Journal of Refractive Surgery

Original Article Supplemental Data

Outcomes for Hyperopic LASIK With the MEL 90® Excimer Laser

Dan Z. Reinstein, MD, MA(Cantab), FRCSC; Glenn I. Carp, MBBCh, FCOphth (SA); Timothy J. Archer, MA(Oxon), DipCompSci(Cantab), PhD; Alexander C. Day, PhD, FRCOphth, CertLRS; Ryan S. Vida, OD, FAAO

Abstract

PURPOSE:

To report the outcomes of laser in situ keratomileusis (LASIK) for hyperopia using the Triple-A ablation profile with the MEL 90 excimer laser (Carl Zeiss Meditec, Jena, Germany).

METHODS:

This retrospective analysis included 1,383 eyes treated by LASIK for hyperopia using the Triple-A ablation profile with the MEL 90 at London Vision Clinic, London, United Kingdom, between September 2013 and December 2016. Inclusion criteria were attempted hyperopic correction of +0.25 diopters (D) or higher and corrected distance visual acuity (CDVA) of 20/40 or better. Patients were observed for 1 year after surgery. Standard outcomes analysis was performed.

RESULTS:

One-year data were available for 1,350 (97%) eyes. Mean attempted spherical equivalent refraction (SEQ) was +2.77 ± 1.34 D (range: +0.13 to +6.50 D) and mean cylinder was −0.67 ± 0.66 D (range: 0.00 to −5.00 D). Mean age was 54 ± 11 years (range: 21 to 75 years), and 57% were female. Postoperative spherical equivalent was ±0.50 D in 73% and ±1.00 D in 93% of eyes. Uncorrected distance visual acuity was 20/20 or better in 75% of eyes, relative to 93% with preoperative CDVA of 20/20 or better. One line of CDVA was lost in 17% of eyes and two lines were lost in 0.6% of eyes. There was a clinically insignificant but statistically significant increase (P < .01) in contrast sensitivity at 3 and 6 cycles per degree (cpd) and no change for 12 and 18 cpd.

CONCLUSIONS:

LASIK for hyperopia with the MEL 90 excimer laser was found to satisfy accepted criteria for safety, efficacy, and stability.

[J Refract Surg. 2018;34(12):799–808.]

Abstract

PURPOSE:

To report the outcomes of laser in situ keratomileusis (LASIK) for hyperopia using the Triple-A ablation profile with the MEL 90 excimer laser (Carl Zeiss Meditec, Jena, Germany).

METHODS:

This retrospective analysis included 1,383 eyes treated by LASIK for hyperopia using the Triple-A ablation profile with the MEL 90 at London Vision Clinic, London, United Kingdom, between September 2013 and December 2016. Inclusion criteria were attempted hyperopic correction of +0.25 diopters (D) or higher and corrected distance visual acuity (CDVA) of 20/40 or better. Patients were observed for 1 year after surgery. Standard outcomes analysis was performed.

RESULTS:

One-year data were available for 1,350 (97%) eyes. Mean attempted spherical equivalent refraction (SEQ) was +2.77 ± 1.34 D (range: +0.13 to +6.50 D) and mean cylinder was −0.67 ± 0.66 D (range: 0.00 to −5.00 D). Mean age was 54 ± 11 years (range: 21 to 75 years), and 57% were female. Postoperative spherical equivalent was ±0.50 D in 73% and ±1.00 D in 93% of eyes. Uncorrected distance visual acuity was 20/20 or better in 75% of eyes, relative to 93% with preoperative CDVA of 20/20 or better. One line of CDVA was lost in 17% of eyes and two lines were lost in 0.6% of eyes. There was a clinically insignificant but statistically significant increase (P < .01) in contrast sensitivity at 3 and 6 cycles per degree (cpd) and no change for 12 and 18 cpd.

CONCLUSIONS:

LASIK for hyperopia with the MEL 90 excimer laser was found to satisfy accepted criteria for safety, efficacy, and stability.

[J Refract Surg. 2018;34(12):799–808.]

In hyperopic laser in situ keratomileusis (LASIK) in accordance with Barraquer's law of thicknesses,1 the required ablation profile is an annular zone of ablation to flatten the peripheral cornea with resulting steepening of the center (optical zone).1 The correction of low to moderate hyperopia by LASIK was first published more than 20 years ago.2,3 Based on initial reports of first generation lasers for hyperopia,4–8 these were associated with significant regression, undercorrection, and loss of corrected distance visual acuity (CDVA). From this, the historic consensus was that excimer laser correction for hyperopia was safe and effective for treatments below +4.00 or +5.00 diopters (D).5,6 However, there have since been improvements in hyperopic correction and studies with modern lasers demonstrate safety and efficacy up to +7.00 D.9–27

The first major improvement in hyperopic corneal ablation surgery came relatively early on as different groups found improved results, in particular improved stability, by increasing the optical zone and transition zone size.4,6,28 The second major improvement was observed with the introduction of flying spot lasers to replace the broad beam scanning slit lasers, with an improvement in outcomes noted with a variety of different lasers.9–27 Third, in addition to the development of excimer laser technology, significant progress has been made with ablation profile design and the use of epithelial thickness mapping diagnostics.10

Outcomes of LASIK for myopia using the MEL 90 excimer laser platform (Carl Zeiss Meditec, Jena, Germany) have previously been reported.29 The aim of this study was to report the visual and refractive results of LASIK for the correction of hyperopia performed with the MEL 90 and VisuMax femtosecond lasers (Carl Zeiss Meditec).

