Using Mitomycin C With an Ahmed Tube Shunt

For Glaucoma Physician's Surgical Pearls video series, Minjy Kang, MD, demonstrates a technique of injecting mitomycin C subconjunctivally after implanting an Ahmed tube shunt to help prevent encapsulation. Transcript of the narration follows below:

This is Minjy Kang, a glaucoma specialist from Northwestern University, and this video demonstrates using mitomycin C with an Ahmed tube shunt.

This was a case of 45 year old man with a history of uveitic glaucoma. Preoperatively, his vision was 20/30 and had a pressure of 34 in the right eye on maximally tolerated topical and oral medication.

It was decided to do an Ahmed with mitomycin C. I like to use mitomycin C with Ahmeds to help minimize a hypertensive phase and encapsulation.

This technique is based on one used by Ying Han at UCSF, which was published by Perez et al in Ophthalmology Glaucoma in 2021.¹

While I open the conjunctiva in the fornix for Baerveldts, I prefer to make the incision at the limbus with Ahmeds since I am injecting mitomycin C posteriorly. I then implant the Ahmed in a typical fashion. At the end of the case, after conjunctiva is closed, I apply a pledget of tetracaine and then administer 0.1cc of mitomycin C at a concentration of 0.4 mg/mL posteriorly over the plate, subconjunctivally (not subtenons). The eye is then rinsed with BSS.

Postoperatively, I will typically give additional injections of mitomycin C in a similar fashion at week 1-2 and sometimes additionally at month 1 depending on how the conjunctiva looks.

This patient did well postoperatively, with an injection of mitomycin C at postop week 1 and week 3, with only a slight increase in pressure to 18 at week 3, but no significant hypertensive phase. At a year and a half out, his IOP is at his goal of low teens on 4 agents, which was down from 34 on 4 agents and an oral medication. GP

J. Minjy Kang, MD, is a glaucoma specialist in the department of ophthalmology at Northwestern University Feinberg School of Medicine in Chicago. She reports no disclosures. Reach Dr. Kang at jmkang@northwestern.edu.

Mary Qiu, MD,, the editor of this series, is a glaucoma and cataract surgeon who completed her glaucoma fellowship at the Cole Eye Institute at Cleveland Clinic and her ophthalmology residency training at the Wilmer Eye Institute at Johns Hopkins. Her special interests include neovascular glaucoma; tube revisions and exchanges; optimizing technique and outcomes for nonvalved tubes, goniotomy, and canaloplasty; surgical education for trainees; and creating and sharing her surgical videos.

Reference

1. Perez CI, Verdaguer S, Khaliliyeh D, Maul EA, Ou Y, Han Y. Subconjunctival injections of mitomycin c are associated with a lower incidence of hypertensive phase in eyes with Ahmed glaucoma valve. Ophthalmol Glaucoma. 2021;4(3):322-329. doi:10.1016/j.ogla.2020.10.004