Measurement of Visual Acuity (VA) has been used for eye examinations under various clinical conditions. In addition, because of changes in VA with a range of eye diseases, its measurement is used to screen, diagnose, and evaluate response to treatment in numerous eye diseases and predict the patient's Visual function. VA and the likelihood of astigmatism could be evaluated simultaneously using a newly designed Stripped Circle (SC) VA chart. This chart has been developed based on the standard VA measurement scale chart, and the Landolt-C (LC) VA chart and all the standards for a VA chart design were implemented during its development. However, to publicize the clinical application of this VA measurement chart, further studies are required to evaluate its sensitivity, specificity, and repeatability compared with a similar standard VA chart.

Purpose: To determine the Visual Acuity (VA) impairment in patients with retinitis pigmentosa (RP) in different age groups. Materials and Methods: This descriptive study was extracted from the recorded data in the National Registry for Inherited Retinal Diseases (IRDs) in Iran (IRDReg®, ). The clinical records of 441 patients with a diagnosis of RP were investigated in the present study. The comprehensive Visual and ocular examination with retinal imaging were conducted for all study subjects to ascertain the definite clinical diagnosis of RP. VA was classified based on the presenting VA (PGVA) of the better eye according to the International Classification of Diseases reported by the World Health Organization (WHO). Results: In this study, a total of 441 RP patients with the mean age of 38. 66 ±,14. 24 years (range, 4 to 74) were included. Generally, the majority of RP patients in the age range of 20 to 40 years had Visual impairment (80%,95% CI, 74. 3% to 84. 9%). RP patients with younger ages had mild Visual impairment (26. 3%,95% CI, 14. 4% to 41. 7%), while patients with no light perception was only found in older ages (3. 4%,95%CI, 1. 4% to 6. 8%), (P<0. 001). The most frequency of RP patients suffering from Visual impairment had disease onset at age ≤, 20 years (82. 0%,95% CI, 77% to 86. 2%), and also severe Visual impairment was observed in patients with earlier disease onset (2. 6%,95% CI, 1. 2% to 5. 1%), (P=0. 001). Conclusion: Based on our findings, more disease progression and subsequently Visual Acuity reduction was observed in RP patients who had older ages and disease onset in younger ages.

Background: It has been suggested that a decrease in distance stereo Acuity in patients with intermittent exotropia is a good indicator of diminishing control. Walsh et al. claimed that there is a significant relation between the decrease in stereo Acuity and decrease in binocular Visual Acuity (BVA). This can best be assessed by measuring binocular Visual Acuity (BVA). Analysis of BVA could provide a useful clinical tool to evaluate control measures used by patients with intermittent exotropia.Methods: A prospective study of patients with intermittent exotropia, ranging in age from 6 to 60 years, was performed. Only those patients with the presence of either basic or divergence excess (simulated or true) type exodeviation were included in the study.The data analysis included the age of these patients, age at onset of the deviation, monocular and binocular Visual Acuity, oculomotor and fusional status, and near and distance stereo Acuity.Results: Clinical records of 38 patients with intermittent exotropia reviewed and data from 28 patients with the presence of either basic or divergence excess (simulated or true) type exodeviation were included in the study and showed that there is no significant relation between the measurements of BVA and a corresponding loss of distance stereo Acuity.Conclusion: The decrease of distance stereo Acuity reported in patients with exotropia can be a good indicator of diminishing control but as there was no significant relation between the loss of distance stereo Acuity and decreased distance BVA, This measurement cannot be a simple method of quantifying the fusional control of patients with intermittent exotropia.

Background and Aim: Objective measurement of Visual Acuity using VEP is high valued in patients with low levels of cooperation. Therefore, this study aimed to investigate the effect of spatial frequency on VEP components in Visual Acuity using Sweep VEP. Material and Methods: In this cross-sectional study 63 medical students with an age of 22. 81 ±,3. 93 were selected. After a completed eye examination, refractive error was determined, and best-corrected Visual Acuity as subjective was recorded by the Freiburg Acuity contrast test. Sweep VEP using the Roland electrophysiology system was recorded for various spatial frequencies from 2 to 37. 5 cycles per degree. VEP components were the latencies of N1, P1, N135, and the amplitude of VEP. Results: Repeated measures of the ANOVA test showed that the effect of spatial frequency on latencies and amplitude of VEP was significant (P<0. 001). Paired T-test showed that there was a significant difference between subjective Visual Acuity and extrapolation of Visual Acuity with VEP (P<0. 001). Conclusion: According to the significant relationship between VEP amplitude and spatial frequencies of the Visual stimuli obtained in this study, the Sweep VEP technique can be used as a valid and objective tool in the determination of Visual Acuity, especially in patients with low levels of cooperation.

Background and Objective: Age-related cataract is one of the most important causes of blindness. Early detection of cataracts can help alleviate the problems caused by this disease. This study was performed to evaluate the Visual Acuity and contrast sensitivity of patients with early cataract. Methods: This descriptive-analytical study was performed on 54 patients (108 eyes) in the age range of 35 to 50 years with early stage cataract referred to Alzahra Ophthalmology Hospital in Zahedan, souh-west of Iran. The ethnicity of all the participants was Baluchi and Sistani. After correcting the refractive errors if the inclusion criteria were met, Visual Acuity with E chart at 6 m and Pelli Robson contrast sensitivity chart at 3 m were measured as monocular. Results: There was a significant correlation between Visual Acuity and contrast sensitivity (P=0. 033, r 2 =0. 205). The mean of Visual Acuity and contrast sensitivity were not significantly different in the two Baluchi and Sistani ethnicities. But Visual Acuity and contrast sensitivity were significantly different in the two genders (P<0. 05). Conclusion: Early cataract, although having a minor effect on Visual Acuity, can reduce contrast sensitivity. Therefore, measuring of contrast sensitivity in normal light condition in patients with early cataract who complain of blurred vision despite normal Visual Acuity can more accurately assess their Visual function.