Refractive outcomes comparing small-incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis for high myopia

Three-Month Comprehensive Outcomes of Topography-Guided LASIK Versus Keratorefractive Lenticule Extraction (KLEx): A Prospective Contralateral Study

INTRODUCTION

The aim of this study was to compare outcomes of topography-guided laser-assisted in situ keratomileusis (TG-LASIK) and small incision lenticule extraction (SMILE®) for correcting myopia and myopic astigmatism.

METHODS

In this prospective, randomized contralateral study, 34 patients (68 eyes) received TG-LASIK in one eye, and SMILE in their fellow eye. Efficacy, safety, predictability, higher-order aberrations, corneal tomography, biomechanics, and patient-reported outcomes (PROs) were assessed preoperatively and up to 3 months postoperatively.

RESULTS

Both platforms showed comparable efficacy at 3 months (TG-LASIK 1.08 ± 0.19; SMILE 0.98 ± 0.17, p = 0.055). However, TG-LASIK demonstrated quicker visual recovery, with 63% and 89% achieving uncorrected distance visual acuity (UDVA) of 20/16 or better at 1 day and 1 week, respectively, compared to SMILE (34% and 63%; p < 0.05). Safety index at 3 months did not significantly differ between TG-LASIK and SMILE (p = 0.223). TG-LASIK and SMILE had 44% and 56% of eyes within 0.13 D of spherical equivalent (SEQ) target, respectively. SMILE induced more total higher-order aberrations (HOAs), vertical coma, and oblique trefoil than TG-LASIK at 3 months (p < 0.05). Both platforms showed similar increases in epithelial remodeling, but SMILE induced thicker epithelium than TG-LASIK at the 7.0-mm nasal zonal area. No significant differences were found in corneal hysteresis (CH) or corneal resistance factor (CRF) at 3 months (p > 0.05). Reported symptoms of glare, halos, rings, starbursts, or dry eye did not significantly differ between groups at 3 months (p > 0.05). Overall, 59% of patients preferred their TG-LASIK treated eye at 1 month, but 65% of patients had no specific eye preference at 3 months.

CONCLUSION

TG-LASIK and SMILE demonstrate excellent and comparable efficacy, safety, and predictability at 3 months, but TG-LASIK offers faster postoperative visual recovery at 1 day and 1 week. TG-LASIK induces fewer HOAs than SMILE, but both procedures affect corneal biomechanics similarly.

TRIAL REGISTRATION

ClincialTrials.gov identifier, NCT05611294.

Small Incision Lenticule Extraction (SMILE) Versus Laser Assisted Stromal In Situ Keratomileusis (LASIK) for Astigmatism Corrections: A Systematic Review and Meta-analysis

PURPOSE

To compare small incision lenticule extraction (SMILE) and laser assisted stromal in situ keratomileusis (LASIK) for astigmatism correction.

DESIGN

Systematic review and meta-analysis METHODS: We reviewed published studies comparing outcomes after LASIK and SMILE for astigmatism correction by querying PubMed, EMBASE, Cochrane, and Web of Science, with a cut-off date of September 3, 2022. We also compared the changes in visual acuity, refraction, and high-order aberrations between the surgeries. Astigmatism correction outcomes in the low-to-moderate group (less than or equal to -2.00 D) and high group (greater than -2.00 D) were evaluated using vector analysis. The Cochrane risk of bias tool in RevMan software was used for randomized studies (RCT), and Risk Of Bias In Nonrandomized Studies - of Interventions (ROBINS-I) was used for the nonrandomized studies (NRSs).

RESULTS

There were 17 studies (5 randomized studies and 12 cohort studies), including 1,985 eyes. A statistically significant difference was found in the correction index (mean difference [MD] = -0.02, 95% confidence interval [CI] = -0.04 to -0.01, P =0.01), although there was no significant difference in the index of success (MD = 0.01, 95% CI = -0.03 to 0.05, P =0.51), different vector (MD = 0.07, 95% CI = 0.00 to 0.13, P =0.04), and angle of error (MD = 0.56, 95% CI = -0.34 to 1.45, P =0.22) between SMILE and LASIK. However, for low-to-moderate astigmatism correction, SMILE exhibited a smaller correction index (MD = -0.08, 95% CI= -0.13 to -0.02, P =0.008) and a larger difference vector (MD = 0.18, 95% CI = 0.09 to 0.27, P <0.0001) than LASIK. There was no significant difference between the different procedures in visual acuity and refraction (spherical equivalent: MD = -0.04, 95% CI = -0.08 to 0.01, P =0.15) or high-order aberration (MD = -0.01, 95% CI = -0.07 to 0.04, P =0.67), except spherical aberration (MD = -0.12, 95% CI = -0.23 to -0.01, P =0.04). The risk of bias was moderate in most studies because of poor reporting of several bias domains for RCTs, and because of confounding and selective outcome reporting for NRSs.

