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JR Mertz, MH C Howlett, SA McFadden; Ocular All-Trans-Retinoic Acid Levels are Correlated with Eye Growth in the Pigmented Guinea Pig Eye . Invest. Ophthalmol. Vis. Sci. 2002;43(13):207.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Previous reports have suggested that in the chick, ocular all-trans-retinoic acid (at-RA) levels are altered by visual experience 1, 2. We have investigated this in a mammal - the pigmented guinea pig (GP). We studied the effects of form deprivation (FD), recovery from FD and lens wear on the levels of at-RA in the GP retina and combined choroids and sclera. Methods: Ocular elongation rates were increased (see Howlett and McFadden, ARVO 2002) by either FD (16 days of monocular diffuser wear, n=13) or by negative lens wear (10 days of monocular -4D lens, n=5): it was decreased either by removal of a diffuser (for 4 days after 16 days of monocular diffuser wear, n=8) or by positive lens wear (10 days of monocular +4 D lens, n=5). The refractive error response to visual manipulations and ocular growth rates were determined respectively by streak retinoscopy under cycloplegia in awake animals and by high frequency ultrasound in anaesthetized GPs. Eyes were removed, bisected at the ora serata and the retina and choroid plus sclera were removed and weighed. Homogenized tissues were extracted with 2 volumes of CHCl3-MeOH 2:1 (v/v) and at-RA levels determined by normal phase HPLC analysis. Results: FD or negative lens wear caused an increase in retinal at-RA relative to the untreated eyes (69 and 61%, respectively). FD also caused an increase in choroidal/scleral at-RA (165%). In contrast, recovery from FD and positive lens wear caused a decrease in retinal at-RA (31% in both) and in the choroid/sclera at-RA levels. View OriginalDownload SlideView OriginalDownload Slide. Conclusion: Visual manipulations that alter the rate of ocular elongation change the endogenous levels of at-RA in both the mammalian retina and the choroid/sclera, suggesting that at-RA is an important signaling molecule sensitive to the degree and sign of defocus in the pathway involved in the visual regulation of refractive error and eye dimensions. 1. Seko, Y, Shimizu, M. & Tokoro, T. Ophthalmic Res. (1998) 30, 361-7. 2. Mertz, J.R. and Wallman, J. Exp. Eye Res. (2000) 70, 519-27.
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