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Modifications in phaco technique may reduce early postoperative hypotony
Researchers attributed a low rate of hypotony to careful attention to incision architecture and appropriate case completion IOP.
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Surgeons should closely monitor variations in IOP for 24 hours after phacoemulsification with IOL implantation, a study found.
 Bradford J. Shingleton |
IOP elevation of more than 30 mm Hg on the first day after surgery requires keen scrutiny, especially for patients at risk of glaucoma-related optic nerve atrophy. Postoperative hypotony related to wound instability may also pose the risk of an eye developing endophthalmitis, Bradford J. Shingleton, MD, and colleagues reported in the Journal of Cataract and Refractive Surgery.
Incision location and design are critical for yielding strong outcomes and mitigating complications, Dr. Shingleton told Ocular Surgery News in a telephone interview.
“The most important issue is that all corneal incisions are not created equally,” Dr. Shingleton said. “I think the issue with problems is related to incision architecture. There is no question that any incision can have issues. All incisions need to be configured in a way that’s best for a patient.”
The authors referred to an earlier study in which they found that 20% of normal and glaucomatous eyes undergoing phacoemulsification experienced hypotony 30 minutes after surgery. The new study sought to determine how hypotony in the early postoperative interval may be reduced, they said.
Study subjects
The prospective study included 310 consecutive eyes that underwent temporal posterior limbal phaco with implantation of foldable posterior chamber IOLs. Mean patient age was 72.2 years; 200 patients were women and 110 were men.
Of the 310 eyes, 258 were normal, 32 had open-angle glaucoma and 20 were suspected of having open-angle glaucoma.
Dr. Shingleton performed all surgeries at an ASC between September 2004 and December 2004. In each case, he used a 2.85-mm disposable metal keratome to make a temporal tunnel incision involving the vascular arcade and limbal edge of the conjunctiva. Total incision length was 2.5 mm.
Dr. Shingleton said he modified the conventional clear corneal incision to provide a more posterior entry.
“This is still a clear corneal incision,” he said. “This is not a scleral tunnel or anything like that. It’s just a posterior limbal incision, making sure that we engage the limbal vascular arcade and, more importantly, have a length of incision that is 2.5 mm in terms of entry.”
The posterior approach and 2.5-mm incision can enhance safety and efficacy, Dr. Shingleton said.
“It’s my personal belief that a relatively posterior entry and a satisfactory length, which for me is 2.5 mm, is a safer wound, especially if you leave the pressure a little higher at the end of the case,” he said. “You get the natural closure that’s facilitated by higher pressure.”
Two hundred eight-six patients received three-piece LI61U foldable silicone IOLs (Bausch & Lomb) inserted with an M-port injector cartridge. Twenty-four eyes received three-piece AR40e foldable acrylic IOLs (Advanced Medical Optics) inserted with a cylindrical cartridge injector. The acrylic IOL was selected for eyes with proliferative diabetic retinopathy or other retinal disorders. Nine of the eyes with the AR40e IOL were sutured.
None of the cases had intraoperative complications, shallow chambers, choroidal detachments or endophthalmitis, the authors said in the study.
After surgery, the researchers tested all incisions for sealing. Indications for suturing were monocular patients, significant ocular surface disease, diabetic retinopathy or a patient’s need to return to work shortly after surgery.
Results
IOP measurements were taken preoperatively and 30 minutes and 1 day after surgery. Mean IOP was lower at 30 minutes postop than at 1 day for all patients, according to the study.
Thirty minutes after surgery, five eyes (three normal, one glaucomatous and one glaucoma suspect) had an IOP higher than 30 mm Hg.
Differences between mean IOP in all groups at 30 minutes were not statistically significant, the authors said.
At 1 day postop, 27 eyes (8.7%) had IOP higher than 30 mm Hg. At 1 day, differences in IOP were statistically significant between the normal group and the glaucoma group (P < .0000005) and the normal group and the glaucoma suspect group (P < .0014).
The difference between the glaucoma group and the glaucoma suspect group was not statistically significant (P < .995) at 1 day.
None of the 24 eyes implanted with the AR40e acrylic IOL had IOP lower than 5 mm Hg at 30 minutes or 1 day. At 1 day, four eyes (17.4%) implanted with the AR40e IOL and 19 eyes (8%) implanted with the LI61U IOL had IOP higher than 30 mm Hg, the authors reported.
In the overall patient group, 6.1% of eyes had an IOP lower than 5 mm Hg at 30 minutes, compared with 20% in the earlier study. Suturing had “no significant effect on the incidence of hypotony,” the authors said.
“The lower overall incidence of postoperative hypotony reported here may reflect changes in the surgical technique used in this series compared with the technique in our earlier study,” they said.
The changes included a more posterior keratome entry involving the limbal vascular arcade and conjunctiva in lieu of a clear corneal incision; measured incision length of 2.5 mm rather than an estimated length of 2 mm; a case-completion IOP of 20 mm Hg, not 10 mm Hg; use of peribulbar anesthesia with lid taping in lieu of topical anesthesia; and use of methylcellulose rather than chondroitin sulfate or sodium hyaluronate, the authors said.
“We certainly reduced hypotony significantly with these changes,” Dr. Shingleton told OSN. “Hypotony is not an unimportant issue. … There’s more to hypotony than just the incision architecture itself, but [incision architecture] is still probably the most important thing.”
However, despite the development of new techniques, hypotony may not be eliminated completely, Dr. Shingleton said.
“I don’t think we can make it absolutely zero,” he said. “We tested all of these wounds, and none of these wounds leaked. So even with a non-leaking wound, hypotony can occur.”
For more information:
- Bradford J. Shingleton, MD, can be reached at Ophthalmic Consultants of Boston, 50 Staniford St., Suite 600, Boston, MA 02114; 617-314-4800; fax: 617-589-0552; e-mail: bjshingleton@eyeboston.com.
References:
- Shingleton BJ, Rosenberg RB, Teixeira R, O’Donoghue MS. Evaluation of intraocular pressure in the immediate postoperative period after phacoemulsification. J Cataract Refract Surg. 2007;33:1953-1957.
- Shingleton BJ, Wadhwani RA, et al. Evaluation of intraocular pressure in the immediate period after phacoemulsification. J Cataract Refract Surg. 2001;27(4):524-527.
- Matt Hasson is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses on regulatory, legislative and practice management topics.