Study Of Contrast Sensitivity Function Of Refractive Amblyopia Achieving1.0Visual Acuity

Objective:To investigate the contrast sensitivity function of refractive amblyopia patients achieving1.0visual acuity.Methods:Fifty-seven cases with refractive amblyopia, whose visual acuity achieved1.0after the amblyopia therapy, were enrolled in this study from May2011to November2012. All of them included thirty-four male and twenty-three females. The ages ranged from6to12years (mean age8.51±1.894years). Out of all cases, thirty-four (68eyes) had ametropic amblyopia, twenty-three (46eyes) had anisometropic amblyopia. The spherical equivalent refraction in the ametropic amblyopia, amblyopic eye and sound eyes of the anisometropic amblyopia were4.24±2.130DS,4.32±2.175DS, and2.00±1.663DS respectively. Twenty-two (44eyes) had1.0normal visual acuity were enrolled, including seventeen males and five females. The ages ranged from6to12years (mean age8.23±1.541years).Contrast sensitivity function was measured with the OPTEC±6500P under day (photopic:85cd/m2) and night (mesopic:3.0cd/m2) conditions (spatial frequencies:1.5,3,6,12and18cycles/degree) in nine circular patches. Testing was performed from the lowest spatial frequency to the highest one, stopped until the wrong reply. The statistical analysis was performed using SPSS17.0.Results:The peak contrast sensitivity in all groups was noted at3.0cpd. With the spatial frequency increasing, the curve of the CS in refractive amblyopia decreased more than in normal peers from the peak. The CS of the ametropic amblyopia with achieving 1.0visual acuity was still lower at18cpd spatial frequency than the normal peers (P=0.001,0.025<0.05), and no significant difference at low and middle spatial frequencies. The CS of amblyopic eyes of the anisometropic amblyopia were worse than one of the normal group at the18cpd spatial frequency in photopic condition (P=0.005<0.05), and at the6cpd,12cpd,18cpd spatial frequency in scotopic condition (P=0.008,0.000,0.004<0.05). No significant differences were found between anisometropic amblyopia sound eyes and the normal peers at all of the spatial frequencies. The CS values between the amblyopic eyes and sound eyes of anisometropic amblyopia also showed no significant differences in phtopic condition, however it presented significant differences at the6cpd,12cpd,18cpd spatial frequency in scotopic condition (P=0.025,0.045,0.019<0.05)Conclusion:The visual function of amblyopia, such as CS, remained subnormal even their visual acuity achievied1.0, especially at the high spatial frequency and in the scotopic condition. It might be reason of the recurrence in some cured patients who the visual acuity achieved normal. Both of the visual acuity and the CS should be measured and monitored in the treatment of the amblyopia. When the visual acuity of the amblyopia reached the normal, the treatment should be continued until the CS became completely normal. The CS might be more valuable for evaluating the visual function of the cured refractive amblyopia.