Journal of Refractive Surgery

Original Article Supplemental Data

Small Incision Lenticule Extraction (SMILE) for Hyperopia: 12-Month Refractive and Visual Outcomes

Kishore R Pradhan, MD; Dan Z Reinstein, MD, MA(Cantab), FRCSC; Glenn I Carp, MBBCh, FCOphth (SA); Timothy J Archer, MA(Oxon), DipCompSci(Cantab), PhD; Purushottam Dhungana, Moptom, OD, FLVC

Abstract

PURPOSE:

To evaluate visual and refractive outcomes of small incision lenticule extraction (SMILE) for hyperopia.

METHODS:

This was a prospective study of vertex-centered hyperopic SMILE using the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). Inclusion criteria were maximum attempted hyperopic meridian of between +1.00 and +7.00 diopters (D). Lenticule parameters were 6.3- to 6.7-mm diameter, 2-mm transition zone, 30-µm minimum thickness, and 120-µm cap thickness. A standard outcomes and stability analysis was performed for the 12-month data, including contrast sensitivity using the Functional Vision Analyzer.

RESULTS:

For the 93 eyes treated, last follow-up was 12 months for 72 eyes (77%) and 3 months for 11 eyes (12%), with 10 eyes (11%) lost to follow-up. Attempted spherical equivalent refraction (SEQ) was +5.61 ± 1.21 D (range: +1.00 to +6.90 D) and cylinder was −1.01 ± 0.64 D (range: 0.00 to −3.50 D). For eyes targeted for emmetropia (n = 37), uncorrected distance visual acuity was 20/40 or better in 95% of eyes. SEQ relative to target was −0.17 ± 0.85 D (range: −2.20 to +3.00 D) at 3 months and −0.19 ± 0.90 D (range: −2.07 to +3.50 D) at 12 months with 53% within ±0.50 D. For 70 eyes with data at 3 and 12 months, the mean change in SEQ was −0.06 ± 0.53 D (range: −2.00 to +1.75 D) and the mean change in keratometry was −0.22 ± 0.48 D (range: −1.00 to +1.00 D). There was one line loss of corrected distance visual acuity (CDVA) in 16% of eyes and no loss of two or more lines. There was no clinically significant change in contrast sensitivity.

CONCLUSIONS:

Refractive and visual outcomes 12 months after SMILE for hyperopia were promising, given the high degree of hyperopia corrected and relatively reduced CDVA in this population. There was good refractive and topographic stability between 3 and 12 months.

[J Refract Surg. 2019;35(7):442–450.]

Abstract

PURPOSE:

To evaluate visual and refractive outcomes of small incision lenticule extraction (SMILE) for hyperopia.

METHODS:

This was a prospective study of vertex-centered hyperopic SMILE using the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). Inclusion criteria were maximum attempted hyperopic meridian of between +1.00 and +7.00 diopters (D). Lenticule parameters were 6.3- to 6.7-mm diameter, 2-mm transition zone, 30-µm minimum thickness, and 120-µm cap thickness. A standard outcomes and stability analysis was performed for the 12-month data, including contrast sensitivity using the Functional Vision Analyzer.

RESULTS:

For the 93 eyes treated, last follow-up was 12 months for 72 eyes (77%) and 3 months for 11 eyes (12%), with 10 eyes (11%) lost to follow-up. Attempted spherical equivalent refraction (SEQ) was +5.61 ± 1.21 D (range: +1.00 to +6.90 D) and cylinder was −1.01 ± 0.64 D (range: 0.00 to −3.50 D). For eyes targeted for emmetropia (n = 37), uncorrected distance visual acuity was 20/40 or better in 95% of eyes. SEQ relative to target was −0.17 ± 0.85 D (range: −2.20 to +3.00 D) at 3 months and −0.19 ± 0.90 D (range: −2.07 to +3.50 D) at 12 months with 53% within ±0.50 D. For 70 eyes with data at 3 and 12 months, the mean change in SEQ was −0.06 ± 0.53 D (range: −2.00 to +1.75 D) and the mean change in keratometry was −0.22 ± 0.48 D (range: −1.00 to +1.00 D). There was one line loss of corrected distance visual acuity (CDVA) in 16% of eyes and no loss of two or more lines. There was no clinically significant change in contrast sensitivity.

CONCLUSIONS:

Refractive and visual outcomes 12 months after SMILE for hyperopia were promising, given the high degree of hyperopia corrected and relatively reduced CDVA in this population. There was good refractive and topographic stability between 3 and 12 months.

[J Refract Surg. 2019;35(7):442–450.]

