Abstract
PurposeTo assess the time course of optical quality and intraocular scattering in relation to visual acuity after femtosecond lenticule extraction (FLEx) for the correction of myopia.MethodsThis study evaluated 36 eyes of 36 patients with spherical equivalents of −4.38±1.53 D [mean ± standard deviation] who underwent FLEx. Before surgery, and 1 week and 1, 3 and 6 months after surgery, we assessed the modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scattering index (OSI), and OQAS values (OVs), using a double-pass instrument. We also investigated the relationship of the OSI with corrected distance visual acuity (CDVA) preoperatively and postoperatively.ResultsThe mean changes in MTF cutoff frequency, Strehl ratio, OSI, OV100%, OV20%, and OV9% preoperatively and 6 months postoperatively were −5.51±15.01, −0.03±0.07, 0.35±0.83, −0.17±0.48, −0.14±0.38, and −0.09±0.22, respectively. We found no significant preoperative correlation between the OSI and logMAR CDVA (Spearman rank correlation coefficient r = 0.068, p = 0.69), and modest, but significant correlations 1 week and 1, 3, and 6 months postoperatively (r = 0.572, r = 0.562, r = 0.542, r = 0.540, p<0.001, respectively).ConclusionsFLEx induced a transient decrease in optical quality in association with an increase in intraocular scattering in the early postoperative period, possibly due to mild interface haze formation, but gradually recovered with time. It is suggested that this transient degradation in optical quality related to an increase in the intraocular scattering may result in a slight delay of CDVA recovery in the early postoperative period.
Highlights
The femtosecond laser is one of the most revolutionary technologies in medical care in recent years. [1,2,3] This femtosecond laser allows very precise ablation with less thermal damage to the tissues than occurs with other lasers
[5] the refractive lenticule extraction (ReLEx) technique, which can be used for femtosecond lenticule extraction (FLEx) by lifting the flap and by small incision lenticule extraction (SMILE) without lifting the flap, has been proposed as an alternative to conventional laser in situ keratomileusis (LASIK) for the correction of refractive errors. [6,7,8,9,10,11,12,13,14,15,16,17] Interestingly, visual acuity recovery following this novel technique has been reported to be slightly slower than that after other keratorefractive surgeries in the early postoperative period, which may be a unique characteristic of this surgical approach. [11,12,15,16,17] This delay was considered to be mostly associated with interface haze formation, which is one of the most common adverse events after this surgery
We investigated the relationships of the objective scattering index (OSI) with logarithm of the minimal angle of resolution of corrected distance visual acuity (CDVA) before surgery, and 1 week and 1, 3, and 6 months after surgery
Summary
The femtosecond laser is one of the most revolutionary technologies in medical care in recent years. [1,2,3] This femtosecond laser allows very precise ablation with less thermal damage to the tissues than occurs with other lasers. [1,2,3] This femtosecond laser allows very precise ablation with less thermal damage to the tissues than occurs with other lasers It has primarily been utilized as an alternative to the microkeratome for making corneal flaps in laser in situ keratomileusis (LASIK). A recent breakthrough in this laser technology has resulted in a novel refractive procedure called refractive lenticule extraction (ReLEx), which requires neither a microkeratome nor an excimer laser, but uses only the femtosecond laser system as an all-in-one device for flap and lenticule processing. The purpose of this study is twofold: to retrospectively assess the time course of the detailed optical quality of the eye, including the intraocular scattering, and to investigate the relationships of the intraocular scattering with visual acuity, after FLEx for the correction of myopic refractive errors
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