Glaucoma with Descemet’s membrane detachment in five horses.

This research details an investigation into glaucoma in horses, where it is found to associate with Descemet’s membrane detachment. It focuses on five horse cases showing similar conditions, leading to the conclusion that equine glaucoma could potentially be diagnosed from severe corneal edema, originating from the detachment of Descemet’s membrane.

Research Context and Methods

• This study inspected five horses suffering from glaucoma associated with detached Descemet’s Membrane (DM), a vital, clear layer of the cornea. All horses had no prior history of intraocular surgery.
• The horses included three Appaloosas and two Thoroughbreds, aged between 16 to 27 years. They displayed severe and widespread corneal edema, a condition where excess fluid accumulates in the cornea tissue, causing inflammation or swelling.
• To proceed with their examination, the team enucleated (removed surgically) the affected eyes due to intraocular hypertension (ocular high pressure) and/or persistent corneal ulceration. The removed eyes (globes) were methodically processed for histopathology, a microscopic examination of biological tissues and analyzed with light microscopy.
• To conclusively diagnose glaucoma, they had to demonstrate a loss of optic nerve axonal tissue, accomplished by measuring neurofilament-immunopositive axons with automated image analysis software.

Findings

• All five horses had shown unilateral severe diffuse corneal edema between 2 and 16 weeks before the eye was removed. The intraocular pressures for these affected eyes were found to range between 9 and 87 mmHg before enucleation.
• IThe detached DM was histopathologically observed in all five enucleated globes, confirming the condition in every case. Furthermore, an avascular spindle cell proliferation was identified in all eyes, located between the displaced peripheral DM and corneal stroma (the thick, middle layer of the cornea).
• Through neurofilament immunostaining, a process to detect remaining nerve fibers, axonal losses aligned with glaucoma diagnosis were revealed.

Conclusion

• The research finds striking associations between equine glaucoma and DM detachments. It points out that these detachments and the resulting glaucoma can potentially be considered as a cause for severe equine corneal edema.
• In the discussed case series, eyes with DM detachment carried a poor prognosis regarding their retention, suggesting the adverse impact of the condition.