CFL. Subjects with CFL rely on a peripheral preferred retinal locus (PRL) for many visual tasks. It is therefore important to ascertain that contrast sensitivity (CS) is maximized in the PRL. This study evaluates the effect of stimulus motion, in combination with optical correction, on CS in subjects with CFL. The off-axis refractive errors in the PRL of five young CFL subjects were measured with a COAS open-view Hartmann-Shack aberrometer. Low-contrast (25% and 10%) and high-contrast resolution acuity for stationary gratings was assessed with and without optical correction. High-contrast resolution was also measured for gratings drifting at 7.5 Hz (within a fixed Gaussian window). Furthermore, resolution CS was evaluated for both stationary and moving gratings with optical correction for a total of two to three spatial frequencies per subject. High-contrast resolution acuity was relatively insensitive to stimulus drift motion of 7.5 Hz, whereas CS for gratings of 0.5 cycles per degree improved with drift for all subjects. Furthermore, both high- and low-contrast static resolution improved with optical correction. Just as for healthy eyes, stimulus motion of 7.5 Hz enhances CS for gratings of low spatial frequency also in the PRL of eyes with CFL. Concurrently, high-contrast resolution is unaffected by the 7.5-Hz drift but improves with off-axis optical correction. This highlights the importance of providing optimal refractive correction for subjects with CFL and that stimulus motion can be used to further enhance CS at low spatial frequencies.

A pilot randomized clinical trial of intermittent occlusion therapy liquid crystal glasses versus traditional patching for treatment of moderate unilateral amblyopia

To compare the effectiveness of intermittent occlusion therapy (IO therapy) using liquid crystal glasses and continuous occlusion therapy using traditional adhesive patches for treating amblyopia. Children 3-8years of age with previously untreated, moderate, unilateral amblyopia (visual acuity of 20/40 to 20/100 in the amblyopic eye) were enrolled in this randomized controlled trial. Amblyopia was associated with strabismus, anisometropia, or both. All subjects had worn any optimal refractive correction for at least 12weeks without improvement. Subjects were randomized into two treatment groups: a 4-hour IO therapy group with liquid crystal glasses (Amblyz), set at 30-second opaque/transparent intervals (occluded 50% of wear time), and a 2-hour continuous patching group (occluded 100% of wear time). For each patient, visual acuity was measured using ATS-HOTV before and after 12weeks of treatment. Data from 34 patients were available for analysis. Amblyopic eye visual acuity improvement from baseline was 0.15±0.12 logMAR (95% CI, 0.09-0.15) in the IO therapy group (n=19) and 0.15±0.11 logMAR (95% CI, 0.1-0.15) in the patching group (n=15). In both groups improvement was significant, but the difference between groups was not (P=0.73). No adverse effects were reported. In this pilot study, IO therapy with liquid crystal glasses is not inferior to adhesive patching and is a promising alternative treatment for children 3-8years of age with moderate amblyopia.

Pattern glare: the effects of contrast and color.

Aim: To test a theory of visual stress by investigating the inter-relationships between (1) the threshold contrast/saturation at which individuals first report discomfort when viewing colored gratings of progressively increasing contrast and decreasing saturation; (2) the choice of a colored overlay for reading; (3) any increase in reading speed when the overlay is used.Method: Ninety-five young adults, with normal color vision, reported illusions from square-wave gratings (Pattern Glare Test), chose any colored overlays that improved clarity (Intuitive Color Overlays) and read aloud randomly ordered common words (Wilkins Rate of Reading Test). This was followed by an automated choice of tints for text using various screen colors on a tablet, and a test of discomfort from patterns of progressively increasing contrast and decreasing saturation, using software developed for this study. All participants wore their optimal refractive correction throughout the procedure.Results: Fifty-eight participants chose a colored overlay and reported that it made text easier and more comfortable to read. On average, these individuals had a greater improvement in reading speed with their overlays (p = 0.003), a lower contrast threshold at which discomfort from achromatic gratings was first reported (p = 0.015), and a tendency to report more pattern glare (p = 0.052), compared to the other participants. Participants who chose both a most and least preferred tint for text using the automated procedure reported discomfort from colored gratings at a significantly higher contrast with their most preferred color compared to their least preferred color (p = 0.003). The choice of a colored tint was moderately consistent across tests. The most and least preferred colors tended to be complementary.Conclusion: Colored tints that improved reading speed reduced pattern glare both in terms of the illusion susceptibility and in terms of discomfort contrast threshold, supporting a theory of visual stress. An automated test that incorporates colored gratings and a choice of most and least preferred color might better identify individuals whose reading speed improves with colored overlays.

