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Sarah Kochik, Christine Frances Wildsoet, Austin Roorda; Optical Aberrations of Guinea Pig Eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2738.
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© ARVO (1962-2015); The Authors (2016-present)
Guinea pigs are commonly used as models in studies of emmetropization and myopia, yet the optical quality of their eyes has received little attention. In this study, we evaluated the normal optical aberrations in young guinea pigs.
A custom-built Shack-Hartmann wavefront sensor was used to measure the optical aberrations of eight adolescent pigmented guinea pigs (age range 6-11 weeks). Eyes were cyclopleged with 1% cyclopentolate for measurement and were otherwise untreated. Animals were hand-held while their left eyes were aligned to acquire aberration measurements. At least five spot pattern images were acquired for each eye and the best effort was made to measure aberrations along the optical axis of the eye.The raw SHWS images often exhibited elongated or a dual spot patterns consistent with reflections from the inner retinal surface as well as a deeper retinal layer (presumably the photoreceptors). In the analysis, care was taken to choose spots originating from the deeper layer. Analyses were made over a 4mm pupil, which is their typical pupil diameter under laboratory lighting conditions.
Analysis of the 2nd order terms resulted in a mean spherical equivalent cycloplegic refractive error of low hyperopia 2.53 ± 1.6D. The RMS value of the high order aberrations for all eyes was 0.54 ± 0.22um over a 4mm pupil size. Excluding one outlier with a particularly abnormal spot pattern, the average RMS value of the high order aberrations becomes 0.47 ± 0.07um over a 4mm pupil size. RMS aberrations decreased with increasing Zernike order.
The refractive error estimate obtained using this approach is consistent with results with more commonly used recording techniques, such as retinoscopy. Like humans, the RMS decreases with increasing order, but the magnitude of the high order aberrations are about 4-5 times worse than human adults for the same 4mm pupil size.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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