Patients and Methods

This was a retrospective non-comparative case series of all hyperopic LASIK procedures treated consecutively between September 2013 and December 2016 by two experienced LASIK surgeons (DZR and GIC) using the MEL 90 excimer laser and the VisuMax femtosecond laser at London Vision Clinic, London, United Kingdom. The analysis included all eyes in which a hyperopic correction was performed using the Triple-A ablation profile. Inclusion criteria were medically suitable for LASIK, no previous ocular, eyelid, or orbital surgery, no visually significant cataract, corrected distance visual acuity (CDVA) of 20/40 or better, and a minimum follow-up of 1 year. Informed consent and permission to use their data for general analysis and publication was obtained from each patient prior to surgery as part of our routine protocol. Because this was a retrospective study, an exemption from full institutional review board approval was obtained from the United Kingdom Health Research Authority.

A full ophthalmologic examination was performed by one of the in-house optometrists prior to surgery as has been described previously.9 This included a manifest refraction and a cycloplegic refraction according to a standardized protocol to push maximum plus and maximum cylinder, and all optometrists had undergone refraction training with this protocol.30 The manifest refraction was repeated by the treating surgeon at a separate visit before the day of surgery and this refraction was used to plan the treatment.

Treatment Planning

The following criteria were used for planning the primary procedure, as described previously.10 First, the predicted postoperative residual stromal thickness must be greater than 250 μm. 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 at the axis of treatment by vector analysis.

The target postoperative sphere was plano for all patients younger than 42 years and our micro-monovision protocol9 was used for all patients older than 42 years, where the target sphere is plano for the dominant eye and −1.50 D for the non-dominant eye for the majority of patients.

Surgical Protocol

All treatments were performed as bilateral sequential LASIK using the VisuMax femtosecond laser and the MEL 90 excimer laser. The Triple-A profile was used at 500-Hz pulse frequency for all cases, which is based on the aberration smart ablation profile in the MEL 80 laser, but also includes an energy correction function to compensate for radial fluence projection and reflection losses and peripheral biomechanical changes. A personalized nomogram was used for sphere initially based on MEL 80 hyperopic outcomes and subsequently updated for the MEL 90 ablation profile. The first 34 eyes treated prior to the nomogram update were excluded from the study population. A nomogram of 21% reduction of sphere was applied for eyes targeted for emmetropia and 13% reduction of sphere for eyes targeted for monovision. The lower nomogram adjustment for near eyes was intended to ensure that the myopic target was achieved for the majority of eyes.

The optical zone used was between 6.5 and 7 mm (with 2-mm transition zone), with a larger optical zone used where possible. The optical zone was reduced if a small contact glass was needed due to a small corneal diameter, or to reduce the ablation depth in thin corneas. The VisuMax laser was programmed with a flap thickness of 115 μm in the majority of cases, but a thinner flap (down to 90 μm) was used to maximize the stromal tissue available for ablation and adhere to the minimum residual stromal bed thickness of 250 μm. Flap diameter was programmed to be either 8 mm using small contact glasses or 8.8 mm using medium contact glasses. During the study period, a new method for reducing the incidence of opaque bubble layer jets31,32 was introduced and was used for all eyes treated from June 2016. In this method, the flap diameter was increased by 0.1 mm by programming with a larger contact glass than the size used so that the lamellar interface would start closer to the edge of the contact glass, thus allowing the gas to escape peripherally rather than being forced centrally. Side cut for all VisuMax flaps was set as an in-cut of 55° from the normal. A medium contact glass was used where possible to accommodate the large optical zone, except for cases where the white-to-white horizontal diameter was less than 11.5 mm. A 5-mm superior hinge was used in all cases. The VisuMax laser energy profile was set to an energy index of 50 (250 nJ), with spot and track spacing of 5 μm for flap bed and 2 μm for side cut. Treatments were centered on the coaxially sighted corneal light reflex.15,33–37 The standardized surgical technique followed has been described previously.38

Postoperative Evaluation

Patients were instructed to wear plastic shields while sleeping for 7 nights. Tobramycin and dexamethasone (Tobradex; Alcon Laboratories, Inc., Fort Worth, TX) and ofloxacin (Exocin; Allergan Ltd, Marlow, United Kingdom) were applied four times daily for the first week, which is our standard protocol for broad spectrum prophylaxis. Patients were reviewed at 1 day and 1, 3, and 12 months postoperatively. One-day postoperative examinations were conducted by the surgeons (DZR and GIC), including monocular and binocular uncorrected distance visual acuity (UDVA) and spherical manifest refraction, and the flap was adjusted at the slit-lamp using a surgical spear if any microfolds were identified with heavy fluorescein staining. Further follow-up visits at 1, 3, and 12 months were conducted by one of the in-house optometrists and included measurements of monocular and binocular UDVA, manifest refraction, and corrected distance visual acuity (CDVA). Best-corrected mesopic contrast sensitivity (CSV-1000; VectorVision, Greenville, OH) and Atlas front surface topography (Carl Zeiss Meditec) were performed at 3 and 12 months postoperatively.

