Abstract
Purpose: :
To compare the results of retinal function evaluation in patients with diabetes mellitus type II with varying grades of retinopathy ,using Frequency doubling technique ( Matrix® Zeiss– Humphrey) and fundus related Microperimetry.( NIDEK®– MP–1 )
Methods: :
One eye each of 110 patients with proven diabetes mellitus type II was considered for the study. All patients underwent a detailed ophthalmic examination including slit lamp examination, IOP measurement, Fundus evaluation, Fluorescein angiography and Optical Coherence Tomography of the macula.Macula FDT was used to evaluate test duration and function of the central 5 degrees of the macula .A 5 degree square pattern grating test object of dark and light bars with a spatial frequency of 0.50 cycles/ degree was projected over 16 points.Fixation pattern, test duration and retinal sensitivity of the central 5 ° of the macula was also evaluated using Microperimeter.A 10dB threshold white Goldmmann stimulus type II object was projected over 46 points while the eye fixated on a 2 degree single cross . The findings of the two instruments were compared with each other and with that of an equal number of age matched non diabetic controls as well as correlated with the severity of diabetic retinopathy.
Results: :
54 % eyes had no evidence of retinopathy, 46 % eyes had retinopathy (16% proliferative retinopathy,30 % had evidence of non proliferative retinopathy).39% eyes had clinically significant macular edema. Defective central visual field was observed in 60% eyes in the study group using FDT (30% no retinopathy, 20 % NPDR, 50 % CSME ).These eyes also showed unstable fixation and subnormal retinal sensitivity on Microperimetry . 55% eyes in the study group (34 % eyes no retinopathy , 26 % NPDR,40% CSME) reported prolonged test duration ( > than 2 mts ) using FDT and on Microperimetry ( > than 5mts ).
15 % eyes in control group had abnormal visual field on FDT and unstable fixation and subnormal retinal sensitivity on Microperimetry.
10% eyes showed test duration (> 2mts ) using FDT, and (>5mts) Microperimetry
Conclusions: :
Psychophysical changes were observed by frequency doubled technique and fundus related microperimetry in patients with diabetes mellitus type II and correlated with the severity of retinopathy.
Keywords: diabetic retinopathy • perimetry • visual fields