|Year : 1991 | Volume
| Issue : 2 | Page : 62-64
Visual evoked response in macular diseases
Kabra Manoj1, RG Sharma2, Sharma Raj Kumar2
1 Taparia Institute of Ophthalmology, Bombay Hospital, Mumbai, India
2 Department Of Ophthalmology, S.M.S. Medical College & Hospital, Jaipur, India
C-146, Shyam Nagar, Ajmer Road, Jaipur - 302 006
Source of Support: None, Conflict of Interest: None
Visual evoked responses (VER) were recorded in 10 patients with unilateral maculopathy. VER latency and amplitude were compared between the affected and unaffected eyes. Evaluation of results reveals that in macular disease with fluid accumulation (Central Serous Retinopathy and Traumatic Macular Oedema) the VER showed amplitude reduction depending on reduced visual acuity with no significant change in latency, whereas, in disease with degeneration of retinal layers, (Degenerative Maculopathy) latency was markedly increased signifying associated conduction defect.
Keywords: Visual Evoked Response (VER), Maculopathy, Central Serous Retinopathy
|How to cite this article:|
Manoj K, Sharma R G, Kumar SR. Visual evoked response in macular diseases. Indian J Ophthalmol 1991;39:62-4
| Introduction|| |
Visual Evoked Response is elicited mainly from the central part of the visual field and to the largest part, it reflects the function in the macular area. A delayed visual evoked response is widely used to support the diagnosis of optic nerve disease' Visual evoked response amplitude and latency changes were also reported in patients with macular disease ,,. In this study we tried to evaluate the VER in macular disease and to thereby assess the specificity of delayed VER for the diagnosis of optic nerve disease.
| MATERIAL & METHODS|| |
Ten patients in the age group of 8 to 35 years (Mean age 22.3 years) with the diagnosis of unilateral maculopathy were studied. All patients had optically clear media and were wearing the best spectacle correction at the time of VER recording procedure.
Four patients had central serous retinopathy, four had traumatic macular oedema and two patients had degenerative maculopathy. The visual acuity in the affected eyes ranged from 6/36 to 5/60.
VER were also recorded from each eye of 10 normal controls (mean age 21.7 years). The criterion for a normal was best corrected visual acuity of 6/6 or better in each eye and no biomicroscopic or ophthalmoscopic evidence of any abnormalities.
| Ver recording procedure|| |
Transient Ver were recorded In each eye separately On neuromatic 2000C neuromyograph (Dentac, Holland). The checker board pattern stimuli were displayed on a video monitor (Dentac 25004 monitor). An active electrode was placed at the inion (occiput), a reference electrode was placed 5 cm anterior to the vertex and one ground electrode at the forehead. Pattern reversal checker board stimuli were displayed with the frequency of 2 Hz per second and 200 responses were averaged for each recording.
VER latency was taken from stimulus trigger to the main positive peak and the amplitude of the response was determined by measuring the difference between the major negative (Ni) and major positive peaks (PI). Peak latency and amplitude measurement for each eye as well as the difference between the eyes were measured for both study groups and the normal controls.
| Discussion|| |
Ver in Normal Controls:
In 10 normal control (20 eyes) the mean latency and amplitude of the responses were 97.2 ± 6.7 m. sec. and 6.1 ± 2.5 uV respectively. There was no significant interocular difference in the latency and amplitude of response. The mean latency and amplitude of response from right and left eyes were 97.3 ± 6.5 m. sec. and 97.2 +7.2m.sec. and 6.2 + 2.5uVand5.9 + 5.2uV respectively.
Ver in Central Serous Retinopathy:
In all four patients visual acuity in the effected eyes ranged from 6/12 to 6/36. VER recorded from the affected eyes showed mean latency of 103.5 ± 8.5 m. sec. and mean amplitude of 2.6 ± 2.0 uV, as compared to mean latency and amplitude 96.5 m. sec. and 4.2 uV from the unaffected eyes. The results showed in the affected eyes the response were slightly delayed. (9% increase in mean latency) with marked diminution of amplitude (38%) from the fellow normal eyes.
Ver in Traumatic Macular Oedema:
In four cases with unilateral traumatic maculopathy the visual acuity in the affected eyes ranged from 6/9 to 6/36.
VER recorded from the affected eyes showed mean latency of 99.6 m. sec. and mean amplitude of 3-7 ± 1.4 uV as compared to mean latency and amplitude at 96.5 m. sec. and 5.2 uV from unaffected eyes. The results showed there was only slight increase in latency (3%), but amplitude was markedly diminished (28%) in the affected eyes.
Ver in Degenerative Maculopathy:
Of the two patients with unilateral degenerative maculopathy, one had central toxoplasmic retinopathy and the other had long standing retinal detachment involving the macula. VER recorded from the affected eyes showed mean latency and amplitude of 136.5 m sec and 4.9 uV as compared to the values of 98.0 m. sec. and 8.9 uV respectively from the unaffected eyes. Thus, in affected eyes the responses were markedly delayed (39% increase in latency) with reduce amplitude (43%) from the fellow normal eyes.
The results of the study showed there were significant change in VER amplitude and latency in macular diseases. In conditions with fluid accumulation the amplitude was affected more than the latency whereas, in conditions with degeneration of retinal layers the response were markedly delayed - signifying associated condition defect of impulses.
As significant VER delay may occur in the some macular disease, VER delayed response is not a specific feature of optic nerve disease. Thus, in any patient with abnormal VER, a thorough ophthalmoscopic evaluation should be carried out to rule out maculopathy.
| References|| |
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