Small incision lenticule extraction (SMILE) is a well-established procedure for correcting myopia. Application of this method to treat hyperopia has been the subject of a study at the Tilganga Institute of Ophthalmology in Nepal.1 This was a multiphase study, with the initial phases designed as a feasibility study in poorly sighted eyes to optimize energy settings and demonstrate topographic safety before proceeding to investigate visual and refractive outcomes in sighted eyes. Topographic centration,2 achieved optical zone diameter,3 and spherical aberration changes3 were found to be similar to laser in situ keratomileusis (LASIK) control groups, which allowed for initiation of treating sighted eyes. In a previous report, the refractive and visual outcomes at 3 months were shown to be similar to LASIK outcomes for an equivalent treatment range.4

Early studies of hyperopic LASIK were associated with refractive regression.5–9 Regression over the first 3 to 6 months can largely be explained by epithelial thickness changes that compensate for the ablation.10 Advances in ablation profile design and the use of larger optical zones and transition zones have significantly improved stability.5,7,11 These elements all have the effect of producing a more consistent curvature gradient on the stromal surface, which acts to minimize the epithelial remodeling.12,13 However, refractive changes after hyperopic LASIK remain more variable than after myopic LASIK. This, again, can be partly explained by the greater epithelial remodeling in hyperopic corrections due to the steeper curvature gradient required for a hyperopic ablation compared to a myopic ablation. Given that SMILE for hyperopia is removing essentially the same tissue volume as in LASIK, refractive stability would be expected to be similar.

The current study analyzed the refractive and visual outcomes 12 months after SMILE for hyperopia in sighted eyes, including refractive and topographic stability.

Patients and Methods

Patients

Ethics approval was obtained from the Nepal Health Research Council for this prospective case series of consecutive hyperopic SMILE procedures by three experienced surgeons (KRP, DZR, and GIC) using the 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) at the Tilganga Institute of Ophthalmology, Kathmandu, Nepal. Inclusion criteria were attempted correction in the maximum hyperopic meridian between +1.00 and +7.00 diopters (D), astigmatism up to 6.00 D, medically suitable for SMILE, normal corneal topography, and no ocular disease. Additional inclusion criteria were corrected distance visual acuity (CDVA) of 20/200 or worse for Phase I of the study, between 20/100 and 20/200 for Phase II, between 20/40 and 20/80 for Phase III, and 20/40 or better for the final phase (IV) of the study. Phases were advanced once safety had been demonstrated for the previous group. Patients treated as part of phase IV, treated between May 2014 and February 2017, were included in the current study.

A complete ophthalmologic examination was performed prior to surgery by an in-house optometrist, as has been described previously.2,3,14 The preoperative examination also included corneal Placido topography by ATLAS (Carl Zeiss Meditec), corneal tomography by Pentacam (OCULUS Optikgeräte, Wetzlar, Germany), corneal tomography and epithelial thickness mapping by RTVue optical coherence tomography (Optovue, Fremont, CA), pupillometry (VIPTM-200; Neuroptics, Irvine, CA), and handheld ultrasound pachymetry (SP-3000; Tomey Corporation, Nagoya, Japan). Refractions were carried out by the in-house optometrist at the first visit, including both a manifest refraction and a cycloplegic refraction, performed according to the standardized London Vision Clinic protocol to push maximum plus and maximum cylinder.15 The manifest refraction was repeated by the operating surgeon at a second visit on a separate day with the aim of pushing maximum plus in the knowledge of the cycloplegic refraction. This manifest refraction was used to plan the treatment. Contrast sensitivity was measured using the Functional Acuity Contrast Test (FACT; Vision Sciences Research Corp., San Ramon, CA).

Planning

The following criteria were applied for planning the procedure. First, the predicted postoperative residual stromal thickness under the lenticule must be greater than 250 µm at the location of maximum tissue removal. Second, the attempted correction was limited such that the predicted postoperative keratometry was less than 51.00 D, calculated using the manifest refraction at the corneal plane added to the preoperative keratometry values at the axis of treatment by vector analysis. Finally, an arbitrary maximum attempted correction of +7.00 D was applied. Therefore, some young patients were treated as a partial correction to debulk a high hyperopic refraction.

Surgical Protocol

All SMILE treatments were performed using the 500-kHz VisuMax femtosecond laser as described previously.2,16 In all eyes, two incisions were created: a 2-mm incision superonasally and a 2-mm incision superotemporally. Intended cap thickness was 120 µm in all eyes. Cap diameter was 8.8 mm in all eyes, using a medium contact glass. Optical treatment zone diameter was between 6.3 and 6.7 mm, with a 2-mm transition zone. The minimum lenticule thickness was 30 µm in all eyes. The spot and track distance were 4.6 µm for the cap and lenticule interfaces, 1.5 µm for the lenticule side cut, and 2 µm for the small incision. The energy level was set to 34 (170 nJ) in the VisuMax software.

