Iol optic power calculation in patients with eye axial length 24‑28 mm without preceding refractive surgery

Aim. Analysis of effectiveness of IOL calculating formulas and frequency of intra- and postoperative complications of phacoemulsification in patients with eye axial length 24.0‑28.0 mm.

Patients and methods. The study included 39 patients (62 eyes) with varying degrees of myopia and axial length of the eye 24.0‑28.0 mm. All patients carried out phaco (85.5 %) or refractive clear lens exchange (14.5 %) with IOL implantation after a comprehensive survey. Average follow-up was 15.1±3.8 months. Patients were divided into two groups — with axial length 24.0‑25.9 mm (n = 38, group I) and 26.0‑27.9 mm (n = 24, group II). Calculation of IOL was performed according to the formula SRK / T, retrospective comparison — Hoffer-Q, Holladay II, Haigis and Barrett. Amount of surgically induced astigmatism was determined by the program SIA Calculator v.2.1.

Results. There are functional results, mean numerical error and median absolute error (MAE) of refraction after phaco with IOL implantation in the study. In Group I target postoperative refraction (±1.0 diopters in 95 % of cases) met all the studied formulas. Refraction ±0,5 diopters using formulas SRK / T was achieved in 92.3 % of cases, Hoffer-Q — 84.1 %, Holladay II — 91.,3 %, Haigis — 86.5 % and Barrett — 94.2 %. In Group II formulas SRK / T, Haigis and Barrett corresponded to refraction ±1.0, with target refraction of ±0,5 diopters in 90 % of cases, achieved only by using Barrett formula (91.5 %). The value of SIA and frequency of intra- and postoperative complications were not significantly different.

Conclusion. IOL power calculation in patients with eye axial length 24.0‑25.9 mm is possible by using each of five formulas. For eyes with axial length 26.0‑27.9 mm a significantly lower MAE when applying formulas Haigis (0.72±0.45) and Barrett (0.33±0.28) formulas is received, which indicates the high efficiency of these formulas, with the target refraction ±0,5 diopters in 90 % of cases, achieved only by using Barrett formula.

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