JUN 09, 2008
A study from Italy suggests that topography-driven surface ablation may be an option not only for visual rehabilitation in mild to moderate keratoconus patients, but also for providing some stability to the disease.
The authors say an earlier study in rabbits suggest why. Excimer laser ablation performed in rabbits resulted in deposition of newly synthesized type I, III and IV collagen, cellular fibronectin, tenascin and laminin in the extracellular matrix of the anterior corneal stroma. This could provide further tensile strength to the cornea.
In this prospective study from Italy, 18 patients (25 eyes) with bilateral mild or moderate keratoconus (grade 2 - Krumeich classification) underwent PRK with the Zeiss MEL 70 excimer laser using topographically supported customized ablation (TOSCA, which is not currently approved for us in the U.S.). Eight contralateral eyes served as controls.
Videokeratography indices (mean keratoconus index, keratoconus severity index, keratoconus apex, keratoconus predictor index, opposite sector index and differential sector index) were significantly lower (P<0.0001) two years after treatment, while control eyes had significantly worse keratoconus topographic indices compared to baseline during the 24 month follow-up.
Mean UCVA and BSCVA were also significantly improved (P<0.05) among treated patients. Several eyes showed improvement from one to four lines in BSCVA, and in only one eye was there a loss of one line of BSCVA. Most eyes had no haze at 24 months, with the rest having only mild haze.