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Pamela P. Ko, Ricardo A. Carvalho, Robert Sun; The Progress Of Electroretinogram Changes Over Time And Correlation Between A And B-waves, Photopic Negative Response And Flash Visual Evoked Potential After Induced Retinal Detachment In New Zealand White Rabbits. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4613.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the electroretinogram(ERG) a, b-waves, photopic negative response(PhNR) and flash visual evoked potential(fVEP) over time in induced retinal detachment(RD) at different stages of development.
Five New Zealand White rabbits (>=2.4 kg, age>15weeks) were used. Following anaesthesia intramuscularly, retinal partial and total RD were induced by subretinal injection Haelon5®(0.1 ml) in different quadrants of the eye. Left eyes were used as control. A scotopic ERG was recorded using blue filter as stimulus. Photopic responses with low-mid range intensity were evaluated with blue filter as background and green filter as stimulus. Fundus photography, ocular coherence tomography(OCT), fVEP and ophthalmic exam were performed at baseline, day 4,7,14, 21 and 30. Immunohistochemistry analysis was used for quantification of photorecetor and retinal ganglion cells and examination of topography of surviving photoreceptors and retinal ganglion cells. Statistical analysis was performed by using t-test with multiple comparison procedures (p<0.05).
Five rabbits had developed rhegmatogenous-like RD involving 4 quadrants and one developed RD with 2 quadrants nasally at Day 4. The vitreous and subretinal space remained clear throughout the follow up period. The RD evolved from bullous to flat after 2-3 weeks and regressed until only a small area around the optic streaks was observed at Day 21. Loss of a-wave amplitude was the most pronounced change and had the steepest decrease with an amplitude loss of 65% in the first 3 days. B-wave demonstrated a slower decrease that progressed up to 31 days after RD induction. PhNR was affected bilaterally with an approximate 50% drop after 3 days. As fVEP signal transmission strength weakened on the injured eye, there was a spike in the PhNR amplitude on the contralateral eye at Day 4. All studied ERG waves correlated with the fVEP changes in the injured eyes, however, in the contralateral eyes; PhNR had a negative correlation with fVEP.
Unilateral RD injury caused a cascade of multi-cellular responses in the injured eyes. In species where the retina is mainly avascular, the most significant ERG and fVEP changes occurred within 3 days after induced RD with minimal or no vitreous proliferation. It appears that the photoreceptors respond rapidly to the induced injury and trigger a slower functional loss of bipolar cells. PhNR correlated directly to fVEP decrease in the injured eye.
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