Quantifying the Relationship Between Unilateral Induced Metamorphopsia and Stereopsis Impairment.

Purpose: To investigate the relationship between unilateral metamorphopsia, characterized by visual distortions in one eye, and impaired stereopsis. Methods: Utilizing both near and distance measurements through advanced testing systems, including 4K smartphones and an active shutter three-dimensional system, we simulated varying degrees of unilateral metamorphopsia in 30 healthy young adults aged between 21 and 29 years. Two types of contour-based stereotest symbols, lines and squares, were developed. Distortions were classified into six distinct patterns, each further divided into eight grades of severity. Participants were tasked with identifying visual targets, and their stereothresholds were determined under different conditions of induced distortion. Stereopsis was measured within a range of 2.9 to 1.0 log arcsec, at 0.2 log arcsec intervals. Stereopsis changes under different distortion scenarios were analyzed using the generalized estimating equations, with a sequential Bonferroni adjustment applied for pairwise comparisons. Results: A direct and quantifiable correlation was observed between the severity of metamorphopsia and reductions in stereopsis. As the degree of visual distortion increased, notably in both frequency and amplitude, there was a corresponding decline in stereopsis. This relationship held true in both near and distance measurements of stereopsis. Statistical analyses further reinforced these findings, highlighting a significant detrimental effect of distortion components on stereoacuity. Conclusions: The findings highlight the clinical significance of understanding the interplay between unilateral metamorphopsia and stereopsis. Early interventions in conditions leading to metamorphopsia might be critical to maintaining optimal stereopsis.

The influence of simulated visual impairment on distance stereopsis.

The intricate interrelationships between visual acuity (VA) and stereopsis depend on an array of factors, incorporating the nature of vision impairment, its manifestation (monocular versus binocular), and the classification of stereopsis test symbols used. The objectives of this study were to methodically dissect these multifaceted interactions by simulating a diverse range of vision loss conditions. Thirty medical students with normal vision were subjected to simulated vision loss through opacification and blurring methodologies. Stereopsis was assessed at a distance using both contour-based and random-dot-based symbols under equal binocular and varied monocular VA conditions. In this study, opacification consistently affected stereopsis more than blurring at equivalent VA reductions. However, this difference was absent in contour-based symbols under binocular vision impairment conditions. Significant differences in stereopsis emerged between monocular and binocular vision within the opacification contour-based groups. These differences were less evident in the opacification and blurring groups using random-dot-based patterns. In terms of symbols, the contour-based test demonstrated superior results to the random-dot-based test, particularly under decreased VA. In sum, the method of VA reduction and the choice of stereogram significantly impact distance stereopsis outcomes. This understanding can guide clinical assessments of stereopsis in individuals with varying visual impairments.

A comparative study of stereopsis measurements: analyzing natural conditions versus dichoptic presentation using smartphones and ultraviolet printer technology.

Background: Accurate differentiation between stereopsis assessments in the natural and dichoptic presentation states has proven challenging with commercial stereopsis measurement tools. This study proposes a novel method to delineate these differences more precisely. Methods: We instituted two stereopsis test systems predicated on a pair of 4K smartphones and a modified Frisby Near Stereotest (FNS) version. Stereoacuity was evaluated both in the natural environment state (via the modified FNS) and the dichoptic state (via smartphones). Thirty subjects aged 20 to 28 years participated in the study with the best-corrected visual acuity (VA) of each eye no less than 0 logMAR and stereoauity of no worse than 40″. Varying degrees of monocular VA loss were induced using the fogging method, while this study does not explore conditions where the VA of both eyes is worse than 0 logMAR. Results: When the VA difference between the two eyes did not exceed 0.2 logMAR, the modified FNS produced lower stereoacuity values compared to the 4K smartphones (Wilcoxon signed-rank test: difference = 0 logMAR, Z = -3.879, P < 0.001; difference = 0.1 logMAR, Z = -3.478, P = 0.001; difference = 0.2 logMAR, Z = -3.977, P < 0.001). Conversely, no significant differences were observed when the binocular vision difference exceeded 0.2 logMAR (difference = 0.3 logMAR, Z = -1.880, P = 0.060; difference = 0.4 logMAR, Z = -1.784, P = 0.074; difference = 0.5 logMAR, Z = -1.812, P = 0.070). Conclusion: The findings suggest that stereoacuity values measurements taken in the natural environment state surpass those derived from the dichoptic presentation. However, the observed difference diminishes as stereopsis decreases, corresponding to an increase in induced anisometropia.

