RESUMO
PURPOSE: We sought to compare the prediction accuracy of 6 intraocular lens (IOL) formulas, namely, the Haigis, Hoffer Q, Holladay I, SRK/T, Barrett Universal II and Hoffer QST formulas, in microphthalmic eyes, including those with nanophthalmos and relative anterior microphthalmos (RAM). DESIGN: Retrospective case series. METHODS: Twenty-six eyes with nanophthalmos (axial length [AL] 16.84 ± 1.36 mm, range 15.25 mm-19.82 mm) and 12 eyes with RAM (corneal diameter 8.41 ± 0.92 mm, range 7.00 mm-9.50 mm) receiving cataract surgery were included. The IOL Master 500 was used for biometry; thus, lens thickness (LT) was omitted in the IOL power calculation. The mean and median arithmetic and absolute prediction errors (PEs) of the 6 original calculation formulas, the absolute PEs of the 6 formulas after optimization, and the proportion of PEs within ±0.25 diopters (D), ±0.5 D, ±1 D, and ±2 D with each formula were compared. The factors influencing PE were analyzed by multivariate regression. RESULTS: In the nanophthalmos group, the overall prediction results were shifted to myopia. The original Haigis formula had the smallest median absolute PE (1.61 D, P < 0.001), and the optimized Haigis formula had the highest proportion of PEs within ±0.25 D, ±0.5 D, and ±1 D. In the RAM group, the overall prediction results were not significantly different from 0 (P > .05). No significant difference was found among the formulas before optimization (P = .146) and after optimization (P = .161), but the optimized Barrett Universal II formula had the highest proportion of PEs within ±1 D and ±2 D. CONCLUSIONS: When omitting the LT parameter in the calculation, the Haigis formula was the most accurate in cataract patients with nanophthalmos (AL <20 mm) among the 6 IOL calculation formulas, and the Barrett Universal II formula had the highest accuracy in cataract patients with RAM (corneal diameter ≤9.5 mm).