The surgical technique was essentially identical to that used for myopic SMILE, as has been described previously. The treatment was centered on the coaxially sighted corneal light reflex, confirmed by the surgeon by comparing the relative positions of the corneal reflex and pupil center to the Placido eye image obtained by the Atlas topography scan. The femtosecond laser cutting for the hyperopic lenticule was performed as previously described.2–4,17,18 The lenticule dissection was performed as described previously2–4 using the MMSU1297 lenticule separator instrument (Malosa Medical, Halifax, United Kingdom). The lenticule was then hydrated with balanced salt solution on the corneal surface to distend it for visual inspection for completeness and edge smoothness.

On completion, the patient was brought to the operating room slit lamp, fluorescein was instilled, and full central distention of the cap was achieved by centrifugal stroking using a dry microspear sponge to ensure that any redundant cap (due to mismatch of cap vs bed length) was redistributed to the periphery to minimize the appearance of cap folds or microdistortions on Bowman's layer.19

Postoperative Course and Evaluation

Patients were instructed to instill ofloxacin 0.1% together with prednisolone acetate (1%) four times a day for 1 week, as a standard protocol for broad-spectrum prophylaxis, and wear plastic shields for sleeping during the first week. The surgeon reviewed the patient 1 day postoperatively and an optometrist examined the patient at 1, 3, and 12 months as described previously.2–4

Statistical Analysis

Outcome analysis was performed according to the Standard Graphs for Reporting Refractive Surgery.20 Eyes where the intended postoperative refraction was not emmetropia (partial correction patients) were excluded in the efficacy analysis. Vector analysis was performed for refractive cylinder as described by Alpins,21 with the cylinder axes reflected in the vertical meridian for left eyes. Stability analysis was performed for spherical equivalent refraction and refractive cylinder, and for Atlas mean simulated keratometry and corneal astigmatism. Student's t tests were used to calculate the statistical significance of any changes in log contrast sensitivity. Microsoft Excel 2010 (Microsoft Corporation, Redmond, WA) was used for data entry and statistical analysis. A P value of less than .05 was defined as statistically significant.

Results

Population

A total of 93 eyes of 63 patients underwent hyperopic SMILE between April 2014 and February 2017, of which data were available at 12 months in 72 eyes (71%) and 3 months for 11 eyes (12%), with 10 eyes lost to follow-up (11%). Table 1 shows the demographic data for the study population. The population was skewed toward younger patients with high hyperopia due to the nature of the refractive error distribution in Nepal, where there are few patients with low to moderate hyperopic. The optical zone was 6.3 mm for 35 eyes (42%), 6.5 mm for 47 eyes (57%), and 6.7 mm for 1 eye (1.2%). The maximum lenticule thickness was 153 ± 26 µm (range: 54 to 180 µm).

Study Demographicsa

Table 1:

Study Demographics

Outcomes

Figure 1 shows the Standard Graphs for Reporting Refractive Surgery. UDVA was 20/32 or better in 62% of eyes, relative to 62% with preoperative CDVA of 20/32 or better. Spherical equivalent refraction was within ±0.50 D in 53% and within ±1.00 D in 76% of eyes. There was one line loss CDVA in 16% of eyes, and no eyes lost two or more lines.

Nine standard graphs for reporting refractive surgery showing the visual and refractive outcomes for 83 eyes 12 months after hyperopic small incision lenticule extraction. UDVA = uncorrected distance visual acuity; CDVA= corrected distance visual acuity; D = diopters; postop = postoperative; preop = preoperative; SEQ = spherical equivalent refraction; TIA = target induced astigmatism; SIA = surgically induced astigmatism

Figure 1.

Nine standard graphs for reporting refractive surgery showing the visual and refractive outcomes for 83 eyes 12 months after hyperopic small incision lenticule extraction. UDVA = uncorrected distance visual acuity; CDVA= corrected distance visual acuity; D = diopters; postop = postoperative; preop = preoperative; SEQ = spherical equivalent refraction; TIA = target induced astigmatism; SIA = surgically induced astigmatism

Figure 2 shows the vector analysis for refractive cylinder and the main outcome measures are shown in Table 2. The scatter plot for surgically induced astigmatism vector (SIA) vs target induced astigmatism vector (TIA) shows that the refractive cylinder correction was on target in terms of magnitude. The angle of error histogram shows that the refractive correction was placed accurately on the intended meridian for the majority of eyes, with 91% within ±15°. There was one eye where the angle of error was 76°, indicating an induction of refractive cylinder from −1.00 × 168 to −2.00 × 175. On reviewing this case, the preoperative corneal astigmatism was 2.64 D @ 79, so the apparent induced refractive cylinder may have been an underestimation of cylinder in the preoperative manifest refraction, which was subsequently measured after surgery.

