Comparison of corneal curvature parameters obtained from two different instruments-Pentacam and VX120

Intrasession repeatability and agreement of the anterior corneal assessment provided by a multidiagnostic device

CLINICAL RELEVANCE

Multidiagnostic systems have recently appeared on the market. Knowledge of the repeatability and validity of any instrument is mandatory before its introduction in clinical practice.

BACKGROUND

The aim of this work is to examine the intrasession repeatability of anterior pole measurements provided by the multidiagnostic device Wave Analyzer Medica 700 (WAM700) and agreement with Pentacam measurements in normal eyes.

METHODS

In the right eyes of 113 participants, three repeat measurements of central keratometry, central corneal thickness, anterior chamber depth and corneal eccentricity were made with the WAM700 and Pentacam in random order. Intrasession repeatability and agreement were determined.

RESULTS

Employing WAM700, intrasession repeatability for keratometry, central corneal thickness and anterior chamber depth was good (ICCs ≥ 0.992; CV 0.48-0.98%), yet worse than the values obtained for the Pentacam (ICCs ≥ 0.998; CV 0-0.33%). WAM700 showed excellent intrasession repeatability when used to measure the anterior chamber depth (Sw 0.03 mm). However, the repeatability of this device was inferior for central corneal thickness (Sw 4.24 μm) and keratometry measurements (Sw < 0.21 D) and was poor for corneal eccentricity (Sw 0.07; ICC 0.908; CV 14.58%). Agreement between WAM700 and Pentacam showed a high ICC for the keratometry measurements, central corneal thickness and anterior chamber depth (>0.972) but lower for corneal eccentricity (ICC 0.762).

CONCLUSIONS

In healthy eyes, the WAM700 multidiagnostic device showed good intrasession repeatability for keratometry, central corneal thickness and anterior chamber depth measurements. Agreement between WAM700 and Pentacam was good for the anterior chamber depth measurement. However, these instruments cannot be considered interchangeable for keratometry, central corneal thickness and eccentricity readings.

Comparison of Three Different Devices for the Evaluation of Axial Length, Refractive Error, and Keratometry

SIGNIFICANCE

Myopia prevalence is increasing worldwide. Axial length, refractive error, and keratometry are important outcome measures in myopia management. Precise measurement methods are required for myopia management. Various devices are used to measure these three parameters, and it is not known whether their results can be used interchangeably.

PURPOSE

The aim of this study was to compare three different devices to evaluate axial length, refractive error, and keratometry.

METHODS

A total of 120 subjects (37.7 ± 15.5 years) were enrolled in this prospective study. All subjects were measured with DNEye Scanner 2 (Rodenstock GmbH, Munich, Germany), Myopia Master (Oculus Optikgeräte GmbH, Wetzlar, Germany), and IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany). Myopia Master and IOLMaster 700 use interferometry to measure axial length. Rodenstock Consulting software (Rodenstock GmbH, Munich, Germany) was used to calculate axial length from DNEye Scanner 2 measurement. Differences were analyzed using Bland-Altman 95% limits of agreement.

RESULTS

Differences for axial length were as follows: DNEye Scanner 2 versus Myopia Master, 0.67 ± 0.46 mm; DNEye Scanner 2 versus IOLMaster 700, 0.64 ± 0.46 mm; and Myopia Master versus IOLMaster 700, -0.02 ± 0.02 mm. Differences for mean corneal curvature were as follows: DNEye Scanner 2 versus Myopia Master, -0.20 ± 0.36 mm; DNEye Scanner 2 versus IOLMaster 700, -0.40 ± 0.35 mm; and Myopia Master versus IOLMaster 700, -0.20 ± 0.13 mm. The difference in noncycloplegic spherical equivalent between DNEye Scanner 2 and Myopia Master was 0.05 ± 0.25 D.

CONCLUSIONS

The results for axial length and keratometry from Myopia Master and IOLMaster were comparable. The axial length calculated by DNEye Scanner 2 was significantly different from interferometry devices and is not appropriate for myopia management. The differences in keratometry readings were clinically not significant. All refractive outcomes were comparable.

Artificial intelligence applications in different imaging modalities for corneal topography

Interpretation of topographical maps used to detect corneal ectasias requires a high level of expertise. Several artificial intelligence (AI) technologies have attempted to interpret topographic maps. The purpose of this study is to provide a review of AI algorithms in corneal topography from the perspectives of an eye care professional, a biomedical engineer, and a data scientist. A systematic literature review using Web of Science, Pubmed, and Google Scholar was performed from 2010 to 2020 on themes regarding imaging modalities, their parameters, purpose, and conclusions and their samples and performance related to AI in corneal topography. We provide a comprehensive summary of advances in corneal imaging and its applications in AI. Combined metrics from the Dual Scheimpflug and Placido device could be a good starting point to try AI models in corneal imaging systems. The range of area under the receiving operating curve for AI in keratoconus detection and classification was from 0.87 to 1, sensitivity was from 0.89 to 1, and specificity was from 0.82 to 1. A combination of different types of AI applications to corneal ectasia diagnosis is recommended.

Normative Values of Various Pentacam HR Parameters for Pediatric Corneas

PURPOSE

To provide a normative database of several Pentacam parameters for a healthy pediatric population.

METHODS

This was a retrospective study conducted at Al Watany Eye Hospitals, Cairo, Egypt. We explored the Pentacam HR database and collected the data of 432 normal right eyes of children and teenagers aged 3 to 18 years. The subjects were classified into the following 3 groups: group 1 (3-6 years, 17 eyes), group 2 (6-12 years, 126 eyes), and group 3 (12-18 years, 289 eyes). The parameters of the study cohort were compared with those of a healthy adult cohort.

RESULTS

The mean age of the study cohort was 13.5 (13.2-13.8) years. There were significant differences in the following indices among the 3 age groups: anterior chamber (depth and volume), curvature (index of height decentration, index of vertical asymmetry, and center keratoconus index), elevation (front and back elevations from the best fit toric ellipsoid), and pachymetric (minimum and average pachymetric progression indices and average Ambrosio relational thickness) parameters (P values 0.001, 0.001, 0.002, 0.04, <0.001, <0.001, 0.03, 0.02, 0.01, and 0.03, respectively).

CONCLUSIONS

There were significant differences in the normative values of several Pentacam indices between the pediatric and adult cohorts. Based on this finding, it is more credible to incorporate separate software cutoff values for pediatric patients. However, because there were no clinically significant differences in the parameters of the pediatric subgroups, there is no need to consider a separate cutoff value for each pediatric age range.