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A long-term dose-response study of mitomycin in glaucoma filtration surgery
A L Robin1, R Ramakrishnan, R Krishnadas
1Department of International Health, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Md, USA.
Archives of Ophthalmology (Chicago, Ill. : 1960)
|August 1, 1997
Summary
Mitomycin exposure during glaucoma surgery can lower intraocular pressure (IOP), but longer exposure times increase cataract risk. Balancing IOP reduction with complication risk is crucial for effective treatment.
Area of Science:
- Ophthalmology
- Glaucoma Surgery
- Pharmacology
Background:
- Glaucoma surgery, such as trabeculectomy, aims to reduce intraocular pressure (IOP).
- Mitomycin-C is an antimetabolite used adjunctively to enhance surgical outcomes by reducing fibrosis.
- Understanding the dose-response relationship of mitomycin is critical for optimizing efficacy and minimizing toxicity.
Purpose of the Study:
- To determine the long-term dose-response relationship between mitomycin concentration, duration of exposure, and its effect on intraocular pressure (IOP) reduction.
- To evaluate the incidence of complications, particularly cataract formation, associated with varying mitomycin exposure parameters.
- To establish optimal mitomycin application protocols for fornix-based trabeculectomy.
Main Methods:
- A prospective, double-masked, placebo-controlled study involving 300 eyes undergoing fornix-based trabeculectomy.
- Eyes were randomized to receive placebo, or mitomycin at 0.2 mg/mL for 2 minutes, 0.4 mg/mL for 4 minutes, or 0.4 mg/mL for 2 minutes.
- Intraocular pressure (IOP) and complications were monitored over a 1-year period in patients with advanced glaucoma (cup-disc ratio > 0.7).
Main Results:
- All mitomycin treatment groups showed significant IOP reduction compared to placebo beyond 1 month.
- A potential dose-response effect was observed for IOP control and cataract development.
- Progressive lens opacification (cataract) was the most common complication (18.1%), increasing significantly with 4-minute mitomycin exposure. Cataract formation was independent of IOP levels.
Conclusions:
- A dose-response relationship for mitomycin in trabeculectomy appears to exist, with exposure duration being more critical than concentration.
- Increased mitomycin exposure duration correlates with a higher risk of cataract formation.
- The benefits of enhanced IOP reduction must be carefully weighed against the increased risk of ocular complications, particularly cataracts.