Comparison of stereopsis thresholds measured with conventional methods and a new eye tracking method.

PURPOSE: Stereopsis is the ability to perceive depth using the slightly different views from two eyes. This study aims to conduct innovative stereopsis tests using the objective data outputted by eye tracking technology. METHODS: A laptop and an eye tracker were used to establish the test system. Anaglyphic glasses were employed to execute the stereopsis assessment. The test symbol employed was devised to emulate the quantitative measurement component of the Random Dot 3 Stereo Acuity Test. Sub-pixel technology was used to increase the disparity accuracy of test pages. The tested disparities were: 160″, 100″, 63″, 50″, 40″, 32″, 25″, 20″, 16″, and 12.5″. The test was conducted at a distance of 0.65m. Conventional and eye tracking stereopsis assessments were conducted on 120 subjects. Wilcoxon signed-rank test was used to test the difference, while the Bland-Altman method was used to test the consistency between the two methods. RESULTS: The Wilcoxon signed-rank test showed no significant difference between conventional and eye tracking thresholds of stereopsis (Z = -1.497, P = 0.134). There was a high level of agreement between the two methods using Bland- Altman statistical analysis (The 95 per cent limits of agreement were -0.40 to 0.47 log arcsec). CONCLUSIONS: Stereoacuity can be evaluated utilizing an innovative stereopsis measurement system grounded in eye tracking technology.

Evaluating the relationship between induced aniseikonia and distance stereopsis.

Background: The impact of aniseikonia on stereopsis has been studied for decades, however, inconsistency which may be partly attributed to the method of inducing aniseikonia exists among these findings. This study aimed to induce overall and meridional aniseikonia using a three-dimensional (3D) computer and then evaluate the effect of induced aniseikonia on distance stereopsis using contour-based and random-dot-based patterns. Methods: A 3D laptop was used to produce all of the test symbols. Unlike the usual method of creating aniseikonia with size lenses, which would change not only the size but also the relative position of the test symbols in the two images as seen by the two eyes, a new test system was designed to evaluate the aniseikonia, which only modified the size while maintaining the relative position of the test symbols. This new method reduced the disparities induced by location changing of the paired test targets when inducing aniseikonia. Aniseikonia was induced overall or in one of the meridians. The induced meridional aniseikonia included 180°, 30°, 45°, 60°, and 90°, respectively. The range of induced aniseikonia was 0-30% with an increment of 5%. Results: Overall magnification affected stereopsis more than magnification in any one of the meridians. The stereoacuity differences between oblique meridians (30°, 45°, and 60°) were not significant until the aniseikonia increased up to 20%. The difference between 180°, 45°, and 90° was significant when the aniseikonia increased up to 10% in the contour-based test and over 20% in the random-dot-based test. The stereoacuity trend was improved gradually, coupled with the angle changing from 180º to 90º in the contour-based pattern, and deteriorated gradually in the random-dot-based pattern. Conclusions: Overall aniseikonia affected stereopsis more than meridional aniseikonia. The stereoacuity of the contour-based pattern was superior to that of the random-dot-based pattern in the 90° meridian, while the opposite result was obtained in the 180° meridian.

Evaluation of the Relationship Between Aniseikonia and Stereopsis Using a New Method.

Purpose: To investigate the influence of induced aniseikonia on stereopsis measured by contour-based and random-dot-based stereograms using a new method. Methods: Unlike previous studies in which aniseikonia was induced using magnifiers, which potentially influenced the position of the test symbols in the half-view, here the image was magnified while maintaining each test symbol's central position within the half-view. A phoropter and two 4K smartphones were used to measure stereopsis in seventeen young adults aged 20-28 years old. Stereopsis was tested using both contour-based and random-dot-based stereograms under overall or meridional aniseikonia with magnifications ranging from 2.5 to 30%. Repeated measures ANOVA was used to evaluate the effect of aniseikonia on stereopsis. Results: Stereopsis decreased with an increase in aniseikonia magnification in the overall, horizontal, and vertical directions. Stereopsis values (log arcsec) increased from 1.29 ± 0.14 at baseline to 2.38 ± 0.16 with 30% overall aniseikonia of contour-based stereograms. In random-dot based stereograms, stereopsis values increased from 1.29 ± 0.16 at baseline to 2.24 ± 0.23 with 22.5% overall aniseikonia. Overall aniseikonia caused a significantly greater impairment on stereopsis as compared with the changes in meridional directions. In contour-based stereograms, vertical aniseikonia had significantly less impact on stereopsis than horizontal aniseikonia of identical magnification. The opposite phenomenon was found in random-dot-based stereograms. Conclusion: Stereopsis decreased with an increase of magnification of induced aniseikonia. Magnifying patterns (overall, horizontal, or vertical) also significantly affected stereopsis. The conflicting impact of meridional aniseikonia on stereopsis measured by contour-based and random-dot-based stereograms may be associated with the uniqueness of the two test systems.