CONCLUSIONS

When used to treat severe astigmatism, both SMILE and LASIK provide effective and predictable results and generally have equivalent outcomes. However, evidence reveals a tendency toward undercorrection in the SMILE groups for astigmatism correction. In addition, LASIK has a greater probability of causing postoperative spherical aberration.

Changes in effective optical zone after small-incision lenticule extraction in high myopia

PURPOSE

To evaluate the four measurement approaches on the determination of effective optical zone (EOZ) using Scheimpflug tomography after small-incision lenticule extraction surgery in eyes with high myopia.

SETTING

Corneal refractive surgery conducted in an eye hospital in southern China.

DESIGN

This is a retrospective cohort study.

METHODS

In total, 74 subjects were recruited. EOZ was measured at 3 months postoperatively using vertex-based (EOZ_V), pupil-based (EOZ_P), 4 mm-ring-based total corneal refraction method (EOZ₄) and tangential curvature difference map method (EOZ_D), and their consistencies were compared. EOZs and planned optical zone (POZ) were compared and analyzed with eccentricity, ablation degree (AD) and total corneal aberrations.

RESULTS

At 3 months after surgery, the mean root mean square of ΔHOA, ΔComa, ΔTrefoil and ΔSA were 0.53 ± 0.27 μm, 0.36 ± 0.20 μm, 0.01 ± 0.84 μm and 0.16 ± 0.14 μm, respectively. EOZ_V, EOZ_P, EOZ₄ and EOZ_D were 5.87 ± 0.44 mm, 5.85 ± 0.45 mm, 4.78 ± 0.40 mm and 5.29 ± 0.27 mm, respectively, which were significantly smaller than POZ 6.48 ± 0.16 mm. Bland-Altman plots showed a good consistency among the four EOZs. The difference between the EOZ_V and EOZ_P was 0.02 mm within the range of clinically acceptable difference. In addition, the eccentricity was positively correlated with ΔHOA, ΔComa and ΔSA.

CONCLUSIONS

All 4 measurement approaches demonstrated the reduction of EOZs compared to POZ. The EOZ_V was the closest to POZ, followed by EOZ_P. The ΔEOZs showed no significant difference with eccentricity, AD and corneal aberrations.

Comparison of Corneal Optical Quality After SMILE, Wavefront-Optimized LASIK and Topography-Guided LASIK for Myopia and Myopic Astigmatism

Purpose

To compare visual outcomes and corneal optical quality after small incision lenticule extraction (SMILE), wavefront-optimized (WFO) FS-LASIK, and topography-guided customized ablation treatment (TCAT) FS-LASIK for myopia.

Methods

This prospective case-series study included 283 eyes of 283 myopic patients who underwent SMILE or FS-LASIK. There were 102, 100, and 81 eyes in the SMILE group, WFO group and TCAT group, respectively. The tomography system (Sirius) was used to measure corneal aberrations and optical quality.

Results

At postoperative 1 and 6 months, there were no significant differences in uncorrected distance visual acuity and corrected distance visual acuity among the three groups (P > 0.05). Postoperative manifest refractive spherical equivalent was similar among the groups (P > 0.05). There was statistically significant difference in cylinder at 1 month among the three groups, with the highest mean value in TCAT group (P < 0.05). The corneal optical path difference, root mean square of corneal astigmatism and strehl ratio were the most superior in the TCAT group at postoperative 1 and 6 months (P < 0.05).

Conclusion

SMILE, WFO FS-LASIK, and TCAT FS-LASIK provided similar visual results. The corneal visual quality after TCAT FS-LASIK was the best.

Predictive factors for postoperative visual acuity improvement with ICL-V4c for ultrahigh myopia above - 10 D

PURPOSE

The purpose of this study is to evaluate the predictive factors for postoperative visual acuity improvement (PVAI) in subjects who underwent phakic intraocular lens implantation with a central hole (ICL-V4c) for ultrahigh myopia above - 10 D.

