The effect of pupil dilation on AL-Scan biometric parameters

Abstract

The purpose of this study was to investigate the effects of pupil dilation on the parameters of the AL-Scan (Nidek Co., Ltd, Gamagori, Japan). We compared the measurements of axial length (AL), anterior chamber depth (ACD), central corneal keratometry reading, pupil diameter, and intraocular lens (IOL) power of 72 eyes of 72 healthy volunteers and patients scheduled for cataract surgery before and 45 min after instillation of cyclopentolate hydrochloride 1 % using the AL-Scan. Intraobserver repeatability was assessed by taking three consecutive recordings of ACD and AL. Only ACD readings were significantly different between predilation and postdilation (P < 0.001). The difference of the other measurements between two sessions was not statistically significant (P > 0.001). Only two cases in the study demonstrated changes in IOL power higher than 0.5 D. The intraobserver repeatability of both devices was good (CV values for ACD and AL were 0.16 and 0.20 %, respectively). Dilated pupil size did not affect the measurement of IOL power using the A-Scan optical biometer, but increase in ACD after dilation should be taken into account when performing refractive surgeries in which ACD is very important such as phakic anterior chamber IOL implantation.

Influence of pupil dilation on the Barrett Universal II (new generation), Haigis (4th generation), and SRK/T (3rd generation) intraocular lens calculation formulas: a retrospective study

“…3) Many studies have investigated the influence of pupil dilation on these biometric measurements. 8,[10][11][12][13][14][15][16] In a clinical setting, pupil dilation is a vital process of preoperative examination. Therefore, it is important to analyze its possible influence on PPR and recommended IOL power in third, fourth, and new generation IOL power calculation formulas, and to investigate the correlation between variables.…”

“…[10][11][12] However, ACD has been reported to be influenced by pupil dilation. [10][11][12][13][14] Compared to ACD, few studies have dealt with the influence of pupil dilation on LT and WTW. Wang X et al 8) demonstrated that LT was significantly affected by pupil dilation.…”

Comparison of the influence of pupil dilation on predicted postoperative refraction and recommended intraocular lens power among Barrett Universal II, Haigis, and SRK/T calculation formulas: a retrospective study

“…In many studies, AL and corneal curvature radius are not affected by pupil dilation. [10][11][12] However, ACD was reported to be influenced by pupil dilation. [10][11][12][13][14] Compared to ACD, few researches have dealt with the influence of pupil dilation on LT and WTW.…”

Agreement of anterior ocular biometric measurements with a new optical biometer and a Scheimpflug tomographer

“…However, they did not report the LoA for these parameters. Can et al 22 studied the effects of pupil dilation (with cyclopentolate) on the parameters of the AL-Scan biometer in 72 eyes. The AL and ACD were compared before and after pupil dilation.…”

“…Only the ACD readings were significantly different before and after dilation, and only 2 cases in the study showed changes in IOL power higher than 0.5 D. The study advised that increases in ACD after dilation should be taken into account when performing refractive surgeries in which the ACD is very important, such as in anterior chamber phakic IOL implantation. 22 Srivannaboon et al 11 also compared the AL-Scan biometer and the IOLMaster 500 biometer. They assessed the precision (repeatability and reproducibility) of the AL-Scan biometer in 137 eyes and found excellent repeatability and reproducibility as assessed by intraclass correlation coefficients (ICCs) and LoA.…”