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Eighteen year follow-up of excimer laser photorefractive keratectomy (PRK) with 6.00mm optical zone
Session Title: Surface Ablation I
Session Date/Time: Sunday 06/10/2013 | 08:00-09:30
Paper Time: 08:06
Venue: Main Lecture Hall (Ground Floor)
First Author: : Z.Shalchi UK
Co Author(s): : D. O"Brart P. Patel R. McDonald J. Marshall
To evaluate the long-term refractive and topographic stability of excimer laser photorefractive keratectomy (PRK) with 6.00mm optical zone surgery.
St Thomas Hospital, London, United Kingdom
Forty four patients underwent clinical assessment 18 years after myopic PRK with 6.00mm optical zone as part of a number of randomized controlled clinical trials. Only one eye per patient was selected for analysis. The pre-operative mean spherical equivalent (MSE) refractive error was -4.80D (range -2.75 to -7.38D) with mean programmed correction -4.37D (range -2.50 to -7.00D).
At 18 years, the MSE refraction was -0.74D (range -4.63 to +1.50D), with 25% of eyes within 0.5D and 54% within 1.0D of intended correction. There was no difference in MSE between 1 and 18 years (p=0.06). However, patients aged 60 years or younger at 18 year review (n=22) showed mild myopic regression (-0.62D, p<0.01) which was not true for those aged over 60 (n=22) (+0.03D, p=1.00). The efficacy index was 0.65 and safety index 1.01. 95% of corneas were clear, with 2 showing only trace haze. There was no evidence of ectasia on Scheimpflug topographic examination.
Excimer laser PRK shows refractive stability between 1 and 18 years. There is mild myopic regression in younger patients. The procedure is safe with no long-term sight-threatening complications.