Effects of Different Levels of Refractive Blur on Nighttime Pedestrian Visibility.

The aim of this study was to systematically investigate the effect of different levels of refractive blur and driver age on nighttime pedestrian recognition and determine whether clothing that has been shown to improve pedestrian conspicuity is robust to the effects of blur. Nighttime pedestrian recognition was measured for 24 visually normal participants (12 younger mean = 24.9 ± 4.5 years and 12 older adults mean = 77.6 ± 5.7 years) for three levels of binocular blur (+0.50 diopter [D], +1.00 D, +2.00 D) compared with baseline (optimal refractive correction). Pedestrians walked in place on a closed road circuit and wore one of three clothing conditions: everyday clothing, a retro-reflective vest, and retro-reflective tape positioned on the extremities in a configuration that conveyed biological motion (known as "biomotion"); the order of conditions was randomized among participants. Pedestrian recognition distances were recorded for each blur and pedestrian clothing combination while participants drove an instrumented vehicle around a closed road course. The recognition distances for pedestrians were significantly reduced (P < 0.05) by all levels of blur compared with baseline. Pedestrians wearing biomotion clothing were recognized at significantly longer distances than for the other clothing configurations in all blur conditions. However, these effects were smaller for the older adults, who had much shorter recognition distances for all conditions tested. In summary, even small amounts of blur had a significant detrimental effect on nighttime pedestrian recognition. Biomotion retro-reflective clothing was effective, even under moderately degraded visibility conditions, for both young and older drivers.

Effect of Optical Defocus on the Kinetic Perimetry in Young Myopic Participants

ABSTRACTPurpose: The prospective study evaluated the effects of optical defocus on kinetic sensitivity using automated kinetic perimetry.Materials and Methods: The 17 eyes of 17 healthy young participants were evaluated. All of the participants had myopia (≥ −5.00 D) and mild to no astigmatism (<1.00 D). Automated kinetic perimetry was performed using the Octopus 900 perimeter with Goldmann stimuli III4e, I4e, I3e, I2e, and I1e, with stimuli presented at 14 predetermined meridians, and a velocity of 3°/s. Optical defocus was induced with soft contact lenses, and varied in 1 D increments between 0 and +7 D. Kinetic sensitivity at each defocus was evaluated and compared to sensitivity with no defocus.Results: Although kinetic sensitivity with the III4e and I4e stimuli decreased slightly at the inferior nasal, total kinetic sensitivity measured with the III4e and I4e stimuli was unaffected by optical defocus. Conversely, kinetic sensitivity measured with the I3e, I2e, and I1e stimuli decreased at defocus greater than +6 D (p < 0.05), + 3 D (p < 0.01), and at a defocus greater than +1 D (p < 0.01), respectively.Conclusions: Kinetic sensitivity was unaffected by defocus when measured with III4e and I4e stimuli. However, measurements with I3e, I2e, and I1e stimuli were affected, in particular measurements with I2e and I1e stimuli. Therefore, we conclude that optimal refractive correction with a contact lens or a spectacle lens is required in order to obtain accurate kinetic perimetry results, particularly for lower intensity stimuli.

