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B Lei, W Tao, RA Bush, PA Sieving; Effect Of Encapsulated Cell Based Intraocular Delivery of Ciliary Neurotrophic Factor (CNTF) on Rabbit Eyes: Electroretinogram, Histological and Funduscopic Observations . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1783.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Exogenous ciliary neurotrophic factor (CNTF) protects against photoreceptor degeneration in some animal models but can cause an acute ERG decrease. As little is known about CNTF effects on normal retinal function, we investigated whether intravitreal CNTF from encapsulated cell therapy (ECT) affected the ERG of normal rabbit. Methods:Fifteen adult New Zealand albino rabbits had ECT implanted in left eyes in 3 groups, secreting CNTF in high (22 ng/day), low (5 ng/day), or zero doses. Right eyes were untreated controls. Ganzfeld ERGs were recorded before and at 5, 15, and 25 days after implantation and eyes then taken for histology. Results:Anterior segments remained normal in all cases, but 2 rabbits each in low and high dose groups developed minimal vitreous membranes. The retina was normal by ophthalmoscopy and by light microscopic histology. Dark-adapted rod b-wave amplitudes were unchanged except for increases with very dim stimuli at 15 and 25 days for low and high doses. Dark-adapted rod a-wave tended to be smaller in the high dose group, but this was significant only at 5 days. Light-adapted cone b- and a-waves were reduced over the entire intensity range at 25 days in the high dose group. However, this was deemed nonspecific, as even the empty device group showed decreases in a-waves and some b-wave responses at 25-days. Conclusion:Continuous CNTF release at low dose (5 ng/day) did not cause significant functional or morphological changes in the normal rabbit retina. However, higher release (22 ng/day) may reduce cone ERG responses by 30%.
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