METHODS

This was a retrospective study. Eyes with ultrahigh myopia above - 10 D undergoing ICL-V4c implantation were studied. Univariable linear regression models were used to assess the association between PVAI and preoperative parameters. Myopic maculopathy was classified into 5 categories by fundus photography. After the 1-month follow-up, the PVAI was compared within different age and preoperative spherical degree groups.

RESULTS

This study included 726 eyes from 419 patients (111 men and 308 women), and the mean age, spherical refraction, and axial length were 28.67 ± 7.93 years, - 13.61 ± 3.44 D, and 28.59 ± 1.50 mm, respectively. At baseline, myopic maculopathy was classified (grades C0-C4) as follows: C0 was observed in 200 eyes (27.5%), C1 in 297 eyes (40.9%), C2 in 147 eyes (20.2%), C3 in 22 eyes (3.0%), and C4 in 60 eyes (8.3%). The PVAI was significantly negatively associated with age and positively associated with SD-pre(-Sph), but no significant association between myopic maculopathy classification and axial length was found. After 1 month, 417 eyes (57.4%) gained more than 1 line at BCVA, 250 eyes (34.4%) remained the same, and 59 eyes (8.13%) lost 1 line. The postoperative visual acuity of 52 eyes was improved by more than 3 lines, and 42.3% were grade C4.

CONCLUSIONS

The ICL performed well for the correction of ultrahigh myopia above - 10 D. Younger patients and those with a higher preoperative spherical degree had greater postoperative satisfaction.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2000036335). Date of registration: 2020/8/22.

Long-term efficacy and safety profiles following small incision lenticule extraction in eyes with ≥ 5-year follow-up

PURPOSE

To evaluate long-term efficacy, safety, predictability and stability (refractive and keratometric) of myopic and myopic astigmatism correction with Small Incision Lenticule Extraction (SMILE).

METHODS

Single center retrospective review of eyes undergoing SMILE from 2012-2015. Forty-two eyes (23 patients) with ≥ 5-year follow-up. Variables analyzed were preoperative, 3-month, 1-year and last follow-up uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, spherical equivalent (SE) and mean keratometry. Descriptive statistics were performed and results reported following the Standard for Reporting Astigmatism Outcomes.

RESULTS

Mean follow-up of 5.98 ± 0.90 years. Mean preoperative SE was -5.26 ± 1.22D (range -2.50 to -8.12D). Mean preoperative cylinder was -0.66 ± 0.61D (range 0.00 to -2.25D). Efficacy and safety indices were 0.86 and 0.98, respectively. In total, 81% of operated eyes achieved an UDVA of ≥ 0.09 logMar (20/25 Snellen). At the last follow-up, ≥1 line of CDVA was gained in 14% of eyes. Five percent lost 1 line of CDVA, and no eye loss ≥2 lines of CDVA. Sixty-nine percent of eyes were within ± 0.50D and 86% within ± 1.00D of the attempted SE correction. Ninety-one percent of eyes had ≤0.50D of postoperative astigmatism and 71% were within ± 15° from the intended correction axis. At the final follow-up, a statistically significant myopic regression of 0.19 ± 0.50D was observed (p = 0.01).

CONCLUSIONS

Long-term results demonstrate that SMILE is effective, predictable and safe. SMILE has good stability, low regression compared to LASIK, and no signs of corneal ectasia staging within our standard criteria.

Comparison of 1-Year Outcomes Between Small Incision Lenticule Extraction With Prophylactic Cross-Linking and Femtosecond Laser-Assisted In Situ Keratomileusis With Prophylactic Cross-Linking

PURPOSE

To compare small incision lenticule extraction with prophylactic cross-linking (SMILE Xtra) and femtosecond laser-assisted in situ keratomileusis with prophylactic cross-linking (FS-LASIK Xtra) in their safety, efficacy, predictability, and stability.

METHODS

This is a prospective cohort study. Forty-eight eyes subjected to SMILE Xtra and 90 eyes subjected to FS-LASIK Xtra were enrolled. The enrolled eyes exhibited either borderline corneal topography or high myopia with thin cornea. The following parameters were evaluated before surgery and at 1 day; 1 week; and 1, 3, 6, and 12 months after surgery: corrected distance visual acuity, uncorrected distance visual acuity, manifest refractive spherical equivalent (MRSE), keratometry values, and thinnest corneal thickness.

