Corneal astigmatism correction with opposite clear corneal incisions or single clear corneal incision: comparative analysis.J Cataract Refract Surg. 2006 Sep; 32(9):1432-7.JC
To compare the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on the steep axis with that of single clear corneal incisions (CCIs) in cataract patients having phacoemulsification.
Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.
This randomized prospective clinical study comprised 40 eyes of 40 patients with topographic astigmatism of more than 1.50 diopters (D). Paired 3.2 mm OCCIs were made in the steep axis in Group 1 and single CCIs in Group 2. Preoperative evaluation included uncorrected visual acuity, refraction, applanation tonometry, dilated fundoscopy, biomicroscopic examination, keratometry, and topography. The steep axis was marked before sub-Tenon's anesthesia was given and routine phacoemulsification was performed through a 3.2 mm CCI on the steep axis. An additional opposite 3-step self-sealing CCI was made in Group 1. Patients were examined 1, 4, and 12 weeks postoperatively. Visual acuity, refraction, keratometry, and topography were evaluated.
The mean preoperative and postoperative topographic corneal astigmatism was 2.51 D +/- 0.92 (SD) and 0.91 +/- 0.54 D, respectively, in Group 1 and 2.16 +/- 0.80 D and 1.57 +/- 0.70 D, respectively, in Group 2. Mean astigmatic correction was 1.66 +/- 0.5 D and 0.85 +/- 0.75 D in Group 1 and Group 2, respectively. Mean surgically induced astigmatism, measured by a vector-corrected method, was 1.66 +/- 0.50 D and 0.85 +/- 0.75 D in Group 1 and Group 2, respectively (P = .00). The coupling ratio was -0.96 in Group 1 and -0.87 in Group 2. The spherical equivalent was +0.23 +/- 0.41 D in Group 1 and +0.11 +/- 0.17 D in Group 2 at 12 weeks. Uncorrected visual acuity was better in Group 1 than in Group 2 (P = .032). There was no difference in best corrected visual acuity between the groups. There were no incision-related complications.
Paired OCCIs were predictable and effective in providing an enhanced effect for correcting preexisting corneal astigmatism in cataract surgery.