Vector analysis of refractive cylinder displayed as polar plots for target induced astigmatism vector (TIA), surgically induced astigmatism vector (SIA), difference vector (DV), and correction index (CI). D = diopters

Figure 2.

Vector analysis of refractive cylinder displayed as polar plots for target induced astigmatism vector (TIA), surgically induced astigmatism vector (SIA), difference vector (DV), and correction index (CI). D = diopters

Vector Analysis of Refractive Cylindera

Table 2:

Vector Analysis of Refractive Cylinder

Table 3 shows mean simulated keratometry and corneal astigmatism before surgery and 3 and 12 months after surgery. The change in mean simulated keratometry and corneal astigmatism between 3 and 12 months is also included (Figure 3). Table 4 includes the mesopic contrast sensitivity data before and after surgery showing that there was no change at 3, 12, and 18 cycles per degree (cpd), but there was a statistically significant decrease at 6 cpd.

Stability of SEQ and Atlas Simulated Keratometrya

Table 3:

Stability of SEQ and Atlas Simulated Keratometry

Histogram of the change between 3 and 12 months for (A) spherical equivalent refraction (SEQ) and (B) topographic mean simulated keratometry (K). D = diopters; postop = postoperative

Figure 3.

Histogram of the change between 3 and 12 months for (A) spherical equivalent refraction (SEQ) and (B) topographic mean simulated keratometry (K). D = diopters; postop = postoperative

Change in Contrast Sensitivity (Functional Acuity Contrast Test) in log Unitsa

Table 4:

Change in Contrast Sensitivity (Functional Acuity Contrast Test) in log Units

Discussion

In the current study, we found the refractive and visual outcomes 12 months after SMILE for hyperopia to be promising, particularly after considering the high degree of hyperopia corrected (up to +6.90 D spherical equivalent refraction) and the relatively reduced CDVA in this population. Overall for eyes targeted for emmetropia, uncorrected distance visual acuity (UDVA) was 20/32 or better in 62% of eyes, relative to 62% with preoperative CDVA of 20/32 or better. The results were similar to those for LASIK and refractive lens exchange for high hyperopia, as demonstrated in a previous literature review.4

In the current study, there was an initial spherical equivalent refraction on postoperative day 1 of −0.36 D that reduced to −0.17 D at 3 months, after which the spherical equivalent remained stable with a mean of −0.19 D at 12 months. The main weakness of the study is that 12-month data were not available for 12% of eyes and a further 11% were lost to follow-up before 3 months, which may introduce some bias. Table 1 presents the demographic data for the group of eyes for which 3- and 12-month data were available, which shows that the mean attempted hyperopic correction was lower in the group with 3-month data. Therefore, the stability analysis was not biased toward lower corrections that might be expected to be more stable.

For comparison to previous studies, a literature review was performed using the search terms “LASIK” and “hyperopia” or “hyperopic” in PubMed for studies published in the past 10 years.22–36 Previous studies of hyperopia treated by femtosecond lenticule extraction (FLEx) were also included.17,18,37 A full literature review of the main outcomes measures for efficacy, predictability, and safety has been previously reported,4,33,35 so this review focused on stability from 3 to 12 months or to the last visit if follow-up was less than 12 months, as set out in Table A (available in the online version of this article). The exception was the contralateral eye study of LASIK Xtra, where data were reported for “regression from treatment” to 2 years.24 Studies where stability was not reported were excluded.

Literature Review of Refractive Stability After Hyperopic LASIK and SMILE Literature Review of Refractive Stability After Hyperopic LASIK and SMILE

Table A:

Literature Review of Refractive Stability After Hyperopic LASIK and SMILE

The mean change across the SMILE and FLEx studies was +0.08 D (range: −0.06 to +0.14 D). In comparison, the mean change between time points across all LASIK studies was +0.25 D (range: 0.00 to +0.72 D). However, it should be noted that the degree of hyperopia treated in the three FLEx studies was lower than most LASIK studies. The largest change of +0.72 D was for a 2-year time range24 and two other studies26,30 reporting a large change were for very high hyperopia. If these studies were excluded, the mean for LASIK was +0.18 D (range: 0.00 to +0.52 D). If the time range is taken into account, the mean change per month was +0.01 D for FLEx and SMILE and +0.03 D for LASIK (with the same studies excluded as above). The current study was the only instance where a myopic shift was found between 3 and 12 months, but there were three LASIK studies that reported essentially no change between 3 and 6 months (0.00 D,32 +0.01 D,31 and +0.02 D36).

