Aqueous humor vascular endothelial growth factor in dogs: association with intraocular disease and the development of pre‐iridal fibrovascular membrane

Abstract

To examine the concentrations of vascular endothelial growth factor (VEGF) in aqueous humor of dogs with intraocular disease and to evaluate the association of aqueous humor VEGF with pre-iridal fibrovascular membrane (PIFM) formation. Two hundred and twenty six aqueous humor samples and 101 plasma samples were collected from 178 dogs with a variety of intraocular diseases (including cataract, primary glaucoma, uveitic glaucoma, aphakic/pseudophakic glaucoma, retinal detachment, lens luxation, and intraocular neoplasia), and aqueous humor was collected from 13 ophthalmically normal control dogs. Systemic disease status and administration of select medications were recorded. Aqueous and plasma VEGF was assayed via enzyme-linked immunosorbant assay validated for canine VEGF. Available histopathology samples were examined for the presence of PIFM. Where present, PIFMs were categorized as none, cellular, vascular or fibrous, and fibrovascular. Data were evaluated by mixed model anova, with application of Tukey-Kramer adjustment for multiple comparisons. There was no association between aqueous humor and plasma VEGF levels. Compared with normal controls, aqueous humor VEGF was significantly elevated for all intraocular diseases (P < 0.05) except for primary and diabetic cataracts. Systemic disease and administered medications had no significant effect on aqueous humor VEGF concentration. Compared to dogs without PIFM, aqueous humor VEGF was significantly higher in dogs with fibrovascular PIFM (P = 0.001), but not cellular (P = 0.1704) or fibrous/vascular PIFM (P = 0.0667). These findings confirm that VEGF is commonly elevated in aqueous humor of dogs with intraocular disease and likely plays a role in the causation or progression of a variety of intraocular disorders, including the development of PIFM.