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Background and Aim: Optic neuritis causes some deficits in visual function in the affected eye and there are some differences in these functions between the affected and unaffected eyes. The purpose of the study is to compare visual functions of both eyes to demonstrate the minimum and maximum value of affection in patients with acute unilateral optic neuritis.
Materials and Methods: Thirty patients (23 female, 7 male aged between 18 and 45 years) who 22 patients with retro-bulbar and 8 patients with anterior optic neuritis, enrolled in the study and their affected and unaffected eyes underwent visual function assessments. Visual acuity (VA), contrast sensitivity (CS), color vision (CV), and visual field (VF) (consist of MA and PSD) were examined for both eyes of all the patients and the significance of the differences between two eyes were calculated and compared by Independent T-test.
Results: According to our results, all the investigated visual functions consist of VA (t-test, t=7.29, P=0.00), CS (t-test, t=9.20, P=0.00), CV (t-test, t= -21.95, P=0.00), MD (t-test, t=5.29, P=0.01) except PSD (t-test, t=0.67, P=0.71) were affected by optic neuritis and there was a significant difference between the affected and unaffected eyes (P<0.01). The most significant difference were found for contrast sensitivity with letters (P=0.00) and there wasn`t any significance in the difference between two eyes for PSD parameter in VF (P=0.71).
Conclusion: Considering the most significant difference of contrast sensitivity between affected and unaffected eyes in patients with acute unilateral optic neuritis, it is suggested to pay more attention to the test in evaluating, diagnosis and follow up patients with acute unilateral optic neuritis.

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Abstract

Background and Aim: consider ing based on the presence or absence of swelling of the optic disc, optic neuritis classified nto two types of anterior and retrobulbar optic neuritis. The aim of this study was to compare the visual functions of patients with anterior optic neuritis and retrobulbar optic neuritis.

Materials and Methods:This cross-sectional study was conducted in 48 patients with optic neuritis including 35 patients (26 females) with retrobulbar optic neuritis and 13 patients (10 females) with anterior optic neuritis. Total cases aged ranging from 18 to 45 years old.The patients underwent clinical tests of visual functions, including visual acuity, contrast sensitivity and color vision. The collected data was recorded and statistical analysis was performed by SPSS software. The significance of the differences between two types of the diseases were calculated and compared by independent t-test.

Results: The anterior optic neuritis patients were slightly older than the retrobulbar optic neuritis ones (Average30.6yearsVs26.6years). Average defect to the visual functions was more severe in anterior optic neuritis in compare to retrobulbar. The visual functions of visual acuity (t=1.74, P=0.048) and color vision (t=-3.00, P=0.005) were significantly different between two types of the diseases. However, there was not a statistically significant difference (t=1.64, P=0.104) for contrast sensitivity as a visual function.

Conclusion: In the retrobulbar optic neuritis that there is not a specific appearance of fundoscopy ,the visual function of contrast sensitivity can be used as a helpful tool for primary diagnosis of the disease. especially

Key words: Anterior optic neuritis, etrobulbar optic neuritis, visual acuity, contrasts ensitivity ,colorvision.