When considering refractive stability after hyperopic correction, it is important to take into account the optical zone and transition that were used, because it is known that there is less refractive stability and greater scatter for smaller optical zones.5,7,11 The optical zone used is included in Table A. In all studies where a range of optical zones was used, the majority of treatments were done with the larger zone. The most used optical zone was at least 6.5 mm, except for two studies that used a 6-mm optical zone: the 3-to 12-month change was +0.10 D in one study23 and +0.52 D in the other.27 The labeled optical zone diameter for SMILE was 6.3 mm, which is smaller than the 6.5- to 7-mm zone commonly used for LASIK. However, topographic analysis has shown that the achieved optical zone diameter for 6.3-mm SMILE was similar to that for 7-mm LASIK.3

Comparison of the results from the current study should be considered in the context of the differences in population relative to the other studies. The mean age of 27 years was significantly younger than other studies. The average across all other studies was 45 years and the mean age was less than 40 in only two studies (33 years30 and 37 years23). Due to the young age, there may be latent accommodation or obtaining an accurate refraction may be more challenging. However, the refraction protocol used is designed to push maximum plus.15 The second difference is the bias toward higher corrections (mean spherical equivalent refraction treated was +5.62 D) and included patients with high hyperopia where the treatment was intentionally a partial correction to debulk the refraction. Third, the current population was also biased toward reduced preoperative CDVA (25% were 20/20 or better). Although CDVA was 20/40 or better in all eyes, obtaining an accurate manifest refraction may be more difficult than in a population where CDVA was 20/20 or better in all eyes.

However, stability was also evaluated based on the change in mean topographic simulated keratometry, which provided an objective measurement of corneal stability. In the current study, mean simulated keratometry changed by −0.22 D between 3 and 12 months. Table B (available in the online version of this article) shows the topographic stability for all studies from the literature review above where this was reported.23,24,33,35,38 The mean change in simulated keratometry was less than the current study for two LASIK studies (−0.07 D23 and −0.13 D35), but the mean hyperopia corrected was lower than in the current study. The mean change in simulated keratometry was greater for the other three LASIK studies than in the current study. The largest topographic change was reported in the contralateral eye study for LASIK Xtra with a change of −0.60 D in the LASIK Xtra group and −1.10 D in the LASIK group.24

Literature Review of Topographic Stability After Hyperopic LASIK and SMILE

Table B:

Literature Review of Topographic Stability After Hyperopic LASIK and SMILE

Refractive and visual outcomes including stability 12 months after SMILE for hyperopia were promising, given the high degree of hyperopia corrected and relatively reduced CDVA in this population. Further follow-up is intended to document refractive stability over 2 years and over the long term. Over the course of this prospective study for hyperopic SMILE, it has been demonstrated that topographic centration, achieved topographic optical zone, induced higher order aberrations, refractive and visual outcomes, and refractive and topographic stability are similar to the results of modern, large optical zone hyperopic LASIK.

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  34. El-Naggar MT, Hovaghimian DG. Assessment of refractive outcome of femtosecond-assisted LASIK for hyperopia correction. Electron Physician. 2017;9:3958–3965. doi:10.19082/3958 [CrossRef]
  35. Reinstein DZ, Carp GI, Archer TJ, Day AC, Vida RS. Outcomes for hyperopic LASIK with the MEL 90((R)) excimer laser. J Refract Surg. 2018;34:799–808. doi:10.3928/1081597X-20181019-01 [CrossRef]
  36. Garcia-Gonzalez M, Iglesias-Iglesias M, Drake Rodriguez-Casanova P, Gros-Otero J, Teus MA. Femtosecond laser-assisted LASIK with and without the adjuvant use of mitomycin C to correct hyperopia. J Refract Surg. 2018;34:23–28. doi:10.3928/1081597X-20171116-01 [CrossRef]
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  38. Kanellopoulos AJ. Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform. Clin Ophthalmol. 2012;6:895–901. doi:10.2147/OPTH.S23573 [CrossRef]

