Reviewed by Eric D. Donnenfeld, MD
Rockville Centre, NY—Clear corneal incisions are commonly used in today’s modern cataract surgery, as they tend to be no more than 3 mm wide; have minimal effect on pre-existing astigmatism; do not damage the conjunctiva; and can be made superiorly, temporally, or at the steepest axis of the cornea.
They are not, however, free from potential complications.
More than a decade ago, members of the American Society of Cataract and Refractive Surgery Cataract Clinical Committee issued a white paper on the association between these types of incisions and postop endophthalmitis, 1and the concern remains today. 2, 3
There are suggestions today, however, that using a femtosecond laser to create these incisions may help resolve these issues and concerns.
One study has now shown one particular type of femtosecond-created incision to substantially reduce wound leakage compared with other types of incisions.
A 110° reverse side cut primary incision created with a femtosecond laser provides “the most effective seal for potential wound leakage, especially compared with manual incisions,” in patients undergoing cataract surgery, according to Eric D. Donnenfeld, MD, and colleagues.
With femtosecond lasers becoming more integrated into cataract surgery procedures, the group wanted to evaluate and compare self-sealing efficacy and safety of 110° reverse side cuts, 70° forward side cuts, and manually created forward corneal incisions. Dr. Donnenfeld is founding partner of Ophthalmic Consultants of Long Island and Connecticut, Rockville Centre, NY, and clinical professor of ophthalmology, New York University Medical Center, New York.
In this single-center, randomized, observer-masked, parallel clinical study, Dr. Donnenfeld randomly assigned 45 patients undergoing cataract surgery to one of three groups: 110° three-plane reverse side cut created with the femtosecond laser (Catalys, Abbott) (n = 15; Group A); 70° three-plane forward side cut created with the Catalys (n = 15; Group B); or three-plane corneal incision created manually with a metal blade (n = 15; Group C).
In the manual group, the side-port incision was constructed before the corneal incision.
Each patient received the same preoperative, intraoperative, and postoperative open-label medications, and all patients received the same monofocal IOL, Dr. Donnenfeld said.
Follow-up was at postoperative day 1, between postoperative weeks 1 and 2, and at postoperative month 1. The stability of the incisions was evaluated intraoperatively by increasing the IOP by irrigating fluid through the side port incision until the primary incision began to leak without pressure on the wound, at 1 day and 2 weeks postoperative with and without incision pressure for incision leakage (Seidel test). Adverse events were recorded and noted.
The mean age of the patients was 67.3 years at time of surgery, and there were more women (n = 26) than men (n = 19). The majority of patients were Caucasian (n = 35).
At baseline, the majority of patients were 20/100 (67% in Group A, 80% in Group B, and 87% in Group C).
At day 1 postoperatively, the majority of patients in all groups achieved 20/32 uncorrected visual acuity (UCVA): 80% in Group A, 73% in Group B, and 60% in Group C. Of note, 13% of Group B and 7% of Group C reached 20/20 UCVA on postoperative day 1, but none of the patients in Group A did.
At the 7- to 14-day postoperative visit, 73% in Group A, 79% in Group B, and 67% in Group C had 20/25 UCVA, with 27% in Group A, 14% in Group B, and 13% in Group C achieving 20/20.
At the month 1 postoperative visit, however, 13% in Group A, and 20% in Group C had achieved 20/20 UCVA, but 0% in Group B. Best-corrected visual acuity (BCVA) of 20/20 was achieved in 87% in Group A, 80% in Group B, and 73% in Group C at month 1, with every patient achieving 20/25 BCVA.
IOP spikes on the day of surgery were statistically significant between Groups A and B (p = 0.003), Groups A and C (p < 0.001) and between Groups B and C (p = 0.041). By month 1 postoperatively, only differences between Groups A and C were significant (p = 0.017), and hovered around 15 mm Hg.
In Group A, 10 of 15 eyes did not leak even when the IOP was raised to 35 mm Hg and the mean IOP at which the primary incision began to leak was 28.2 mm Hg, 4 of 15 eyes in Group B did not leak and the mean IOP at which the primary incision began to leak was 15.1 mmHg, and 5 of 15 eyes in Group C did not leak and the mean IOP at which the primary incision began to leak was 9.9 mm Hg.
On the first postoperative day, there were no spontaneous Seidel tests without pressure in Group A and B and one patient (in Group C) had a positive Seidel test on postoperative day 1 without pressure.
With mechanical pressure at the wound 0/15 patients in Group A, 8/15 patients in Group B and 13/15 patients in Group C had a positive Seidel test on day 1 postoperatively, with significant differences in all groups: Group A to Group B (p = 0.003), Group A to Group C (p < 0.001), Group B to Group C (p = 0.009)
“Our results suggest a similar outcome in visual acuity results at postoperative month 1, although the initial visual outcomes seem to favor the femtosecond laser,” he said.
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“However, the most important finding in this study is the improved architecture of the reverse side cut incision that creates a better cataract wound that does not leak as often in-traoperatively or on postoperative day 1 as a manual keratome incision,” Dr. Donnenfeld said. “The reverse side cut is an advantage of the femtosecond laser, since the same results cannot be accomplished manually.”
1. Nichamin LD, Chang DF, Johnson SH, et al. ASCRS White Paper: What is the association between clear corneal cataract incisions and postoperative endophthalmitis? J Cataract Refract Surg. 2006;32:1556-1559.
2. Al Mahmood AM, Al-Swailem SA, Behrens A. Clear corneal incision in cataract surgery. Middle East Afr J Ophthalmol. 2014;21:25-31.
3. Yoon JH, Kim KH, Lee JY, Nam DH. Surgically induced astigmatism after 3.0 mm temporal and nasal clear corneal incisions in bilateral cataract surgery. Indian J Ophthalmol. 2013;61:645-648
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Eric D. Donnenfeld, MD
This article was adapted from Dr. Donnenfeld’s presentation at the 2016 meeting of the American Society of Cataract and Refractive Surgery. He has a financial interest with Abbott.