contrast sensitivity

Alcohol consumption is a globally prevalent practice with well-documented systemic effects. However, its specific impact on visual performance, a critical component for tasks like driving, remains relatively under-investigated. This study aimed to investigate the effects of a standardized dose of alcohol on visual performance parameters. A single-blind, randomized study design was employed, and data were analyzed using the IBM Statistical Package for Social Sciences (SPSS) version 22.0, incorporating descriptive statistics and repeated measures ANOVA. The study comprised sixty participants (mean age 24.1 ± 2.8 years), randomly assigned to an Alcohol group (n = 30) that consumed 250ml of red wine (12% alcohol) or a Control group (n = 30) that consumed an equal volume of a matched placebo. Visual performance parameters, which includes visual acuity (distance and near), contrast sensitivity, amplitude of accommodation, and near point of convergence, were measured at baseline, 30 minutes, and 60 minutes post-consumption. The findings of this study showed that the consumption of alcohol induced a significant deterioration in visual function: distance visual acuity (LogMAR) worsened from a baseline of -0.06±0.14 to 4.29±1.50 at 30 minutes (p = 0.002), near visual acuity (N-notation) worsened from 0.02±0.05 to 3.40±0.67 (p = 0.003), amplitude of accommodation decreased from 13.20±3.40D to 9.83±3.01D (p = 0.001), and near point of convergence (break) receded from 5.50±3.93cm to 8.50±4.38cm (p = 0.003). In contrast, alcohol consumption did not produce a statistically significant effect on contrast sensitivity at any time point (p > 0.05). In conclusion, this study showed that acute, moderate alcohol intake significantly impairs key aspects of visual performance essential for depth perception and focusing. These findings hold clinical significance for optometry, providing evidence-based data to counsel patients on the specific visual risks of alcohol consumption, particularly for activities requiring precise oculomotor control and sharp vision, such as driving at night.

Background:Contrast sensitivity and depth perception are critical components of functional vision that extend beyond conventional visual acuity assessment. Myopia and hyperopia, as common refractive errors, are known to alter the optical quality of the retinal image, potentially affecting contrast detection and stereopsis. However, the degree and pattern of these alterations remain inconsistently reported in literature. Aim:This study aimed to compare contrast sensitivity and depth perception between myopic and hyperopic individuals with best-corrected visual acuity of 6/6, to determine the extent to which these refractive conditions influence visual performance. Methods: A cross-sectional analytical study was conducted among participants with diagnosed myopia and hyperopia attending the Optometry Clinic. Contrast sensitivity was assessed using the Pelli-Robson Contrast Sensitivity Chart, while depth perception was measured with the Lang stereotest under standardized illumination and testing distance. Refractive status was confirmed through objective and subjective refraction. Data were analyzed using appropriate statistical tests to compare mean contrast sensitivity and stereoacuity values between refractive groups, with significance set at p < 0.05. Results: The findings demonstrated a statistically significant reduction in mean contrast sensitivity among myopes compared to hyperopes (p < 0.05), indicating that myopia has a greater detrimental effect on contrast detection, particularly at lower spatial frequencies. In contrast, hyperopes exhibited relatively preserved contrast sensitivity but showed mild variability in binocular fusion responses. Regarding depth perception, myopic participants displayed poorer stereoacuity thresholds compared to hyperopic participants, suggesting that optical blur and aniseikonia secondary to myopic elongation may impair fine binocular disparity processing. No significant association was found between gender and either parameter, while age showed a mild negative correlation with both contrast sensitivity and stereopsis. Conclusion: The study concludes that myopia exerts a more pronounced impact on both contrast sensitivity and depth perception compared to hyperopia, even in the presence of full optical correction and normal visual acuity. These findings highlight the importance of including contrast sensitivity and stereopsis evaluation in routine refractive assessments to provide a more comprehensive understanding of visual function.

Background: Dual sensory impairment, involving both visual and auditory deficiencies, significantly impacts an individual’s ability to communicate, learn, and navigate their environment. Research suggested that hearing-impaired individuals were at a higher risk of developing ocular abnormalities, including refractive errors and contrast sensitivity deficits. Given their reliance on vision for communication, understanding the prevalence and nature of visual impairment in this population was crucial for effective healthcare interventions. Purpose: To determine the relationship between visual and hearing impairment in affected individuals. Method: A cross-sectional study was conducted at the school for the hearing impaired in Benin City using purposive sampling. Participants were selected based on inclusion criteria, with demographic and hearing-impairment data obtained from school records and teachers. Visual assessments included Tumbling E visual acuity testing, ophthalmoscopy, retinoscopy, subjective refraction, contrast sensitivity testing using the Pelli-Robson chart, and cover test. Data were collected using structured forms and analyzed using SPSS Version 25.0. Data Analysis: Descriptive and inferential statistical methods were employed. The prevalence of visual impairment and contrast sensitivity abnormalities was determined. Chi-square tests assessed associations between age, gender, and dual sensory impairment. Results: Among the 100 hearing-impaired participants examined, hyperopia (34%) was the most common refractive anomaly, followed by compound hyperopic astigmatism (15%), while mixed astigmatism (4%) was the least. Visual impairment before correction was 6%, and after refraction, normal vision increased to 96% with 2% impaired. Contrast sensitivity was normal in 96% of participants, with 2% showing mild reduction. No severe visual impairment, blindness, or significant association with age or gender was found. Conclusion: Hearing-impaired individuals showed a high prevalence of correctable refractive errors. Most visual deficits improved with refraction, underscoring the importance of routine vision screening and timely optical correction in schools for the hearing impaired. Contribution to Optometry: This study provided valuable insights into the relationship between visual and auditory impairments, supporting improved screening and management strategies for individuals with dual sensory impairment.