Meta-analysis shows combined procedures more effective

Improved surgical options and techniques have led to better combined surgeries.

There are definite advantages to combining cataract and glaucoma surgeries, and the choice of surgical methods significantly affects outcomes, according to a meta-analysis of published reports.

Karim F. Tomey, MD, FACS, FRCOphth, of Beirut, Lebanon, said small-pupil management, smaller cataract incision sizes, more successful bleb management and possibly improved modulation of wound healing have led to better outcomes in combined procedures.

Dr. Tomey presented results of a metastudy of various surgical methods of combined cataract and glaucoma procedures in his talk, “Current Status of Combined Cataract and Glaucoma Procedures,” at a meeting earlier this year.

Immediate, long-term benefits

Cataract surgery has an immediate effect on intraocular pressure (IOP) in normal and glaucomatous eyes, Dr. Tomey said. Pressure control may become better or worse postoperatively, depending on the severity of disease, type of glaucoma, surgical technique and surgical complications.

“Certainly combined surgery has some well-established advantages,” Dr. Tomey said. “In addition to achieving immediate IOP control and restoring vision, combined procedures may safeguard against IOP spikes that frequently occur following cataract extraction, especially in glaucomatous eyes. Moreover, combined surgery has a positive impact on the patient’s quality of life, insofar as it obviates repeated operations.

“A recent review of the literature by Friedman et al has shown that there is strong evidence for better long-term control of IOP with combined glaucoma and cataract operations compared with cataract surgery alone,” Dr. Tomey said.

Small-pupil management

Limbal-based mattress suture. Limbal-based flap is closed using 10-0 Vicryl in a running-mattress suture. This offers a watertight closure that aids healing.

Fornix-based closure. With a fornix-based flap, closure is achieved using at least two sutures. Note the direction in which the sutures pull (arrows). All photos courtesy Karim F. Tomey, MD, FACS, FRCOphth

The better outcome of combined procedures can be attributed to the many surgical advances and techniques that minimize potential complications, Dr. Tomey said. Among the factors that can improve outcomes are the better techniques for management of small pupils, without destroying or distorting their shape or size.

These techniques include mechanical stretching with iris hooks or iris retractors available from Grieshaber and other companies, and the Graether or Perfect Pupil collars.

Dr. Tomey prefers the Moria Beehler Pupil Dilator, which engages the pupil with three prongs and a hook to stretch it in four directions.

“We may still do some sphincterotomy or iridotomy, with or without sutures, but these last two options are becoming less and less common,” Dr. Tomey said. “No matter which technique of pupil enlargement is employed, one must avoid excessive stretching, retraction or making large cuts into the pupillary sphincter. Such aggressive maneuvers may leave a large, permanently disfigured pupil, which often results in significant photophobia and glare.”

Technique of cataract extraction

Operative variables that can influence the outcome of combined procedures include the type of conjunctival flap, the effect of incision size and site, the choice of combined vs. staged surgery and the use of trabeculectomy vs. other procedures.

The choice of phacoemulsification vs. extracapsular cataract extraction (ECCE) can also make a difference in combined cataract and glaucoma procedures, but this is less of an issue today because the majority of cataracts are being removed by phacoemulsification.

Established advantages of phacoemulsification include a safer, closed-system surgery that allows faster visual rehabilitation, less astigmatism and more stable refraction because of the smaller incision. Some reports describe a less fibrinous reaction and fewer IOP spikes with phacotrabs, Dr. Tomey said.

“More importantly, with a smaller incision you have less tissue manipulation, less inflammation and consequently less scarring and improved bleb quality,” he said.

The metastudy found that most published reports have said phacotrabeculectomy is associated with better IOP control, better blebs, faster visual rehabilitation, less astigmatism, fewer postoperative medications and fewer complications than ECCE-trabeculectomy, he said.

However, Dr. Tomey said, the literature search by Jampel et al. found no randomized, controlled trials that addressed the issue.

Types of conjunctival flaps

Source: Karim F. Tomey, MD, FACS, FRCOphth

Limbal-based flaps offer some advantages over fornix-based flaps, Dr. Tomey said, even though the former are more difficult to dissect, provide poor exposure and are more associated with the possibility of buttonholes.

