Minimum Acuity Research Articles

Minimum visual acuity: a new cone specific clinical test.

Minimum visual acuity: a new cone specific clinical test.

Evaluating the level of visual acuity to minimise false-positives in different colour vision tests

ABSTRACT Clinical relevance Accurate colour vision assessment is important in clinical settings to minimise false-positive errors and enhance the reliability of diagnoses outcomes. Background Colour vision testing is valuable in assessing the visual system, particularly given the high proportion of individuals with poor vision. This study aimed to determine the minimum visual acuity level required to perform a colour-vision test without errors. Methods After fogging the right eyes of 52 healthy participants using plus lenses to 1.60 logMAR, vision was evaluated using Ishihara, Hardy – Rand – Rittler Standard Isochromatic, Waggoner Pseudo-isochromatic, City University, Waggoner Computerised, and Farnsworth D-15 tests. Participants then completed these tests at lower fogging degrees (in 0.1-logMAR intervals). The acuity at which 5% of the tested population was considered abnormal was determined. Results Significant differences were found in the average visual acuity required to perform colour vision tests without errors (p < 0.05). The Waggoner Computerized test required the highest average visual acuity among the tests utilised. The Farnsworth D-15 test yielded the highest logMAR values. No significant differences were observed between the Waggoner Pseudo-isochromatic test and Hardy – Rand – Rittler Standard Isochromatic, Ishihara, and Farnsworth D-15 tests (p > 0.05). Additionally, no significant differences were found between the Ishihara and Hardy – Rand – Rittler tests (p > 0.1) or between the Waggoner Computerized and City University tests (p = 0.11). Colour vision testing maintained an accuracy ≤ 1.0 logMAR with the Ishihara and Hardy – Rand – Rittler tests, 1.1 logMAR with the Waggoner Pseudo-isochromatic and Farnsworth D-15 tests, and 0.9 logMAR with the Waggoner Computerized and City University tests. Conclusions Insights are provided into the visual acuity thresholds required for accurate colour vision testing, which can serve as a basis for future research and provide a reference for clinical practice in this field.

The Natural History of Retinal Sensitivity Loss in Diabetic Macular Ischemia over One Year Evaluated by Microperimetry.

Background/Objectives: This one-year prospective observational study, conducted at two centers, aimed to report the natural history of retinal sensitivity (RS) loss in diabetic macular ischemia (DMI). Methods: Patients with stable-treated proliferative diabetic retinopathy (PDR) were recruited if there was evidence of DMI on optical coherence tomography angiography, defined as a foveal avascular zone ≥ 0.5 mm2 or parafoveal capillary dropout ≥ 1 quadrant. The minimal visual acuity required for performing microperimetry (MP) was ≥54 Early Treatment Diabetic Retinopathy Study letters (Snellen equivalent 20/80). The overall RS (oRS) and pointwise sensitivity (PWS) within the 3 × 3 mm macula were assessed at baseline and twelve months. A value <25 decibels (dB) was defined as impaired RS, and a decrease of 2 and 7 dB was regarded as mild and severe loss, respectively. Results: A total of 88 patients (97 eyes) were included. No statistically significant MP changes were detected at one year. However, 10% of the cohort lost oRS ≥ 2 dB, and 73% lost ≥2 dB PWS in ≥5 loci, whereas 1% lost oRS ≥ 7 dB, and 4% lost ≥7 dB PWS in ≥5 loci. The foveola and temporal parafovea were the most vulnerable to severe RS loss. Compared to their counterpart, eyes with baseline oRS ≥ 25 dB had significantly more RS loss in the macula and superior parafovea (55% versus 32% and 53% versus 28%, both p = 0.01). Conclusions: Rather than oRS loss, ≥2 dB loss in PWS in ≥5 loci is a more feasible outcome measure for clinical trials in DMI.

