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.

OBJECTIVE

To investigate responses to surgical interventions in concentrations of transforming growth factor-β2 (TGF-β2) 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-β2 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 = 6) and from post-surgical eyes when tissue plasminogen activator was injected (post-surgery group; n = 7); fluid aspirated from blebs during surgical revision (bleb group; n = 6), and normal control AH samples from both client-owned dogs undergoing ocular surgery for non-glaucomatous conditions and research Beagles (control group; n = 9).

RESULTS

TP and TGF-β2 concentrations were significantly higher in all PACG groups compared to normal AH (p < 0.01). Bleb fluid exhibited the highest TP and TGF-β2 concentrations among glaucomatous groups. Post-surgical AH had significantly lower TGF-β2 concentrations than both pre-surgical and bleb fluid (p = 0.0168, p = 0.0023, respectively). No significant correlation was found between IOP and either TP or TGF-β2 in any group (p > 0.05).

CONCLUSIONS

Elevated TGF-β2 in PACG could contribute to disease progression and post-surgical fibrosis. These findings support future studies to examine the potential of TGF-β2 modulation as a therapeutic approach to improving long-term surgical outcomes following Ahmed glaucoma valve surgery in canine PACG.