RESULTS

After 1 month, no eye showed loss of 1 or more lines of corrected distance visual acuity. At 12 months, uncorrected distance visual acuity was 20/20 or better for 98% and 99% eyes in the SMILE Xtra and FS-LASIK Xtra groups, respectively (P = 0.657). For 93.8% eyes in the SMILE Xtra group and 90% eyes in the FS-LASIK Xtra group, the achieved MRSE was within ±0.50 diopter of the intended MRSE (P = 0.669). The correlation coefficients for predictability of MRSE correction by SMILE Xtra and FS-LASIK Xtra were 0.987 and 0.983, respectively. The mean MRSE values, keratometry values, and thinnest corneal thickness measured at the different time points showed no significant intra- or intergroup differences.

CONCLUSIONS

Our evaluations of 1-year outcomes suggest that the safety, efficacy, predictability, and stability of SMILE Xtra are comparable with those of FS-LASIK Xtra.

Comparative study of small-incision lenticule extraction and phakic intraocular lens implantation for the correction of high myopia: 6-year results

PURPOSE

To compare the long-term safety, efficacy, and complications of small-incision lenticule extraction (SMILE) and flexible iris-fixated anterior chamber phakic intraocular lens (pIOL) implantation for the treatment of high myopia.

SETTING

University of Health Science Turkey, Beyoğlu Eye Training and Research Hospital, İstanbul, Turkey.

DESIGN

Retrospective comparative case series.

METHODS

Data of patients who underwent SMILE or pIOL (Artiflex) implantation for myopia were retrospectively reviewed. Only patients with preoperative manifest refraction spherical equivalent from -6.00 to -10.00 diopters (D) were included in the study.

RESULTS

There were 47 eyes of 32 patients in the SMILE group and 52 eyes of 29 patients in the pIOL group. The mean postoperative follow-up was 63.75 ± 18.40 months in the SMILE group and 65.38 ± 16.22 months in the p-IOL group (P = .71). At 6 years postoperatively, refractive predictability was slightly better in the pIOL group, and the percentages of eyes within ±0.50 D of the attempted correction were 77% and 83% in the SMILE and pIOL groups, respectively. Although mean uncorrected distance visual acuity was comparable (SMILE, 0.12 ± 0.06 logarithm of the minimum angle of resolution [logMAR]; p-IOL, 0.09 ± 0.05 logMAR), the safety indices (1.08 ± 0.22 vs 1.11 ± 0.20; P = .02) and the efficacy indices (0.92 ± 0.24 vs 1.11 ± 0.22; P = .03) were statistically significantly higher after pIOL implantation. Despite a mean of 11.09% of the endothelial cell being lost at 6 years after pIOL implantation, no pIOL was explanted due to endothelial cell loss.

CONCLUSIONS

In this comparative and long-term study, iris-fixated anterior chamber pIOL implantation for high myopic correction showed slightly better safety and efficacy profiles but with statistically significant endothelial cell loss.

Associations between optic disc characteristics and macular choroidal microvasculature in young patients with high myopia

BACKGROUND

This study aimed to examine changes to optic disc characteristics and macular choroidal microvasculature, and their relationships in young patients with high myopia (HM).

METHODS

A total of 90 patients were enrolled in this cross-sectional study. Based on their refractive power, the patients were divided into three groups: 27 in the control group, 34 in the HM group and 29 in the extremely high myopia group. Images of each patient's macula and optic disc were taken by ocular coherence tomography angiography. The macular choroidal and retinal thickness, capillary vessel density and capillary flow area were measured using Matlab software. Parapapillary atrophy (PPA) and the ovality index (OI) obtained from the scanning laser ophthalmoscopy images and the degree of optic disc tilt obtained from the optic nerve head ocular coherence tomography B-scans were analysed by Image J and Matlab software.

RESULTS

The PPA area, OI and degree of optic disc tilt were significantly different among the three groups (all p ≤ 0.001). The macular choroidal thickness and microvasculature were significantly different among the three groups (all p < 0.05). Macular choroidal thickness was significantly correlated with PPA area and the degree of optic disc tilt (r = -0.331, p = 0.003; r = -0.394, p = 0.001, respectively). Macular choroidal capillary vessel density and choriocapillaris flow area were associated with PPA area (r = -0.251, p = 0.047; r = -0.326, p = 0.009, respectively).

