ABSTRACT
A. INTRODUCTION Keratoconus patients have problems with contact lenses and poor visual acuity with glasses, which contributes to the patients’ natural tendency to consider refractive surgery. Keratoconus is a progressive, bilateral, and noninflammatory corneal disease associated with central and paracentral stromal thinning; it is characterized by anterior and posterior corneal protrusion, irregular astigmatism, stromal scarring, and decreased visual acuity, which may reduce the patient’s ability to achieve 20/20 corrected visual acuity with spectacles (1). Keratoconus may be associated with systemic diseases (Down’s syndrome, Leber’s congenital amaurosis, connective tissue disease), trauma (2) (contact lens wear, eye rubbing), and positive family history (3-5). Stromal thinning, epithelial iron ring (Fleischer ring), Vogt’s striae, and scarring (6) are often noted on slit lamp examination. Hydrops (Fig. 10.1) is generally associated with advanced keratoconus. Due to the pathologic conditions surgical trauma may exacerbate the disease. The corneas may be weakened by a lamellar cut and cause further corneal instability.
