Applications of dynamic visual acuity test in clinical ophthalmology

Dynamic visual acuity test (DVAT) plays a key role in the assessment of vestibular function, the visual function of athletes, as well as various ocular diseases. As the visual pathways conducting dynamic and static signals are different, DVATs may have potential advantages over the traditional visual acuity tests commonly used, such as static visual acuity, contrast sensitivity, and static perimetry. Here, we provide a review of commonly applied DVATs and their several uses in clinical ophthalmology. These data indicate that the DVAT has its unique clinical significance in the evaluation of several ocular disorders.

Evaluation of Fusion and Stereopsis in Anisometropic Patients

Background Binocular vision has many important advantages on monocular vision as it helps in determination of the distance of an object, gives much greater depth of perception, and the ability to have stereopsis and view the world in three dimension (3D). There is an evidence that binocular vision is present in many patients with anisometropia even who have amblyopia but with grades lower than normal. Purpose This study evaluates the effect of anisometropia on BSV functions. Method sixty-four patients above 6 years with anisometropia equal to or more than 2.5D never had their vision corrected either by glasses or refractive surgeries or went on patching treatment, Anisometropic patients were devided into two groups amblyopic group (AA) and non-amblyopic group (NA) were examined for assessing their fusion by Worth four dot test and their stereopsis by fly test (Titmus stereo acuity test) by their best corrective glasses based on their cycloplegic refraction. Results Anisomyopes shows better stereopsis 62% of them and better fusion 65% of them than anisohypropes which had only 8% with good stereopsis and 32% with good fusion. However, antimetropes showed bad fusion and stereopsis as all of the five cases have amblyopia. Only 29.5% of anisomyopes have amblyopia but 68% of anisohypropes have amblyopia. As regard worth four dot test (P < 0.001), as 90.6% of cases with amblyopia had suppressed eye but only 9.4 % of this amblyopic cases had normal fusion. However, in patients without amblyopia 15.6% had suppressed eyes but 84.4% had normal fusion. As regard Titmus test there was statistically significant difference between both groups (P < 0.001), as 100 % of cases with amblyopia had bad stereo acuity but 28.1% of patients without amblyopia had defect in their stereo acuity. Conclusion Fusion and stereopsis as binocular single vision functions were significantly affected in AA patients with best-corrected anisometropic glasses than in NA patients.

The evaluation of a novel tool to remotely assess visual acuity in chronic uveitis patients during the COVID-19 pandemic

BackgroundRestrictions due to the recent COVID-19 pandemic catalysed the deployment of telehealth solutions. A novel web‐based visual acuity test, validated in a healthy population, may be of great value in the follow‐up of uveitis patients.ObjectiveTo determine the measurement accuracy of the unsupervised remote Easee web‐based visual acuity test in uveitis patients, when compared to a conventional in‐hospital assessment.MethodsCross‐sectional diagnostic accuracy study. Between April 2020 and September 2020, consecutive adult uveitis patients were invited for the web‐based visual acuity test (index test) within two weeks prior to their conventional in‐hospital assessment (reference test).ResultsA total of 269 patients were invited by mail, of whom 84 visited the website (31%). Ultimately 98 eyes met the criteria for statistical analysis. The mean difference between the two tests was low and non‐significant: 0.02 logMAR (SD 0.12, P = 0.085). The 95% limits of agreement ranged from ‐0.21 to 0.26 logMAR. No relevant differences were identified in clinical characteristics between subgroups with a good performance (i.e. difference between the tests 0.15 logMAR) or underperformance (i.e. difference >0.15 logMAR) on the web‐based test.ConclusionThe web‐based visual acuity test is a promising tool to remotely assess visual acuity in the majority of uveitis patients, especially relevant when access to ophthalmic care is limited. No association between patient‐ or uveitis‐related variables and (under)performance of the test were identified. These outcomes underline the potential of remote vision testing in other common ophthalmic conditions. A proper implementation of this web‐based tool in health care could be of great value for revolutionizing teleconsultations.

Establishing Prediction Intervals for the SpeedWheel Acuity Test in Adults and Children

Background The SpeedWheel (SW) test is an objective test of visual acuity (VA) using suppression of the optokinetic nystagmus (OKN). Here, we established prediction intervals of the SW measures compared to Snellen acuity in adults and children. Subjects and Methods In this prospective, single center study, subjects aged at least 4 years underwent testing of VA with SW, Landolt-C, and Tumbling-E symbols (Freiburg acuity test: FrACT-C, FrACT-E). Prediction intervals were established for SW compared to FrACT-C or -E and for FrACT-E compared to FrACT-C. Mixed linear effect models were applied for statistical analysis. Results From 241 subjects, 471 eyes were included: median age 36 years, range 4 – 88 years, 43.6% male, 56.4% female. Eyes included were either healthy or had various underlying ophthalmic conditions. Prediction intervals for SW to estimate FrACT-C or -E acuity showed a similar range compared to the prediction interval of FrACT-C for the estimation of FrACT-E acuity. For each acuity step, there was no influence of age. Up to an SW acuity of 0.7 logMAR, 80% of the subjects had a FrACT-C acuity that was at most 1.6 logMAR lines below, and for an SW acuity of 1.0 logMAR, FrACT-C acuity was not worse than 4 logMAR lines. Prediction intervals for eyes with refractive error, cataract, visual field loss and retinal disease did not differ significantly from healthy eyes in contrast to eyes with amblyopia or multiple ophthalmic disorders. SW correlated well to FrACT tests and results of a previous study fell within our prediction estimates. Conclusion Our prediction intervals for SW acuity may be used to estimate Snellen acuity (FrACT-C and -E) in the clinic in adults and children unable to cooperate in other acuity testing.

Visual fixations rather than saccades dominate the developmental eye movement test

When children have visual and/or oculomotor deficits, early diagnosis is critical for rehabilitation. The developmental eye movement (DEM) test is a visual-verbal number naming test that aims to measure oculomotor dysfunction in children by comparing scores on a horizontal and vertical subtest. However, empirical comparison of oculomotor behavior during the two subtests is missing. Here, we measured eye movements of healthy children while they performed a digital version of the DEM. In addition, we measured visual processing speed using the Speed Acuity test. We found that parameters of saccade behavior, such as the number, amplitude, and direction of saccades, correlated with performance on the horizontal, but not the vertical subtest. However, the time spent on making saccades was very short compared to the time spent on number fixations and the total time needed for either subtest. Fixation durations correlated positively with performance on both subtests and co-varied tightly with visual processing speed. Accordingly, horizontal and vertical DEM scores showed a strong positive correlation with visual processing speed. We therefore conclude that the DEM is not suitable to measure saccade behavior, but can be a useful indicator of visual-verbal naming skills, visual processing speed, and other cognitive factors of clinical relevance.