Study Demographicsa

Parameter All 3-Month Data 12-Month Data
Eyes (patients) 83 (55) 13 70
Age (years) 27 ± 7 (21 to 52) 29 ± 11 (21 to 52) 27 ± 6 (21 to 50)
Gender (M/F) (%) 73 / 27
Attempted maximum hyperopia (D) +6.05 ± 1.17 (+1.25 to +7.00) +5.30 ± 1.99 (+1.25 to +6.90) +6.19 ± 0.90 (+2.50 to +7.00)
Attempted spherical equivalent refraction (D) +5.61 ± 1.21 (+1.00 to +6.90) +4.91 ± 1.97 (+1.00 to +6.90) +5.73 ± 0.97 (+2.38 to +6.50)
Attempted refractive cylinder (D) −0.90 ± 0.67 (0.00 to −3.50) −1.25 ± 0.77 (0.00 to −1.25) −0.91 ± 0.73 (0.00 to −3.50)
Preoperative minimum corneal thickness (µm) 546 ± 33 (478 to 624)
Scotopic pupil diameter (mm) 6.06 ± 0.78 (4.20 to 7.90)
Last postoperative spherical equivalent relative to intended target (D) −0.22 ± 0.88 (−2.20 to +3.00)
Last postoperative cylinder relative to intended target (D) −0.19 ± 0.29 (0.00 to −2.00)

Vector Analysis of Refractive Cylindera

Parameter Spherical Treatments All Eyes With Cylinder
Eyes 8 75
Target induced astigmatism vector (D)
  Arithmetic mean 1.01 ± 0.64 (0.25 to 3.50)
  Summated vector mean 0.44 Ax 132
Surgically induced astigmatism vector (D)
  Arithmetic mean 0.03 ± 0.09 (0.00 to 0.25) 0.94 ± 0.58 (0.13 to 3.25)
  Summated vector mean 0.03 Ax 30 0.43 Ax 128
  Correction index–geometric mean 0.96 (0.50 to 2.22)
Difference vector (D)
  Arithmetic mean 0.03 ± 0.09 (0.00 to 0.25) 0.22 ± 0.31 (0.00 to 2.00)
  Summated vector mean 0.03 Ax 120 0.06 Ax 171
  Index of success–geometric mean 0.55 (0.00 to 2.00)
Angle of error (°)
  Arithmetic mean −3.5 ± 12.7 (−76 to 27)
  Absolute mean 6.1 ± 11.6 (0.0 to 76)
Postop cylinder magnitude ⩾ 0.25 D 100% 87%
Postop cylinder magnitude ⩾ 0.50 D 100% 95%
Postop cylinder magnitude ⩾ 1.00 D 100% 98.7%
Postop cylinder magnitude ⩾ 2.00 D 100% 100%
Cylinder induced ⩾ 0.50 D 0.0% 1.3%
Cylinder induced ⩾ 1.00 D 0.0% 1.3%
Cylinder induced ⩾ 2.00 D 0.0% 0.0%

Stability of SEQ and Atlas Simulated Keratometrya

Parameter Preoperative 3 Months 12 Months 3- to 12-Month Change % Change Within ±0.50 D % Change Within ±1.00 D
Eyes 83 82 70 70 70 70
SEQ adjusted for intended target (D) +5.62 ± 1.20 (+1.00 to +6.90) −0.17 ± 0.85 (−2.20 to +3.00) −0.19 ± 0.90 (−2.07 to +3.50) −0.06 ± 0.53 (−2.00 to +1.75) 83 92.9
Refractive cylinder (D) −0.90 ± 0.67 (0.00 to −3.50) −0.27 ± 0.38 (0.00 to −2.00) −0.17 ± 0.21 (0.00 to −2.00) −0.10 ± 0.25 (−1.50 to +0.25) 98.6 98.6
Average simulated keratometry (D) 42.75 ± 1.87 (38.50 to 46.50) 47.45 ± 2.15 (41.00 to 52.00) 47.14 ± 2.33 (41.00 to 51.50) −0.22 ± 0.48 (−1.00 to +1.00) 78 100
Corneal astigmatism (D) 1.18 ± 0.74 (0.04 to 3.90) 1.31 ± 0.64 (0.28 to 3.26) 1.25 ± 0.69 (0.00 to 2.96) −0.05 ± 0.36 (−1.18 to 0.81) 84 98.6

Change in Contrast Sensitivity (Functional Acuity Contrast Test) in log Unitsa

Parameter 3 cpd 6 cpd 12 cpd 18 cpd
Preoperative 1.79 ± 0.27 (0.55 to 2.20) 1.60 ± 0.34 (0.70 to 2.11) 1.09 ± 0.31 (0.78 to 1.93) 0.68 ± 0.16 (0.60 to 1.36)
3 months 1.73 ± 0.28 (0.55 to 2.20) 1.46 ± 0.41 (0.70 to 2.26) 1.02 ± 0.31 (0.78 to 1.93) 0.67 ± 0.19 (0.60 to 1.52)
Change −0.05 ± 0.35 (−1.36 to 1.21) −0.13 ± 0.45 (−1.11 to 0.82) −0.05 ± 0.37 (−0.75 to 0.85) 0.00 ± 0.20 (−0.76 to 0.63)
Contrast increase more than 0.25 log units 20.8% 23.6% 20.8% 8.3%
Contrast decrease more than 0.25 log units 25.0% 41.7% 34.7% 11.1%
P .233 .019 .225 .963

