Single session, intrauser repeatability of anterior chamber biometric and corneal pachy-volumetric parameters using a new Scheimpflug+Placido device

Abstract

PurposeTo analyze single session, intrauser reliability of a Scheimpflug device for anterior chamber (AC) and corneal parameters.MethodsIn this observational study, 100 normal candidates underwent Scheimpflug analysis with Sirius 3D Rotating Scheimpflug Camera and Topography System (Costruzione Strumenti Oftalmici, Italy). Two scans in dark room conditions were performed by the same experienced user. The candidates were asked to keep both eyes closed for 5 min before the scans. Exclusion criteria were previous ocular surgery, corneal scarring and anterior segment/posterior segment anomalies. Only the right eyes were used for the analysis. Both corneal (central, minimum, and apical thickness, volume, horizontal visible iris diameter, and apical curvature) and anterior chamber (volume, depth, angle, horizontal diameter) measurements were evaluated.ResultsThere was no difference in the means of repeated measurements (p > 0.05, ANOVA). Intraclass correlations between the measures were high and ranged from 0.995–0.997 for corneal to 0.964–0.997 for anterior chamber (AC) parameters. The precision of repeatability measures (1.96 × Sw) was approximately 5 μ for the central and minimum corneal thickness, 8 μ for the apical corneal thickness, 0.06 mm for AC (anterior chamber) depth and less than 2° for the AC angle.ConclusionsSirius Scheimpflug system has high repeatability for both corneal and AC parameters in normal eyes.

Intrasession repeatability of ocular anatomical measurements obtained with a multidiagnostic device in healthy eyes

“…The intrasession repeatability of central and peripheral pachymetric readings obtained with the VX120 system in our sample was also excellent, with S w values below 9 μm, CV below 1.6% and ICC of more than 0.97. Specifically, S w for central corneal thickness was 6.41 μm in our sample, a value which is consistent with those reported using the Sirius system in healthy (Prakash et al [ 6 ] S w : 5 μm; Montalbán et al [ 18 ] S w : 2.80 μm; Chen et al [ 17 ] S w : 3.10 μm) and keratoconus eyes (Montalbán et al [ 14 ] S w : 2.30 μm). However, VX120 pachymetric repeatability outcomes were better than those reported for optical biometry systems (Zhao et al [ 15 ] S w : 14.24 μm, healthy eyes; Kunert et al [ 4 ] S w : 19.5 μm) (Table 4 ).…”

“…This confirms that the multidiagnostic device evaluated is able to provide repeatable consecutive measurements of the depth of the anterior chamber of the healthy eye. Our intrasession repeatability outcomes for ACD are consistent with those reported with other commercially available devices, including Scheimpflug-based topography systems, [ 3 , 5 , 6 , 10 – 14 , 16 – 19 ] biometers, [ 2 – 4 , 8 , 9 , 15 , 17 ] and optical coherence tomographers [ 3 , 11 ] (Table 4 ). Kurian et al [ 2 ] obtained in 100 eyes evaluated with the IOL-Master (Carl Zeiss Meditec) and Lenstar 900 (Haag-Streit) optical biometry systems, S w values for ACD of 0.04 and 0.06 mm, and CV of 1.22 and 1.99%, respectively.…”

“…Shin et al [ 5 ] reported an ICC > 0.980 for ACD measurements obtained with the Galilei G6 system in a sample of 140 eyes with cataract, and Savini et al [ 19 ] obtained CV < 3.5% and ICC > 0.94 in 45 healthy eyes using the same system. With the Sirius system from CSO, Prakash et al [ 6 ] obtained a mean value of 0.06 mm for 1.96xS w corresponding to ACD measurements in a sample of 100 healthy subjects. Likewise, Masoud et al [ 10 ] obtained a CV < 2% in 100 healthy eyes of 50 patients, Nasser et al [ 16 ] a CV of 0.56% in 45 healthy eyes, and Montalbán et al [ 18 ] S w , CV and ICC of 0.02 mm, 0.54% and 0.999 in 117 healthy eyes, respectively.…”

“…There are several studies evaluating the repeatability of anterior segment anatomical measurements provided by different types of instruments, most of them based on Scheimpflug imaging or partial coherence interferometry [ 2 – 19 ]. Specifically, good intrasession repeatability data have been reported with a variety of devices for anterior chamber depth (ACD), [ 2 – 19 ] central corneal thickness (CCT), [ 4 , 6 , 10 , 13 – 18 ] peripheral corneal thickness (PCT) [ 21 ], white-to-white corneal diameter, [ 3 , 5 , 8 – 10 , 14 , 15 , 20 ] and irido-corneal angle (IA) [ 6 , 10 , 19 , 21 ]. All these studies confirm the good performance of currently available devices for measuring the anatomical dimensions of the anterior segment of the eye.…”

Validation of refraction and anterior segment parameters by a new multi-diagnostic platform (VX120)

“…Several studies evaluating have obtained similar or even worse Sw values for CCT with the Sirius system (Prakash et al 29 Sw: 5 μm; Montalbán et al 30 Sw: 2.80 μm; Chen et al 31 Sw: 3.10 μm) and optical biometry systems (Zhao et al 32 Sw: 14.24 μm; Kunert et al 33 Sw: 19.5 μm). Likewise, the level of intra-session repeatability obtained for IA with the VX120 was consistent with that reported for other devices.…”