Statistical Analysis

Outcome analysis was performed according to the Standard Graphs for Reporting Refractive Surgery39 and vector analysis was performed using the Alpins method.40 Eyes where the intended postoperative refraction was not emmetropia were excluded in the efficacy analysis. Subgroup analysis was performed to report the results for each diopter bin of maximum hyperopia treated. The key outcome statistics for efficacy, safety, and predictability were recorded for each subgroup. The outcomes were analyzed for the primary treatment data, excluding re-treatments. Student's t tests were used to calculate the statistical significance of any changes in log contrast sensitivity.

Microsoft Excel 2010 software (Microsoft Corporation, Seattle, WA) was used for data entry and statistical analysis. A P value less than .05 was defined as statistically significant.

Results

Patient Population

During the study period, 1,383 eyes were treated and 1-year follow-up data were available for 1,350 eyes (97% follow-up). A re-treatment was performed at the 6-month time point for 5 eyes; the 6-month data were carried forward and used as the 1-year time point. Table 1 shows demographic data for the study population and Table 2 shows the number of eyes by each diopter combination of maximum hyperopia and cylinder treated. The optical zone was 6.5 mm for 87 eyes (6.5%), 6.75 mm for 7 eyes (0.5%), and 7 mm for 1,256 eyes (93.0%). Intended flap thickness was 90 μm in 63 eyes (4.7%), 100 μm in 22 eyes (1.6%), 105 μm in 148 eyes (11.0%), 110 μm in 81 eyes (6.0%), 115 μm in 1,020 eyes (75.6%), and 120 μm in 16 eyes (1.2%).

Study Demographics

Table 1:

Study Demographics

Distribution of Eyes by Maximum Hyperopia and Cylinder Treated

Table 2:

Distribution of Eyes by Maximum Hyperopia and Cylinder Treated

Figure 1 shows the Standard Graphs for Reporting Refractive Surgery. UDVA was 20/20 or better in 75% of eyes, relative to 93% with preoperative CDVA of 20/20 or better. Spherical equivalent refraction was within ±0.50 D in 73% and within ±1.00 D in 93% of eyes. Table 3 presents the key outcome parameters with the population grouped by the maximum hyperopia treated.

Nine standard graphs for reporting refractive surgery showing the visual and refractive outcomes for 1,350 hyperopic treatments using the VisuMax femtosecond laser and MEL 90 excimer laser (both Carl Zeiss Meditec, Jena, Germany), using the Triple-A ablation profile at 500-Hz frequency. 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 1,350 hyperopic treatments using the VisuMax femtosecond laser and MEL 90 excimer laser (both Carl Zeiss Meditec, Jena, Germany), using the Triple-A ablation profile at 500-Hz frequency. 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

Key Outcome Parameters for Each Diopter Bin for Maximum Hyperopia Treated

Table 3:

Key Outcome Parameters for Each Diopter Bin for Maximum Hyperopia Treated

Cylinder Vector Analysis

Figure 1 shows the vector analysis for refractive cylinder and the main outcome measures are shown in Table 4. The scatter plot for surgically induced astigmatism vector versus target induced astigmatism vector shows that there was a consistent slight overcorrection of refractive cylinder magnitude of 0.23 D. The angle of error histogram shows that the refractive correction was placed accurately on the intended meridian with 75% of eyes within ±15°.

Vector Analysis of Refractive Cylinder

Table 4:

Vector Analysis of Refractive Cylinder

Stability

As shown in Figure 1, the mean spherical equivalent refraction was −0.26 ± 0.55 D at 3 months and −0.11 ± 0.55 D at 1 year, a mean change of +0.15 D (95% confidence interval: +0.13 to +0.17 D). Table 5 shows spherical equivalent refraction, refractive cylinder, Atlas average keratometry, and corneal astigmatism before surgery and change between 3 and 12 months after surgery.

Stability of Spherical Equivalent Refraction and Atlas Keratometry

Table 5:

Stability of Spherical Equivalent Refraction and Atlas Keratometry

Safety and Complications

There was a gain of one or more lines of CDVA in 19% and no change in 64% of eyes. There was a loss of one line of CDVA in 17% and two or more lines in 0.6% of eyes (n = 8). However, of these 8 eyes, if the change in CDVA is considered in terms of letters, the change was between five and nine letters (ie, one-line loss) for 7 eyes (0.52%) and 10 letters (ie, two-line loss) in 1 eye (0.07%). Table 6 includes the mesopic contrast sensitivity data before and after surgery, showing that there was a small but statistically significant improvement at 3 and 6 cycles per degree (cpd) and no change at 12 and 18 cpd.

