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S. G. Rosolen, B. Lamory, N. Chateau, S. Picaud, J. A. Sahel, J.-F. Le Gargasson; Wavefront Aberration Measurement in Dog and Cat Eyes. Invest. Ophthalmol. Vis. Sci. 2008;49(13):982.
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To evaluate the feasibility of ocular wavefront measurements in dog and cat using a Hartmann-Shack aberrometer designed for the human eyes.
Two dogs and one cat were sedated (Methedomidine, 0.1 mg/kg) and their right eye (RE) pupils were artificially dilated (tropicamide). Wavefront aberrations were measured using an irx3 aberrometer (Imagine Eye, Orsay, France). Prior to each measurement, the eye was aligned with the instrument optical axis by centering both the eye pupil and Purkinje images. The Hartmann-Shack spot images were produced by an array of 1024 microlenses that defined a 7.2x7.2 mm square area in the pupil plane. In preliminary tests, spot image histograms were optimized by adjusting the sensor acquisition time. Wavefront aberrations were then repeatedly measured 10 times in each animal’s RE. Spherical defocus, astigmatism and Zernike coefficients up to the 8th order were finally analyzed.
The optimal acquisition time was 10 ms for all animals, instead of 33 ms when measuring human eyes. Refractive errors could be analyzed in a 6 mm pupil diameter in all cases. The dilated pupil often exceed the sensor area. The average refractive errors in dog #1, dog #2 and the cat were +2.9D(-2.0D)111°;-0.8D(-0.8D)126° and +3.3D(-2.1D)98°, respectively while their Root Mean Square (RMS) higher-order aberrations amounted to 1.9, 1.1, and 2.1 µm RMS respectively. Standard deviation in sphere and cylinder was 1.0D in the cat and less than 0.5D in both dogs. Standard deviation in the higher-order RMS was 0.8 µm in the cat and less than 0.5 µm in both dogs. The observation of individual data revealed that a significant part of this bvariability was due to blink-related changes in aberrations.
Wavefront aberrations can be measured in dog and cat using a conventional aberrometer with reduced image acquisition time. The tested animals had large higher-order wavefront aberrations. Our results reveal that one dog and one cat are myopic with astigmatism and one dog is hyperopic with astigmatism. Measurement reproducibility was poorer than usually found in human eyes and strongly affected by blinks. This variability could be reduced using a larger sensor area, specific head contention device and artificial tears.
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