Literature Review of Refractive Stability After Hyperopic LASIK and SMILE

First Author Year N (Eyes) Technique Optical Zone (Transition) (mm) Mean (Range) Preop SEQ (D) Mean ± SD (Range) Age (y) Mean (Range) Stability Time Range (Mo) SEQ Stability Mean ± SD (Range) % SEQ Changed >0.50 D
Blum1 2013 47 FLEx 6.00 (0.20 to 1.60) +2.80 ± 1.30 (+0.25 to +5.38) 42 ± 9 (22 to 59) 3 to 9 +0.11 NR
Sekundo2 2016 9 FLEx 5.75 (1.78 to 2.29) +1.82 ± 0.56 (+1.25 to +3.00) 56 (46 to 63) 3 to 9 +0.13 NR
Sekundo3 2018 39 FLEx 5.75 to 6.75 (1.80 to 2.89) +1.96 ± 1.04 (+0.63 to +4.50) 49 (27 to 56) 3 to 9 +0.14 NR
Current study 2019 83 SMILE 6.30 to 6.70 (2.00) +5.62 ± 1.20 (+1.00 to +6.90) 27 ± 7 (21 to 52) 3 to 12 −0.06 ± 0.53 (−2.00 to +1.75) 17%
Reinstein4 2009 258 Hansatome MEL 80 6.50 to 7.00 (2.00) +2.54 ± 1.16 (+0.25 to +5.75) 56 (44 to 66) 3 to 12 +0.11 ± 0.36 (−1.13 to +1.13) 14%
Llovet5 2009 49 Moria I MEL 80 6.00 (2.00) +3.30 ± 1.30 (+3.60 to +6.25) 37 (20 to 56) 3 to 12 +0.10 NR
U.S. Food & Drug Administration6 2011 369 MEL 80 6.00 to 6.50 (2.00) +2.97 ± 1.22 (+0.88 to +6.38) 47 ± 9 (22 to 69) 3 to 12 +0.17 NR
Kanellopoulos7 2012 34 FS200, EX500 NR +3.40 ± 1.78 (+0.25 to +8.00) NR 1 to 24 +0.72 ± 0.19 NR
Kanellopoulos7 2012 34 LASIK Xtra FS200, EX500 NR +3.15 ± 1.46 (+0.25 to +8.00) NR 1 to 24 +0.22 ± 0.31 NR
Alió8 2013 27 Intralase Amaris 6.20 to 6.90 (1.50) +6.33 ± 0.83 (+5.00 to +8.50) NR 3 to 6 +0.41 NR
Leccisotti9 2014 800 LDV Z2, 217P 6.00 +3.41 ± 1.16 (+1.00 to +6.50) 41 ± 9 2 to 9 +0.52 NR
Plaza-Puche10 2015 86 Intralase Amaris 6.30 to 7.00 (0.60 to 2.50) +2.66 ± 1.68 (−1.38 to +5.75) 40 ± 10 (23 to 64) 3 to 12 +0.36 22%
Antonios11 2015 53 M2 Amaris NR +2.25 ± 1.06 (+0.75 to +5.00) 45 ± 12 (19 to 61) 3 to 6 +0.16 NR
Antonios11 2015 72 LDV femto Amaris NR +2.24 ± 0.95 (+0.50 to +4.75) 46 ± 10 (18 to 66) 3 to 6 +0.08 NR
Plaza-Puche12 2016 51 Intralase Amaris 6.20 to 6.90 (2.50) +6.33 ± 0.83 (+5.00 to +8.50) 33 ± 9 (21 to 54) 3 to 6 +0.64 NR
Arba-Mosquera13 2016 46 Carriazo-Pendular Amaris NR +3.64 ± 1.42 (+1.27 to +6.18) 45 ± 11 (18 to 62) 3 to 6 +0.01 6%
de Ortueta14 2017 38 Carriazo-Pendular Amaris 5.50 to 7.00 (1.32 to 2.40) +4.07 ± 0.90 (+2.38 to +5.75) 40 ± 10 (18 to 57) 3 to 6 0.00 NR
Reinstein15 2017 785 MEL 80 VisuMax or Hansatome zero compression 6.50 to 7.00 (2.00) +4.52 ± 0.84 (+2.00 to +6.96) 50 ± 12 (18 to 70) 3 to 12 +0.28 ± 0.61 (−2.13 to +3.75) 32%
El-Naggar16 2017 20 Wavelight FS200, Wavelight EX500 7.00 +2.55 ± 1.17 (+1.00 to +6.00) 47 ± 4 (42 to 56) 3 to 12 0.25 4%
Reinstein17 2018 1,350 VisuMax MEL 90 6.50 to 7.00 (2.00) +2.77 ± 1.34 (+0.13 to +6.50) 54 ± 11 (21 to 75) 3 to 12 +0.15 ± 0.39 (−1.88 to +2.38) 15%
Garcia-Gonzalez18 2018 76 Intralase Esiris with MMC 7.20 ± 0.20 +2.71 ± 1.30 (+2.00 to +6.25) 45 ± 1 (41 to 55) 3 to 6 +0.02 7%
Garcia-Gonzalez18 2018 76 Intralase Esiris no MMC 7.00 ± 0.20 +2.90 ± 1.10 (+2.00 to +6.25) 44 ± 1 (41 to 55) 3 to 6 +0.03 11%

