Literature in Mansoura Ophthalmic Center ,Mansoura University

This cross-sectional study was carried out on patients presenting keratoconus in one eye and forme fruste keratoconus in the fellow eye; the patients attended the outpatient clinic of Mansoura ophthalmic center between January 2014 and February 2015. This study was approved by the institutional research board of the Mansoura faculty of medicine and was performed in accordance with the ethical standards of the Declaration of Helsinki. All patients included in the study provided informed consent.

Ocular examinations were performed on all eyes included in the study. Clinical Keratoconus was diagnosed if all the following criteria were found:1)asymmetric bow tie with skewed radial axis (SRAX), inferior or central steepening on the topography map, 2)mean keratometry (K)>47diopters or an inferior-superior (I-S) value >1.4diopters according to the Rabinowitz and McDonnell criteria[8],and 3)at least one clinical symptom(i.e., stromal thinning, conical protrusion of corneal apex,Fleischer ring, Vogt striae or anterior stromal scar). Forme fruste keratoconus was diagnosed if all the following criteria were found: 1) normal topography, 2) mean K<47D and I-S ≤1.4,3) normal slit lamp, and 4)keratoconus in the fellow eye.

The eyes with an evident keratoconus diagnosis were included in (Group A)and the fellow eyes were included in (Group B).Control cases(Group C) were selected from the normal database of candidates for refractive surgery with the following:1)normal topography, 2)negative rotating Scheimpflug device indices and negative topographic keratoconus classification, 3)normal slit lamp examination, and 4)no history of eye disease(only one eye of each normal candidate was included in the study depending on a computer-based randomizing program).

The exclusion criteria included previous ocular surgery or trauma, significant corneal scarring or associated ocular pathology.

All eyes were examined by rotating Scheimpflug corneal tomography (Pentacam, Oculus Optikgerate GmbH).No patients in the study wore contact lenses. During the Scheimpflug corneal tomography examination, the patient was properly positioned on the chin rest and forehead strap. The patient was asked to blink several times then open both eyes and stare at a fixed target. After obtaining proper alignment, the automatic release mode started the scan; a total of25 single Scheimpflug images were captured within 2 sec for each eye. Three consecutive scans were taken of each eye by the same examiner. The average of the results of three acceptable measurements was included in the study. Each eye was required to have a corneal map with at least 9 mm of corneal coverage and no extrapolated data.