astigmatism

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Comparison in Reduction of Preoperative Astigmatism after Cataract Surgery with Toric IOLs versus Limbal Relaxing IncisionsAlexander Chop PhD MD(no financial interests to disclose)Dan Straka & Asmaneh Siavosh M4(no financial interests to disclose)William G. Martin MD, FACS(consultant to Alcon and AMO)The University of Toledo College of Medicine : 

Comparison in Reduction of Preoperative Astigmatism after Cataract Surgery with Toric IOLs versus Limbal Relaxing IncisionsAlexander Chop PhD MD(no financial interests to disclose)Dan Straka & Asmaneh Siavosh M4(no financial interests to disclose)William G. Martin MD, FACS(consultant to Alcon and AMO)The University of Toledo College of Medicine

Introduction : 

2 Introduction There are three main options for reducing astigmatism at or around the time of cataract surgery, namely performing one or more limbal relaxing incisions (LRIs), implanting an intraocular lens known as a Toric IOL which corrects for astigmatism and finally postoperative PRK. Here we compare the short term results of the first two methods at the three month postoperative period.

Disadvantages of LRIs : 

3 Disadvantages of LRIs Technique is less precise than a Toric IOL - the cornea may undergo an over-correction or under-correction. The cornea will heal over time, altering the result. The depth, length and curvature of the wound will vary both within each eye and between eyes and patients, as well as surgeons.

Disadvantages of Toric IOls : 

4 Disadvantages of Toric IOls Cost - generally more expensive than LRIs. Concern over rotational stability of the lens in the bag. Amount of correction available is not as great as with LRIs and has larger steps between lens powers compared to LRIs.

Retrospective Study Design : 

5 Retrospective Study Design Chart review from 2006 -2008 comparing 32 eyes of patients undergoing LRI at the time of cataract surgery using the Alcon SN60WF IOL with 37 eyes of patients undergoing implantation with the Alcon AcrySof SN60T3/4/5 Toric IOL, matched for cataract density, age and sex and treated using the Wallace LRI nomogram and IOL Master. Consistency: all procedures performed by the same surgeon (WGM) in the same ASC using the same superior scleral tunnel approach with pre- and postoperative measurements by the same technicians

Results for LRIs + Alcon SN60WF IOL Implantation : 

6 Results for LRIs + Alcon SN60WF IOL Implantation Residual postoperative astigmatism measured at 3 months (N = 32) reflects an improvement of 1.41 D cylinder (64% reduction in astigmatism) LRI patient average preoperative cylinder = 2.20 D (range 0.75 - 6.00) LRI patient average postoperative cylinder = 0.79 D (range plano - 3.00)

Results for Alcon SN60T3/4/5 Toric IOL Implantation : 

7 Results for Alcon SN60T3/4/5 Toric IOL Implantation Residual postoperative astigmatism measured at 3 months (N = 37) reflects an improvement of 2.25 D cylinder (77% reduction in astigmatism) Toric IOL average preoperative cylinder = 2.92 D (range 1.50 - 4.75) Toric IOL average postoperative cylinder = 0.67 D (range plano - 2.50)

Conclusion : 

8 Conclusion Both methods are effective in reducing preoperative astigmatism and both should be offered to patients. At the three month postoperative period, the Toric IOL shows a slightly greater reduction in preoperative astigmatism (77% compared to 64%) but was not statistically significant. Average Toric IOL patient had more preoperative astigmatism than LRI patient, potentially biasing results. Longer term results of at least the three year postoperative period must be measured. Prospective study is needed with patients matched for equal preoperative astigmatism and controlling all other variables.

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