Journal of Refractive Surgery

Original Article Supplemental Data

Long-term Outcomes After LASIK Using a Hybrid Bi-aspheric Micro-monovision Ablation Profile for Presbyopia Correction

Michiel H.A. Luger, MD; Colm McAlinden, MD, PhD; Phillip J. Buckhurst, PhD; James S. Wolffsohn, PhD; Shwetabh Verma, MSc; Samuel Arba-Mosquera, PhD

Abstract

PURPOSE:

To evaluate visual outcomes 6 years after hybrid bi-aspheric multifocal central laser in situ keratomileusis for presbyopia correction (PresbyLASIK) treatments.

METHODS:

Thirty-eight eyes of 19 patients consecutively treated with central PresbyLASIK were assessed. The mean age of the patients was 51 ± 3 years at the time of treatment with a mean spherical equivalent refraction of −0.57 ± 1.98 diopters (D) and mean astigmatism of 0.58 ± 0.57 D. Monocular corrected distance visual acuity (CDVA), corrected near visual acuity (CNVA), and distance-corrected near visual acuity (DCNVA), uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity (DCIVA), and uncorrected near visual acuity (UNVA) were assessed preoperatively and postoperatively for the dominant eye, non-dominant eye, and binocularly. Subjective quality of vision and near vision were assessed using the 10-item, Rasch-scaled, Quality of Vision (QoV) Questionnaire and Near Activity Visual Questionnaire (NAVQ), respectively.

RESULTS:

At 6 years postoperatively, mean binocular UDVA was 20/18 ± 4 and mean binocular UNVA and UIVA were 0.11 ± 0.13 and −0.08 ± 0.08 logRAD, respectively. Spherical equivalent showed a slow hyperopic drift of +0.10 D per year with refractive astigmatism stable from 6 weeks postoperatively. Defocus curves showed an improvement of 0.4 Snellen lines at best focus from 1 to 6 years of follow-up, reaching preoperative levels. Compared to the preoperative status, the corneal and ocular spherical aberrations (at a 6-mm diameter) decreased and were stable from 3 months of follow-up. Questionnaires revealed a postoperative unaided QoV score comparable to preoperative scores and with an improved postoperative unaided NAVQ score compared to preoperative scores with best correction.

CONCLUSIONS:

Presbyopic treatment using a hybrid bi-aspheric micro-monovision ablation profile is safe and efficacious even after 6 years postoperatively. The postoperative outcomes indicate improvements in binocular vision at far, intermediate, and near distances. An 8% re-treatment rate should be considered to increase satisfaction levels, including a 3% reversal rate.

[J Refract Surg. 2020;36(2):89–96.]

Abstract

PURPOSE:

To evaluate visual outcomes 6 years after hybrid bi-aspheric multifocal central laser in situ keratomileusis for presbyopia correction (PresbyLASIK) treatments.

METHODS:

Thirty-eight eyes of 19 patients consecutively treated with central PresbyLASIK were assessed. The mean age of the patients was 51 ± 3 years at the time of treatment with a mean spherical equivalent refraction of −0.57 ± 1.98 diopters (D) and mean astigmatism of 0.58 ± 0.57 D. Monocular corrected distance visual acuity (CDVA), corrected near visual acuity (CNVA), and distance-corrected near visual acuity (DCNVA), uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity (DCIVA), and uncorrected near visual acuity (UNVA) were assessed preoperatively and postoperatively for the dominant eye, non-dominant eye, and binocularly. Subjective quality of vision and near vision were assessed using the 10-item, Rasch-scaled, Quality of Vision (QoV) Questionnaire and Near Activity Visual Questionnaire (NAVQ), respectively.

