Evaluation of corneal topography with Orbscan II in first-degree relatives of patients with keratoconus.
OBJECTIVE
To evaluate the corneal topographic characteristics of first-degree relatives of patients with keratoconus with corneal topography to determine the incidence of clinical keratoconus and topographic abnormalities.


METHODS
Between February and August 2006, Orbscan II analysis was done in 144 eyes of 72 cases who were first-degree relatives of patients diagnosed with clinical keratoconus. The findings were compared with preoperative Orbscan analyses of 52 clinically normal individuals who underwent laser in situ keratomileusis surgery and did not develop corneal ectasia in 3 years of follow-up.


RESULTS
In 8 of the 72 first-degree relatives of patients with keratoconus, clinical keratoconus was diagnosed by the topographic pattern in Orbscan and clinical examination (group 1). The remaining 64 subjects (group 2) were compared with the control group (group 3). The central corneal thickness was 523.7 +/- 40.4 microm in group 2, whereas it was 546.3 +/- 33.1 microm in group 3 (P < 0.05). The central corneal thickness, thinnest pachymetric reading, posterior elevation value, distance between the greatest anterior/posterior elevation points, and corneal center, posterior best fit sphere (BFS) values, posterior BFS:anterior BFS ratio, and irregularity values were significantly different between group 2 and group 3 (P < 0.05).


CONCLUSIONS
The keratoconus incidence was found to be 11% in first-degree relatives of patients with keratoconus as opposed to a reported incidence of keratoconus of 0.05% in the general population. In first-degree relatives of patients with keratoconus who did not have a topographic keratoconus pattern, abnormal corneal topographic values were detected. The asymptomatic relatives of patients with keratoconus should undergo a thorough preoperative analysis for subtle topographic abnormalities before any keratorefractive surgery.
Department of Ophthalmology, Beyoglu Eye Research and Training Hospital, Yeditepe University, Balmumcu, Istanbul, Turkey.
Vedat
V
Kaya
Canan Asli
CA
Utine
Muhsin
M
Altunsoy
Deniz
D
Oral
Omer Faruk
OF
Yilmaz
D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D006801:Humans; D015994:Incidence; D007640:Keratoconus / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics / Q000601:surgery; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use