Repeatability of On- and Off-Axis Eye Length Measurements Using the Lenstar

Abstract

Purpose To determine the repeatability of eye length measurements made centrally and off-axis using a low-coherence interferometer. Methods Eye length was measured (left eye) in twenty-nine adults with a Haag-Streit Lenstar LS 900. Five measurements were made centrally, 10° temporally, and 10° nasally on the retina by the same examiner at two separate visits. Inter-visit repeatability was assessed by plotting the difference versus the mean of each pair of measurements (bias) and calculating the 95% limits of agreement (LoA). Within-session repeatability was determined by calculating the within-subject standard deviation (Sw) of five consecutive measurements at a visit. Due to variability noted 10° nasally, the Sw was also determined on a subset of 10 subjects using five measurements at one visit 30° nasally and 30° temporally. Results The mean ± SD age, spherical equivalent refractive error, and central axial length (at visit 1) were 24.0 ± 1.4 years, −3.46 ± 2.69 D, and 24.91 ± 1.10 mm, respectively. There was no significant bias for central, 10° nasal, or 10° temporal measurements between visits (all p > 0.09). The 95% LoA were: ±0.05 mm central, ±0.12 mm 10° nasal, and ±0.05 mm 10° temporal. The Sw (visit 1) were: 0.025 mm central, 0.045 mm 10° nasal, and 0.028 mm 10° temporal. The Sw in the subset of subjects with 30° measurements were 0.023 mm (30° nasal) and 0.030 mm (30° temporal). Conclusions Lenstar central and off-axis eye length measurements are very repeatable, though repeatability was not as good 10° nasally on the retina as indicated by the larger 95% LoA between visits and larger Sw. The Sw for measurements centrally and 30° off-axis were similar, suggesting the reduced repeatability 10° nasally is anatomical in nature. Despite greater variability 10° nasally, Lenstar off-axis repeatability is still superior to the repeatability of on-axis ultrasonography.

Axial Biometry of the Entire Eye Using Ultra-Long Scan Depth Optical Coherence Tomography

“…However, the CoR of AL was higher than that obtained by the IOLMaster and Lenstar. 9, 10 In the present study, rather than using of group refractive index, AL was the sum of CCT, ACD, LT and VL. The bias of each element may affect the AL measurement.…”

“…These methods are used by the IOLMaster (Carl Zeiss Meditec, Dublin, CA) 7, 8 and Lenstar (Haag-Streit USA, Mason, OH); these imaging modalities can only make axial measurements in a single dimension, similar to the A-scan ultrasound. 9–11 Most of the devices do not have a fixation target and use the group index for converting optical length to geometrical length. 10, 32–34 These measurements of axial length may thus be influenced by changes due to accommodation during measurement.…”

“…Traditional methods for axial biometry include ultrasound and optical low coherence reflectometry (OLCR) based devices, such as the IOLMaster (Carl Zeiss Meditec, Dublin, CA) 7, 8 and the Lenstar (Haag-Streit USA, Mason, OH). 9–11 These methods use a single axial measurement like the A-scan. Real-time imaging may be difficult with these traditional methods.…”

Versatile optical coherence tomography for imaging the human eye

“…With four reference mirrors, the full-length ocular biometry was sequentially obtained, which may be used for the precise measurement of the axial length and intraocular lens calculation. Compared with IOLMaster (Carl Zeiss Meditec, Dublin, CA) or LENSTAR (Haag-Streit USA, Mason, OH) [31,32], the two-dimensional image of each component element of the anterior segment and the retinal image were obtained during the biometric measurement, although the repeatability and accuracy of each part was not validated. For some hyperopes with a short axial length, the retinal image was also present in the image obtained with the fourth mirror position.…”

Agreement between Central Corneal Thickness Measured Using Pentacam, Ultrasound Pachymetry, Specular Microscopy and Optic Biometer Lenstar LS 900 and the Influence of Intraocular Pressure

“…Our study revealed that LE agreement with SM and UP is excellent and this, added to the ease of its use and its noninvasiveness, results in a very promising tool [23,30]. Moreover, for LE and SM proper alignment has shown to be easier and less time-consuming than for UP and PC [21].…”