الفهرس 
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Abstract
Primary congenital glaucoma (PCG) is a developmental glaucoma occurring in the first 3 years of life resulting from isolated trabeculodysgenesis and manifests with elevated IOP, globe enlargement (increased corneal diameter and axial length and broadening of the corneoscleral limbus) and optic nerve affection. The optic nerve demonstrates increased cupping that is initially attributed to posterior bowing of the lamina cribrosa rather than to true neuronal loss. Treatment is surgical with goniotomy, trabeculotomy, trabeculectomy, combined procedures, glaucoma drainage devices and cyclodestruction being the available options.
The visual evoked potential (VEP) is the potential recorded from the occipital region in response to visual stimuli with a long latency response. It is very useful in evaluating visual function. It is noninvasive and has excellent temporal resolution. For recording VEP, a stimulus is presented to the subject for a selected number of times, and the cerebral responses are amplified and averaged by a computer and displayed on an oscilloscope screen or printed out on paper. It is generally elicited by the monocular stimulation of each eye, while the other is covered.
The aim of this study is to describe the electrophysiologic changes in the visual evoked potentials after glaucoma surgery in operated cases of primary congenital glaucoma.
The study enrolled children presenting with PCG to the ophthalmology department of Alexandria Main University Hospital in the period between June and December 2019. All study participants were subjected to a standard protocol of examination, to confirm the diagnosis of PCG. The child was then referred for flash VEP testing. Peaks were designated as negative and positive waves in a numerical sequence (N1, P1, N2, P2, N3 and P3). The child was then scheduled for surgery within 1 week of presentation. Postoperative VEP testing was scheduled as soon as feasible and was conducted in the same way as the preoperative VEP testing.
The study was conducted on 11(4 right) eyes of 8(5 males) children. The mean±standard deviation of the age of the study children at presentation and at postoperative VEP testing was 3.5±1.6 and 5.1±3.0months respectively. The study eyes mean±standard deviation IOP at presentation and at postoperative VEP testing was 23.0±6.7 and 8.3±2.4mmHg respectively (p<0.0001). There was a statistically insignificant reduction of P2 implicit time (p=0.235) and a statistically insignificant increase of each of N1-P1 (p=0.15) and N2-P2 (p=0.67) amplitudes postoperatively than preoperatively. from the current study it can be concluded that IOP elevation in PCG adversely affects the optic nerve function, but, at least in the short term, has no permanent detrimental effect on the optic nerve function as evidenced by the improvement of the VEP parameters.