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Riley Hall, Gunpreet Singh, Maurice Agha, Neil Wade; The effect of a second 2.4mm keratome incision on reducing post-operative astigmatism in cataract surgery. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1831.
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Astigmatism correction remains a major challenge post-cataract surgery. The introduction of toric intraocular lenses (IOL’s) has greatly aided in this regard, however not all patients are candidates for these premium lenses. Limbal relaxing incisions (LRI’s) have successfully been used to help reduce post-operative astigmatism. This study assesses the effect of a placing second 2.4mm full thickness keratome incision on the steep axis on reducing post-operative astigmatism in cataract surgery.
A retrospective comparative study was performed at a university outpatient ambulatory surgical center in Vancouver, British Columbia. Prospective data was collected in patients scheduled for routine phacoemulsification. Patients with senile cataract and 0.50 diopter to 2.0 diopters of astigmatism scheduled for routine cataract surgery were randomly selected into two groups either receiving routine cataract surgery, or a second 2.4mm keratome incision at the end of their surgery along a temporal/nasal axis. Astigmatism was measured using a Carl Zeiss Meditec Atlas 9000 corneal topographer. Pre and post-operative astigmatism in the two groups was then analyzed and surgically induced astigmatism (SIA) between the 2 groups was compared for standard deviation.
Post-operative astigmatism was analyzed and compared in 34 eyes of which 21 had received a second 2.4mm keratome incision following cataract surgery and 13 had not. The average pre-operative total astigmatism was 1.044D (SD=0.39D) in the treated eyes, and 0.90D (SD=0.38D) in the untreated eyes. The average post-operative total astigmatism was 0.83D (SD=0.34D) in the treated eyes, and 0.74D (SD=0.36D) in the untreated eyes. SIA was 0.81D (SD=0.54) in the treated group, and 0.48D (SD=0.27) in the control patients. Total average astigmatism was reduced by 0.21D (20.2%) in the treated population and 0.16D (17.8%) in the controls.
Post-operative astigmatism control remains a challenge for the cataract surgeon. The use of a second 2.4mm keratome incision can be utilized to flatten the steep axis, thereby resulting in a lower post-operative total astigmatism. This can be used in practice to improve astigmatic outcomes in patients who may not be candidates for toric IOL’s.
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