Functional and morphological characterization of ocular phenotype in C3H/HeOuJ (Pde6b‐rd1) mice

Aims: C3H/HeOuJ mice (The Jackson Laboratory strain #000635) are homozygous for the retinal degeneration 1 mutation Pde6brd1 (rd1) causing severe visual deficits. The purpose of this study was to characterize the ocular phenotype of male and female mice with the rd1 mutation.Methods: The ophthalmic phenotype of mixed sex rd1 and aged‐matched C57BL/6J wild type (WT) mice (6 females and 4 males for rd1 group, 6 females and 5 males for WT group) was assessed at 3 months of age. Retinal photoreceptor function was quantified using scotopic flash electroretinography (fERG) with six different light intensities: 0.003, 0.01, 0.1, 1, 3 and 10 cd.s/m2 (Celeris, Diagnosys LLC). Retinal morphology was evaluated with spectral domain optical coherence tomography (SD‐OCT) (Envisu R2200, Bioptigen Inc./Leica Microsystems). Retinal thickness was measured from SD‐OCT images using a proprietary convolutional neural network. Optomotor reflex (OMR) was measured as photopic visual acuity and contrast sensitivity at 0.019 and 0.06 cyc/° (OptoDrum Plus, Striatech GmbH). Data were analysed by unpaired t‐test or Mann–Whitney test.Results: At 3 months of age, the rd1 mutation resulted in significant impairment of visual function in both male and female mice compared to age‐matched WT. fERG a and b‐wave amplitudes were decreased by 90% in both sexes (p &lt; 0.001). The rd1 mice had only minimal visual acuity and contrast sensitivity assessed by OMR. Functional decline correlated with structural changes, notably the significant thinning of the retina (p &lt; 0.001).Conclusions: The Pde6brd1 mutation resulted in severe functional and structural changes at 3 months of age. The mice presented significantly decreased but detectable fERG amplitudes, however, they had no functional vision as assessed by OMR. Combining fERG and OMR offers longitudinal in‐life quantification of retinal circuitry and functional vision with great utility for evaluation of novel therapeutic approaches for regeneration of the visual system.

Big Data Analysis of Vision Screening Standards Used to Evaluate Fitness to Drive

Purpose Visual acuity (VA) assessment is the most commonly performed vision screening method for drivers. The standards and repeat assessment intervals used, however, are arbitrary, lack an evidence base and are highly variable across different countries. This study utilizes the power of Big Data to provide evidence-based recommendations for standardized driver vision screening. Methods Anonymized electronic medical record data were gathered from 40 Irish optometry practices comprising 81,184 unique patients. A Kaplan–Meier Survival (KMS) analysis was used to determine the effect of increasing age and time since screening on the likelihood of passing the VA standard for driving. A logistic function was fit to assess the effect of varying the minimum VA standard required to drive on the screening pass rate within the population. Results The likelihood of failing repeat screening increased as a function of time since initial screening for all age groups (χ 2 =1447, df = 6, p<.001), with older patients most affected. Rescreening intervals for individuals who initially met the vision standard unaided reduced as a function of age. Using an 80% survivability threshold, intervals ranged from every eight years for drivers under 50, reducing to every two years for those aged over 80. Rescreening intervals for drivers requiring optical correction to meet the standard also decreased with age. Approximately, 1% of individuals are excluded from driving using a 0.3 logMAR VA standard with correction. Conclusions VA-based screening should take place at regular intervals for all drivers, not just those over 70. Re-screening intervals should be based on age, with shorter intervals for older drivers due to the combined effect of age and time on the likelihood of passing the driving VA standards. The most commonly used standard of 0.3 logMAR results in a minimal number of potential drivers being excluded from driving.

Comparison of clinical usefulness of central 30-2 and 24-2 threshold tests using SITA strategy.

