Abstract
Purpose:
Glaucoma is a common phenomenon among dogs often associated with an acute onset, choroidal ischemia, and damage to all retinal layers. This project examines the normal anatomy of the blood supply to the retinal layers of the dog: the short posterior ciliary arteries (SPCA) and compares the quantity and luminal size of these vessels to those in dogs with acute glaucoma.
Methods:
Nine normal globes from research breeding dogs scheduled to be humanely euthanized and nine acute glaucomatous globes (enucleation occurred within 7 days of the owner noticing a red and painful eye) from dogs in the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) database were obtained. Each optic nerve was cross-sectioned in 20 micron step sections and labeled dorsally and temporally with ink. At the scleral cross section, vessels were counted and Cell Sens® software was used to determine vessel luminal area.
Results:
Normal globes had an average of 12.44 total SPCA (9-14) with an average total vascular luminal area of 0.085 mm2 (0.044- 0.137). In comparison, glaucomatous globes had an average of 10.22 total SPCA (5-17) with an average total vascular luminal area of 0.042 mm2 (0.021- 0.072). Using a student’s T- Test to compare normal and glaucomatous globes, there was not a statistically significant difference in the number of SPCA (p value of: 0.1232), however there was a statistically significant difference in the total luminal area when comparing normal globes to glaucomatous globes (p value of 0.0023).
Conclusions:
Acute glaucoma in the dog is often accompanied with damage to all retinal layers consistent with choroidal ischemia. The blood flow to these retinal layers is provided by the SPCA and appears to be compromised during acute glaucoma and instances of increased intraocular pressure.
Keywords: 568 intraocular pressure •
629 optic nerve •
472 comparative anatomy