ObjectiveTo compare the accuracy of a new intraocular lens (IOL) power formula (Kane formula) with existing formulas using IOLMaster, predominantly model 3, biometry (measures variables axial length, keratometry and anterior chamber depth) and optimised lens constants. To compare the accuracy of three new or updated IOL power formulas (Kane, Hill-RBF V.2.0 and Holladay 2 with new axial length adjustment) compared with existing formulas (Olsen, Barrett Universal 2, Haigis, Holladay 1, Hoffer Q, SRK/T).Methods and analysisA single surgeon retrospective case review was performed from patients having uneventful cataract surgery with Acrysof IQ SN60WF IOL implantation over 11 years in a Melbourne private practice. Using optimised lens constants, the predicted refractive outcome for each formula was calculated for each patient. This was compared with the actual refractive outcome to give the prediction error. Eyes were separated into subgroups based on axial length as follows: short (≤22.0 mm), medium (>22.0 to <26.0 mm) and long (≥26.0 mm).ResultsThe study included 846 patients. Over the entire axial length range, the Kane formula had the lowest mean absolute prediction error (p<0.001, all formulas). The mean postoperative difference from intended outcome for the Kane formula was −0.14+0.27×1 (95% LCL −1.52+0.93×43; 95% UCL +0.54+1.03×149). The formula demonstrated the lowest absolute error in the medium axial length range (p<0.001). In the short and long axial length groups, no formula demonstrated a significantly lower absolute mean prediction error.ConclusionUsing three variables (AL, K, ACD), the Kane formula was a more accurate predictor of actual postoperative refraction than the other formulae under investigation. There were not enough eyes of short or long axial length to adequately power statistical comparisons within axial length subgroups.

Purpose: To assess the accuracy of intraocular lens (IOL) power formulas modified specifically for patients with keratoconus (Holladay 2 with keratoconus adjustment and Kane keratoconus formula) compared with normal IOL power formulas (Barrett Universal 2, Haigis, Hoffer Q, Holladay 1, Holladay 2, Kane, and SRK/T). Design: Retrospective consecutive case series. Participants: A total of 147 eyes of 147 patients with keratoconus. Methods: Data from patients with keratoconus who had preoperative IOLMaster biometry were included. A single eye per qualifying patient was randomly selected. The predicted refraction was calculated for each of the formulas and compared with the actual refractive outcome to give the prediction error. Subgroup analysis based on the steepest corneal power measured by biometry (stage 1: 48 diopters [D], stage 2: >48 D and 53 D, and stage 3: >53 D) was performed. Main Outcome Measure: Prediction error. Results: On the basis of the mean absolute prediction error (MAE), the formulas were ranked as follows: Kane keratoconus formula (0.81 D), SRK/T (1.00 D), Barrett Universal 2 (1.03 D), unmodified Kane (1.05 D), Holladay 1 (1.18 D), unmodified Holladay 2 (1.19 D), Haigis (1.22 D), Hoffer Q (1.30 D), and Holladay 2 with keratoconus adjustment (1.32 D). The Kane keratoconus formula had a statistically significant lower MAE compared with all formulas (P < 0.01). In stage 3 keratoconus, all nonmodified formulas had a hyperopic mean prediction error ranging from 1.72 to 3.02 D. Conclusions: The Kane keratoconus formula was the most accurate formula in this series. The SRK/T was the most accurate of the traditional IOL formulas. All normal IOL formulas resulted in hyperopic refractive outcomes that worsened as the corneal power increased. Suggestions for target refractive aims in each stage of keratoconus are given. Ophthalmology 2020;127:1037-1042 ª 2020 by the American Academy of Ophthalmology Keratoconus is a progressive disorder characterized by central or paracentral corneal thinning and ectasia. Intraocular lens (IOL) power calculation in these eyes represents a significant challenge. Kamiya et al 1 reported on 71 patients with keratoconus comparing the Haigis, Hoffer Q, Holladay 1, Holladay 2, and SRK/T formulas and found that that the SRK/T formula was the most accurate with 36% of eyes within 0.50 diopters (D) of the final manifest refraction. Savini et al 2 also found that the SRK/T was the most accurate formula in 41 patients (compared with Barrett Universal 2, Haigis, Hoffer Q, and Holladay 1), with 43.9% of eyes within 0.50 D. Both studies found that all formulas resulted in a hyperopic refractive surprise that worsened with more advanced stages of the disease. Suggestions regarding an appropriate myopic refractive target to avoid unwanted postoperative hyperopic error have been proposed. 3 These refractive results in keratoconus studies are significantly worse than the 75% to 80% of eyes within 0.50 D usually seen in nonkeratoconic eyes, 4 for which there are many reasons. First, the calc...

Bacterial orbital cellulitis is a condition that rarely presents with complete loss of vision. A case is reported of a 69-year-old man who presented with fulminant onset of proptosis, significant ophthalmoplegia and no perception of light. Computed tomography showed no evidence of paranasal sinus disease. Despite treatment with intravenous flucloxacillin, ceftriaxone and metronidazole, and later, penicillin after Streptococcus pyogenes was grown from tissue culture, there was no improvement in vision; however ocular motility returned to normal.

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The keratometry and axial length readings of healthy eyes (405 subjects) and cataractous eyes (63 subjects) from a sample of Tigrinians living in the Eritrean capital of Asmara were obtained. All subjects were at least 40 years of age. The mean keratometry reading for healthy eyes was 43.37 diopters (SD +/- 1.61), while that for cataractous eyes was 43.57 diopters (SD +/- 1.79). These values were not significantly different. Similarly, there was no significant difference in the mean ocular axial length for the two groups (healthy eyes; 23.03 mm, SD +/- 1.24: cataractous eyes; 23.34 mm, SD +/- 1.54). There was no correlation between age and the biometry readings of healthy eyes. Data from this study has been used to calculate a standard intraocular lens power for use by Eritrea's Blindness Prevention Programme during cataract surgery on this population (22 diopters at A constant 118.3). With this intraocular lens, 48% of patients will be within +/- 1D of emmetropia when left without spectacle correction; 73% will need a spectacle correction within +/- 2D to produce emmetropia.

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