Change in Contrast Sensitivity (CSV-1000) in Log Units

Table 6:

Change in Contrast Sensitivity (CSV-1000) in Log Units

For intraoperative complications, there were 114 cases (8.4%) of a mild peripheral epithelial defect, which were managed with a bandage contact lens. The bandage contact lens was removed at the day 1 postoperative appointment in all cases with no consequence or sequelae. There was one case of a micro-buttonhole centrally; the epithelium was scraped to expose the stromal surface and the ablation was performed. There was no adverse effect on the outcome and no change in CDVA. There were 4 cases (0.30%) of suction loss during flap creation. The flap cutting was repeated immediately using the same settings and the flap was created successfully in all cases, with no sequelae. One of these eyes lost one line (3 letters) of CDVA, and there was no change in CDVA in the other 3 eyes.

For postoperative complications that required intervention, there were 30 cases (2.22%) of grade I diffuse lamellar keratitis (DLK) on day 1 after surgery. These were managed successfully using the standard protocol of prednisolone acetate drops every 2 hours until resolution, with no sequelae. There was a loss of one line of CDVA in 4 eyes and no change in the remaining 26 eyes. There were 5 cases (0.37%) of epithelial in-growth that were treated by flap lift (n = 1) or Nd:YAG laser (n = 4). The epithelial ingrowth was resolved in all cases with no sequelae or change in CDVA. There were no cases of visually significant microfolds requiring flap lift intervention, infection, ectasia, retinal detachment, or glaucoma over the 1-year follow-up.

Discussion

The current study found the MEL 90 laser to be effective at treating a wide range of hyperopia up to +6.75 D in a large population with 1 year of follow-up. Three-quarters of eyes targeted for emmetropia achieved UDVA of 20/20 or better, relative to 93% with CDVA of 20/20 or better before surgery. Safety was demonstrated by a loss of two lines of CDVA (10 or more letters) in only 1 eye (0.07%) and no significant loss of contrast sensitivity at any of the frequencies tested.

The subgroup analysis by maximum hyperopic meridian treated showed that, as expected, the treatment was more effective for lower corrections. Predictability in terms of spherical equivalent refraction within ±0.50 D of the intended target was 93% for the +0.25 to +1.00 D group, but reduced to 49% for the +6.01 to +7.00 D group. There were almost 90% of eyes within ±1.00 D for high hyperopia of +4.00 and above, which was similar to what we previously reported for the MEL 80 laser.10 These predictability results were also similar to intraocular lens surgery for high hyperopia, as set out in a literature review in our previous study.10 This group of patients were counseled before surgery that a re-treatment would likely be required, using epithelial thickness mapping (rather than keratometry) to assess the safety of performing further steepening to avoid apical syndrome.10,41 There was a difference in the mean postoperative spherical equivalent refraction relative to target with this being slightly myopic for the groups between +2.01 and +5.00 D, and for the +3.01 to +4.00 D group in particular. This was due to the use of different nomograms for distance and near eyes in presbyopic patients, with a lower nomogram adjustment applied for near eyes. The intention of this was to ensure that the near eye reached a minimum myopic target in the majority of eyes to maximize the near vision outcome given that patients can choose their preferred reading distance for the majority of tasks if slightly more myopic. Due to the myopic target, the hyperopic correction required is greater for near eyes than distance eyes, meaning that the higher diopter groups were biased toward near eyes.

Similarly, the safety in terms of change in CDVA was slightly worse for higher corrections. No eye lost two or more lines of CDVA with a maximum attempted hyperopia correction of +3.00 D or less compared to 1.35% of eyes for hyperopia above +3.00 D. However, the maximum change in CDVA was 10 letters from 20/32+1 to 20/50+1 in one eye, which was also amblyopic. The trend in CDVA change can also be partially explained by the loss of magnification effect of high hyperopic spectacle lenses. As set out in our previous literature review, this level of safety is comparable to intraocular surgery without introducing the more unusual but potentially catastrophic visual complications of intraocular surgery.10

Vector analysis of refractive cylinder showed there was a constant overcorrection of refractive cylinder of 0.23 D in terms of vector magnitude. However, this was partially due to unintended surgically induced astigmatism, as shown by a mean −0.43 D refractive cylinder following sphere only treatments, with a tendency for against-the-rule cylinder induction (vector mean 0.11 Ax 99). The induced astigmatism increased for higher corrections; the mean refractive cylinder was −0.24 D for treatments between +0.25 and +1.99 D, −0.47 D for treatments between +2.00 and +3.99 D, and −0.53 D for treatments between +4.00 and +6.75 D. This implies that the astigmatic shift is related to the ablation rather than being due to the creation of a flap.

