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Comparison of the visual acuity after photorefractive keratectomy using Early Treatment Diabetic Retinopathy Study
Saeedeh Ghorbanhosseini1, Hassan Hashemi2, Ebrahim Jafarzadehpur3
1Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
Purpose:
To compare the visual responses of post refractive surgery's patients using Early Treatment Diabetic Retinopathy Study Chart (ETDRS) and E-chart with and without color filters.
Methods:
The uncorrected Logarithm of the Minimum Angle of Resolution Visual Acuity (LogMAR VA) of 70 patients with a mean age of 26.2 ± 3.76 years (from 19 to 34 years) who had undergone Photorefractive Keratectomy (PRK) (the range of post operation refractive error: ±0.5 D) was measured under the light conditions of with and without asymmetrical glare by using red, green, and yellow filters and ETDRS chart and E-chart.
Results:
In both light conditions of with and without glare, the mean visual acuity of the three filters in the right and left eyes was significantly better with the E-chart versus the ETDRS chart (P < 0.0001). Only in the glare light condition, the mean visual acuity of the left eye showed no significant difference between the two charts using the red filter (P = 0.30).
Conclusions:
Visual acuity measurements were different with ETDRS chart and E-chart. These two charts cannot be used interchangeably.
