M A S AbdelMegeed
Alexandria University, Ophthalmology, Alexandria, Egypt
Background: Glaucoma is one of the major causes of blindness in the world. It is important to develop new tests to diagnose the disease before severe visual loss occurs.
Purpose: to evaluate the pattern electroretinography (PERG) and pattern visual evoked potential(VEP)changes in glaucoma and ocular hypertension.
Methods: The study was conducted on 30 eyes with primary open angle glaucoma, 20 eyes with ocular hypertension and 20 normal control eyes. All subjects were in the age group 40 V 70 years. All eyes had best corrected visual acuity,,d 6/9 and clear media. The cases were subjected to ophthalmological examination and automated perimetry. PERG and VEP were determined using a reversing black and white checkerboard pattern. Three check sizes (15, 60 and 240 minutes) and three temporal frequencies (1.9 Hz, 7.5 Hz and 15 Hz) were used. The amplitudes and implicit times were determined at each check size and repetition rate.
Results: Eyes with glaucoma showed significant reduction of amplitudes and delay in implicit time at all spatial and temporal frequencies. Eyes with ocular hypertension showed significant changes only with low spatial frequency and high temporal frequency stimulation. PERG and VEP could identify 100% of eyes with glaucoma and 45% of eyes with ocular hypertension as being abnormal.
Conclusions: PERG and VEP are simple, rapid and objective tests that can reveal abnormalities in eyes with glaucoma, and OHT even in the absence of cupping or visual field defects. The use of low spatial frequency checkerboard patterns reversing at high temporal frequency increases the sensitivity of these tests in identifying eyes with glaucoma and ocular hypertension.
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