This induced astigmatism may be related to asymmetries introduced in eyes with an angle kappa. First, because the corneal surface is aspheric, the presence of an angle kappa means that the eye is rotated and thus creates an asymmetry in corneal curvature presenting to the laser, which likely results in differences in laser fluence projection and reflection between one side of the ablation and the other. These fluence effects have been studied and are taken into account by modern ablation profiles,42,43 but these algorithms assume radial symmetry. There may also be an asymmetric biomechanical response if a hyperopic ablation is applied non-concentrically with the corneal pachymetric profile. The rate of change of corneal thickness increases from the center to the periphery,44 and therefore application of a hyperopic ablation will induce a more abrupt stromal curvature gradient for the sector applied closer to the center of the corneal pachymetric profile. This has been shown to result in an asymmetric epithelial thickness profile due to increased epithelial thickening where the stromal curvature gradient is higher; in a study using very-high frequency digital ultrasound, the mean epithelial thickening was 81 μm at the 3-mm temporal location compared to 59 μm at the 3-mm nasal location.41

In the current study, there was an initial refraction on postoperative day 1 of −0.43 D that reduced to −0.26 D at 3 months, after which there was a mean hyperopic shift of +0.15 D between 3 and 12 months to −0.11 D. This is similar to refractive stability reported for other modern excimer lasers; for example, the change between 3 and 12 months with the MEL 80 laser was +0.13 D in our previous study10 and +0.17 D in the U.S. Food and Drug Administration trial.25 The hyperopic refractive shift was primarily attributable to corneal flattening as indicated by the −0.13 D change in average corneal keratometry between 3 and 12 months. This shift may also be partially due to natural hyperopic progression; for example, a progression of 0.42 D over 5 years (0.08 D per year) has been reported in patients 50 years or older.45

To compare the current study to published LASIK studies in the past 5 years, a literature review was performed using the search terms “LASIK” and “hyperopia” or “hyperopic” in PubMed, as well as referring to the database of U.S. Food and Drug Administration premarket approval studies. For comparison to the previous generation MEL device, studies reporting outcomes for the MEL 80 laser were also included. Table A (available in the online version of this article) summarizes the preoperative key outcome measures of the studies that were identified.9,10,15,18–27,33 The UDVA results in the current study were similar to the results of hyperopic treatments with the MEL 80 and other modern excimer laser platforms. UDVA varied between 18% and 87% of eyes achieving 20/20 or better and between 84% and 100% of eyes achieving 20/40 or better after the primary treatment compared to 75% and 99% in the current study. Similarly, predictability of spherical equivalent refraction within ±0.50 D varied between 47% (for high hyperopic populations) and 87% compared to 73% in the current study.

Literature Review of Hyperopic LASIK StudiesLiterature Review of Hyperopic LASIK Studies

Table A:

Literature Review of Hyperopic LASIK Studies

The current study found that 1-year outcomes of LASIK using the Triple-A ablation profile and the MEL 90 laser for hyperopia up to +6.75 D to be safe, effective, and stable.

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  33. Reinstein DZ, Gobbe M, Archer TJ. Coaxially sighted corneal light reflex versus entrance pupil center centration of moderate to high hyperopic corneal ablations in eyes with small and large angle kappa. J Refract Surg. 2013;29:518–525. doi:10.3928/1081597X-20130719-08 [CrossRef]
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  36. Park CY, Oh SY, Chuck RS. Measurement of angle kappa and centration in refractive surgery. Curr Opin Ophthalmol. 2012;23:269–275. doi:10.1097/ICU.0b013e3283543c41 [CrossRef]
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Study Demographics

ParameterAllFull CorrectionMonovision Near Eyes
Eyes (patients)1,350 (713 patients)738612
Age (years)54 ± 11 (21 to 75)51 ± 13 (21 to 75)56 ± 7 (40 to 75)
Gender (M/F %)43 / 5745 / 5540 / 60
Attempted maximum hyperopia (D)+3.10 ± 1.41 (+0.25 to +6.75)+2.63 ± 1.43 (+0.25 to +6.75)+3.68 ± 1.16 (+0.25 to +6.50)
Attempted spherical equivalent refraction (D)+2.77 ± 1.34 (+0.13 to +6.50)+2.25 ± 1.29 (+0.25 to +6.50)+3.40 ± 1.10 (+0.13 to +6.50)
Attempted refractive cylinder (D)−0.67 ± 0.66 (0.00 to −5.00)−0.75 ± 0.73 (0.00 to −5.00)−0.56 ± 0.53 (0.00 to −5.00)
Intended target spherical equivalent refraction (D)−0.68 ± 0.76 (−1.88 to +0.39)0.00 ± 0.04 (−0.38 to +0.39)−1.50 ± 0.18 (−1.88 to −0.50)
Preoperative minimum corneal thickness (μm)544 ± 33 (446 to 650)544 ± 33 (446 to 649)545 ± 32 (460 to 650)
Scotopic pupil diameter (mm)4.90 ± 0.93 (2.58 to 7.87)4.91 ± 0.93 (2.58 to 7.87)4.84 ± 0.89 (2.64 to 7.87)
Postoperative spherical equivalent relative to intended target (D)−0.11 ± 0.55 (−2.13 to +2.50)−0.09 ± 0.57 (−1.63 to +2.25)−0.34 ± 0.60 (−2.13 to +2.50)
Postoperative cylinder relative to intended target (D)−0.45 ± 0.37 (0.00 to −2.75)−0.39 ± 0.34 (0.00 to −2.75)−0.52 ± 0.39 (0.00 to −2.50)