CONCLUSIONS

PPA area, OI and the degree of optic disc tilt were increased in patients with HM, and these changes were correlated with macular choroidal thickness and choroidal microvasculature.

IMI 2021 Yearly Digest

Purpose

The International Myopia Institute (IMI) Yearly Digest highlights new research considered to be of importance since the publication of the first series of IMI white papers.

Methods

A literature search was conducted for articles on myopia between 2019 and mid-2020 to inform definitions and classifications, experimental models, genetics, interventions, clinical trials, and clinical management. Conference abstracts from key meetings in the same period were also considered.

Results

One thousand articles on myopia have been published between 2019 and mid-2020. Key advances include the use of the definition of premyopia in studies currently under way to test interventions in myopia, new definitions in the field of pathologic myopia, the role of new pharmacologic treatments in experimental models such as intraocular pressure-lowering latanoprost, a large meta-analysis of refractive error identifying 336 new genetic loci, new clinical interventions such as the defocus incorporated multisegment spectacles and combination therapy with low-dose atropine and orthokeratology (OK), normative standards in refractive error, the ethical dilemma of a placebo control group when myopia control treatments are established, reporting the physical metric of myopia reduction versus a percentage reduction, comparison of the risk of pediatric OK wear with risk of vision impairment in myopia, the justification of preventing myopic and axial length increase versus quality of life, and future vision loss.

Conclusions

Large amounts of research in myopia have been published since the IMI 2019 white papers were released. The yearly digest serves to highlight the latest research and advances in myopia.

Comparison of correcting myopia and astigmatism with SMILE or FS-LASIK and postoperative higher-order aberrations

AIM

To compare the effect of myopia and astigmatism correction and postoperative change in higher-order aberration as results of receiving small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK).

METHODS

A prospective and non-randomized controlled study was conducted. The subjects are divided into two groups according to different operations received: 229 eyes of 116 patients in the SMILE group and 168 eyes of 86 patients in the FS-LASIK group. All subjects were followed up for 3mo by monitoring their uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent, higher-order aberrations, and the preoperative and postoperative complications.

RESULTS

At 1wk, 1, and 3mo post-surgery, 224 eyes (97.8%), 227 eyes (99.1%) and 229 eyes (100%) had UCVA≥20/20 in the SMILE group, while 165 eyes (98.2%), 167 eyes (99.4%) and 167 eyes (99.4%) had UCVA≥20/20 in the FS-LASIK group, respectively (χ ²=0.146, 2.135, and 1.124; all P>0.05). BCVA reduction was not observed in both groups at 1 and 3mo of post-surgery (χ ²=0.734 and 1.898, P>0.05). There was no statistically significant difference in the spherical equivalent between the two groups at 1 and 3mo post-surgery, though the percentage of the spherical equivalent within ±0.50 D at 3mo post-surgery was 98% in the SMILE group, which was higher than that of the FS-LASIK group (92%, χ ²=1.872, P>0.05). The root mean square (RMS) values of total high-order aberration, coma, and spherical aberration of the two groups increased significantly in the early postoperative period and decreased after 3mo, but the values were still higher than the preoperative levels (P<0.05); there was no significant difference between the two groups in the RMS values of total higher-order aberrations and specific higher-order aberrations (P>0.05). The incidence of complications in the SMILE group was lower than that in the FS-LASIK group (χ ²=14.52, P<0.05).

CONCLUSION

SMILE and FS-LASIK can effectively treat myopia, significantly improve visual acuity, and increase the total high-order aberration, spherical aberration, and coma. The incidence of complications after SMILE is relatively low.

Clinical outcomes after small-incision lenticule extraction versus femtosecond laser-assisted LASIK for high myopia: A meta-analysis

AIM

To compare postoperative clinical outcomes of high myopia after small-incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).

METHODS

From March 2018 to July 2020, PubMed, MEDLINE, Embase, the Cochrane Library, and several Chinese databases were comprehensively searched. The studies meeting the criteria were selected and included; the data were extracted by 2 independent authors. The clinical outcome parameters were analyzed with RevMan 5.3.

