Posters

20 years of PRK: long-term efficacy and safety

Poster Details

First Author: G.Lascaratos UK

Co Author(s):    D. O'Brart   Z. Shalchi   R. McDonald   P. Patel   T. Archer   J. Alio del Barrio

Abstract Details

Purpose:

To investigate the long-term efficacy and safety of Photorefractive Keratectomy (PRK)

Setting:

University Hospital

Methods:

42 patients (42 eyes) who had as part of a randomized, prospective trial undergone PRK 20 years previously attended for examination at our University Hospital. All had received -3.0 or -6.0 diopter (D) corrections with either 5.0 or 6.0 millimeter optical zones or a multi-zone treatment. Mean pre-operative spherical equivalent refractive error (SEQ) was -5.13D (range -2.75 to -8.0D).

Results:

Between 1 and 20 years there was an increase in mean myopic SEQ of -0.54D (p<0.02). In patients under 40 at time of correction, this increase was -0.92D (p<0.002) with an accompanying increase in variance (p<0.02), while in those over 40 it was -0.08D (p=0.8). In female patients the change was -0.69D (p<0.01), while in males it was -0.26D (p=0.6). The efficacy index at 20 years was 0.49 and the safety index was 0.97. Corrected distance visual acuity (CDVA) improved from 1 to 20 years (p<0.01). 93% of corneas were clear at 20 years. 3 eyes had trace haze. There was an improvement in haze scores between 1 and 20 years (p<0.02). Corneal power remained unchanged between 6 months and 20 years (p=0.4). Axial length increased by a mean of 0.84mm (p<0.0001). There was no ectasia.

Conclusions:

There was a slight, but significant, increase in myopic SEQ after PRK between 1 and 20 years, particularly in those under 40 at the time of treatment and female patients. Corneal power remained unchanged, but axial length increased. The procedure was safe with no long-term sight-threatening complications and improvements in CDVA and corneal transparency with time. FINANCIAL INTEREST: NONE