Accuracy of axial length measurements obtained by optical biometry and acoustic biometry in rhegmatogenous retinal detachment: a prospective study

Abstract

PurposeWe compared the accuracy of axial length (AL) measurement obtained by optical biometry with that obtained by acoustic biometry in eyes with rhegmatogenous retinal detachment (RRD).Patients and methodsThis prospective descriptive analytic study measured the AL of eyes with RRD preoperatively and 3 months postoperatively using optical biometry (intraocular lens [IOL] master group) and acoustic biometry (immersion A-scan group). Preoperative and postoperative measurements were compared by paired t-test. The agreement between preoperative and postoperative measurements was analyzed using a Bland–Altman plot. Subgroup analysis of macular involvement status was performed.ResultsTwenty-seven eyes were analyzed in this study. The mean AL in the IOL master group was 23.58±0.97 mm preoperatively and 24.17±1.16 mm postoperatively; the mean difference was −0.59±0.90 mm (P = 0.007). The mean AL in the immersion A-scan group was 24.29±1.59 mm preoperatively and 24.27±1.69 mm postoperatively; the mean difference was 0.02±0.48 mm (P = 0.827). Bland–Altman analysis revealed disagreement between preoperative and postoperative AL measurements in both techniques. In subgroup analysis of macula with RRD, there were significant differences between preoperative and postoperative AL measurements in the IOL master group (P = 0.014).ConclusionSignificant underestimation of AL measurement was observed when using the IOL master in eyes with RRD with macular involvement, which could affect IOL power selection.

Changes in Axial Length After Vitrectomy for Rhegmatogenous Retinal Detachment With Associated Choroidal Detachment

“…As the advances emerging in microsurgical instrumentation on small-gauge vitrectomy, combined surgery has, therefore, become a popular procedure in treating RRD [5][6][7] . A high level of consistency of AL measured before and after PPV has been shown in both macula-sparing RRD cases [8] and macula-off RRD cases [1,2] . In RRD cases treated by combined surgery, selection of the IOL power using AL data measured before PPV is reported to result in a small biometric error and a small myopic shift that is within the tolerable range in most cases [9] .…”

“…It has been reported the macula-off status may in uence the measurement of AL [1,2] . We ruled out macular-on cases to lessen the impact of macular-on status on AL measurement.…”

“…The accuracy of the measurement of AL can be affected by several factors. High retinal detachment in the upright position [1] , macula-off status [1,2] and low IOP [3,4] may cause underestimation of AL.…”

Comparison of Axial Ocular Measurements with Contact and Non-contact Biometry

“…Both ultrasound (US) A-scan biometry and non-contact PCI based devices are used for calculating IOL power 6,8 . AL in ultrasound method is measured from corneal vertex to the internal limiting membrane (ILM) 9 . The ultrasound biometry can be performed by applanation of the probe to the corneal surface or by indirectly contact of probe to corneal surface in immersion technique (by using saline filled shell).…”

“…Another advantage of non-contact Biometer over ultrasound contact method is to provide different IOL power formulas for single IOL model, however, it is unable to measure biometric parameters in dense cataract 12 . Therefore, in all cases ultrasound biometry cannot be replaced by non-contact biometry 9,13 . A recent study on comparison between contact and noncontact biometry reported that both techniques were comparable with no clinical significant difference in measuring AL 13 .…”