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Keratoconus Detection in High-Astigmatism Pediatric Patients: Optimal Pentacam Indices and Cutoff Points
Renato Souza Oliveira1,2,3, João Quadrado Gil2,4, Andreia Rosa2,4
1Instituto Brasileiro de Oftalmologia - IBOL, Rio de Janeiro, Brazil.
Insights
Pentacam indices accurately detect keratoconus (KC) in children, especially those with high astigmatism. Specific metrics like anterior corneal aberrations and pachymetry offer reliable diagnostic cutoff values for pediatric KC detection.
Area of Science:
- Ophthalmology
- Corneal Imaging
- Pediatric Eye Care
Background:
- Keratoconus (KC) diagnosis in pediatric patients, particularly those with high astigmatism, presents diagnostic challenges.
- Accurate identification of KC is crucial for timely intervention and management to prevent vision loss.
Purpose of the Study:
- To evaluate the diagnostic accuracy of various Pentacam indices for identifying keratoconus (KC) in pediatric patients with high astigmatism.
- To determine optimal cutoff values for these indices in the pediatric population.
Main Methods:
- A prospective, multicenter, cross-sectional study involving 312 eyes from 167 pediatric patients (aged 6-18 years).
- Patients were classified into KC, forme fruste KC, high astigmatism (Cyl2D and Cyl4D subgroups), and control groups.
- Twenty-three Pentacam indices were analyzed using receiver operating characteristic (ROC) curves to determine sensitivity, specificity, and optimal cutoff points.
Main Results:
- Several Pentacam indices demonstrated high accuracy in distinguishing KC from high astigmatism, including anterior corneal high-order aberrations (RMS), Belin/Ambrosio enhanced ectasia total deviation, and pachymetric progression index.
- Diagnostic accuracy varied across groups, being highest in controls and lowest in the Cyl4D subgroup.
- Optimal cutoff values for astigmatic pediatric patients were generally higher than those for non-astigmatic children and differed from adult norms.
Conclusions:
- Pentacam indices are effective in differentiating KC from normal pediatric eyes.
- For pediatric patients with high astigmatism, specific indices like anterior corneal RMS, Belin/Ambrosio enhanced ectasia total deviation, and pachymetric progression index are recommended for KC detection.
- Established cutoff values for these indices in astigmatic children are higher than in non-astigmatic children and distinct from adult values, necessitating tailored interpretation.
Purpose:
To assess the accuracy of various Pentacam indices in distinguishing keratoconus (KC) in pediatric patients with high astigmatism and to establish appropriate cutoff values.
Methods:
This prospective multicenter cross-sectional study included 312 eyes from 167 patients aged 6 to 18 years (mean age, 13.1 ± 3.2 years) evaluated with Oculus Pentacam HR. Patients were categorized into 4 groups: KC, forme fruste keratoconus, astigmatism greater than 2 diopters (Cyl2D), and control. A subgroup of Cyl2D comprised patients with astigmatism greater than 4 diopters (Cyl4D). Twenty-three Pentacam indices were analyzed, and receiver operating characteristic curves determined optimal cutoff points, sensitivity, and specificity.
Results:
The best indices for distinguishing KC from Cyl2D were high-order aberration root mean square of the anterior corneal surface (area under the receiver operating characteristic curve 0.987), Belin/Ambrosio enhanced ectasia total derivation (0.971), index of vertical asymmetry (0.971), average pachymetric progression index (0.962), maximum Ambrosio relational thickness (0.960), posterior elevation (0.952), and anterior elevation (0.948). The accuracy of these indices was highest in the control group and lowest in the Cyl4D group. Area under the receiver operating characteristic curve was significantly lower for fruste keratoconus than KC. Optimal cutoff values were higher for astigmatic patients than for those with no refractive error.
Conclusions:
Most indices effectively distinguished between KC and normal pediatric patients. For individuals with high astigmatism, we suggest focusing on specific indices such as high-order aberration root mean square, Belin/Ambrosio enhanced ectasia total derivation value, maximum Ambrosio relational thickness, average pachymetric progression index, and index of vertical asymmetry. Optimal cutoff points for these patients were higher than those for nonastigmatic children and differed from adult populations.
