Accuracy of user-adjusted axial length measurements by optical biometry in eyes having combined phacovitrectomy for macular-off rhegmatogenous retinal detachment

PURPOSE: To evaluate the accuracy of user-adjusted axial length measured by optical biometry (OB) for intraocular lens (IOL) power calculations in eyes having combined phacovitrectomy for macula-off rhegmatogenous retinal detachment (RRD). SETTING: Department of Ophthalmology, Calderdale Royal Hospital, Halifax, UK. DESIGN: Prospective Retrospective case series review of 22 consecutive eyes that underwent phacovitrectomy for macula-off RRD. METHODS: Axial lengths (ALs) were measured using OB with user adjustment to identify a posterior peak corresponding to the eye’s AL and ultrasound (US). These measurements were compared and analysed for accuracy to each other and the accurate indication of the eye’s AL. RESULTS: User-adjusted OB was similar to US and post-operative OB measurements. There was no statistically significant difference between the means of the AL measurements derived from user-adjusted OB and ultrasound AL (p=0.964). User-adjusted OB was not statistically significantly different to post-operative OB (p=0.242). Compared to postoperative OB, IOL power was within 0.5 Dioptre in 12 out of 13 cases (92%; 95% confidence interval (77.8%, 100.0%) for user-adjusted OB, and in only 10 out of 13 cases (77%; 95% confidence interval (54.0%, 99.8%) of US measurements. CONCLUSIONS: User-adjusted OB may be used as an alternative method for the measurement of AL in macula-off RRD for primary repair by combined phacovitrectomy. OB will, however, require assessment of agreement with US AL in cases where a posterior peak is not easily identifiable. We have also shown that user-adjusted OB may outperform US AL when calculating IOL power; however, a larger study may be needed to confirm thi

Accuracy of Intraocular Lens Power Estimation in Eyes Having Phacovitrectomy for Rhegmatogenous Retinal Detachment

Purpose: To evaluate the accuracy of intraocular lens power estimation in eyes having phacovitrectomy for rhegmatogenous retinal detachment. Methods: Retrospective case review of 100 consecutive eyes that underwent phacovitrectomy for rhegmatogenous retinal detachment. Axial lengths were measured using optical biometry and/or ultrasound A-scan. Achieved and predicted refraction were compared to calculate the mean postoperative refractive prediction error and the mean absolute prediction error. Factorial analysis of variance models were developed to assess outcome on the whole and that between the subgroups. Results: Ninety-five eyes had postoperative refraction: 41 macula-on (43%) and 54 macula-off (57%). The mean postoperative prediction error was -0.34 +/- 0.89 diopters. There was no statistical significant difference in the refractive outcomes between macula-on and macula-off groups (P > 0.05). Overall, using mean absolute prediction error as the outcome measure, optical biometry was more accurate than ultrasound (P = 0.040). However, significantly more ultrasound-measured axial lengths were selected for intraocular lens power estimation in macula-off group compared with the macula-on group (P = 0.016). Conclusion: Combined phacovitrectomy in rhegmatogenous retinal detachment included a small biometric error that was within the tolerable range in most cases. Both optical biometry and ultrasound should be used to estimate axial lengths, for macula-off rhegmatogenous retinal detachment cases, to improve the accuracy of intraocular lens power calculation