Distribution of Eyes by Maximum Hyperopia and Cylinder Treated

Sphere (D)Cylinder (D)

0.00 to −1.00−1.01 to −2.00−2.01 to −3.00−3.01 to −4.00−4.01 to −5.00Total
0.00 to +1.007272
+1.01 to +2.0027613289
+2.01 to +3.00357354396
+3.01 to +4.002433662287
+4.01 to +5.0011438432161
+5.01 to +6.00562355392
+6.01 to +7.00281580253
Total1,146160271071,350

Key Outcome Parameters for Each Diopter Bin for Maximum Hyperopia Treated

Parameter+0.25 to +1.00 D+1.01 to +2.00 D+2.01 to +3.00 D+3.01 to +4.00 D+4.01 to +5.00 D+5.01 to +6.00 D+6.01 to +7.00 D
Eyes722893962871619253
Age (y)55 ± 6 (35 to 70)55 ± 7 (24 to 73)55 ± 9 (21 to 75)56 ± 10 (21 to 73)54 ± 13 (21 to 75)47 ± 16 (21 to 73)47 ± 13 (21 to 66)
Attempted maximum hyperopia (D)+0.86 ± 0.20 (+0.25 to +1.00)+1.63 ± 0.28 (+1.13 to +2.00)+2.63 ± 0.28 (+2.13 to +3.00)+3.59 ± 0.27 (+3.13 to +4.00)+4.55 ± 0.29 (+4.11 to +5.00)+5.55 ± 0.28 (+5.25 to +6.00)+6.40 ± 0.16 (+6.05 to +6.75)
Attempted spherical equivalent refraction (D)+0.72 ± 0.21 (+0.13 to +1.00)+1.38 ± 0.30 (+0.75 to +2.00)+2.35 ± 0.38 (+1.25 to +3.00)+3.27 ± 0.39 (+1.63 to +4.00)+4.10 ± 0.48 (+2.24 to +5.00)+4.93 ± 0.61 (+3.00 to +5.88)+5.77 ± 0.58 (+3.75 to +6.50)
Attempted refractive cylinder (D)−0.29 ± 0.12 (0.00 to −0.75)−0.51 ± 0.33 (0.00 to −1.50)−0.56 ± 0.46 (0.00 to −3.00)−0.64 ± 0.60 (0.00 to −3.50)−0.89 ± 0.86 (0.00 to −4.75)−1.22 ± 1.06 (0.00 to −4.75)−1.27 ± 1.09 (0.00 to −5.00)
UDVA/CDVA 20/20 or better (eyes intended plano)87% / 99% (67)85% / 98% (268)74% / 94% (199)61% / 92% (85)69% / 92% (52)58% / 67% (43)14% / 50% (22)
Postop spherical equivalent refraction relative to target (D)−0.03 ± 0.29 (−0.75 to +0.63)+0.02 ± 0.33 (−0.88 to +1.00)−0.12 ± 0.51 (−1.63 to +1.88)−0.27 ± 0.61 (−2.13 to +1.50)−0.14 ± 0.67 (−1.75 to +2.50)+0.01 ± 0.73 (−1.63 to +1.75)−0.02 ± 0.74 (−1.63 to +1.75)
Postop spherical equivalent refraction within ±0.50 D of target93%89%77%64%64%55%49%
Postop spherical equivalent refraction within ±1.00 D of target100%100%94%89%89%83%89%
Postop cylinder ≤ 0.50 D93%91%80%64%63%59%43%
Loss one line CDVA14%13%15%17%23%18%22%
Loss two or more lines CDVA0.0%0.0%0.0%0.7%1.9%1.1%3.8%
Postop CDVA 20/20 or better (eyes preop CDVA 20/20 or better)100% (71)100% (284)100% (379)100% (271)100% (147)100% (72)100% (35)