Literature Review of Topographic Stability After Hyperopic LASIK and SMILE

First Author Year N (Eyes) Technique Optical Zone (Transition) (mm) Mean (Range) Preop SEQ (D) Mean ± SD (Range) Age (Y) Mean (Range) Stability Time Range Mean K Stability Mean ± SD (Range)
Current study 2019 83 SMILE 6.30 to 6.70 (2.00) +5.62 ± 1.20 (+1.00 to +6.90) 27 ± 7 (21 to 52) 3 to 12 −0.22 ± 0.48 (−1.00 to +1.00)
Llovet1 2009 49 Moria I MEL 80 6.00 (2.00) +3.30 ± 1.30 (+3.60 to +6.25) 36.9 (20 to 56) 3 to 12 −0.07
Kanellopoulos2 2012 34 FS200, EX500 NR +3.40 ± 1.78 (+0.25 to +8.00) NR 3 to 12 −1.10
Kanellopoulos2 2012 34 LASIK Xtra FS200, EX500 NR +3.15 ± 1.46 (+0.25 to +8.00) NR 3 to 12 −0.60
Kanellopoulos3 2012 202 Eye-Q NR +3.04 ± 1.75 (+0.75 to +7.25) (sphere) 40 ± 12 (19 to 62) 3 to 12 −0.33 (max K), −0.52 (min K)
Reinstein4 2017 785 MEL 80 VisuMax or Hansatome zero compression 6.50 to 7.00 (2.00) +4.52 ± 0.84 (+2.00 to +6.96) 50 ± 12 (18 to 70) 3 to 12 −0.34 ± 0.50 (−3.32 to 1.22)
Reinstein5 2018 1,350 MEL 90 VisuMax 6.50 to 7.00 (2.00) +2.77 ± 1.34 (+0.13 to +6.50) 54 ± 11 (21 to 75) 3 to 12 −0.13 ± 0.41 (−3.02 to +2.43)
Authors

From Tilganga Institute of Ophthalmology, Kathmandu, Nepal (KRP, PD); London Vision Clinic, London, United Kingdom (DZR, GIC, TJA); the Department of Ophthalmology, Columbia University Medical Center, New York (DZR); Sorbonne Université, Paris, France (DZR); and Biomedical Science Research Institute, University of Ulster, Coleraine, Northern Ireland (DZR, TJA).

Dr. Reinstein is a consultant for Carl Zeiss Meditec (Carl Zeiss Meditec, Jena, Germany) and has a proprietary interest in the Artemis technology (ArcScan Inc., Golden, Colorado) through patents administered by the Center for Technology Licensing at Cornell University (CTL), Ithaca, New York. Drs. Carp and Pradhan receive travel expenses from Carl Zeiss Meditec. The remaining authors have no proprietary or financial interest in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (KRP, DZR, GIC, TJA); data collection (KRP, DZR, GIC, TJA, PD); analysis and interpretation of data (KRP, DZR, GIC, TJA, PD); writing the manuscript (DZR, TJA); critical revision of the manuscript (KRP, GIC, PD); statistical expertise (DZR, TJA)

Correspondence: Dan Z. Reinstein, MD, MA(Cantab), FRCSC, London Vision Clinic, 138 Harley Street, London W1G 7LA, United Kingdom. E-mail: dzr@londonvisionclinic.com

Received: March 27, 2019
Accepted: May 27, 2019

10.3928/1081597X-20190529-01

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