A Pilot Investigation of Transforming Growth Factor-β2 and Total Protein Concentrations in Aqueous Humor of Canine Glaucomatous Eyes With and Without Ahmed Glaucoma Valve Surgery.

Abstract

OBJECTIVE: To investigate responses to surgical interventions in concentrations of transforming growth factor-&#x3b2;2 (TGF-&#x3b2;2) and total protein (TP) in the aqueous humor (AH) of primary angle-closure glaucoma (PACG) eyes, with and without Ahmed glaucoma valve surgery in dogs. ANIMAL STUDIED: Nineteen eyes diagnosed with PACG from client-owned dogs and nine non-glaucomatous eyes from both client-owned dogs and research Beagles. PROCEDURES: AH samples were collected and analyzed for TP and TGF-&#x3b2;2 via bicinchoninic acid assay and an enzyme-linked immunosorbent assay. The samples included AH from pre-surgical eyes that had aqueous paracentesis for intraocular pressure (IOP) management (pre-surgical group; n&#x2009;=&#x2009;6) and from post-surgical eyes when tissue plasminogen activator was injected (post-surgery group; n&#x2009;=&#x2009;7); fluid aspirated from blebs during surgical revision (bleb group; n&#x2009;=&#x2009;6), and normal control AH samples from both client-owned dogs undergoing ocular surgery for non-glaucomatous conditions and research Beagles (control group; n&#x2009;=&#x2009;9). RESULTS: TP and TGF-&#x3b2;2 concentrations were significantly higher in all PACG groups compared to normal AH (p&#x2009;<&#x2009;0.01). Bleb fluid exhibited the highest TP and TGF-&#x3b2;2 concentrations among glaucomatous groups. Post-surgical AH had significantly lower TGF-&#x3b2;2 concentrations than both pre-surgical and bleb fluid (p&#x2009;=&#x2009;0.0168, p&#x2009;=&#x2009;0.0023, respectively). No significant correlation was found between IOP and either TP or TGF-&#x3b2;2 in any group (p&#x2009;>&#x2009;0.05). CONCLUSIONS: Elevated TGF-&#x3b2;2 in PACG could contribute to disease progression and post-surgical fibrosis. These findings support future studies to examine the potential of TGF-&#x3b2;2 modulation as a therapeutic approach to improving long-term surgical outcomes following Ahmed glaucoma valve surgery in canine PACG.