NOA Midwestern Symposium 2025: Hypotony-related complications post-trabeculectomy

Dana Shannon, OD, FAAO, detailed a presentation from the 2025 Midwestern Symposium, sponsored by the National Optometric Association and co-hosted by Indiana University, on April 5. Shannon focused on hypotony, specifically its relationship to trabeculectomy, a surgical procedure designed to lower eye pressure in glaucoma patients. Trabeculectomy creates a new drainage pathway in the eye by making an incision in the conjunctiva and sclera, establishing a bleb (fluid collection area) typically located at 12 o'clock underneath the eyelid. While intended to manage eye pressure, this procedure can lead to various complications, particularly hypotony. Hypotony is defined both statistically (eye pressure below 6.5 mmHg) and clinically, with the clinical definition being more significant for optometrists. Shannon outlined several potential complications associated with low eye pressure:

1. Corneal changes: Scleral collapse can cause corneal edema and endothelial compromise.
2. Choroidal effusions: Fluid-filled dome-shaped packs develop in the suprachoroidal space, potentially mimicking retinal detachment.
3. Hypotony maculopathy: The choroid and retina can wrinkle and buckle, detectable through OCT scans.
4. Lens nutrient disruption: Reduced aqueous humor can lead to cataract development.
5. Optic disc edema: More likely in patients with intact nerve fibers.
6. Anterior chamber shallowing: Potential flattening that could cause the cornea to touch the iris or lens.

Notably, Shannon emphasized that these complications can occur years after the initial surgery, not just in the immediate post-operative period. Two case studies highlighted hypotony developing 4 to 5 years after trabeculectomy, underscoring the importance of long-term monitoring. For optometrists, Shannon recommended several management strategies, including the use diagnostic tools like OCT scans and retinal photos, employing bandage contact lenses to manage bleb leaks, using cycloplegic drops and topical steroids to manage choroidal effusions, conducting thorough, extended examinations of post-trabeculectomy patients, and promptly referring patients to ophthalmologists when complications are detected.

The ultimate goal is to help optometrists recognize and address subtle clinical findings, ensuring comprehensive patient care and preventing potential long-term eye health complications.