Refractive Predictability of Third-Generation and Modern IOL Power Calculation Formulas in Yamane Intrascleral Fixation.

PURPOSE: To evaluate the refractive predictability of third-generation and modern intraocular lens (IOL) power calculation formulas in eyes undergoing Yamane intrascleral fixation (YISF).

DESIGN

Retrospective, comparative evaluation of IOL power calculation accuracy.

SUBJECTS: Eighty-seven eyes of 87 patients who underwent YISF due to aphakia or single-piece IOL subluxation were evaluated.

METHODS

Third-generation formulas (Hoffer Q, Holladay 1, Sanders Retzlaff Kraff/Theoretical (SRK/T), and T2) and modern formulas (Barrett Universal II[BUII] and emmetropia verifying optical [EVO] 2.0) were assessed.

MAIN OUTCOME MEASURES: Mean prediction error (ME), mean absolute error (MAE), median absolute error (MedAE), and the proportions of eyes with ME within ±0.50D and ±1.00D were calculated. Analyses were performed before and after constant optimization. The constant optimization was performed using the method of zeroing the ME.

RESULTS

In the initial analysis, all formulas demonstrated a hyperopic shift, with ME values ranging from +0.55D to +0.71D. No significant differences were detected among the formulas in terms of ME, MAE, or MedAE (P > .05). The proportion of eyes with ME within ±0.50D was higher for SRK/T (63%), BUII (60%), and EVO 2.0 (54%) than for Hoffer Q (48%) (P < .001, P < .001, and P = 0.004). In contrast, no significant difference was found in the proportion of eyes with ME within ±1.00D (P > .05). After constant optimization, ME reached zero for all formulas, and no significant differences were observed among the formulas regarding MAE, MedAE, or the proportions of eyes with ME within ±0.50D and ±1.00D (P > .05). In both analyses, no statistically significant differences were found among the six formulas with respect to either IOL type or indication (P > .05).

CONCLUSIONS

A systematic hyperopic shift was observed with all formulas after YISF. Although SRK/T, BUII, and EVO 2.0 appeared more successful before optimization, third-generation and modern formulas demonstrated similar refractive performance after constant optimization. These findings suggest that refractive outcomes are largely influenced by surgery-related variability in actual lens position.