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R. A. Honkanen, R. Adyanthaya, T. Chou, S.-Y. Wu, M. A. Torab Parhiz, T. Haque, N. Mehta; Evaluation of 5 Intraocular Lens Power Prediction Formulas Early in Resident Surgical Training. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5443.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the accuracy of five intraocular lens (IOL) power prediction formulas (PPF) in early resident surgical cases.
Retrospective review of cataract surgeries performed between 12/12/2007 and 6/11/2009 by third year residents at a teaching hospital. The following inclusion criteria were used: IOL placed in the capsular bag, post op acuity better than 20/100, available preoperative biometry, and those with at least 3 months followup after surgery. Using preoperative keratometry (Ks), axial length (AxL) and anterior chamber depth (ACD) data, predicted postoperative refractive error (PPOR) was calculated with the Haigis (H), SRK II (S2), SRK/T (ST), Holladay I (H1), and Hoffer Q (HQ) formulas. Actual postoperative refraction (POR) was compared to PPOR. Descriptive statistics were assessed. Paired t-test and multiple regression analysis were performed.
223 cases met inclusion criteria. All preoperative IOL measurements and calculations were performed by 8 third year residents. AxL ranged between 21.1 and 28.2 mm with 86% of cases between 22 and 24.99 mm. Mean difference (POR-PPOR) was -0.77±1.26 (P<0.0001), 0.17±1.52 (P=0.098),-0.00±1.37,-0.02±1.38, and 0.04±1.36 (mean±SD) for H, S2, HQ, H1, and ST formulas respectively. Mean absolute difference (POR-PPOR) was 1.08 ± 1.01, 0.94 ± 1.20, 0.83 ± 1.09, 0.81 ± 1.11, and 0.84 ± 1.06 for H, S2, HQ, H1, and ST formulas respectively (mean ± SD). HQ, H1, and ST formulas were significantly better than the non-optimized H formula (p = 0.01 for all 3). POR and PPOR were within ±0.25 diopters for 20%, 20%, 24%, 24%, and 25% of cases, and differed by more than ±2 diopters for 14%, 9%, 9%, 9% and 9% for the H, S2, HQ, H1, and ST formulas respectively. Predicting errors for most formulas were associated (P<0.05) with axial length and method of biometry (immersion versus applanation).
The H1, HQ, and ST PPF performed well in predicting postoperative refractive error for the ranges of AxL, Ks and ACD seen in this review. H1 and HQ and ST performed statistically better than the non optimized H formula. Despite good results, the variability between POR and PPOR in these early resident cases are higher than those seen in reports performed by experienced surgeons. The degree of variability seen here, may suggest residents at this stage of training should not perform "premium" IOL surgery.
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