This article is more than 5 years old. Information may no longer be current.
Single LRI may reduce corneal astigmatism with neutral impact on higher-order aberrations
The incisional approach was predictable, with no serious complications reported.
Limbal relaxing incisions performed after cataract surgery and IOL implantation reduced corneal astigmatism but had a neutral effect on corneal aberrations, a study found.
Quatrefoil aberrations increased in eyes that underwent a single limbal relaxing incisions (LRI), the study authors reported.
“The most significant finding was the significant reduction of topographic astigmatism by LRI procedure by 51.87%, where it was 1.29 D compared to 0.17 D in the control group,” corresponding author Tamer F. Eliwa, MD, FRCS, told Ocular Surgery News.
The study did not compare LRIs with other methods of astigmatic correction.
“In our study, we did not compare the effect of LRI on corneal aberrations with other procedures of astigmatic correction, but we compared the changes in corneal aberrations induced by LRI vs. control group to show no significant changes in these aberrations except quatrefoil, which reduced significantly due to peripheral location of the LRI,” Eliwa said.
Study design
The retrospective study, published in the Journal of Refractive Surgery, included 45 eyes of 36 patients with visually significant cataract, regular corneal astigmatism less than 2.5 D in preoperative topography, clear cornea, and no history of previous ocular surgery or glaucoma. Peripheral corneal thickness was greater than 660 µm, and pupil size was greater than 5 mm.
All eyes underwent coaxial microincision cataract surgery. A single LRI was performed on 23 eyes of 17 patients; 22 eyes of 19 patients did not undergo an LRI. An AcrySof SN60WF IOL (Alcon) was implanted in all eyes.
Eyes with irregular corneal astigmatism, keratoconus or suspected keratoconus, current uveitis, marked corneal scarring, pannus or pterygium were excluded from the study. Cases with intraoperative complications, such as failure to place the IOL in the capsular bag or suturing of the wound, or any complication requiring enlargement of the incision or insertion of another IOL, were also excluded.
A single LRI was performed on the steepest meridian of corneal topography. The Donnenfeld nomogram was used to determine degrees of arc.
The Keratron Scout topographer (Optikon) was used preoperatively and 1 month postoperatively to perform corneal topography and wavefront analysis for a 6-mm aperture.
The Alpins vectorial method was used to analyze target induced astigmatism vector, surgically induced astigmatism vector, difference vector, magnitude of error, flattening effect and torque.
Both groups had similar mean preoperative astigmatism and root mean square of individual higher-order aberrations.
Results
Mean topographic astigmatism decreased from 1.6 D preoperatively to 0.87 D at 1 month postoperatively in the LRI group and from 1.3 D preoperatively to 1.23 D at 1 month postoperatively in the control group. The decrease was statistically significant in the LRI group (P < .0001).
Mean surgically induced astigmatism was 1.29 D in the LRI group and 0.17 D in the control group. Mean target induced astigmatism was 1.33 D in the LRI group, which was less than the preoperative topographic astigmatism (1.6 D) because of the application of the single LRI.
The changes in corneal higher-order aberrations were not significant in either group. However, quatrefoil aberration increased significantly in the LRI group, from 0.04 µm to 0.13 µm (P = .01); the change was not significant in the control group.
No serious complications were reported in either group. However, complaints of foreign body sensation were reported in 10 of 23 cases in the LRI group (43.48%) and in five of 22 cases in the control group (22.73%). Complaints persisted for about 1 month in the LRI group and less than 1 week in the control group. – by Matt Hasson
- Reference:
- Eliwa TF, et al. J Refract Surg. 2016;doi:10.3928/1081597X-20160121-02.
- For more information:
- Tamer F. Eliwa, MD, FRCS, can be reached at Department of Ophthalmology, Ain Shams University, 154 Gesr Elsuiz Street, El Anan Tower beside Tagneed Bridge, Apt. 36, Cairo, Egypt; email: tamerfahmy4@yahoo.com.
Disclosure: Eliwa reports no relevant financial disclosures.
Perspective
Back to Top
This paper is interesting because it shows how properly performed limbal relaxing incisions are effective in correcting moderate amounts of astigmatism during cataract surgery without changing significantly the optical quality of the cornea.
This paper points out how through the use of an on-axis incision, appropriately selected nomogram, being conservative in the selection of patients, especially the amount of astigmatism to be corrected, and, conversely, the aggressiveness of the surgery, these manual incisions can be an excellent alternative to toric lenses for clear correction of astigmatism, especially in lower ametropia. The role of limbal relaxing incisions in low astigmatism, up to 1.5 D to 2D, is what is established today as an alternative to toric lenses in which the variability is largely due to the role of the posterior corneal surface and the difficulty in calculating the toricity.