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Temporal steepening in keratoconus associated with younger age, study shows
J Refract Surg. 2009;25(11):1012-1016.
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Steepening was temporal in a markedly higher percentage of younger keratoconus patients than older patients, according to a study.
"In keratoconus, the steepest part of the cone can be located temporally, especially in younger patients, which is unusual," the study authors said. "Younger candidates for refractive surgery should be screened for temporal forme fruste."
The study included 482 eyes of 251 patients with keratoconus. Patients were assigned to three groups according to age: younger than 21 years (83 eyes, 17.2%), 21 to 40 years (362 eyes, 75.3%) and older than 40 years (37 eyes, 7.5%).
Investigators conducted full ocular examinations and performed topographical measurements using the Pentacam Scheimpflug camera (Oculus). They compared topographic patterns between groups.
The most frequent topographic measurements were a vertical bow-tie pattern in 28.4% of the youngest patients, an inferior global cone pattern in 23.7% of the middle patients and an inferotemporal global cone pattern in 16.4% of the oldest patients.
Investigators identified a temporal global cone pattern in 22% of eyes in the youngest patients, 6.9% of eyes in the middle patients and 11.1% of eyes in the oldest patients, the authors said.
Keratoconus has irregular astigmatism patterns on topography that are typically steeper inferotemporally. The pattern may vary with age, and so it is important to look clinically at the cornea by slit lamp to make sure that corneal scars, anterior basement membrane dystrophy or dry eye aren’t the reason for topographical abnormalities, but be especially suspicious of the inferotemporal steepening patterns. We also find elevation topography as well as regional pachymetry measurements quite helpful.
– David R. Hardten, MD
OSN
Cornea/External Disease Section Editor