Posters

Post-surgery outcome of -14.00 diopters intraocular lens implantation in extreme axial length eye: a case study

Poster Details

First Author: J.Perez SPAIN

Co Author(s): J. Ares   L. Remon                 

Abstract Details

Purpose:

The aim of this case study is to show a real case of a cataract surgery patient with extreme eye axial length (previous myopia of -25.00 diopters (D)) where the post-surgical refractive results (RefPost) was not ideal with a +6.00 D sphere -2.75 D cylinder at 162º compensation. The SRK/T formula was used to calculate the power of the intraocular lens (IOL) to be implanted.

Setting:

Applied Physics Department, University of Zaragoza, Spain.

Methods:

Corneal power was 48 D. Axial length, measured with Ocuscan® (Alcon. USA), was 32.61±0.10 mm. IOL power calculated with SRK/T formula was -14.00 D, with 119.3 A-constant. After 3 months, RefPost was measured. A model eye was simulated in OSLO (Lambda Research Corp.) with patient and IOL data. As the refractive result is not suitable, the ELP of the -14.00 D to achieve the RefPost was calculated. IOL was also calculated using Wang-Koch correction formula, and the new theoretical RefPost was obtained. Finally, with the calculated ELP in the model eye, IOL power was obtained.

Results:

RefPost was: +6.00 D sphere -2.75 D cylinder at 162º. The visual acuity was counting fingers at 40 cm. ELP value estimated by SRK/T was 9.47 mm. Using the theoretical eye model with the mean spherical equivalent as RefPost (+4.375 D), the ELP that gives the same empirical RefPost was 2.51 mm. The result of Wang-Koch IOL power was -11.00 D with a theoretical RefPost of +2.11 D for a 2.51 mm ELP. Finally, the customized theoretical eye model predicts an IOL power of -8.00 D with a refractive error of -0.31 D for an ELP of 2.51mm.

Conclusions:

The estimation of the postoperative IOL position based on preoperative measurement is the largest source of uncertainty. However, in this case, refractive error cannot be only caused by the wrong ELP estimation. An error in the axial length measurement is a common reason for an unexpectedly large refractive error, which can result in patient dissatisfaction. Our study demonstrates that in extreme axial lengths eyes, it is useful the use of ray-tracing programs to improve the refractive error predictability.

Financial Disclosure:

None