A Limbus - or Fornix - Based Flap ?

CYNTHIA M AT TOX, MD Up until about 4 years ago, I always performed my combined phacoemulsification/trabeculectomy procedures with a fornix-based conjunctival flap and my straight trabeculectomies with a limbus-based flap. I liked the closure I used for each. Fellows would ask me, “Why the difference?” I was not entirely satisfied with the IOP-lowering effect of my combined procedures, but I wanted better exposure and quicker execution for the phacoemulsification/trabeculectomy. The blebs of my trabeculectomies with a limbus-based flap were more effective but more often localized with thinning, predisposing the eye to late bleb leaks and bleb-associated infections. Something had to change. I thought, if I could just make my trabeculectomies with a fornix-based flap more effective and they behaved better long term, it would be the best of both worlds. After studying the technique of Peng Khaw, PhD, FRCS, FRCOphth,1 I realized that I had not been aggressive enough in dissecting posteriorly alongside the superior rectus muscles. Once I began performing deep, spreading dissection to either side of the rectus, I developed larger, more diffuse blebs that lowered the IOP more consistently than my prior technique. That is all it took. I did not incorporate any of Dr. Khaw’s other techniques such as large peritomies and scleral flaps or adjustable sutures. I apply mitomycin C (MMC) with two halves of a cut corneal shield. I use two wing sutures to close, one a purse-string type and the other a horizontal mattress with a 10–0 nylon Ethicon 7707 (a vascular needle with a tiny cutting tip that is also used to close the scleral flap; Ethicon, Inc., Somerville, NJ). I quickly adopted fornix-based flaps for my straight trabeculectomies as well. My blebs are diffuse, elevated, and effective (Figure 1). I do occasionally observe an early leak along the limbus, but, managed promptly, the bleb develops nicely. THOMAS W. SAMUELSON, MD Surgeons have debated the relative merits of limbusversus fornix-based flaps for as long as I have been involved in the specialty of glaucoma. I have seen swings in opinion each way. If we define a trend by comparing the relative number of converts moving away from one technique to adopt the other, there is clearly a current trend toward fornix-based flaps. Nevertheless, many surgeons remain loyal to the limbus-based flap. My own approach depends largely on the case at hand. I use both methods, depending on the clinical circumstance. Five years ago, I employed limbus-based flaps nearly 100% of the time for trabeculectomy. Currently, perhaps 70% of my cases are limbus based, and 30% are fornix based. Why the trend toward more fornix-based flaps? Basically, I am paying attention to what my colleagues are telling me. That is, many believe that the bleb with a fornix-based approach is morphologically more favorable. Specifically, they suggest that fornix-based blebs are more low lying and diffuse. Although I have heard this argument for some time, I have been somewhat slow to change my approach, primarily because I have been able to generate similarly low-lying A Limbusor Fornix-Based Flap?