Treatment of advance keratoconus using donor bowman layer: the zaman technique of bowman layer transplantation (Type I & Type II)

Commonly referred to as an ecstatic, non-inflammatory disease, Keratoconus, usually bilateral and asymmetric, is characterized by progressive steeping and thinning of the cornea. This results in irregular astigmatism which compromises vision [1,2]. Traditionally, early Keratoconus stages have been treated by prescribing a hard contact lens to obtain a regular anterior optical surface. This tendency was discontinued when contact lens intolerance in advanced stages required the use of penetrating keratoplasty (PKP) or deep anterior lamellar Keratoplasty (DALK). An alternative technique of corneal cross-linking was designed in 2003 as a treatment option for keratoconus. The cornea measured at least 400 um thickness after epithelium removal and pre-operative maximum keratometry (Kmax) measured 58D or less. As a result, no corneal transplantation was required or postponed [3].