Determining the efficacy of full-time occlusion therapy in severe amblyopia at different ages

Objective: To find out how much visual improvement is possible in severe amblyopia using full-time occlusion therapy and if improvement is influenced by the patient’s age. Methods: A trial of 115 consecutive cases with unilateral, severe amblyopia was conducted at a tertiary referral center from Jan 2010 to Oct 2012. Patients were divided into three age groups: 3-7 years (n= 38), 8-12 years (n=41), 13-35 years (n=36). After a complete ophthalmological examination by a single ophthalmologist, cases with organic visual loss were excluded; cases with previous part-time occlusion therapy that had failed were included in the study. Patients were given optimal refractive correction for a month, followed by full-time occlusion therapy along with near visual activities for 3-4 hours/day. The therapy was continued until maximum visual recovery was achieved (6/6 Snellen’s). Therapy was gradually reduced and stopped. Patients were followed-up regularly for the next 18 months. Results: There was 100% success in the 3-7 year group, 92.68% in the 8-12 year group and 97.22% in the 13-35 year group. Conclusion: Visual improvement is possible in almost all patients with severe amblyopia irrespective of their age with full-time occlusion therapy.

What Drives Adaptive Gait Changes to Acutely Presented Monocular Blur?

To determine whether gait alterations due to monocular spherical lens blur were a safety strategy or driven by lens magnification. Adaptive gait and visual function were measured in 10 older adults (mean age, 74.9 ± 4.8 years) with the participants' optimal refractive correction and when monocularly blurred with ±1.00 DS and ±2.00 DS lens over the dominant eye. Adaptive gait measurements for the lead and trail foot included foot position before the raised surface, toe clearance of the raised surface edge, and foot position on the raised surface. Vision measurements included binocular visual acuity, contrast sensitivity, and stereoacuity. Equal levels of monocular positive and negative spherical lens blur led to very different stepping strategies when negotiating a raised surface. Positive blur lenses led to an increased vertical toe clearance and reduced distance of the lead foot position on the raised surface. Negative lenses led to the opposite of these changes. Findings suggest that step negotiation strategies were driven by the magnification effect provided by the spherical lenses. Steps appeared closer and larger with magnification from positive lenses and further away and smaller with minification from negative lenses and gait was adjusted accordingly. These results suggest that previously reported adaptive gait changes to monocular spherical lens blur were not safety strategies as previously suggested but driven by lens magnification. The significance of these findings in terms of prescribing large refractive changes in frail older patients is discussed.

Adaptive Gait Changes Due to Spectacle Magnification and Dioptric Blur in Older People

A recent study suggested that updated spectacles could increase fall rate in frail older people. The authors hypothesized that the increased risk may be due to changes in spectacle magnification. The present study was conducted to assess the effects of spectacle magnification on step negotiation. Adaptive gait and visual function were measured in 10 older adults (mean age, 77.1 +/- 4.3 years) with the participants' optimal refractive correction and when blurred with +1.00, +2.00, -1.00, and -2.00 DS lenses. Adaptive gait measurements for the leading and trailing foot included foot position before the step, toe clearance of the step edge, and foot position on the step. Vision measurements included visual acuity, contrast sensitivity, and stereoacuity. The blur lenses led to equal decrements in visual acuity and stereoacuity for the +1.00 and -1.00 DS and the +2.00 and -2.00 DS lenses. However, they had very different effects on step negotiation compared with the optimal correction. Positive-blur lenses led to an increased distance of the feet from the step, increased vertical toe clearance and reduced distance of the leading heel position on the step. Negative lenses led to the opposite of these changes. The step negotiation changes did not mirror the effects of blur on vision, but were driven by the magnification changes of the lenses. Steps appear closer and larger with positive lenses and farther away and smaller with negative ones. Magnification is a likely explanation of the mobility problems some older adults have with updated spectacles and after cataract surgery.

Treatment of Anisometropic Amblyopia with Spectacles or in Combination with Translucent Bangerter Filters

