|In this cohort, the average age at keratoconus diagnosis was 14.9 in individuals with significant astigmatism or high myopia, and 70% of cases occurred in the 15- to 17-year-old group. Photo: Getty Images. Click image to enlarge.|
Early detection is essential to ensure timely treatment that stabilizes keratoconus’s progression. Many believe that Pentacam allows early identification of corneal ectatic disorders by providing information on thickness, elevation and curvature of the anterior and posterior faces. Researchers in Colombia estimated the frequency, severity and risk factors associated with the diagnosis of keratoconus according to Pentacam criteria among the pediatric population with high or oblique astigmatism or high myopia. Atopy was the only statistically significant risk factor, present in 85% of the patient cohort diagnosed with keratoconus.
The cross-sectional study, published in Cornea, included 426 patients younger than 18 years. Pentacam studies stored in the institutional database between 2017 and 2021 were retrospectively reviewed, who had been referred for the study because of significant astigmatism (greater than 2D), oblique axis (15° to 30° or 195° to 210°) or high myopia (greater than 5D) were selected. Pentacam data was reviewed, and diagnosis of keratoconus was evaluated and classified according to Amsler-Krumeich and Belin ABCD severity scales.
In this group, 9.4% (40 subjects) had keratoconus according to Pentacam criteria. The mean age at diagnosis was 14.9 years, with male predilection (75%). Family history was present in 7.5%.
There were no differences in the distribution in groups according to visual acuity or Amsler-Krumeich scale. The most frequent ABCD classification was A2 (35.6%), B4 (47.9%) and C0 (35.6%), with posterior curvature radius being a significant severity criterion. A clear association was found between the diagnosis of keratoconus and the history of atopy (atopic dermatitis, rhinitis, allergic conjunctivitis or asthma). The researchers suggested that it is “probably related as an etiological factor of the disease from eye rubbing and secondary release of inflammatory mediators.”
Diagnostic criteria for keratoconus found in the study group using Pentacam were thinner pachymetry, less than 490μm (average 474.19μm in OD and 478.85μm in OS), Kmax greater than 48.00D (average 48.68D in OD and 48.62D in OS), inferior/superior asymmetry present in 92.5% of right eyes and 82.5% of left eyes, loss of orthogonality present in 90% of right eyes and 82.5% of left eyes, and Belin-Ambrosio display in red present in 92.5% of right eyes and 72.5% of left eyes.
Frequency of keratoconus in the pediatric age was significantly higher in this study than previously reported. However, the researchers noted that their study was conducted in a national reference center and patients with high myopia and high or oblique axis astigmatism were selected for the study, who most likely had a high pretest suspicion for keratoconus.
“When analyzing the variables of interest found in the study group, the value of criteria such as pachymetry, keratometry value, loss of orthogonality, Belin-Ambrosio profile or inferior/superior asymmetry is highlighted, with which the eyecare practitioner can perform a ‘simple scan’ of the Pentacam, in search of reaching the diagnosis of keratoconus,” the researchers concluded.
Calderón S, Andrea N, Córdoba M, et al. Keratoconus frequency and associated risk factors among patients younger than 18 years with significant refractive errors. Cornea. September 13, 2023. [Epub ahead of print].