PURPOSE : To demonstrate the reduction and prediction of refractive errors after penetrating keratoplasty (PK) for keratoconus and evaluate the effect of recipient-donor trephine disparity on the results. METHODS: Retrospective analysis of clinical records of 60 patients that underwent PK for keratoconus performed by the same surgeon, under the same technique, between 2005 and 2009. Spherical equivalent, keratometry and visual acuity were evaluated statistically before surgery and 1.3 and 6 months after. The patients were divided in two groups according to recipient-donor trephine disparity. Group 1 formed by those with disparity smaller than 0,5mm and group 2 with disparity equal to 0.5mm. RESULTS: All patients showed improvement on visual acuity. The hypermetropic effect observed on the 6th postoperative month was of 79%. Both groups showed significant reduction of refractive error, each postoperative day correspond to a hypermetropic effect of 0.68D (p=0.005). Neither the spherical equivalent mean difference between the groups nor the difference of the hypermetropic effect between the groups was statistically significant. Analysing the keratometry, each postoperative day is associated to a decrease of 1.87D (p<0.0001 showing significant difference between groups (p=0.007). Group 1 showed a reduction of 8.93D on mean keratometry compared to the 6.82D reduction observed on group 2 (p=0.035). CONCLUSION: We observed a significant reduction on mean keratometry and spherical equivalent as well as the improvement in visual acuity in keratoconus patients that underwent PK. The preoperative planning of trephine size may provide a significant reduction on refractive error after PK for keratoconus.
Keratoplasty; keratoplasty, penetrating; Keratoconus; Anisometropia; Corneal diseases
