SUMMARY
Purpose:
To evaluate the safety and efficacy of repeated excimer laser for treatment of residual myopia and astigmatism.
Methods:
Eleven eyes (ten patients) with age ranging from 20 to 46 years underwent reablation with excimer laser. Six eyes (54.54%) were treated using photorefractive keratectomy (PRK), two (18.18%) epithelial phototherapeutic keratectomy (PTK-e) followed by PRK, and two (18.18%) with photoastigmatic keratectomy (PARK). Retreatment was done 5 to 16 month after the first treatment (average 9.3 ± 3.4 months) and follow-up ranged from 6 to 23 months (average 9.2 ± 5.4 months). The laser used was the Apex plus Summit excimer laser. Refractive changes, visual acuity and corneal haze were evaluated.
Results:
Mean preoperative spherical equivalent was -8.50 ± 3.66D. After the first treatment there was a reduction in the mean spherical equivalent of 55%, -4.04 ± 2.42D, statistically significant (p = 0.0004). After retreatment there was a reduction in the mean spherical equivalent of 28%o compared to the first treatment but this reduction was not statistically significant (p = 0.09). Pre-operative astigmatism was -2.41 ± 1.84. After the first (-2.30 ± 1.70) and second treatment (-2.10 ± 0.80) there was no significant reduction (p = 0.19 e p = 0.30 respectively). After retreatment 36.36% of the eyes presented an uncorrected visual acuity ≥ 20/40 and 63.63% ≥ 20/60. Thirty three percent were within ±1 diopter of emmetropia and 54.54% within 2 diopters. Five eyes (45.54%) lost between one to five lines of the best spectacle-corrected visual acuity after retreatment when compared to preoperative.
Conclusion:
Excimer laser retreatment lacks efectivity in cases of high refractive residual ametropies. Decrease in the best corrected visual acuity may be expected as a side effect in these cases.
Key words:
Photorefractive keratectomy; Myopia; Cornea; Surgery; Re-intervention; Complication