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J. C. Merriam, L. Zheng; Effect of Iris Hooks on Surgically-Induced Astigmatism (SIA) After Cataract Surgery. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5407.
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To select the power of an IOL it is important for the cataract surgeon to estimate the effect of the incision on SIA. If the pupil fails to dilate or the iris is floppy, the surgeon may anticipate using iris hooks to dilate and stabilize the pupil. This study was designed to estimate the effect of the incisions for iris hooks on SIA after cataract surgery with a temporal 2.6 mm incision.
The IRB of Columbia University Medical Center approved this retrospective study of 194 eyes from 158 patients, with an average age of 76 years. The study included 163 eyes from 130 patients who did not need iris hooks and 31 eyes from 28 patients with iris hooks (Alcon/Grieshaber). In these eyes, the surgeon made 4 incisions in a diamond pattern in peripheral clear cornea for the insertion of iris hooks. The temporal 2.6 mm corneal incision was located directly above the temporal iris hook. At the end of the procedure, the surgeon hydrated the temporal 2.6 mm incision and each of the less than 1 mm incisions for the hooks. The surgeon measured corneal astigmatism with a manual keratometer (Bausch & Lomb) during post-operative visits at 1 day, 1 week, 1 month, 6 months, and 18 months. SIA was calculated with an online "Surgically Induced Astigmatism Calculator" (www.doctor-hill.com), at each follow-up time for both surgical groups. The two groups of data at each time interval were compared with a t-test for two independent populations. Statistical significance was defined as a p value of 0.05 or less.
Mean SIA was slightly greater at all time intervals for the group with iris hooks than the group without iris hooks (Figure). However, there was no significant difference between groups at any time interval after surgery.
This study did not detect a statistically significant effect of the four incisions for iris hooks on SIA after cataract surgery with a temporal 2.6 mm incision.
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