Keratoconus: current perspectives

Abstract

Keratoconus is characterized by progressive corneal protrusion and thinning, leading to irregular astigmatism and impairment in visual function. The etiology and pathogenesis of the condition are not fully understood. However, significant strides have been made in early clinical detection of the disease, as well as towards providing optimal optical and surgical correction for improving the quality of vision in affected patients. The past two decades, in particular, have seen exciting new developments promising to alter the natural history of keratoconus in a favorable way for the first time. This comprehensive review focuses on analyzing the role of advanced imaging techniques in the diagnosis and treatment of keratoconus and evaluating the evidence supporting or refuting the efficacy of therapeutic advances for keratoconus, such as newer contact lens designs, collagen crosslinking, deep anterior lamellar keratoplasty, intracorneal ring segments, photorefractive keratectomy, and phakic intraocular lenses.

Keywords: collagen cross-linking; contact lenses; corneal topography; hydrops; keratoconus; keratoplasty.

Figure 1

Slit-lamp photograph of an eye with keratoconus demonstrating increased corneal curvature (ectasia).

Figure 2

Slit-lamp and anterior segment optical coherence tomographic images of the right eye of a 16-year-old boy with atopy, vernal keratoconjunctivitis, and advanced keratoconus who presented with acute corneal hydrops after an episode of severe eye-rubbing. Corneal edema decreased gradually from presentation (left panel, day 18 after onset of corneal hydrops) to 2 months (middle panel) and 4 months (right panel) thereafter. The patient was treated conservatively with topical steroids and hyperosmotic eye drops. The break and persistent detachment of the Descemet’s membrane (white arrowheads) is clearly discernible on anterior segment optical coherence tomographic imaging.

Figure 3

Anterior segment optical coherence tomography image of an eye with keratoconus, demonstrating central thinning of the cornea.

Figure 4

Slit-lamp photograph of the same eye as in Figure 3, showing apical scarring (yellow arrow) and Vogt’s striae (white arrow).

Figure 5

Slit-lamp photograph of the same eye as in Figures 3 and 4, showing Fleischer’s ring (white arrows).

Figure 6

Tomography maps (Orbscan IIz, Bausch and Lomb, Rochester, NY, USA) before (A) and 9 months after (B) collagen crosslinking showing flattening of corneal surface. Maximum and minimum simulated keratometry values show a decrease of 2.8 and 1.5 diopters, respectively.