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 this