Abstract
Purpose :
Rabbits have long been used as a large eye model in ophthalmic research because of their relative moderate cost, ease of handling, and relevance to human ocular biology. Moreover, rabbit strains have been developed with different characteristics, such as albinism, variable pigmentation, and body size, to meet specific research needs. In the present study, we compared baseline ocular electrophysiology and biometric parameters between the Dutch Belted (DB) and New Zealand Pigmented (Red) (NZP) rabbit strains.
Methods :
Ocular characteristics were evaluated using fundus photography (Topcon TRC-50X), optical coherence tomography (OCT, Leica/Bioptigen Envisu R2200), and photopic flash and flicker electroretinography (Ocuscience HMsERG handheld tester) to characterize retinal gross morphology, thickness, and visual response, respectively. Three females of each strain were studied, and all animal procedures were carried out with the rabbits anesthetized with isoflurane.
Results :
Fundus photography revealed no consistent differences in the gross morphology of the DB and NZP retinas. Photopic flash ERGS did not show significant differences in mean a-wave amplitude (DB: 21.3 ± 4.7 μV, NZP: 20.8 ± 7.5 μV), b-wave amplitude (DB: 113.9 ± 20.0 μV, NZP: 100.5 ± 25.6 μV), nor in implicit time (DB: 33.7 ± 2.7 mS. NZP: 31.8 ± 2.5 mS); P>0.05 in all comparisons using one-way ANOVA with repeated measures. Photopic flicker mean amplitude did not differ significantly (DB: 49.6 ± 27.8 μV, NZP: 44.7 ± 31.5 μV, P=0.496, Wilcoxon Rank Sum test). The retinal thickness, measured by OCT, differed significantly between the two strains (DB: 233.6 ± 14.0 μm, NZP: 295.7 ± 15.6 μm; P<<0.001, unpaired t-test).
Conclusions :
It is well known that NZP rabbits are larger and heavier compared to DB animals (averaging 3.6 kg vs 1.9 kg, respectively, in our cohorts), and NZP eyes are also larger than DB eyes; however, to our knowledge, the difference in retinal thickness between the two strains has not been reported previously. Because retinal thickness may indicate ocular inflammation and reflect homeostasis, it is an important variable impacting the interpretation of ocular studies. Despite the difference in retinal volume, we did not find strain differences in the photopic ERG responses as reported by others. Although the DB and NZP rabbit strains are both suitable for eye research applications, the potential impact of retinal thickness difference must be considered.
This is a 2021 ARVO Annual Meeting abstract.