Abstract
Purpose: :
Conventional clinical wisdom has long held that younger age at keratoconus onset was associated with worse disease, faster disease progression, and/or a shorter time to penetrating keratoplasty. The purpose of this analysis was to evaluate age as a factor in severity–related outcomes in keratoconus among patients in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.
Methods: :
Up to 1,065 keratoconus patients enrolled in the CLEK Study were evaluated for associations between younger age and the following outcomes after up to eight years of annual follow–up: incident corneal scarring, penetrating keratoplasty, change in visual acuity, and change in corneal curvature (first definite apical clearance lens [FDACL]).
Results: :
In univariate analyses, younger age at baseline was associated with a higher incidence of corneal scarring. In patients 19 years old or younger, 35.7% had at least one scarred cornea by year 5 (10/28 patients) compared with 12.9% of patients 20 years old or older (110/850 patients) (p=0.001). Likewise, younger age at baseline was associated with a higher incidence of penetrating keratoplasty among unoperated eyes at CLEK Study baseline. The eight–year incidence of penetrating keratoplasty was higher (15%) among patients 40 years old or younger compared to patients 40 years old or older (8%). There was no difference in the slope of the change in either high– or low–contrast visual acuity as a function of younger age, but younger eyes demonstrated a greater slope of the change in corneal curvature. Multivariate analyses revealed a significant association between five–year incident scarring in patients younger than 20 years old (odds ratio = 6.34; 95% confidence interval = 2.57, 15.00, p<0.001) when controlling for corneal staining, corneal curvature, and contact lens wear and a significant association between eight–year incident penetrating keratoplasty and younger age (odds ratio = 0.72 for every decade younger; 95% confidence interval 0.58, 0.89; p=0.003) when controlling for high–contrast, best–corrected visual acuity and corneal curvature. No significant association between visual acuity and younger age was evident with multivariate analysis, but there was a significant association between younger age (less than 35 years old) and corneal curvature (FDACL) (odds ratio = 2.45; 95% confidence interval 1.82, 3.30; p<0.0001.
Conclusions: :
Younger age appears to be associated with the development of corneal scarring, penetrating keratoplasty, and corneal steepening in patients with keratoconus.
Keywords: keratoconus • clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: natural history