Laser Assisted Sub Epithelial Keratectomy for Hyperopia Using 213 Nm Wavelength Solid State Laser, 3 Year Follow Up Study of Refractive and Visual Outcomes

Abstract

PURPOSE:To evaluate the visual and refractive outcomes, using 213 nm solid lasers for the correction of broad range of hyperopia, covering pediatric age group to presbyopic age group. MATERIALS AND METHODS:The Present study is a prospective case series in a private practice setup, analysed series of eyes, with low to high hyperopia, who underwent conventional LASEK. Long term (3 year) visual and refractive outcomes and overall patient satisfaction studied. RESULTS: This cohort study of 37 eyes included broad range of hyperopia between +1.5 D to +7.5 D. For 70.27% of eyes, there was no change in CDVA post operatively and there was a significant Gain of one line in 21.62% of eyes and the paediatric eyes (4) CONCLUSION:The conventional LASEK can be performed using solid laser, safely and effectively for hyperopia covering broad age groups and it can achieve effective visual outcomes with excellent overall patient satisfaction. KEYWORDS: LASEK, CDVA, UDVA, logMAR and PRK. INTRODUCTION:Corneal photo ablation has been performed over the years using refractive excimer laser 193nm wavelength safely and effectively. [1][2][3][4] In recent times, solid state refractive laser platform has been developed, [5][6] providing an alternative to excimer lasers with certain added advantages. The newer solid state laser is a quintupled Nd: Yag laser with a 213nm wavelength, small spot size 0.6mm. Experimental studies indeed found that solid lasers (213nm wavelength) don't induce thermal damage or collateral damage in deep corneal layers. [6][7] Photo ablation of the stromal tissue within the wavelength ranging from 190nm to 220nm is with high degree of accuracy and minimal collateral damage. [4][5] This laser has higher pulse to pulse energy stability.There is no need of using toxic gas and it has least noise levels in the operation theatre, less maintenance costs and the greatest advantage is its ready to use option anytime unlike with excimer laser. The repetition rate of solid state laser is 300hz, much higher than in the excimer laser. This laser provides true Gaussian profile of the beam. The 213 nm wavelength is less sensitive to corneal hydration than 193 nm, due to its better transmissibility in hydrated cornea. [8] The hydrated cornea has bearing on corrections. The over hydrated cornea results in frequent under corrections, dry stromal bed (under hydrated) results in over corrections. [9] The solid state lasers are more complex to manufacture and needs frequent and meticulous maintenance of the machine.

One-year follow-up of patients with hyperopia undergoing photorefractive keratectomy with Allegretto WaveLight Eye Q 400

“…According to Autrata R et al [ 18 ], after 2 years of follow-up, 86% of patients in the PRK group showed an emmetropia of ±1.00 D interval and 57% SE of ±0.5 D in their eyes. In the studies by Kaluzny BJ et al [ 13 ] and Yenugandula R et al [ 21 ] (after 3 years), 78% and 92% of the eyes were in the range of ±0.5 and ±0.1.00 D, respectively. Also, in a study by El-Agha MS et al [ 4 ], in the PRK group, after one year, 83.3% and 100% of the eyes had an SE of ±0.5 D and ±1.00 D, respectively, which was not in line with our results.…”

“…Preoperative UCVA in the PRK group increased from mean LogMAR of 0.37±0.28 to mean LogMAR of 0.03±0.11 at 6 months postop [ 19 ]. Furthermore, UCVA ≥20/20 was observed in 59% of eyes at the 3 years postop [ 13 ] and vision ≥20/40 was observed in 78.4% of the eyes at the 3 years postop [ 21 ]. In O'Brart DP et al study [ 10 ], the UCVA ≥20/20 and ≥20/40 was observed in 15% and 57.5% of the eyes, respectively.…”