1. 10 year follow up of LASIK surgery for low to high levels of myopia Qasim Qasem FRCS, Caitriona Kirwan MRCOpth, Michael O’Keefe FRCS. Institutional Affiliations: Mater Private Hospital1, Eccles Street, Dublin University College Dublin2, Ireland

2. Introduction: Introduction: ► LASIK, lamellar flap creation followed by laser ablation, is largely responsible for the popularising of corneal refractive surgery. ► Follow up studies are very important for improvement of treatment algorithms, better definition of treatment boundaries, management and outcome of early postoperative complications, monitoring visual acuity results and stability at short and long term.

3. Objective: Objective: To evaluate the long term safety and stability of laser in situ keratomileusis (LASIK) for the treatment of low to high levels of myopia To evaluate the long term safety and stability of laser in situ keratomileusis (LASIK) for the treatment of low to high levels of myopia

4. Methods: ► Out of Ninety patients invited for review after ten years from their refractive laser surgery, forty three patients were assessed ( 48 %.). ► All procedures performed by one surgeon (MOK) by Technolas 117 laser platform (Bausch & Lomb) ► date of surgery, age at the time of surgery, refractive error treated, optical zone used, flap thickness, ablation depth, early postoperative complications, visual and refractive outcome three months postoperatively and re-treatments recorded. ► At ten year follow up of patients ( 74 Eyes) had a full ophthalmic assessment, unaided and best corrected visual acuity were recorded, current refractive error, Corneal Topography by (Orbscan, Bausch & Lomb), Aberrometry by (Zywave, Bausch & Lomb), Corneal hysteresis by (Reichert Ocular Response Analyzer), Contrast sensitivity (Pellie Robson), Slit lamp examination & dilated funduscopy. ► All patients were also questioned regarding any night vision complaints and satisfaction in general.

5. Results: Results: ► The average age at the time of surgery was 32.5 with a range between 20 to 54 years of age. ► Mean refractive spherical equivalent treated was -5.67 dioptre, with a range of - 1.75 dioptre to -12.5 dioptre, target of treatment was emmetropia for all patients. ► Preoperative central corneal thickness average was 557.5 ± 46.96 (microns), with a range between 442 to 670 microns. ► Optical zone of treatment average was 5.8 ± 0.4 mm with a range between 5 to 7 mm. ► Depth of ablation range was 50 to 167 micron, with an average of 114.9 ± 26.4 microns, and average flap thickness was 160.4 micron. ► There was one intra-operative complication of a free flap which was managed with no loss of best corrected visual acuity. ► Three eyes out of the seventy four had re- treatment at early period within the first year and another two were re-treated within the first five years. ► At ten year follow up further 7 eyes required enhancement

6. Three Months Ten Years Three Months Ten Years ► ≥6/6 58.1% 49.2% ► 6/7.5- 6/9 22.97% 28.9% ► 6/12 8.10% 8.6% ► 6/15 – 6/24 5.40% 8.6% ► 6/36 – 6/60 5.40% 4.3% Three months post treatment Vs 10 Years unaided visual acuity Three months post treatment Vs 10 Years unaided visual acuity

7. Aberration profile: Aberration profile: ► All patients had an aberration scan at their ten year visit. ► Out of the 43 patients, only eight patients (18.6 %) described some degree of difficulties with night vision and continued to experience symptoms of glare which was confirmed with aberrometry. Majority of patients were asymptomatic even with a level of high order aberrations above normal level. ► The average high order aberration at 6 mm is 0.84± 0.3 microns, the average 4th order spherical aberration is -0.48 ± 0.2 microns. ► The total level of aberration is higher than 0.80 microns. (Table 3), ► 19 eyes (27.5%) had HOA at 6mm higher than one, 42 eyes (60.8%) between 0.5 and 1.00 micron and the remaining were below 0.50 microns. (Figure 1) ► Figure 1- Zywave Aberrometry

9. Predictability Predictability ► The percentage of patients within plus or minus 0.5D and plus minus 1.00D of intended correction. Within ±0.5 D At 3/12 At 10 Yrs Within ±1.0 D At 3/12 At 10 yrs Within ±0.5 D At 3/12 At 10 Yrs Within ±1.0 D At 3/12 At 10 yrs ► All levels 45.9% 28.37% 79.73% 58.1% ► Low Myopia 57.1% 42.80% 100% 85.7% ► Moderate Mope 58.9% 35.9% 94.8% 69.23% ► High Mope 25.0% 14.28 % 53.7% 35.71 %

10. Retreated Patients: Retreated Patients: ► MRSE Age at Rx Regression Sex ► -5.625 D 21 -1.5 D F ► -7.75 D 45 -2.0 D F ► ► -7.375 D 41 -3.25 D M ► -6.00 D 34 -1.75 D F ► -5.00 D 29 -0.75 D M ► -6.5o D 34 -1.75 D F ► -8.75 D 23 -3.35 D F ► - 5.0 D 30 -1.25 D F ► -6.0 D 21 -1.25 D F ► -5.6 D 21 -1.00 D F ► -8.5 D 24 -1.75 D F ► -6.15 D 24 - 1.50 D F

11. Conclusion Conclusion ► at ten year follow up, Lasik is a safe procedure ► however, there was a 15 % regression. ► this was mostly in high myopic patients and it seems to be associated with the younger patients. Recommendation ► Patients with high myopia should be informed of the potential to become myopic again and require glasses. ► Surgeons treating those patients should be aware of this and perhaps build in the option of further surgical re- treatment as part of their initial surgical approach.