To compare the clinical utilities of the SITA-based central 24-2 and 30-2 threshold tests. Three hundred sixty-five (365) eyes of 183 glaucoma and glaucoma suspect patients who had undergone both central 30-2 and 24-2 threshold testing using the Swedish interactive threshold algorithm (SITA) standard strategy were retrospectively reviewed. The tests were performed in patients with a minimum visual acuity of LogMAR best-corrected visual acuity (BCVA) 0.3. We compared test time, fixation loss (%), false-positive error rate (%), and false-negative error rate (%), all of which are indices of reliability. We additionally compared the mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI), all of which are indices of the visual field test. The mean age was 54.67 ± 14.95. MD, VFI, and fixation loss showed no significant difference between the 30-2 and 24-2 tests. As expected, 24-2 was shorter in duration: 5.64 ± 1.09min versus 7.51 ± 1.38min (p < .001), a 24.51 ± 9.45% difference. The false-positive error rate was significantly higher, but the false-negative error rate was lower, with the 24-2 threshold test (p = .009, p < .001). The PSD also was lower with 24-2 than with 30-2 (p < .001). The two tests' VFI and MD are comparable. The 24-2 test may be a more efficient examination for most patients in terms of test time. In the other relevant aspects, the two tests are not identical. Therefore, it would be advisable to tailor visual field testing to the individual patient.

The Effect of Spectacle-Induced Low Myopia in the Non-Dominant Eye on the Binocular Defocus Curve with a Non-Diffractive Extended Vision Intraocular Lens.

PurposeTo quantify the changes in the binocular defocus curve associated with the Vivity™ non-diffractive extended vision intraocular lens when the dominant eye was targeted for emmetropia and the non-dominant eye was artificially targeted for slight myopia using spectacles.Patients and MethodsThis was a non-interventional research study of the corrected binocular defocus curve associated with binocular emmetropia (Setting A) and with emmetropia in the dominant eye and two different levels of myopia simulated in the non-dominant eye (−0.50 D, Setting B and −1.00 D, Setting C). Subjects were patients implanted with the AcrySof® IQ Vivity® intraocular lens in both eyes 3 to 12 months previously. Using the defocus data, the percentage of subjects with a continuous 2.5 D range of vision (distance to 40 cm) was calculated for various levels of minimum visual acuity (VA).ResultsForty subjects were enrolled. The mean spherical equivalent refraction was −0.06 D ± 0.36 D, with 0.37 D ± 0.29 D of refractive cylinder. There was no statistically significant difference in the mean VA at −0.25 D or at −0.50 D vergences between the test Settings, but there was a statistically significant difference at all other vergences. Differences were particularly noticeable at −2.00 D, −2.50 D and −3.00 D, where higher myopia in the non-dominant eye yielded better binocular VA. A 2.5 D range of functional vision (20/25) was achieved by 38% of subjects at Setting A, 68% of subjects at Setting B and 85% of subjects at Setting C. At setting C, all but one subject (39/40, 97.5%) had a 2.5 D range of vision with a VA of 20/32 or better.ConclusionSignificant gains in binocular near vision, with only a nominal effect on distance vision, can be achieved with the Vivity IOL by leaving the non-dominant eye of patients with 0.50 D or 1.00 D of myopia.

Pre-participation Vision Screening and Comprehensive Eye Care in National Collegiate Athletic Association Athletes.

Pre-participation physical evaluation and its vision screenings have been the mainstay of medical clearance for competitive play for decades. The ability of screening to address athlete's sports-specific vision needs is unknown. Fifty-eight intercollegiate football players consented to participate in a comprehensive, sports-specific eye examination in addition to the standard pre-participation vision screening. Sensitivity, specificity, and positive and negative predictive values were determined for screening's ability to detect athletes whose vision might improve with correction, athletes who had significant ocular findings that impact safety, and either of the two conditions together. The effect no recent eye examination added to pre-participation vision screening results was evaluated for change in screening yield. Descriptive statistics of the cohort and associations with no recent comprehensive eye examination were generated. The pre-participation vision screening was able to identify three athletes not meeting visual acuity requirements for medical clearance to play without a comprehensive assessment. A failed screening was poorly able to identify athletes who might benefit from improved acuity (sensitivity, 9.1%; specificity, 100%), have sports-specific significant ocular findings (sensitivity, 10.5%; specificity, 97.3%), or have either together (sensitivity, 7.5%; specificity, 100%). Sixty percent (33/55) of athletes reported never having a comprehensive examination or one within the last 10 years. Fifty-eight percent (34/58) had improved best-corrected visual acuity after comprehensive examination, and 81% (47/58) had improved acuity or a sports-specific significant finding. The pre-participation vision screening was largely able to identify athletes meeting the minimum visual acuity requirement for athlete clearance. It poorly identified those who might benefit from improved vision with refractive correction and those in whom sport-specific significant eye findings were noted. Comprehensive eye care had a clear benefit for the majority of athletes tested. This benefit needs to be balanced with the potential added costs and time constraints to players and athletic department staff.