To compare spectacle correction alone with spectacle correction with Bangerter filters to treat anisometropic amblyopia in children. Prospective, randomized clinical trial. Eighty children (mean age, 4.4 years) with untreated anisometropic amblyopia and a median best-corrected visual acuity (BCVA) in the amblyopic eye of 0.4 logarithm of the minimum angle of resolution (logMAR). Optimal refractive correction was provided, and the children were assigned to treatment with either spectacles or spectacles in combination with a Bangerter filter worn on the spectacle lens of the better eye. The BCVA, binocular function, and refractive errors were measured repeatedly over the course of 1 year. The time course to resolution of the amblyopia (interocular difference, < or =1 line). The difference in the mean time to the resolution of amblyopia was 3.9+/-3.2 months for the spectacles group versus 2.2+/-1.9 months for the filter group, and the difference reached significance (P<0.05). The BCVA in the amblyopic eye improved significantly (P<0.001 for both comparisons) in both groups. After 1 year, there was no significant difference in the BCVA between the groups. The binocular function improved in both groups; at 1 year there was no significant difference between the groups. The median spherical equivalent refractive error increased significantly during the study in the amblyopic eyes (P<0.05) and the fellow eyes (P<0.001). The median anisometropia decreased significantly from the first visit to the 1-year visit in both groups (P<0.001 for both comparisons). We found a more rapid visual acuity recovery with the Bangerter filters than with spectacles alone in eyes with anisometropic amblyopia. However, the 1-year visual acuity outcome was not statistically significantly different between the 2 treatments.

Habitual vs optimal distance visual acuity

The maintenance of a good level of vision is desirable for developmental and social reasons; it is also a requirement that should not be overlooked in the clinical research environment. This study set out to quantify and analyse any difference between 'habitual' (pre-sight test) and 'optimal' (post-refraction) distance visual acuity in an optometric population. It is intended that the outcome of this work will inform not only clinicians but also those undertaking vision research. Binocular logMAR visual acuity was determined at 6 m before and after optometric intervention in patients attending optometric practice for a routine sight test. Cases were recorded seriatim but restricted to the 'core' refraction range representative of typical optometric practice; three further exemption criteria included subject illiteracy, the necessity for a non-standard test distance and contact lens wear. Over a 12-month period, two-thirds of patients examined satisfied the study inclusion criteria; it is the clinical data of these 1288 individuals that are described and analysed here. These data provide a quantitative demonstration that an optometric intervention will most likely improve the habitual distance visual acuity of subjects, irrespective of gender, age group, time interval since last test, refractive status and whether or not the subject is a habitual spectacle wearer. The improvement found was typically within one logMAR chart line (<5 letters), being greatest in spectacle-wearing teenagers and in individuals beyond retirement age (increasing to eight letters in elderly habitual non-spectacle wearers); also in non-wearers who left an interval of 2 years or more between sight tests. Clinical and laboratory-based investigators are advised that a current and optimal refractive correction should be worn by subjects of all ages enrolled in vision-related studies. Refractive defocus may introduce or exaggerate test outcome variability.

Recognition versus Resolution: a Comparison of Visual Acuity Results Using Two Alternative Test Chart Optotype

Purpose To quantify the difference between recognition (letter) and resolution (Landolt) visual acuity (VA) in a group of normally sighted subjects. Is it reasonable to assume that the two acuity measures are clinically equivalent? Methods A pair of 6 m acuity test charts was produced: one comprised letters and the other Landolt broken rings. Construction of both charts conformed to the logMAR design format. Monocular VA was determined for the dominant eye of 300 screened and normally sighted optometric patients aged 16 to 40, each wearing an optical refractive (spectacle) correction. Results Letter acuity was superior to Landolt acuity ( P≤0.0001). The mean paired acuity difference was -0.041 logMAR (standard deviation 0.034): the 95% limits of agreement were ±0.067 logMAR units or ±3.3 chart optotype. Repeatability was high and similar for each chart type (±2.1 and ±2.4 optotype for letter and Landolt, respectively). Gender, test sequence, and laterality of the dominant eye (left or right) were each non-statistically significant variables. Conclusions For normally sighted subjects wearing an optimal refractive correction, a bias was recorded in favour of recognition over resolution acuity: the clinical difference amounted to approximately 40% of one logMAR chart line, with similar high repeatability for either chart optotype. We conclude that the assumption of clinical equivalence between letter and Landolt acuity is reasonable under optimum test conditions.

