Purpose
The bugeye zebrafish with a recessive mutation in the lrp2 gene has some similarities with human glaucoma due to its elevated intraocular pressure and optic nerve pathology. The purpose of this study was evaluate and compare the ocular parameters of bugeye and wild-type zebrafish using Fourier Domain Optical Coherence Tomography (OCT).
Methods
Adult zebrafish (22 eyes of 22 fish, age 19.3 months SD 0.5) Wild-type (TU/TL; n=10) and bugeye (n=12) were anesthetized in tricaine and placed on a styrofoam bed. Tricaine solution was perfused over the gills to keep the fish oxygenated and sedated. The Ivue OCT (Optovue) with an adapter to image anterior chamber was brought towards the fish eye. Eight line scans centered on the pupil (see figure) were captured automatically and machine software was utilized to analyze the scans (see figure). Ocular parameters measured were the central corneal thickness, anterior chamber angles, pupil diameter, distance between iris plane & posterior cornea, lens diameter in three axes, vitreous chamber depth and axial length. Analysis of variance was performed to evaluate if the ocular parameters measured were statistically significant between the two strains.
Results
The mean distance between iris plane to corneal endothelium was shorter and the mean pupil was smaller in the eyes of bugeye when compared to wild-type (p=0.02 and p=0.005). The axial length and vitreous chamber depth was longer in the bugeye when compared to the wild-type (p=0.0002 and p=0.0001). The anterior chamber angles, lens dimensions and central corneal thickness were not significantly different between the zebrafish strains.
Conclusions
Additional to the known elevated intraocular pressure in the bugeye there may be anterior chamber differences compared to the wild-type that explains glaucoma pathogenesis in part. The OCT provides the ability to measure such differences without sacrificing the animal.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
421 anterior segment •
419 anatomy