Abstract
Purpose :
Cobalt-containing metal hip implants can in rare cases cause retinopathy. Previous retinal ganglion cell studies in rabbit showed cobalt (1mM) caused a rapid loss of the light response however recovery was poor. Here we used optical coherence tomography (OCT) M-scans to study the effect of cobalt on the photoreceptor structure in the ex-vivo rabbit retina.
Methods :
We studied the effects of cobalt using a retinal eyecup preparation and time lapse OCT. New Zealand white rabbits were used. The retina was superfused with an oxygenated Ames Ringer on a modified Leica MP multiphoton microscope stage . Time lapse cross sectional B-scan images of the rabbit retina were taken at 15 sec intervals. After a control period, cobalt ( 8-1000μM) was bath applied to the retina for 10min, and then washed out. In some cases the retina was processed for histology. Using OCT M-scans, temporal changes in the dimensions of the retinal structures affected by cobalt were examined and quantified.
Results :
We studied how cobalt affected the retinal thickness in OCT M-scans. In the control condition, OCT M-scans showed there was little change in the retinal thickness to sham applications of Ringer (n=5). In contrast, application of 1mM cobalt caused a rapid shrinkage in the retinal thickness averaging -3.3±1.9 μm (n=7) (p<0.01, 1-tailed T-test). In the presence of 1mM cobalt, the width of the retinal pigment epithelium to inner segment (IS) line declined an average of -2.0± 1.2 μm n=7.mean.s.d. (P< 0.01 1-tailed T-test). This suggested a large effect of 1mM cobalt was on the photoreceptor outer segments. In addition, there was reduction in the peak intensity of the IS line of 9± 4.5 AU (SEM) in 1mM cobalt, n=7. No retinal shrinkage was seen in cobalt at doses of 40μM, however there were effects on the photoreceptor IS and outer segment lines in OCT M-scans.
Conclusions :
We found cobalt caused rapid changes in the structure of the rabbit retinal tissue. At (0.2-1.0 mM), cobalt caused a retinal shrinkage, which was largely due to a reduction in the photoreceptor outer segment width and a disruption of the photoreceptor tips in the OCT image.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.