Prevalence of ectatic corneal conditions among keratorefractive candidates

Background Noninflammatory corneal ectasias is a group of diseases including keratoconus (KC), pellucid marginal degeneration (PMD), and keratoglobus. KC is the most common form of corneal ectasia characterized by progressive thinning of the central or inferior cornea, causing corneal steepening and cone formation. The disease typically presents during the second decade of life and is bilateral, but often one eye precedes the other. Detecting the cases of subclinical KC had always been a challenge for refractive surgeons especially when the suggestive clinical signs and symptoms to differentiate subclinical KC from the normal are not observed. Aim The aim of the study is to determine the prevalence of ectatic corneal conditions among keratorefractive population admitted for refractive surgery at Al-Mashreq Eye Centre, during the period from June 2017 till December 2017, using data from the Scheimpflug tomographer imaging system. Patients and methods Our study was conducted on patients seeking consultation for refractive surgery at Al-Mashreq Eye Centre during the period from June 2017 to December 2017. We used the Pentacam device to screen 1439 refractive surgery candidates after being subjected to precise ocular examination and full general and ocular history taking. Results In our study, a total of 42 patients (84 eyes) showed topographic signs of manifest and subclinical KC, making a total prevalence of 3.0%. No cases with PMD or keratoglobus were found, but cases with KC having a topographic pattern mimicking PMD called pellucid-like KC were found in five eyes (three patients). Compound myopic astigmatism was the commonest refractive error in keratoconic eyes (71.4%). Conclusion Prevalence of KC in refractive population may reflect an approximate idea of its prevalence in general population. Meticulous examination before refractive surgery can forbid bad consequences in patients at high risk of developing post-laser-assisted in situ keratomileusis ectasia and may save patients discovered at mild or moderate KC stages from the ultimate fate of keratoplasty. Moreover, surgeons should be aware that hypermetropia and mixed astigmatism do not eliminate the possibility of an associated ectatic corneal disease.