“On the other hand, once you manage to make these flaps successfully, they are usually easier to close,” Dr. Tomey said. “The leakage, in general, is less common than with a fornix-based flap.”

For closure of a limbus-based flap, Dr. Tomey uses a fine, absorbable monofilament suture such as 10-0 Vicryl on a round needle to create a running-mattress type of closure, in two layers if possible.

“I like to use the running-mattress approach, especially when using anti-metabolites,” Dr. Tomey said. “Such an approach does not leave any exposed sutures. It is watertight. The patient is more comfortable.”

Dr. Tomey said that if he does resort to a fornix-based approach, he uses at least two sutures on each side.

Effect of antimetabolites

Studies have shown that 5-fluorouracil does not improve IOP reduction, Dr. Tomey said, and only a small benefit has been established for mitomycin-C. According to Shin et al., mitomycin may be of some benefit only in the presence of certain risk factors, such as African origin, preoperative IOP greater than 20 mm Hg, the use of two or more medications and previously failed filtering surgery.

Shin et al. also observed that mitomycin seemed to have a beneficial effect by preventing posterior capsular opacification, especially with a 0.03% concentration applied for 3 minutes.

However, use of mitomycin is associated with more against-the-rule astigmatic drift over 12 months postop-
eratively than cases without it, according to a report by Choe et al., Dr. Tomey said.

Other variables

Most reports did not find any major differences be-ween single-site and two-site techniques, nor between combined and staged procedures. The incision size also did not seem to make any difference, Dr. Tomey said.

There was insufficient evidence as to whether procedures such as trabeculotomy, nonpenetrating procedures, cyclodestruction or tube shunts were better than trabeculectomy when combined with cataract extraction, he said. Evidence was also insufficient as to the impact of cataract surgery on pre-existing filtering blebs.

Conclusions

Long-term IOP control is better with combined surgery than with cataract extraction alone, Dr. Tomey said. Phaco combined with trabeculectomy as compared with extracapsular surgery offers faster visual rehabilitation and seems to offer better pressure control, less postoperative astigmatism and fewer postoperative complications, he found.

“Modern small-incision techniques allow cataract removal and IOP implantation practically through the unenlarged trabeculectomy opening,” Dr. Tomey said. “Therefore, tissue manipulation and trauma are reduced to a minimum, which decreases the chances of scar formation and bleb failure. The success rates of combined procedures have thus approached those of trabeculectomy alone. Antimetabolites may improve these rates further, at least in some of the high-risk cases.”

For Your Information:

• Karim F. Tomey, MD, FACS, FRCOphth, can be reached at Beirut Eye Specialist Center, Rizk Hospital, P.O. Box 11-3288, Beirut, Lebanon; +(961) 1-20-25-16; fax: +(961) 1-20-28-57; e-mail: ktomey@cyberia.net.lb.

References:

• Friedman DS, et al. Surgical strategies for coexisting glaucoma and cataract: An evidence-based update. Ophthalmology. 2002;109:1902-1915.
• Jampel HD, et al. Effect of technique on intraocular pressure after combined cataract and glaucoma surgery. Ophthalmology. 2002;109:2215-2224.
• Yamagami et al. Risk factors for unsatisfactory pressure control in combined trabeculectomy and cataract extraction. Ophthalmic Surg Lasers. 1997;28:476-482.
• Wise JB. Mitomycin-compatible suture technique for fornix-based flaps in glaucoma filtration surgery. Arch Ophthalmol. 1993;111:992-997.
• Shin DH, et al. Primary glaucoma triple procedure in patients with primary open-angle glaucoma: The effect of mitomycin C in patients with and without prognostic factors for filtration failure. Am J Ophthalmol. 1998;125:346-352.
• Shin DH, et al. The role of adjunctive mitomycin C in secondary glaucoma triple procdure as compared to primary glaucoma triple procedure. Ophthalmology. 1998;105:740-745.
• Choe CM, et al. The effect of mitomycin-C on postoperative corneal astigmatism in trabeculectomy and triple procedure. Invest Ophthalmol Vis Sci. 1996;37(ARVO suppl):S25.