Vector Analysis of Refractive Cylinder

ParameterSpherical TreatmentsAll Eyes With CylinderCylinder 0.25 to 0.50 DCylinder ≥ 0.75 D
Eyes1781,172626546
Target induced astigmatism vector (D)
  Arithmetic mean0.77 ± 0.65 (0.25 to 5.00)0.38 ± 0.13 (0.25 to 0.50)1.22 ± 0.71 (0.75 to 5.00)
  Summated vector mean0.16 Ax 960.10 Ax 810.25 Ax 102
Surgically induced astigmatism vector (D)
  Arithmetic mean0.43 ± 0.34 (0.00 to 1.61)1.02 ± 0.77 (0.02 to 6.69)0.63 ± 0.37 (0.02 to 2.22)1.46 ± 0.86 (0.24 to 6.69)
  Summated vector mean0.11 Ax 990.34 Ax 940.25 Ax 860.47 Ax 100
Correction index – geometric mean1.32 (0.03 to 8.79)1.46 (0.03 to 8.79)1.17 (0.24 to 3.00)
Difference vector (D)
  Arithmetic mean0.43 ± 0.34 (0.00 to 1.61)0.45 ± 0.37 (0.00 to 2.75)0.42 ± 0.35 (0.00 to 2.00)0.50 ± 0.38 (0.00 to 2.75)
  Summated vector mean0.11 Ax 990.18 Ax 30.15 Ax 1780.22 Ax 7
Index of success – geometric mean0.76 (0.00 to 8.00)1.10 (0.00 to 8.00)0.49 (0.00 to 2.00)
Angle of error (°)
  Arithmetic mean−0.3 ± 19.8 (−87 to 87)−0.5 ± 25.1 (−87 to 87)−0.1 ± 10.9 (−78.4 to 61.5)
  Absolute mean12.3 ± 15.5 (0.0 to 87)17.1 ± 18.3 (0.0 to 87)6.7 ± 8.6 (0.0 to 78.4)
Postop cylinder magnitude ≤ 0.25 D52%49%54%43%
Postop cylinder magnitude ≤ 0.50 D74%75%78%71%
Postop cylinder magnitude ≤ 1.00 D94%95%96%94%
Postop cylinder magnitude ≤ 2.00 D100%99.7%100%99.5%
Cylinder induced ≥ 0.50 D42%5%7%2%
Cylinder induced ≥ 1.00 D9%1%2%0.0%
Cylinder induced ≥ 2.00 D0.0%0.0%0.0%0.0%
CDVA 20/20 or better98%92%96%88%
UDVA 20/20 or better71%75%81%69%
Spherical equivalent refraction within ±0.50 D63%75%76%74%

Stability of Spherical Equivalent Refraction and Atlas Keratometry

ParameterPreoperative3 Months12 Months3 to 12 Months ChangeMean Change per Month3 to 12 Months Change Within ±0.50 D3 to 12 Months Change Within ±1.00 D
Eyes with refraction1,3501,2751,3501,2751,2751,2751,275
Spherical equivalent refraction adjusted for intended target (D)+2.77 ± 1.34 (+0.13 to +6.50)−0.26 ± 0.55 (−2.38 to +2.50)−0.11 ± 0.55 (−2.13 to +2.50)+0.15 ± 0.39 (−1.88 to +2.38)0.01785%98%
Refractive cylinder (D)−0.67 ± 0.66 (0.00 to −5.00)−0.45 ± 0.40 (0.00 to −2.75)−0.45 ± 0.37 (0.00 to −2.75)0.00 ± 0.36 (−2.00 to +2.25)0.00093%99%
Eyes with topography1,3501,2481,3451,2441,2441,2441,244
Average keratometry (D)42.95 ± 1.46 (38.19 to 47.14)45.41 ± 2.03 (38.94 to 51.18)45.26 ± 2.01 (38.91 to 51.13)−0.13 ± 0.41 (−3.02 to +2.43)0.01483%97%
Corneal astigmatism (D)0.79 ± 0.59 (0.01 to 4.96)0.93 ± 0.47 (0.04 to 3.11)0.93 ± 0.47 (0.00 to 3.18)+0.01 ± 0.31 (−2.66 to +2.11)0.00192%99%

Change in Contrast Sensitivity (CSV-1000) in Log Units

Parameter3 cpd6 cpd12 cpd18 cpd
Preoperative1.57 ± 0.16 (1.00 to 2.08)1.78 ± 0.17 (0.91 to 2.29)1.44 ± 0.20 (0.61 to 1.99)0.99 ± 0.23 (0.17 to 1.55)
12 months1.60 ± 0.17 (1.00 to 2.08)1.80 ± 0.17 (1.21 to 2.29)1.44 ± 0.22 (0.61 to 1.99)0.98 ± 0.23 (0.17 to 1.55)
Change0.04 ± 0.15 (−0.61 to 0.59)0.02 ± 0.17 (−0.64 to 0.79)0.00 ± 0.21 (−1.08 to 1.08)−0.01 ± 0.23 (−0.93 to 1.23)
Contrast increase more than 0.25 log units9.6%9.3%10.1%12.4%
Contrast decrease more than 0.25 log units3.4%7.2%11.3%13.5%
P< .01< .01.391.142

Literature Review of Hyperopic LASIK Studies

First AuthorYearNo. (Eyes)TechniquePreop SEQ (D)Age (y)TimepointAccuracyCDVA Preop≤ 20/20UDVASafety



