EXCIMER RETREATMENT FOR SCARRING AND REGRESSION AFTER PHOTOREFRACTIVEKERATECTOMY FOR MYOPIA

Aims/Background-Scarring associated with regression of refractive effe ct can occur after photorefractive keratectomy (PRK) for myopia. The e xperience of treating these complications is reported. Methods-Eightee n of 285 eyes (6 . 3%) were retreated with the excimer laser. Age, sex , preoperative primary treatment keratometry, pre-primary treatment, p re-retreatment and post-retreatment spherical equivalents, best correc ted and uncorrected visual acuities were recorded and analysed. Result s-At 6 months post-retreatment, the mean spherical equivalent was -2 . 07 dioptres (D) (SD 4 . 60 D). This spherical equivalent persisted in eyes followed for 12 months (-2 . 85 D, SD 4 . 09 D). Nine of 18 eyes (50%) had uncorrected visual acuity of 6/12 (20/40) or better. If ret reatment was undertaken within 6 . 5 months of the initial PRK, then s carring was likely to recur (p=0 . 035). Nine of 10 eyes (90%) which h ad a retreatment spherical equivalent less than two thirds of their pr imary treatment spherical equivalent were within plus or minus 1 . 25 D from emmetropia after retreatment. Four of 11 eyes (36%) followed fo r 12 months after retreatment rescarred with further regression. Concl usion-The data showed that eyes with scarring and regression of myopia should not be treated with PRK within 6 months of the initial procedu re. Eyes with the highest percentage of regression towards their initi al myopia tend to have a poor response to retreatment.