Ultraviolet Devices

Keratoconus is a corneal disease affecting 1 in 2000 individuals. The disease usually starts in young adults, and is characterized by progressive thinning and outward protrusion of the cornea. (Cornea is the clear structure in front of the human eye responsible for focusing of rays of light into the eye for a clear image) The cornea takes a conical shape, and produces astigmatism due to which the rays of light cannot be focused properly, resulting in deterioration of the quality of vision. In the early stage of keratoconus, vision can often be improved using cylindrical correction in the glasses. However in later stages most patients require rigid gas permeable lenses for improvement in quality of vision. Intacs are plastic ring segments which can be inserted into the mid-peripheral cornea to produce flattening of the central cornea. This results in reduction of the severity of keratoconus, and improves both vision & contact lens fitting to a certain extent. However it does not affect the progression of keratoconus. It is estimated that almost 21% of keratoconus patients ultimately progress to an advanced stage of disease requiring corneal transplantation surgery to restore corneal architecture and improve eyesight. Dr Rajesh Fogla, Senior Consultant, Corneal Surgeon at Apollo Hospitals, Hyderabad, India, has special interest in Keratoconus & its management. He has been providing specialized contact lens fitting for keratoconus patients, and also performs deep anterior lamellar keratoplasty (DALK) surgery. Compared to conventional full thickness corneal transplantation surgery, DALK surgery has several advantages. Unlike conventional corneal transplantation surgery wherein a central disc of full thickness cornea is entirely replaced with donor tissue, in lamellar keratoplasty the healthy inner layer of the patientâ''s cornea is retained and not sacrificed. (this layer called the endothelium is the most vital layer of the cornea responsible for maintaining the corneal clarity). Only the outer 80 -90% of the cornea is replaced with healthy donor tissue. The other advantage of lamellar keratoplasty, is that as the inner layer is retained, the immune cells of the body do not recognize the outer donor tissue as being foreign. Hence there is no risk of endothelial rejection with lamellar keratoplasty, unlike full thickness graft wherein steroid therapy has to be continued for years to prevent graft rejection episodes. Dr Fogla has been performing deep anterior lamellar keratoplasty since 1998, and currently performs the same in all his patients with advanced keratoconus. He has been conducting instruction courses at various national and international meetings on the same subject. Dr Fogla, has started performing collagen crosslinking treatment using the photo-sensitizer riboflavin (Vitamin B2) and ultraviolet light (365nm) exposure for keratoconus patients. In extensive experimental studies, researchers have demonstrated a significant increase in corneal rigidity / stiffness after collagen cross-linking using this riboflavin / UVA treatment. The 3 & 5 year results of Dresden clinical study in human eyes has shown arrest of progression of keratoconus in all treated eyes. (Wollensak G. Crosslinking treatment of progressive keratoconus: New Hope. Current Opinion in Ophthalmology 2006; 17: 356 - 360). Keratoconus patients now have a new hope, a new treatment modality which can arrest the disease progression and thereby prevent the need for surgical intervention in future. Although the procedure does not provide a cure for keratoconus, it certainly can stop its progression and patients can continue using their glasses or contact lenses for improved eyesight. Hence attempt should be made to diagnose keratoconus early enough and stop its progression using collagen crosslinking. Corneal topography can detect keratoconus much before it can be picked up on a routine eye examination. Hence this test should therefore be performed in all cases with high astigmatism ie cylindrical power to detect keratoconus at an early stage. Further ongoing studies will help establish collagen cross-linking treatment as the primary modality of treatment for keratoconus. Currently this treatment is available only at select centers all over the world, and is performed only under an ethics committee or IRB (Institutional Review Board) approved study protocol. Dr Fogla has initiated a prospective study on collagen crosslinking at Apollo Hospitals, Hyderabad. If you have keratoconus and desire more information, or wish to undergo this treatment, write to Dr Fogla at dr_fogla@yahoo.com or visit www.corneaclinic.com or call +919866076750