Objective aement of tranient corneal haze and it relation to viual performance after photorefractive keratectomy

PURPOE: Photorefractive keratectomy ha the potential to caue tranient corneal haze. The purpoe of thi tudy wa to evaluate the relationhip between tranient corneal haze a meaured by an objective mean and high and low contrat viual performance. METHOD: In a propective tudy, 44 eye of 28 patient were examined preoperatively and at 1, 3, 6, and 12 month after photorefractive keratectomy. Five laer in itu keratomileui and two intratromal corneal ring egment (Intac [KeraViion, Fremont, CA]) were included for comparion, becaue thee procedure are not expected to caue haze. Haze wa meaured uing a prototype objective hazemeter, TPC-3, a modification of the Nidek EA-1000. Viual performance wa meaured uing high-contrat viual acuity and the Rabin mall Letter Contrat Tet. REULT: Corneal haze wa greatet at the 1-month examination and wa conitent with a decreae in viual performance on both tet. Corneal haze reolved in 82% of eye by 10 ± 4 month after photorefractive keratectomy. However, viual performance had not returned to preoperative level in 65% and 81% of thee eye on the high-contrat viual acuity tet and the mall Letter Contrat Tet, repectively. Eye that underwent laer in itu keratomileui and Intac did not develop corneal haze; however, viual decrement were meaured. CONCLUION: A a clinical tool, the TPC-3 hazemeter objectively meaure very ubtle change in haze level. Corneal haze appear to account for only approximately 50% of viual performance change in the early healing period after photorefractive keratectomy. Other factor, namely topographic abnormalitie, are more likely to be an important caue of peritent viual diturbance.