Static accommodative responses following adaptation to differential levels of blur

To investigate the effects of two levels of blur adaptation on visual resolution and steady-state accommodation responses in emmetropes and myopes. Eleven emmetropes (mean refractive error +0.01 +/- 0.31 DS) and 11 early-onset myopes (EOM, mean refractive error -4.44 +/- 1.64 DS) fixated monocularly at 4 m in three trials of 45 min duration with either: optimal refractive correction, +1 DS defocus, or +3 DS defocus. Monocular logMAR visual acuity (VA) was measured at 10 min intervals during each trial, and immediately following completion of the trial. Accommodative stimulus-response function (ASRF), refractive error and pupil size were measured before and after each trial. Blur adaptation was found to have no effect on pupil size or baseline refraction, irrespective of the power of the blurring lens. Adaptation to +1 DS of defocus yielded an improvement in VA of -0.16 +/- 0.07 logMAR and -0.17 +/- 0.11 logMAR in the emmetropes and myopes respectively. An improvement in VA of -0.20 +/- 0.18 logMAR in the emmetropes and -0.26 +/- 0.17 logMAR in the myopes was observed following adaptation to +3 DS of defocus. The changes in acuity became significant following 30 min of exposure to defocus. Blur adaptation was found to have no effect on the ASRF gradient or individual steady-state accommodative responses. Following blur adaptation, visual resolution was found to increase in both emmetropes and myopes. The magnitude of the blur level did not produce significantly different increases in resolution. Blur adaptation failed to affect either the steady-state responses to an accommodative stimulus or ASRF gradient.

Penetrating Keratoplasty for Keratoconus: The Nexus Between Corneal Wavefront Aberrations and Visual Performance

To compare the visual and optical performance after penetrating keratoplasty (PK) for keratoconus to normal patients and to examine the relationship between corneal wavefront aberrations and visual performance in patients with PK. Visual performance testing, with optimal refractive correction, included low contrast visual acuity (LCVA) and Pelli-Robson contrast sensitivity with and without glare, and high contrast visual acuity. Corneal first surface wavefront aberrations were calculated from EyeSys topography data using VOL-Pro software v7.00 for a 4.0-mm pupil as a 10th order Zernike expansion and converted into single value metrics. Normal patients were compared to patients with PK using analysis of variance, and linear regression was used to compare wavefront aberration metrics to visual performance. Patients with PK (n=14, age 41.6 +/- 7.0 years) and normal patients (n=14, age 36.7-9.0 years) were of similar age (F(1, 26) = 2.54, P = .12). Normal patients saw significantly better on all visual performance measures and had better optical performance for total higher order root-mean-square corneal wavefront aberration (mean-SD): PK, 0.67 +/- 0.41 microm; normal, 0.09 +/- 0.02 microm (F(1,26) = 28.41, P < .001) and across all Zernike orders and modes. Wavefront aberrations in PK eyes were dominated by trefoil 0.35 +/- 0.27 microm, coma 0.47 +/- 0.37 microm, spherical aberration 0.17 +/- 0.10 microm, and tetrafoil 0.12 +/- 0.07 microm. The relationships between corneal wavefront aberration and visual performance metrics were strongest for LCVA = 0.30-0.98 Pupil fraction for wavefront (tessellation) -0.04 Half width at half height, R2=0.75. In this series, patients with PK had poorer visual performance compared to normal patients, which is due to increased corneal wavefront aberrations. Outcomes research in corneal transplantation should include measurement of wavefront aberrations and visual performance in the contrast domain.

Treatment of Anisometropic Amblyopia in Children with Refractive Correction

To evaluate the effectiveness of refractive correction alone for the treatment of untreated anisometropic amblyopia in children 3 to <7 years old. Prospective, multicenter, noncomparative intervention. Eighty-four children 3 to <7 years old with untreated anisometropic amblyopia ranging from 20/40 to 20/250. Optimal refractive correction was provided, and visual acuity (VA) was measured with the new spectacle correction at baseline and at 5-week intervals until VA stabilized or amblyopia resolved. Maximum improvement in best-corrected VA in the amblyopic eye and proportion of children whose amblyopia resolved (interocular difference of < or =1 line) with refractive correction alone. Amblyopia improved with optical correction by > or =2 lines in 77% of the patients and resolved in 27%. Improvement took up to 30 weeks for stabilization criteria to be met. After stabilization, additional improvement occurred with spectacles alone in 21 of 34 patients observed in a control group of a subsequent randomized trial, with amblyopia resolving in 6. Treatment outcome was not related to age, but was related to better baseline VA and lesser amounts of anisometropia. Refractive correction alone improves VA in many cases and results in resolution of amblyopia in at least one third of 3- to <7-year-old children with untreated anisometropic amblyopia. Although most cases of resolution occur with moderate (20/40-20/100) amblyopia, the average 3-line improvement in VA resulting from treatment with spectacles may lessen the burden of subsequent amblyopia therapy for those with denser levels of amblyopia.

