Abstract
[Purpose] To report how we determined the intraocular lens (IOL) power in two patients with corneas in distorted shapes.
[Case 1] The patient had keratoconus in both eyes. In addition to an autokeratometer and IOLMaster® (Zeiss), TMS-5（TOMEY) and Pentacam® (Oculus) were also used to measure the preoperative corneal refractive powers for IOL power calculation by the SRK/T formula or ray-tracing. The IOL powers targeted for emmetropia had fluctuated. Considering residual corneal astigmatism, the MA60MA±0.0 D and MA60BM+17.5 D IOLs using the predicted values of -0.54 D and +0.35 D by IOLMaster® for simple myopic astigmatism were implanted. The postoperative refractive errors of -0.54 D (right) and +0.35 D (left) and visual acuity of 0.7 (1.0, right) and 0.5 (0.9, left) were obtained. Regardless of the residual corneal astigmatism, satisfactory improvement in astigmatism by subjective refraction was achieved.
[Case 2] The patient's left eye had received phototherapeutic keratectomy (PTK). The TMS-5 indicated a flat curvature in the central cornea. Calculated by the same method used in Case 1, the resulted IOL powers for emmetropia had fluctuated. Reportedly, eyes after PRK or LASIK tend to be hyperopic for 3 D. Considering the possibility of hyperopia in this PRK-treated case, the SN6CWS+26.5 D IOL using the IOLMaster® predicted value of -1.75 D was implanted. The postoperative refractive error of +1.125 D and visual acuity of 0.6 (0.8) were obtained, and mild hyperopia was observed.
[Conclusion] To determine the IOL power in eyes with a distorted shape of the cornea, corneal measurements by various devices for corneal topography and the IOL power calculated by different formulas should be carefully evaluated.
