Abstract
Purpose: :
Residual spherical aberration (SA) following cataract surgery is on average the sum of the SA of the cornea and the implanted intraocular lens (IOL). The purpose of this study is to show that the individual ocular SA may be predicted from corneal geometry and true IOL position.
Methods: :
In order to be able to predict ocular spherical aberrations, simulations were performed using a realistic eye model. This eye model exhibits the average corneal spherical and chromatic aberration found in a population of cataract patients. Published clinical data on the variations in corneal geometries and a 2mm range in intraocular lens position were used as inputs to the model. From the simulations a predictive model was built using different ocular geometries. Additionally, a predictive model is built with respect to IOL position. The true lens position is verified with clinical data from 47 subjects following implantation of two different IOL models. All relevant distances were measured preoperatively and 1 year postoperatively in order to be able to predict the true lens position. This information is then used in the eye model to examine the true influence of lens position on post-operative SA.
Results: :
The clinical data showed that for both IOLs (n=30 and n=17) the true lens position is strongly correlated (R2 >=0.9) with preoperative axial length, crystalline lens thickness and anterior chamber depth. The simulations resulted in a linearly predictive model, with a high degree of correlation (R2 =0.98) showing that the ocular SA depends on corneal SA and the true lens position.
Conclusions: :
The true postoperative IOL position can be predicted from preoperative biometric data. The postoperative ocular SA of the pseudophakic eye can be theoretically simulated with a partial least square model including true lens position and corneal SA.
Keywords: intraocular lens • aberrations • optical properties