RESULTS:

At 6 years postoperatively, mean binocular UDVA was 20/18 ± 4 and mean binocular UNVA and UIVA were 0.11 ± 0.13 and −0.08 ± 0.08 logRAD, respectively. Spherical equivalent showed a slow hyperopic drift of +0.10 D per year with refractive astigmatism stable from 6 weeks postoperatively. Defocus curves showed an improvement of 0.4 Snellen lines at best focus from 1 to 6 years of follow-up, reaching preoperative levels. Compared to the preoperative status, the corneal and ocular spherical aberrations (at a 6-mm diameter) decreased and were stable from 3 months of follow-up. Questionnaires revealed a postoperative unaided QoV score comparable to preoperative scores and with an improved postoperative unaided NAVQ score compared to preoperative scores with best correction.

CONCLUSIONS:

Presbyopic treatment using a hybrid bi-aspheric micro-monovision ablation profile is safe and efficacious even after 6 years postoperatively. The postoperative outcomes indicate improvements in binocular vision at far, intermediate, and near distances. An 8% re-treatment rate should be considered to increase satisfaction levels, including a 3% reversal rate.

[J Refract Surg. 2020;36(2):89–96.]

Presbyopia occurs when the physiological age-related reduction in the eye's focusing range reaches a point, when optimally corrected for distance vision, that the clarity of vision at near is insufficient to satisfy an individual's requirements.1 The etiology of the condition is predominantly attributed to a loss of elasticity of the crystalline lens, accompanied by a change in the ciliary muscle strength and lens curvature.2 Corneal inlays and intraocular lenses have been used as a treatment for presbyopia.3 Monovision techniques4 usually involve correcting the dominant eye for distance as opposed to crossed monovision,5 where the dominant eye is corrected for near vision.

Multifocal ablations are designed to achieve a pseudo-accommodative cornea in the form of either a peripheral near zone (pericentral annulus for near vision)6 or central near zone (central disc for near vision).7 Laser in situ keratomileusis for presbyopia correction (PresbyLASIK) is one such technique based on traditional LASIK to correct the visual defect for distance while simultaneously reducing the near spectacle dependency in patients with presbyopia.8 PresbyLASIK is considered a promising technology, but is less established when compared to traditional monovision strategies.9 The goal of presbyopia refractive surgery is to provide patients with improved near vision without decreasing their distance vision. Previous approaches have failed for at least one of three reasons: the improvement in near vision was insufficient, the decrease in distance vision was not tolerated, or there was a lack of intermediate visual performance. A hybrid method combining micro-monovision and multifocal ablation could potentially achieve full range of vision.

Long-term follow-up data after presbyopic corrections are scarce in the literature, although they are essential to understand the effects and implications of increasing presbyopia with age as a negative impact on outcomes for presbyopia surgery. It also remains unknown whether the induced aberrations in multifocal/hyperprolate/aspheric ablations remain stable in the cornea in the long term.

In this study, an already established cohort of patients treated with a hybrid bi-aspheric micro-monovision technique10 were followed up for 6 years and the outcomes were retrospectively analyzed.

Patients and Methods

Patients

This cohort study was based on a consecutive case series of patients treated by a single surgeon (MHAL), with a hybrid bi-aspheric micro-monovision technique to correct presbyopia, at Bergman Oogzorg/VisionClinics, Utrecht, the Netherlands.10 Signed informed consent was obtained from each patient, for both the treatment and use of their de-identified clinical data for publication. The Independent Review Board Nijmegen evaluated the study and stated that the investigation in this form is not subject to the Medical Research Involving Human Subjects Act. Of the original cohort, 38 eyes (19 patients) completed the 6-year follow-up and were included for analyses. A summary of the preoperative demographics is presented in Table 1. The details of the cohort have been reported previously in detail.10

Preoperative Demographics

Table 1:

Preoperative Demographics

Postoperative Evaluation

Patients were evaluated at 66 ± 1 months postoperatively (range: 63 to 68 months [6 years]). The clinical follow-up at 1 year postoperatively has been reported previously.10 The results presented in this study expand the clinical follow-up to 6 years, and compares them to the previous follow-up visits. The follow-up rates are presented in Table 2. The 6-year follow-up visit included measurements of monocular and binocular uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), uncorrected intermediate visual acuity (UIVA), manifest refraction, corrected distance visual acuity (CDVA), distance-corrected near visual acuity (DCNVA), distance-corrected intermediate visual acuity (DCIVA), and defocus curves. The response to the Quality of Vision (QoV) Questionnaire and Near Activity Visual Questionnaire (NAVQ), topography, and aberrometry were also recorded. A full ophthalmologic examination was performed on all patients. CDVA and UDVA were evaluated using the Early Treatment Diabetic Retinopathy Study (ETDRS) charts. Near and intermediate acuity were assessed both unaided and distance corrected (UNVA, DCNVA, UIVA, and DCIVA), with the Dutch version of the Radner Reading Charts at 40 and 80 cm, respectively. All tests were conducted monocularly and binocularly.

Follow-up Rates

Table 2:

Follow-up Rates

The corrected visual acuity was always assessed with a phoropter. Binocular defocus curves were measured (with both eyes corrected for distance, eliminating the effect of the micro-monovision component) with induced lens blur from +1.50 to −4.00 diopters (D) in 0.50-D randomized spherical steps, using distance ETDRS charts with the letters randomized between presentations and magnification effects being accounted for.11

Corneal and ocular aberrometry was performed with the OPD-Scan II (Nidek, Gamagori, Japan) over a 6-mm diameter. Root mean square (RMS) higher order aberrations, Strehl ratio, and corneal asphericity were extracted.

Subjective patient-reported outcomes were assessed using two questionnaires: the QoV Questionnaire and the NAVQ. The QoV Questionnaire was developed by McAlinden et al.12 to assess symptoms such as glare, halos, and starbursts with the use of simulation photographs. Symptoms are scored based on scales of symptom frequency, severity, and bothersomeness. The questionnaire is valid for use with spectacle wearers, contact lens wearers, and patients who have undergone laser refractive surgery, intraocular refractive surgery, or having eye disease including cataract.13–15 The NAVQ was used to assess patient satisfaction with near functional vision.16 The questionnaire has been validated for use with spectacles, contact lenses, and intraocular refractive surgery. Patients were instructed to answer the questionnaires to record their subjective impression in corrected conditions preoperatively and unaided conditions postoperatively.

Statistical Analysis

Data were assessed for normality using the Shapiro–Wilk test. Analysis of variance and t tests were performed on normally distributed data and Friedman tests and post-hoc Wilcoxon signed-ranks tests when the data were not normally distributed. Distance visual acuity was measured in logMAR units but converted to equivalent Snellen fractions for reporting comparability. Similarly, near visual acuity was evaluated in logRAD units but converted to Jaeger scale for reporting comparability.

Results

Standard Graphs for Reporting Astigmatism Outcomes of Refractive Surgery

Binocularly at 6 years postoperatively, 53% of the patients reached a UDVA of 20/16 or better (Figure 1A), UDVA remained within one line of preoperative CDVA for 95% of the patients (Figure 1B), and no patient lost lines of CDVA (although 16% of the non-dominant eye lost two lines of CDVA) (Figure 1C). Binocularly at 6 years postoperatively, 68% of the patients reached a UNVA of J2 or better (Figure 1D), UNVA remained within one line of preoperative CNVA for 47% of the patients (Figure 1E), and no patient lost two lines of CNVA (although 21% of the dominant eyes and 11% of the non-dominant eyes lost two lines of CDVA) (Figure 1F).

Standard graphs for reporting astigmatism outcomes of refractive surgery. UDVA = uncorrected distance visual acuity; CDVA = corrected distance visual acuity; DE = dominant eye; NE = non-dominant eye; Bin = binocular; SEQ = spherical equivalent; D = diopters

Figure 1.

