Abstract

FR.19.06

Current status of IOL calculation for problem eyes

Wolfgang Haigis

Labor für Biometrie und Intraokularlinsenberechnung, Universitäts-Augenklinik Würzburg, Würzburg

Objective
Today, the majority of all implantations of an intraocular lens (IOL) in cataract and refractive surgery results in very good outcomes. Problems for biometry and IOL calculation are caused by extremely long and short eyes as well as eyes after corneo-refractive surgery. The peculiarities of these cases will be treated in the following.
Methods
Current formulas and methods for IOL calculation in ’normal’ eyes were analyzed theoretically with respect to their applicability for problem eyes and compared with clinical results. Special solutions and procedures for eyes after refractive surgery were treated in the same manner.
Results
IOL power formulas for ’normal’ eyes show pronounced axial length dependencies of their prediction errors resulting in specific formula preferences for long and short eyes. Measurement errors affect especially short eyes; distinctive anatomical features (staphyloma) are more frequent in long eyes. Generally, optimized measurement procedures should be applied. In extremely long eyes requiring minus power lenses IOL constants need special consideration. In practice, procedures for IOL power calculation after refractive surgery based on current measurements rather than on historic data are of special importance.
Conclusions
Biometry and IOL power calculation for problem eyes require special care in the selection of measurement and calculation procedures. With today’s means it is nevertheless possible to achieve results in these eyes which are only slightly inferior to those from normal eyes.

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