Longitudinal Microperimetric Changes of Macular Sensitivity in Stargardt Disease After 12 Months

Functional end points for clinical trials investigating the efficacy of emerging treatments for Stargardt disease type 1 (STGD1) are needed. To assess the yearly rate of change of macular function in patients with STGD1 using microperimetry. This multicenter prospective cohort study was conducted in an international selection of tertiary referral centers from October 21, 2013, to February 15, 2017. The study included participants with ABCA4-related STGD1 who were enrolled in the Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study at baseline. Data were analyzed from February 16, 2017, to December 1, 2019. ABCA4-related STGD1 with a minimum lesion size on fundus autofluorescence and a minimum visual acuity. Changes in overall macular sensitivity (MS), deep scotoma count, number of points that tested normal, and location-specific sensitivity changes. Among the 359 eyes from 200 patients (87 [43.5%] men; mean [SD] age, 33.3 [15.2] years) who underwent microperimetry examination graded at baseline and month 12, the mean (SD) yearly change in MS was -0.68 (2.04) dB (95% CI, -0.89 to -0.47 dB; P < .001), and deep scotoma points increased by a mean (SD) of 1.56 (5.74) points per year. The points with sensitivity of 12 dB or higher decreased in sensitivity by a mean (SD) of -3.01 (9.84) dB (95% CI, -4.03 to -1.99 dB; P < .001). The mean (SD) yearly change in MS was not significantly different between the eyes with a grading of good or fair pattern placement at both visits (-0.67 [2.1] dB) and the eyes with a poor pattern placement during at least 1 visit (-0.64 [2.2] dB) (P = .91). This study showed that MS and the number of deep scotoma points had measurably changed after follow-up of approximately 1 year. Microperimetry may serve as a useful functional outcome parameter for clinical trials aimed at slowing the progression of STGD1.

Visual acuity and structure‐function relationships in acute and chronic LHON patients treated with idebenone

AbstractPurposeLeber's hereditary optic neuropathy (LHON) is a mitochondrial disease characterised by a subacute and progressive impairment and subsequent degeneration of macular retinal ganglion cells and their nerve fibres causing permanently reduced visual acuity (VA) in most cases. Idebenone is currently the only approved treatment for LHON. This study aims to evaluate the course of VA and its correlations with inner retinal layer morphology in LHON patients treated with idebenone.Methods42 eyes of 21 genetically confirmed LHON patients treated with idebenone were examined in regular intervals. VA was measured using logMAR charts. Macular ganglion cell layer volume (GCLV) and peripapillary retinal nerve fibre layer thickness (pRNFLT) were measured by spectral domain OCT. Patients were divided into three groups according to their time from LHON onset until treatment start including acute patients (&lt;1 year, 12 eyes), chronic group 1 (1 to 5 years, 14 eyes) and chronic group 2 (&gt;5 years, 16 eyes).ResultsA significant increase of VA compared to minimum VA was observed in all groups (acute: ‐0.25 logMAR, chronic 1: −0.29 logMAR, chronic 2: −0.31 logMAR; p &lt; 0.001 all groups). VA at baseline was similar between groups, but 6 eyes of 4 acute patients showed a marked decline during the first year reaching a minimum after 9 months. Minimum VA of all patients was significantly correlated with final pRNFLT (r = 0.48, p = 0.002) and GCLV (r = 0.40, p = 0.008), but OCT and maximum VA during continued treatment showed stronger correlations (pRNFLT: r = 0.50, p = 0.001; GCLV: r = 0.43, p = 0.004). VA gain was not associated with OCT and not different between all groups.ConclusionsVA in LHON patients with recent disease onset can decrease during the first months of treatment with idebenone. The increase of VA after this nadir is comparable to the treatment effects observed in chronic patients and may be the result of a reactivated signal transduction in surviving dysfunctional ganglion cells.

