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Optimization of intraocular lens calculation in cataract surgery

Session Details

Session Title: Cataract II

Session Date/Time: Saturday 15/02/2014 | 08:30-11:00

Paper Time: 09:44

Venue: Gallus Hall (Level -1)

First Author: : IvanCima CROATIA

Co Author(s): :    Ivana Behin   Mirjana Bjelos Roncevic   Mladen Busic        

Abstract Details

Purpose:

Demonstrate the method of calculation of intraocular lens (IOL) power and surgically induced astigmatism which helps to achieve a better refractive result after cataract surgery.

Setting:

Prospective clinical trial.

Methods:

This prospective study included 124 patients with cataract. Calculation of IOL power was done in 2 ways: 1) using the Haigis formula and biometric data from optical biometry, 2) using the SRK/T formula and biometric data obtained with A-scan ultrasonography and autokeratometry. All patients were operated by the same surgeon using phacoemulsification through a 2.75 mm claer corneal incision. Power of the implanted IOL was calculated with the first method. At least three months after the surgery subjective refraction and optical biometry were done. Using the Haigis formula expected refractive error was calculated in the case that the implanted IOL strength was calculated by the second method. Surgically induced astigmatism was additionally calculated. For statistical comparison of the results of two methods t-test and Mann-Whitney U test were used.

Results:

The data for the parameters tested were collected in 96 of 124 patients. The median age was 76 years (range: 60-88 years). There was statistically significant difference between the two methods tested in axial length (23.33 ±0.99 mm vs. 23.02 ±0.97 mm, P <0.05) and postoperative spherical refractive error (-0.15 ±0.31 D vs. -0.71 ±0.55 D, P <0.01). Investigated methods did not differ significantly in keratometry (43.59 ±1.55 D vs. 43.09 ±4.70 D, P = 0.326), calculated IOL refractive error (22.29 ±2.16 D vs. 22.28 ±2.11 D, P = 0.973) and postoperative astigmatism (0.76 D ±0.55 vs. 0.74 ±0.63 D, P = 0.403). With the first method postoperative spherical refraction within 0.75 D of expected was achieved in 97.9% and within 0.50 D in 87.5% of patients. With the second method postoperative spherical refraction within 0.75 D of expected would be achieved in 62.5%, and within 0.50 D in 40.6% of patients. Surgically induced astigmatism was 0.38 D.

Conclusions:

Important factors for optimal postoperative refractive outcome after cataract surgery are method of biometry, choice of IOL calculation formula and knowledge of surgically induced astigmatism. Optical biometry and fourth generation formulas allow better postoperative refractive result which is especially important in the case of implantation of "premium" IOLs. FINANCIAL INTEREST: NONE