RESULTS

This meta-analysis included twelve studies involving 766 patients (1400 eyes: 748 receiving SMILE and 652 receiving FS-LASIK). Pooled results revealed no significant differences in the following outcomes: the logarithm of the mean angle of resolution (logMAR) of postoperative uncorrected distance visual acuity (weighted mean difference (WMD) = -0.01, 95% confidence interval (CI): -0.02 to 0.00, I2 = 0%, P = 0.07 at 1 mo; WMD = -0.00, 95% CI: -0.01 to 0.01, I2 = 0%, P = 0.83 at 3 mo; WMD = -0.00, 95% CI: -0.01 to 0.00, I2 = 32%, P = 0.33 in the long term), and the postoperative mean refractive spherical equivalent (WMD = -0.03, 95% CI: -0.09 to 0.03, I2 = 13%, P = 0.30). However, the SMILE group had significantly better postoperative corrected distance visual acuity (CDVA) than the FS-LASIK group (WMD = -0.04, 95% CI, -0.05 to -0.02, I2 = 0%, P<0.00001). In the long term, postoperative total higher-order aberration (WMD = -0.09, 95% CI: -0.10 to -0.07, I2 = 7%, P<0.00001) and postoperative spherical aberration (WMD = -0.15, 95% CI: -0.19 to -0.11, I2 = 29%, P<0.00001) were lower in the SMILE group than in the FS-LASIK group; a significant difference was also found in postoperative coma (WMD = -0.05, 95% CI: -0.06 to -0.03, I2 = 30%, P<0.00001).

CONCLUSION

For patients with high myopia, both SMILE and FS-LASIK are safe, efficacious and predictable. However, the SMILE group demonstrated advantages over the FS-LASIK group in terms of postoperative CDVA, while SMILE induced less aberration than FS-LASIK. It remains to be seen whether SMILE can provide better visual quality than FS-LASIK; further comparative studies focused on high myopia are necessary.

Four-Year Outcomes of Small Incision Lenticule Extraction for Extreme High Myopia and Myopic Astigmatism

Purpose: To evaluate the long-term safety, efficacy, predictability, and stability of small incision lenticule extraction (SMILE) for the treatment of high myopia and myopic astigmatism >−10.0 D.

Methods: This was a prospective study that incorporated 35 consecutive patients (35 eyes) undergoing SMILE from September 2015 to March 2016. These patients had a mean preoperative spherical equivalent refraction of −10.06 ± 0.64 D. Patients were followed over a 4-year period and assessed for outcomes including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, and corneal topography.

Results: At 4 years post-SMILE, respective efficacy and safety indices were 1.01 ± 0.19 and 1.07 ± 0.15. In total, 97% of operated eyes achieved an UDVA of 20/25 or better. ≥1 line was gained for 9 eyes (26%), with 25 eyes (71%) remaining stable. Twenty-four (69%) and 33 (94%) eyes, respectively, were within ±0.50 D and ±1.0 D of target refraction. From 3 months to 4 years postoperatively, a mean refractive regression of −0.22 D (−0.06 D per year) was detected, whereas no significant changes in mean corneal back curvature or posterior central elevation were detected (P = 0.617 and 0.754, respectively). We detected significant increases in higher-order aberrations (HOAs) of the anterior and total cornea (all P < 0.001), with spherical aberrations and vertical coma being particularly common, whereas posterior corneal HOA remained fairly stable (all P < 0.05).

Conclusion: SMILE is a safe, effective, predictable, and stable means of correcting high myopia and myopic astigmatism over a 4-year postoperative period.

Refractive surgery beyond 2020

Refractive surgery refers to any procedure that corrects or minimizes refractive errors. Today, refractive surgery has evolved beyond the traditional laser refractive surgery, embodied by the popular laser in situ keratomileusis or 'LASIK'. New keratorefractive techniques such as small incision lenticule extraction (SMILE) avoids corneal flap creation and uses a single laser device, while advances in surface ablation techniques have seen a resurgence in its popularity. Presbyopic treatment options have also expanded to include new ablation profiles, intracorneal implants, and phakic intraocular implants. With the improved safety and efficacy of refractive lens exchange, a wider variety of intraocular lens implants with advanced optics provide more options for refractive correction in carefully selected patients. In this review, we also discuss possible developments in refractive surgery beyond 2020, such as preoperative evaluation of refractive patients using machine learning and artificial intelligence, potential use of stromal lenticules harvested from SMILE for presbyopic treatments, and various advances in intraocular lens implants that may provide a closer to 'physiological correction' of refractive errors.