Do school classrooms meet the visual requirements of children and recommended vision standards?

BackgroundVisual demands of school children tend to vary with diverse classroom environments. The study aimed to evaluate the distance and near Visual Acuity (VA) demand in Indian school classrooms and their comparison with the recommended vision standards.Materials and methodsThe distance and near VA demands were assessed in 33 classrooms (grades 4 to 12) of eight schools. The VA threshold demand relied on the smallest size of distance and near visual task material and viewing distance. The logMAR equivalents of minimum VA demand at specific seating positions (desk) and among different grades were evaluated. The near threshold was converted into actual near VA demand by including the acuity reserve. The existing dimensions of chalkboard and classroom, gross area in a classroom per student and class size in all the measured classrooms were compared to the government recommended standards.ResultsIn 33 classrooms assessed (35±10 students per room), the average distance and near logMAR VA threshold demand was 0.31±0.17 and 0.44±0.14 respectively. The mean distance VA demand (minimum) in front desk position was 0.56±0.18 logMAR. Increased distance threshold demand (logMAR range -0.06, 0.19) was noted in 7 classrooms (21%). The mean VA demand in grades 4 to 8 and grades 9 to 12 was 0.35±0.16 and 0.24±0.16 logMAR respectively and the difference was not statistically significant (p = 0.055). The distance from board to front desk was greater than the recommended standard of 2.2m in 27 classrooms (82%). The other measured parameters were noted to be different from the proposed standards in majority of the classrooms.ConclusionThe study suggests the inclusion of task demand assessment in school vision screening protocol to provide relevant guidance to school authorities. These findings can serve as evidence to accommodate children with mild to moderate visual impairment in the regular classrooms.

Influence of intraocular lens subsurface nanoglistenings on functional visual acuity

To investigate the influence of intraocular lens subsurface nanoglistenings (SSNGs) on functional visual acuity (FVA), thirty-nine eyes of 29 patients were examined in this study. The SSNG group comprised 19 eyes of 14 patients (75.7± 5.4 years, mean ± standard deviation), and the control group comprised 20 eyes of 15 patients (73.6 ± 6.5 years). The SSNGs were diagnosed on the basis of the typical whitish IOL appearance upon slit-lamp examination and results of densitometry regarding surface light scattering using Scheimpflug images. The FVA measurement system (AS-28; Kowa, Aichi, Japan) was used to examine changes in continuous visual acuity (VA) over time, and visual function parameters such as FVA, visual maintenance ratio (VMR), maximum VA, minimum VA, standard deviation of VA, and number of blinks were assessed. The results were compared between the SSNG and control groups, and correlations of FVA parameters with the intensity of surface light scattering, time after surgery, and age were also evaluated. There were significant differences in VMR (P = 0.035) and standard deviation of VAs (P = 0.031) between the two groups, although no significant differences were found in baseline VA, FVA, maximum VA, minimum VA, and number of blinks. None of the FVA parameters showed any significant correlations with the intensity of surface light scattering, time after surgery, or age. There is a possibility that VA is unstable during a continuous gazing task in patients with SSNGs.

Functional visual acuity in patients with successfully treated amblyopia: a pilot study.

The aim of this study was to use conventional visual acuity measurements to quantify the functional visual acuity (FVA) in eyes with successfully treated amblyopia, and to compare the findings with those for contralateral normal eyes. Nineteen patients (7 boys, 12 girls; age 7.5 ± 2.2years) with successfully treated unilateral amblyopia and the same conventional decimal visual acuity in both eyes (better than 1.0) were enrolled. FVA, the visual maintenance ratio (VMR), maximum and minimum visual acuity, and the average response time were recorded for both eyes of all patients using an FVA measurement system. The differences in FVA values between eyes were analyzed. The mean LogMAR FVA scores, VMR (p < 0.001 for both), and the LogMAR maximum (p < 0.005) and minimum visual acuity (p < 0.001) were significantly poorer for the eyes with treated amblyopia than for the contralateral normal eyes. There was no significant difference in the average response time. Our results indicate that FVA and VMR were poorer for eyes with treated amblyopia than for normal eyes, even though the treatment for amblyopia was considered successful on the basis of conventional visual acuity measurements. These results suggest that visual function is impaired in eyes with amblyopia, regardless of treatment success, and that FVA measurements can provide highly valuable diagnosis and treatment information that is not readily provided by conventional visual acuity measurements.

