Fluctuation in straylight measurements during the visual recovery phase after small incision lenticule extraction

Abstract

Purpose To investigate the postoperative straylight changes during the visual recovery phase after small incision lenticule extraction (SMILE) and their association. Methods Seventy consecutive eyes from 37 patients with a mean age of 30.92 ± 7.26 years and a mean preoperative spherical equivalent of −5.24 ± 1.90 dioptres undergoing myopic or myopic astigmatism SMILE correction were included in this prospective study. Patients were followed up at days 1, 3, 7, 14, 21 and 28 after standard SMILE. Straylight was measured using the C-Quant straylight meter (Oculus GmbH, Germany) preoperatively and at each postoperative visit. Results Preoperatively, the mean straylight measurement was 1.16 ± 0.16. After SMILE, the mean straylight values were 1.12 ± 0.14 and 1.13 ± 0.13 at days 7 and 14, which were significantly reduced compared to preoperative values (p ≤ 0.028). Straylight returned to baseline by week 3 (p = 0.160) and remained stable onwards (p = 0.651). A lower ablation ratio was associated with less straylight level at days 1, 3, 14 and 21 (p ≤ 0.0497) in the multivariable regression model. Likewise, better visual acuity was associated with lower straylight at days 7, 14 and 28 postoperatively (p ≤ 0.038). A small proportion of eyes (range: 0-12.86%) had ≥0.30 log(s) increase in postoperative straylight within the first month after SMILE. Conclusions SMILE induced a temporary decrease in straylight. It gradually returned to the preoperative level, which could be related to a number of dynamic processes during corneal healing. In the small proportion of patients with an increase in straylight postoperatively, this can affect their visual recovery during the early postoperative period.

Differences in Image Quality after Three Laser Keratorefractive Procedures for Myopia

“…The interocular difference in image quality reduced in the follow-up visits, and this may also explain the small improvement in stereoacuity of these patients over time in the study by Sarkar et al 3 The results of the present study (Figs. 2 to 8) and previous reports of visual functions 3 and photic phenomenon [36][37][38] remaining similar to pre-operative values after SMILE all together indicate that the SMILE procedure may be relatively superior to PRK and FS-LASIK for comparable levels of pre-operative myopia. Several qualifiers are, however, required for this statement to be placed in the perspective of the overall outcomes of the three keratorefractive procedures.…”

“…In other words, their expanded depth of focus might support useful intermediate and near vision with the onset of presbyopia but with a small loss of optical quality for distance viewing. This multifocality and its influence on intermediate and near vision will obviously depend on pupil size, 34 retinal illuminance, 35 and other psychophysical factors such as tolerance to reduced contrast, photic phenomenon (glare, stray light, forward scatter), [36][37][38] and compromised stereopsis. 39 Furthermore, multifocal lens designs have been shown to influence the accommodative response in young nonpresbyopes, 40,41 and it is conceivable that a similar influence is seen on the accommodative and the cross-coupled vergence response of the patient undergoing refractive surgery, [42][43][44] at least up until the onset of presbyopia (typically over a decade for an average patient of keratorefractive surgery).…”

Effect of femtosecond laser cutting parameters on the results of small-incision lenticule extraction

“…5,23 Wan et al proposed several factors that could affect postoperative straylight during the visual recovery phase after SMILE, including high preoperative straylight, capstromal interface coupling, intrastromal fluid absorption, Bowman microdisruption, and lamellar wound healing. 21 In this study, our results suggest that lower energy levels could reduce postoperative interface scattering.…”

“…17 Several other factors may influence vision quality, such as age, crystalline lens clarity, corneal irregularities, and tear film quality. 21 Similar to FS-LASIK and FS laser lenticule extraction, SMILE causes increased HOAs, such as coma and spherical aberrations, but to a lesser extent than the other procedures. 15,22 Similarly, our results also show an increase in HOAs postoperatively, but no significant difference was noted between the 2 groups.…”