Assessment of the posterior segment of the cat eye by optical coherence tomography (OCT).
OBJECTIVE
To assess the feasibility of optical coherence tomography (OCT) for examining the cat ocular fundus, to provide normative data on retinal thickness in different fundus regions, and to demonstrate selected surgically induced vitreoretinal pathologies in the cat.


METHODS
Forty-five eyes of 28 healthy domestic cats and two eyes of domestic cats that had undergone subretinal implantation surgery for a visual prosthesis were examined.


METHODS
An optical coherence tomograph (Zeiss-Humphrey) was used to examine the anesthetized animals. At least five vertical and five horizontal scans in regular distribution were recorded for each cat including (1) the peripapillary region, (2) the area centralis, and (3) the peripheral retina. Thickness was measured manually at five locations in each scan. Retinal thickness was compared in the three above-mentioned fundus regions, between eyes and between vertical and horizontal scans. OCT was additionally performed in animals with retinal detachment and a subretinal visual prosthesis.


RESULTS
OCT measurements required only minimal adjustments of human settings and yielded high quality images. In comparison to humans intraretinal layers were more difficult to differentiate. Retinal thickness was highest in the peripapillary region (245 +/- 21 microm), followed by the peripheral retina (204 +/- 11 microm) and the area centralis (182 +/- 11 microm; all P < 0.0001). There was no statistically significant difference between right and left eye or between vertical and horizontal scans. OCT demonstrated retinal detachment, an iatrogenic break and a subretinal prosthetic device in high detail.


CONCLUSIONS
Retinal thickness was measurable with high precision; values compare well to older histologic studies. OCT bears significant advantages over histology in enabling one to repeat measurements in living animals and thus allowing longitudinal studies. Various vitreoretinal pathologies common in feline eyes are detectable and quantifiable by OCT.
Gekeler
Florian
F
University Eye Hospital, Schleichstrasse 12-16, D-72076 Tübingen, Germany. gekeler@uni-tuebingen.de
Gmeiner
Helmut
H
Völker
Michael
M
Sachs
Helmut
H
Messias
Andre
A
Eule
Corinna
C
Bartz-Schmidt
Karl Ulrich
KU
Zrenner
Eberhart
E
Shinoda
Kei
K
D000818:Animals; D002371:Cat Diseases / Q000175:diagnosis; D002415:Cats / Q000033:anatomy & histology*; D011237:Predictive Value of Tests; D012016:Reference Values; D012160:Retina / Q000033:anatomy & histology*; D012163:Retinal Detachment / Q000175:diagnosis; D041623:Tomography, Optical Coherence / Q000379:methods / Q000662:veterinary*