| Popis: |
Keratoconus is a condition in which the corneal shape becomes steeper and more irregular between adolescence and the mid-thirties. It is a common cause of visual impairment with disease progression typically managed with rigid contact lens. Traditionally, no intervention has been available to arrest or slow disease progression. As a result, keratoconus is the commonest indication for corneal transplantation in young people. Over the last decade, outcome data has accumulated for new interventions for keratoconus that have radically altered the treatment options for these patients and promises to avoid the sight loss associated with this condition. These interventions include corneal collagen cross-linking (CXL), intracorneal ring implantation and photorefractive keratectomy (PRK). The laboratory and clinical work presented in this thesis explores these new interventions under two key headings: corneal shape stabilisation and visual rehabilitation. I have developed two novel ex vivo techniques which provide quantitative means of measuring riboflavin across the whole cornea in both epithelium-off and –on techniques. Using these methods I have concluded that no existing commercial transepithelial CXL protocol matches the riboflavin penetration achieved following epithelial debridement. I present novel iontophoretic protocols that, by increasing riboflavin concentration, soak duration and current dosage, matches epithelium-off absorption. I additionally report prospective outcomes of an accelerated version of CXL in keratoconus confirming it is a safe and effective iteration of the original ‘Dresden’ protocol. Finally, I present interim outcomes from a prospective study of simultaneous ocular wavefront-guided PRK and CXL showing significant improvements in corrected distance visual acuity beyond that expected with standard CXL. |