Nonsteroidal anti-inflammatory drugs for retinal neurodegenerative diseases.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most common prescription drugs for inflammation, and topical NSAIDs are often used in ophthalmology to reduce pain, photophobia, inflammation, and edema. In recent years, many published reports have found that NSAIDs play an important role in the treatment of retinal neurodegenerative diseases, such as age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma, pathological myopia, and retinitis pigmentosa (RP). The aim of the current review is to provide an overview of the role of various NSAIDs in the treatment of retinal neurodegenerative diseases and the corresponding mechanisms of action. This review highlighted that the topical application of NSAIDs for the treatment of retinal degenerative diseases has been studied to a remarkable extent and that its beneficial effects in many diseases have been proven. In the future, prospective studies with large study populations are required to extend these effects to clinical settings.

Effect of Luminance and Contrast Variation on Stereoacuity Measurements Using Smartphone Technology.

Owing to the limitations of printed stereoacuity tests, the effects of luminance and contrast on stereopsis have not yet been sufficiently investigated, despite its important implications in designing stereoacuity measuring instruments, particularly for electronic devices. A stereopsis measurement system was established using two 4 K smartphones and a phoropter to evaluate the effects of luminance and contrast variations on the stereoacuity test. Seventeen young subjects with normal visual acuity and stereopsis were recruited. Two types of test symbols, contour-based and random-dot-based, were used in the experiment. Four series tests were established with different maximum brightness values, including 240 lux, 120 lux, 60 lux, and 30 lux. Each series test contained 19 pages with different contrasts between 95% and 5% and was calculated using the Michelson contrast formula. No significant difference was found for both contour-based and random-dot-based stereograms in any of the contrast groups with different maximum brightness. Similarly, no significant difference was found between contour-based and random-dot-based patterns under different contrasts of above 35%. As the contrast decreased below 30%, the stereopsis was significantly better in the contour-based pattern than in the random-dot-based pattern for some degrees of contrast. The luminance and contrast of the digital display are not critical factors for stereoacuity under normal circumstances. This implies that a standard monitor with a certain 3D technology can be used to measure the stereoacuity threshold without calibrating the luminance and contrast.

Analysis of risk factors for progressive fibrovascular proliferation in proliferative diabetic retinopathy.

PURPOSE: To investigate the risk factors associated with progressive fibrovascular proliferation (FVP) in proliferative diabetic retinopathy (PDR). METHODS: We retrospectively reviewed the clinical data of patients who underwent pars plana vitrectomy for PDR between August 2017 and October 2019 at our department of ophthalmology. The FVP was divided into five grades based on the coverage area of proliferative membrane. Then we compared the patients with different severities of FVP to analyze the risk factors for higher grade of FVP in PDR. RESULTS: Univariate analysis showed that positive urinary protein (p = 0.007), higher levels of serum blood urea nitrogen (BUN) (p < 0.001) and serum creatinine (p < 0.001), more severe stage of estimated glomerular filtration rate (p < 0.001), age < 45 years (p = 0.005), longer duration of diabetic retinopathy (p = 0.007), history of hypertension (p = 0.034) and smoking (p = 0.008) were related to FVP grade ≥ 3. Multivariate analysis showed that the level of BUN, age < 45 years and smoking were independent risk factors for FVP grade ≥ 3 in PDR patients. CONCLUSION: This study demonstrated that BUN (odds ratio [OR] = 1.318, 95% confidence interval [CI] = 1.150-1.511, p < 0.001), age ≤ 45 years (OR = 3.774, 95% CI = 1.762-8.082, p = 0.001) and smoking (OR = 2.111, 95% CI = 1.040-4.288, p = 0.039) were independent risk factors for progressive FVP in PDR among northeastern Chinese patients.