Standard graphs for reporting astigmatism outcomes of refractive surgery. UDVA = uncorrected distance visual acuity; CDVA = corrected distance visual acuity; DE = dominant eye; NE = non-dominant eye; Bin = binocular; SEQ = spherical equivalent; D = diopters

At 6 years postoperatively, the scattergram showed 10% undercorrection in spherical equivalent with 1.00 D separation between the dominant eye and the non-dominant eye (Figure 1G), 74% of the dominant eyes were within ±0.50 D from emmetropia, 58% of the non-dominant eyes were within ±0.50 D from −0.90 D target (Figure 1H), and 89% and 74% of the eyes were within ±0.50 D of refractive astigmatism for the dominant eye and the non-dominant eye (Figure 1I), respectively.

Efficacy

At 6 years postoperatively, the mean monocular UDVA was 20/20 ± 5 letters in the dominant eye, 20/43 ± 12 letters in the non-dominant eye, and 20/18 ± 4 letters binocularly (Figure AA, available in the online version of this article). The mean UIVA was J3.2 for the dominant eye, J1.0 for the non-dominant eye, and J1.0 binocularly (Figure AB). The mean UNVA was J8.5 for the dominant eye, J2.1 for the non-dominant eye, and J1.7 binocularly (Figure AC).

Efficacy: Mean uncorrected visual acuity up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) uncorrected distance visual acuity (UDVA), (B) uncorrected intermediate visual acuity (UIVA), and (C) uncorrected near visual acuity (UNVA). DE = dominant eye; NE = non-dominant eye; Bin = binocular

Figure A.

Efficacy: Mean uncorrected visual acuity up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) uncorrected distance visual acuity (UDVA), (B) uncorrected intermediate visual acuity (UIVA), and (C) uncorrected near visual acuity (UNVA). DE = dominant eye; NE = non-dominant eye; Bin = binocular

Accuracy

Good refractive separation was observed between the dominant eye and the non-dominant eye for spherical equivalent and astigmatic error (Figure B, available in the online version of this article). Spherical equivalent showed a +0.10 D per year increase (hyperopic drift) (P = .002) for the dominant eye and the non-dominant eye (Figure BA). Refractive astigmatism was stable from 6 weeks postoperatively (P = .100) for the dominant eye and the non-dominant eye (Figure BB).

Accuracy: Mean manifest refraction (MRSE) assessed preoperatively and up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) MRSE and (B) refractive astigmatism. D = diopters; DE = dominant eye; NE = non-dominant eye; Bin = binocular

Figure B.

Accuracy: Mean manifest refraction (MRSE) assessed preoperatively and up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) MRSE and (B) refractive astigmatism. D = diopters; DE = dominant eye; NE = non-dominant eye; Bin = binocular

Safety

At 6 years postoperatively, mean CDVA was 20/15 ± 3 letters for the dominant eye, 20/19 ± 5 letters for the non-dominant eye, and 20/14 ± 3 letters binocularly (Figure CA, available in the online version of this article). The mean CIVA was J1.0 for the dominant eye, J1.0 for the non-dominant eye, and J1.0 binocularly (Figure CB). The mean CNVA was J2.2 for the dominant eye, J1.5 for the non-dominant eye, and J1.0 binocularly (Figure CC).

Safety: Mean corrected visual acuity up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) corrected distance visual acuity (CDVA), (B) corrected intermediate visual acuity (CIVA) and (C) corrected near visual acuity (CNVA). D = diopters; DE = dominant eye; NE = non-dominant eye; Bin = binocular

Figure C.

Safety: Mean corrected visual acuity up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) corrected distance visual acuity (CDVA), (B) corrected intermediate visual acuity (CIVA) and (C) corrected near visual acuity (CNVA). D = diopters; DE = dominant eye; NE = non-dominant eye; Bin = binocular

Pseudoaccommodation

At 6 years postoperatively, the mean DCIVA was J2.5 for the dominant eye, J1.8 for the non-dominant eye, and J1.1 binocularly (Figure DA, available in the online version of this article). The mean DCNVA was J8.5 for the dominant eye, J5.4 for the non-dominant eye, and J4.7 binocularly (Figure DB).

Pseudoaccommodation: Mean distance corrected visual acuity up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) Distance-corrected intermediate visual acuity (DCIVA) and (B) distance-corrected near visual acuity (DCNVA). DE = dominant eye; NE = non-dominant eye; Bin = binocular

Figure D.

