Abstract
Purpose :
Glaucoma is characterized as a group of disorders that lead to retinal ganglion cell loss and decreased vision partly related to elevated intraocular pressure (IOP). Similarly, the Lrp2 mutant zebrafish (bugeye) have elevated IOP and loss of retinal ganglion cells. Previous studies have shown Zeaxanthin protect and improve vision in both humans and animals. We compared the effects of Zeaxanthin on bugeye to normal wild-type zebrafish. Our results will further elucidate the effects that carotenoids have on vision and thus protecting the retina from disease, especially glaucoma.
Methods :
Bugeye and wild-type TU zebrafish aged 6 months were used (N=15 for bugeye and N=10 for wild-type) and mono/binocular visual acuities (VA) were measured using the optokinetic response. VA was correlated to eye and body size due to the asymmetric buphthalmia present in the Lrp2 fish. Zeaxanthin was administered (0.46ng/uL) using an intracameral injection of 9.2 nL. For each animal, one eye was injected with saline and the other with Zeaxanthin. VA, measured in cycles/degree (c/d) were obtained before treatment and subsequently at 2 weeks, 1 month, and 2 months following post-injection. A paired t-test was used to compare VA between the subjects at each time point.
Results :
Intracameral injection of Zeaxanthin improved VA by as much as 13% in the injected eye, but not the control eye for both the bugeye and wild-type group. (p=0.008 and 0.02 respectively) OU acuity also increased in the groups, likely due to the improved eye having a dominant effect on the visual experience. For both groups the VA improvement peaked at 2 weeks after the Zeaxanthin injection – bugeye: 13% and wild-type: 7%. The VA improvement in the bugeye group was larger compared to the wild-type, but did not persist beyond 2 weeks. The VA improvement in the wild-type persisted through the 2 month post injection time point.
Conclusions :
Zeaxanthin significantly improved VA in both the Lrp2 zebrafish model and wild-type zebrafish. The larger improvement observed in the bugeye is likely due to their lower initial vacuity, 0.55c/d compared to 0.74c/d. The shorter duration in vision improvement in the Lrp2 zebrafish model compared to wild-type fish is likely due to the difference in IOP and retina damage. Further testing in zebrafish using other carotenoids or combinations may provide additional insights into the effectiveness of carotenoid treatments in glaucoma.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.