Influence of schooling and age on cognitive performance in healthy older adults.

Few studies have examined the influence of a low level of schooling on age-related cognitive decline in countries with wide social and economic inequalities by using the Cambridge Automated Neuropsychological Test Battery (CANTAB). The aim of the present study was to assess the influence of schooling on age-related cognitive decline using unbiased cognitive tests. CANTAB allows cognitive assessment across cultures and education levels with reduced interference of the examiner during data acquisition. Using two-way ANOVA, we assessed the influences of age and education on test scores of old adults (61–84 years of age). CANTAB tests included: Visual Sustained Attention, Reaction Time, Spatial Working Memory, Learning and Episodic Memory. All subjects had a minimum visual acuity of 20/30 (Snellen Test), no previous or current history of traumatic brain/head trauma, stroke, language impairment, chronic alcoholism, neurological diseases, memory problems or depressive symptoms, and normal scores on the Mini Mental State Examination (MMSE). Subjects were grouped according to education level (1 to 7 and ≥8 years of schooling) and age (60–69 and ≥70 years). Low schooling level was associated with significantly lower performance on visual sustained attention, learning and episodic memory, reaction time, and spatial working memory. Although reaction time was influenced by age, no significant results on post hoc analysis were detected. Our findings showed a significantly worse cognitive performance in volunteers with lower levels of schooling and suggested that formal education in early life must be included in the preventive public health agenda. In addition, we suggest that CANTAB may be useful to detect subtle cognitive changes in healthy aging.

Level of visual acuity necessary to avoid false-positives on the HRR and Ishihara color vision tests.

Minimizing false-positives (FPs) when evaluating color vision is important in eye care. Identification of plate 1 (demonstration plate) is often considered a way to avoid FPs. However, few studies have quantified the minimum level of visual acuity (VA) that would minimize FPs for the Ishihara and HRR color tests. Threshold levels of optical defocus were obtained from 25 color normal subjects. Blur levels were obtained for Ishihara (38 plate) plates 1, 10, and 15 and 4th edition HRR plates 1, 7, 10, and 20 using the method of limits. Corresponding VAs were measured through these blur levels at 40 centimeters after adjusting for the dioptric distance difference. Analysis of variance testing was used to analyze the data. Mean optical defocus values in diopters (mean ± SD) for HRR plates 1, 7, 10, and 20 were 6.23 ± 1.61, 1.23 ± 1.16, 2.41 ± 1.31, and 7.96 ± 2.03, respectively, and for Ishihara plates 1, 10, and 15 were 5.70 ± 1.52, 3.68 ± 1.71, and 4.62 ± 1.56, respectively. There was a significant difference between the screening and demonstration plates for both tests (p<0.001). Based on the plate in each test that was found to be the least tolerant to blur, the average minimum VAs needed to identify the screening plates were approximately 20/180 for the Ishihara test and 20/50 for the HRR test. Identifying the demonstration plate in the Ishihara and HRR tests does not ensure FPs will be avoided.