Pseudoaccommodation: Mean distance corrected visual acuity up to 6 years of follow-up after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) Distance-corrected intermediate visual acuity (DCIVA) and (B) distance-corrected near visual acuity (DCNVA). DE = dominant eye; NE = non-dominant eye; Bin = binocular

Defocus Curves

Binocular defocus curves (preoperatively and at 1 and 6 years of follow-up) are presented in Figure E (available in the online version of this article). The difference in defocus curves shows an improvement of 0.4 Snellen lines at best focus from 1 to 6 years of follow-up (P = .008), reaching preoperative levels (P = .50).

Defocus curves: binocular defocus curves from uncorrected vision asymmetrically to longer (+1.50 diopters [D]) and shorter vergences (−4.00 D), assessed preoperatively and at 1 and 6 years postoperatively after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. The error bars represent the upper and lower 95% confidence limits of the mean of measurements, preoperatively.

Figure E.

Defocus curves: binocular defocus curves from uncorrected vision asymmetrically to longer (+1.50 diopters [D]) and shorter vergences (−4.00 D), assessed preoperatively and at 1 and 6 years postoperatively after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. The error bars represent the upper and lower 95% confidence limits of the mean of measurements, preoperatively.

Aberrations

Asphericity was more prolate after surgery, indicating central myopia (within a 3-mm diameter, P = .0003 for OPD-Scan II but not for Pentacam [Oculus Optikgeräte, Wetzlar, Germany], P = .40). Throughout the follow-up, asphericity became less prolate (0.03 units per year, P = .01 for OPD-Scan II but not for Pentacam, P = .100) (Figure FA, available in the online version of this article). Compared to the preoperative status, the corneal and ocular spherical aberrations (at approximately 5.4-mm diameter, Figure FB) decreased (P = .0005) and were stable from 3-month follow-up (P = .10) (Figure FC), with an increase in RMS higher order aberrations (at a 6-mm diameter) (P = .05) stable from 3-month follow-up (P = .10) (Figure FD).

Aberrations: Corneal asphericity (Q value) at 3-mm diameter, root mean square of higher order aberrations (RMS HOAs) (at 6-mm diameter), corneal and ocular spherical aberrations (Corn SA and OC SA, respectively, at 6-mm diameter) preoperatively and up to 6 years postoperatively after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (Top left) Corneal asphericity, (top right) analysis diameter for ocular aberrations, (bottom left) spherical aberration, and (bottom right) RMS HOAs. The Pentacam is manufactured by Oculus Optikgeräte, Wetzlar, Germany, and the OPD Scan II is manufactured by Nidek, Gamagori, Japan. DE = dominant eye; NE = non-dominant eye

Figure F.

Aberrations: Corneal asphericity (Q value) at 3-mm diameter, root mean square of higher order aberrations (RMS HOAs) (at 6-mm diameter), corneal and ocular spherical aberrations (Corn SA and OC SA, respectively, at 6-mm diameter) preoperatively and up to 6 years postoperatively after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (Top left) Corneal asphericity, (top right) analysis diameter for ocular aberrations, (bottom left) spherical aberration, and (bottom right) RMS HOAs. The Pentacam is manufactured by Oculus Optikgeräte, Wetzlar, Germany, and the OPD Scan II is manufactured by Nidek, Gamagori, Japan. DE = dominant eye; NE = non-dominant eye

Subjective Rating

Compared to the corrected preoperative scores, the QoV scores at 6 years were comparable to preoperative scores for all questionnaire items (P = .10), but improved from 1-year scores mainly with a reduction in reported halos (P = .01) and blurred vision (P = .03) (Table A, available in the online version of the article). Composite Rasch-scaled scores are displayed in Figure GA (available in the online version of this article). Scores continued to improve up to 6 years, returning to preoperative levels.