Mean ± SD (Range)±0.50 D±1.00 D≤ 20/20≤ 20/401 Line≥ 2 Lines
Current study20181,350MEL 90; VisuMax+2.77 ± 1.34 (+0.13 to +6.50)54 ± 11 (21 to 75)12 months−0.11 ± 0.55 (−2.13 to +2.50)7393937599170.6
Reinstein12009258MEL 80; Hansatome zero compression+2.54 ± 1.16 (+0.25 to +5.75)56 (44 to 66)12 months+0.09 ± 0.487995948198140.5
FDA22011160MEL 802.70 ± 1.07 (+0.88 to +6.38)47 ± 9 (22 to 69)12 months−0.023 ± 0.541789267970.3
Reinstein3201330MEL 80; Hansatome zero compression; small angle kappa+4.15 ± 1.10 (+2.50 to +5.88)51 ± 9 (22 to 60)12 months+0.40 ± 0.78 (−1.38 to +2.29)53779380100200.0
Reinstein3201330MEL 80; Hansatome zero compression; large angle kappa+4.33 ± 0.89 (+2.75 to +5.75)43 ± 12 (18 to 60)12 months+0.45 ± 0.74 (−1.13 to +1.87)47709377100200.0
Alió4201327Intralase & 500-kHz Amaris excimer; OZ 6.2 to 6.9 mm+6.33 ± 0.83 (+5.00 to +8.50)Not reported6 months+0.55 ± 1.09 (−0.50 to +3.38)7057449280.0
Leccisotti52014800Ziemer LDV Z2; Technolas 217P+3.41 ± 1.16 (+1.00 to +6.50)41 ± 99 months−0.06 ± 0.267488957.30.3
Plaza-Puche6201586Intralase & 500-kHz Amaris excimer; OZ 6.3 to 7 mm+2.66 ± 1.68 (−1.38 to +5.75)40 ± 10 (23 to 64)36 months+0.40 ± 0.65 (−1.63 to +2.00)70857776996.21.2
Amigó7201524Wavelight Allegretto 400 Hz & Hansatome; wave-front optimized+3.66 ± 0.61 (+2.75 to +5.00)39 ± 9 (20 to 49)6 months+0.08 ± 0.56 (−0.75 to +1.25)5796796792214
Amigó7201516Wavelight Allegretto 400 Hz & Hansatome; aspheric customized profile+4.05 ± 0.59 (+2.75 to +5.13)39 ± 9 (20 to 49)6 months+0.21 ± 0.44 (−0.50 to +1.00)871008181100120.0
Antonios8201553Amaris; M2+2.25 ± 1.06 (+0.75 to +5.00)45 ± 12 (19 to 61)6 months+0.22 ± 0.75 (−1.25 to +1.75)43729085920.00.0
Antonios8201572Amaris; LDV femto+2.24 ± 0.95 (+0.50 to +4.75)46 ± 10 (18 to 66)6 months−0.32 ± 0.76 (−2.13 to +1.50)659096871000.00.0
de Ortueta9201638Amaris; Carriazo-Pendular+4.07 ± 0.90 (+2.38 to +5.75)40 ± 10 (18 to 57)6 months+0.28 ± 0.58619633188488
Plaza-Puche10201651Intralase & Amaris; OZ 6.2 to 6.9mm+6.33 ± 0.83 (+5.00 to +8.50)33 ± 9 (21 to 54)6 months+0.50 ± 1.06 (−0.50 to +3.38)71925398116.5
Arba-Mosquera11201646AMARIS 750S; Carriazo-Pendular+3.64 ± 1.42 (+1.27 to +6.18)45 ± 11 (18 to 62)6 months+0.19 ± 0.616193523085136.5
Reinstein122017785MEL80; VisuMax or Hansatome zero compression+4.52 ± 0.84 (+2.00 to +6.96)50 ± 12 (18 to 70)24 months+0.30 ± 0.85 (−3.63 to +4.25)50771006296220.5

El-Naggar13201720WaveLight FS200; WaveLight EX500+2.55 ± 1.17 (+1.00 to +6.00)47 ± 4 (42 to 60)12 months+0.109510085901000.00.0

Garcia-Gonzalez14201876Esiris; Intralase 60 kHz with mitomy-cin C+2.71 ± 1.30 (+2.00 to + 6.25)45 ± 1 (41 to 55)6 months+0.188797711006.62.6

Garcia-Gonzalez14201876Esiris; Intralase 60 kHz no mitomycin C+2.90 ± 1.10 (+2.00 to +.6.25)44 ± 1 (41 to 55)6 months+0.427591541009.26.6
Authors

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

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

AUTHOR CONTRIBUTIONS

Study concept and design (DZR, GIC, TJA); data collection (DZR, GIC, TJA); analysis and interpretation of data (DZR, GIC, TJA, ACD, RSV); writing the manuscript (DZR, TJA, ACD); critical revision of the manuscript (GIC, RSV); 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: July 24, 2018
Accepted: October 10, 2018

10.3928/1081597X-20181019-01

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