Pitfalls in the Use of Stereoacuity in the Diagnosis of Nonorganic Visual Loss

The Titmus Stereotest (Stereo Optical Co., Inc., Chicago, IL) has been used to estimate visual acuity (VA) in the evaluation of nonorganic visual loss. Previous predictions were derived from optical degradation of VA in normal subjects and may not account for the variability seen in patients with neuro-ophthalmic pathologies included in the differential diagnosis of nonorganic visual loss. The purpose of this study was to evaluate the relationship between Titmus stereoacuity and minimal VA based on a real-world testing environment. Cross-sectional observational study. All patients treated at the authors' neuro-ophthalmology service between April 25, 2014, and July 31,2014. All subjects underwent routine neuro-ophthalmic examination, including Titmus stereoacuity measurements. A compound Bayesian logit-lognormal model accounting for heteroscedasticity was used to determine 95% and 99% prediction intervals of the worse eye's near VA based on stereoacuity. Logarithm of the minimum angle of resolution VA and log stereoacuity were analyzed. Titmus stereoacuity and worse eye VA. Of 561 patients, 364 subjects 11 to 91 years of age were included. Titmus stereoacuity was associated positively with VA: 9 circles correct (40 seconds of arc) indicated VA of at least 20/40 with 95% confidence and VA of at least 20/79 with 99% confidence; 6 circles correct (80 seconds of arc) indicated VA of at least 20/62 and 20/180, respectively; and 4 circles correct (140 seconds of arc) indicated VA of at least 20/110 and 20/570, respectively. When fully accounting for individual variation and the full spectrum of neuro-ophthalmic diseases affecting VA, stereoacuity remains associated with VA, but previous commonly used VA estimates based on stereoacuity overestimated VA. Our results more accurately predict minimum VA from Titmus stereoacuity and should be used preferentially when evaluating patients with suspected nonorganic visual loss. We demonstrated that Titmus stereoacuity cannot definitively establish normal VA, and therefore can suggest, but not fully establish, the diagnosis of nonorganic visual loss.

Long-Term Results of the Boston Keratoprosthesis for Unilateral Corneal Disease.

To report the results of unilateral implantation of a Boston keratoprosthesis (BKPro) in patients with good visual acuity in the fellow eye. A retrospective analysis of 37 eyes of 37 patients who underwent an optical BKPro and had a preoperative best-corrected visual acuity (BCVA) of 20/40 or better in the fellow eye at Wills Eye Hospital from September 2005 to November 2013 was performed. Patients were excluded if they had less than 1 year of postoperative follow-up. The mean follow-up after BKPro implantation was 31.7 months (range, 12-78 months; SD, 21). Twenty-eight patients underwent a BKPro for failed penetrating keratoplasty, and 9 patients underwent a primary BKPro. The most common complications were elevated intraocular pressure and retroprosthetic membrane formation in 16 eyes (43%) each. The mean final BCVA (1.0 ± 0.8 logMAR; median, 1.0 logMAR) was statistically better than the mean preoperative BCVA (1.8 ± 0.2 logMAR; median, 1.8 logMAR) (P < 0.001). The probability of postoperative BCVA of 20/200 or better was 54.1% with an average 45.1 ± 4.7 (confidence interval: 35.9-54.3) months of follow-up. The probability of postoperative BCVA of 20/40 or better was 37.8% with an average 51.8 ± 4.9 (confidence interval: 42.0-61.5) months of follow-up. Half of the patients in our study achieved the minimum visual acuity required for binocular functioning, whereas one-third of the patients achieved a BCVA somewhat similar to that of the contralateral eye. The complications were similar to those reported previously with good retention of the device. BKPro implantation is a reasonable option for patients with good vision in the fellow eye.

Mesopic Functional Visual Acuity in Normal Subjects.

To evaluate mesopic functional visual acuity (FVA) with a newly developed system in normal subjects and to compare the results with photopic FVA, sixty-eight healthy volunteers (24.03 ± 4.42 [mean ± standard deviation] years) were enrolled in this study. A commercially available FVA measurement system (AS-28; Kowa, Aichi, Japan) was modified to measure FVA under mesopic conditions as well as photopic conditions. Measurements were performed monocularly in photopic conditions during 60 seconds. After dark adaptation for 15 minutes, the same measurements were repeated in mesopic conditions. Outcomes included starting visual acuity (VA), FVA (the average of VAs), visual maintenance ratio (VMR), maximum VA, minimum VA, and numbers of blinks during the 60-second measurement session, and were compared between mesopic and photopic conditions. Starting VA was –0.11 ± 0.08 and 0.39 ± 0.12 logarithm of the minimum angle of resolution (logMAR) in photopic and mesopic conditions, respectively. FVA was –0.06 ± 0.09 and 0.52 ± 0.14 logMAR, VMR was 0.98 ± 0.02 and 0.94 ± 0.04, maximum VA was –0.15 ± 0.06 and 0.33 ± 0.12 logMAR, the minimum VA was 0.05 ± 0.12 and 0.78 ± 0.20 logMAR, and the number of blinks was 8.23 ± 7.54 and 7.23 ± 6.20, respectively. All these parameters except the number of blinks were significantly different between the two conditions (P < 0.001). Besides, the difference between maximum and minimum VAs and standard deviation of VA were significantly larger in mesopic than in photopic conditions (P < 0.001). This study revealed that not only overall visual function decline but also instability of vision under mesopic conditions even in healthy subjects.