A Randomized Trial to Evaluate 2 Hours of Daily Patching for Strabismic and Anisometropic Amblyopia in Children

To compare 2 hours of daily patching (combined with 1 hour of concurrent near visual activities) with a control group of spectacle wear alone (if needed) for treatment of moderate to severe amblyopia in children 3 to 7 years old. Prospective randomized multicenter clinical trial (46 sites). One hundred eighty children 3 to 7 years old with best-corrected amblyopic-eye visual acuity (VA) of 20/40 to 20/400 associated with strabismus, anisometropia, or both who had worn optimal refractive correction (if needed) for at least 16 weeks or for 2 consecutive visits without improvement. Randomization either to 2 hours of daily patching with 1 hour of near visual activities or to spectacles alone (if needed). Patients were continued on the randomized treatment (or no treatment) until no further improvement was noted. Best-corrected VA in the amblyopic eye after 5 weeks. Improvement in VA of the amblyopic eye from baseline to 5 weeks averaged 1.1 lines in the patching group and 0.5 lines in the control group (P = 0.006), and improvement from baseline to best measured VA at any visit averaged 2.2 lines in the patching group and 1.3 lines in the control group (P<0.001). After a period of treatment with spectacles, 2 hours of daily patching combined with 1 hour of near visual activities modestly improves moderate to severe amblyopia in children 3 to 7 years old.

Visual and Perceptual Consequences of Congenital Nystagmus

One way to assess the influence of retinal image motion on visual functioning in congenital nystagmus (CN) is to examine the effects of comparable image motion in observers with normal vision. A second approach is to evaluate visual functioning in subjects with CN when the retinal image motion is reduced. Using these approaches, we determined that spatial contrast sensitivity and visual acuity are not limited by the parameters of retinal image motion in some subjects with CN, but rather by a form of amblyopia. Clinical evidence from patients with bilateral refractive amblyopia suggests that a gradual improvement of visual acuity may be possible in persons with CN, if the optimal refractive correction is worn and parameters of the retinal image motion undergo long-term amelioration.

A Randomized Controlled Trial to Determine the Effectiveness of Prism Spectacles for Patients With Age-Related Macular Degeneration

To determine the effectiveness of prism spectacles in people with age-related macular degeneration by relocating the retinal image. We implemented a randomized, placebo-controlled, double-masked trial. Participants with age-related macular degeneration received a standard low-vision assessment and the prescription of conventional low-vision aids 6 weeks before the study intervention. Participants were randomized to receive 1 of the following, including the optimal refractive correction: (1) custom, incorporating bilateral prisms to match participants' preferred power and base direction; (2) standard, incorporating standard bilateral prisms (6 prism diopters [Delta] base up for logMAR [logarithm of the minimum angle of resolution] visual acuity (VA) of 0.48-1.00 and 10Delta base up for logMAR VA of 1.02-1.68); or (3) placebo, consisting of spectacles matched in weight and thickness to prism spectacles but without prism. Outcomes measured binocularly at baseline and 3-month follow-up included distance logMAR VA, reading speed, critical print size, visual functioning questionnaires, and observed visual task performance. Scores on the 25-item National Eye Institute Visual Functioning Questionnaire and the Melbourne Low-Vision ADL (Activities of Daily Living) Index were converted to linear estimates using Rasch analysis. The Manchester Low Vision Questionnaire was used to collect descriptive data. A total of 225 participants completed the trial (median age, 81 years). We found no significant effect of treatment group on any of the outcome measures, including VA, the primary outcome (adjusted for baseline) (P = .63). Participants' responses to the Manchester Low Vision Questionnaire suggested that the prism spectacles added to their problems. Prism spectacles are no more effective than conventional spectacles for people with age-related macular degeneration.