Keratoprosthesis in the Filatov Institute: development, study, and results of application

To present results of development and study of the keratoprosthesis method used at the Filatov Institute of Eye Diseases and Tissue Therapy since 1966. A retrospective case series analysis is used to describe the development of new types of keratoprostheses and methods of implantation as well as different ways of leukoma strengthening. Keratoprosthesis was performed in 1060 eyes of 1040 patients with leukomas of different etiology: burns, 725 eyes (68.4 %); trauma, 120 eyes (11.3 %); keratitis, Stevens–Johnson syndrome and ocular pemphigoid, 108 eyes (10.2 %); and aphakic/pseudophakic keratopathy, 107 eyes (10.1 %). Visual acuity before keratoprosthesis consisted of light perception in 962 eyes (92 %), and 98 eyes (8 %) had minimal visual acuity (1/200–1/50). Both eyes were blind (visual acuity less than 1/200) in 955 patients (91.8 %). The period of blindness varied from 1 to 52 years. As a result of keratoprosthesis, visual acuity of ≥ 1/200 was restored in 1023 of 1060 eyes (96.5 %). Visual acuity of 20/200–20/20 was achieved in 716 eyes (67.5 %). At the last follow-up visit, visual acuity of ≥ 1/200 was preserved in 806 eyes (76 %), visual acuity of 20/200–20/20 was measured in 583 of 1060 eyes (55 %), and good keratoprosthesis fixation in the cornea was achieved in 986 of 1060 eyes (93 %). The minimal follow-up was 12 months (range: 12 months to 37 years, median: 5 years). Our techniques of keratoprosthesis effectively restore vision in patients with leukomas that cannot be treated by optical corneal grafting.

Changes in Functional Visual Acuity and Ocular Wavefront Aberration After Administration of Eye Ointment

To investigate the influence of an eye ointment on functional visual acuity (FVA) and ocular wavefront aberration. In 11 healthy volunteers (6 men and 5 women), visual function parameters, such as FVA, visual maintenance ratios (VMR), and minimal visual acuity (minVA), were assessed by the FVA measurement system before and 2, 5, 10, 20, 30, 40, 50, 60, 90, 120, 180, and 240 min after administration of ofloxacin eye ointment. Ocular aberration was also measured, and the root mean square (RMS) of second-, third-, fourth-, and total higher-order aberrations was determined. The time course of changes in each parameter was statistically analyzed by using repeated-measures analysis of variance and the Dunnett post hoc test, and relationships between visual function and ocular aberration parameters were also analyzed by the Pearson correlation test. FVA, VMR, and minVA showed significant deteriorations at 2-, 5-, 10-, and 20 min after administration of eye ointment compared with the baseline values (P<0.05). All components of ocular wavefront aberration such as second-, third-, fourth-, and total higher-order RMS significantly increased at 2- and 5 min after the administration of eye ointment compared with the baseline values (P<0.05). In addition, deteriorations of these visual function parameters were significantly correlated with reduced blink numbers (Pearson's correlation coefficient; r=- 0.76, P=0.017 for FVA, r=0.79, P=0.013 for VMR, and r=-0.62, P=0.040 for minVA), and VMR was significantly related with changes in second-order RMS (r=-0.60, P=0.049). Eye ointment significantly reduced visual function for at least 20 min. Especially, minVA was worse than 0.155 logMAR, which is legally required for driving, for 3 h after the administration. In addition, increases in lower-order aberration and low blink rates were associated with the degradation of visual function.