QoV Questionnaire

Table A:

QoV Questionnaire

Subjective rating: Patient-reported outcomes assessed preoperatively and up to 6 years after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) Quality of Vision (QoV) Questionnaire and (B) Near Activity Visual Questionnaire (NAVQ).

Figure G.

Subjective rating: Patient-reported outcomes assessed preoperatively and up to 6 years after treating with a hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments. (A) Quality of Vision (QoV) Questionnaire and (B) Near Activity Visual Questionnaire (NAVQ).

Compared to the preoperative scores, the NAVQ scores at 6 years improved from little to high satisfaction level for all items (P = .002), but the scores for reading small print, medicine and food packaging, bank statements, writing letters, and conducting near work worsened from 1 to 6 years postoperatively (P = .04) (Table B, available in the online version of the article). Overall scores are displayed in Figure GB. Scores worsened between 1 and 6 years, but symptoms remained well below the preoperative levels.

NAVQ Questionnaire

Table B:

NAVQ Questionnaire

Re-Treatments

Secondary treatment was performed in 3 eyes (3 patients: 8% from the 38 eyes, but 16% of the patients) to improve distance outcomes. The secondary treatments were performed using a non-wavefront–guided aspheric treatment to alter the distance refraction to the desired value. One of them (3% from the 38 eyes, but 5% of the patients) was combined with a partial presbyopic reversal treatment to reduce the effects of the primary treatment, due to the patient's perceived intolerance (mainly loss of CDVA) to the induced multifocality. The details about the reversal of this technique and corresponding aberrations and topography changes have been published elsewhere.17 All re-treatments were performed between 6 months and 1 year after the initial treatment. No further re-treatments were performed after 1 year postoperatively, and no retreated eyes required a further re-treatment.

Discussion

This study analyzed the long-term longitudinal changes up to 6 years postoperatively of the efficacy and safety of presbyopic treatment using a hybrid bi-aspheric micro-monovision ablation profile. This technique aims to combine the benefits of multifocal ablations and micro-monovision with enhanced depth of focus and a wider range of intermediate vision. The analysis revealed stable long-term results after the treatment. The binocular vision was expected to improve overall, with the non-dominant eye imparting an improvement in NAVQ scores and the dominant eye imparting an improvement in QoV scores. Most of the outcome measures showed significant improvement compared to the preoperative status. The improvement in visual acuities was significant. In addition, analyzing the NAVQ responses revealed an improvement in all topics from little (preoperative) to high (postoperative) satisfaction. Although it would be interesting to know the profile of the defocus curves monocularly for the presbyopic eyes, this was not part of the study protocol. However, the defocus curves with both eyes corrected for distance (ie, eliminating the effect of the micro-monovision component) revealed an improvement of half a Snellen line at the best focus for distance compared to 1-year follow-up, reaching preoperative levels, but an overall loss compared to 1 year at near vergences. Monocularly, it would be expected that the defocus curves would be shallower, with refractive separation between the dominant and non-dominant eyes. Defocus curves were assessed with trial lenses additive to the distance refraction while observing the ETDRS distance charts. This means that the naturally occurring pupil miosis (enhancing depth of focus) has been eliminated from the measurements, and actual reading and intermediate acuities may actually be better than those obtained in the defocus curves.

As often found in long-term follow-up studies, the number of patients attending the different follow-up visits was not constant and the analyses performed were based on both a paired comparison (ie, only the subset of patients attending all follow-up visits) and unpaired comparisons (ie, comparing the mean and standard errors for the different follow-up visits). Both analyses revealed the same trends. However, the main concern remains the relatively high loss to follow-up of 41% from preoperative, or 32% from 1-year follow-up baseline. The potential impact of this loss to follow-up is difficult to assess. Clearly, this reduced follow-up rate decreases the statistical power of the analyses (ie, the probability of making a type II error [wrongly failing to reject the null hypothesis] increases).

UDVA was stable for the dominant eye (from 6 weeks postoperatively) and binocularly (from 6 months postoperatively) and continued to improve for the non-dominant eye through the years. Although UIVA worsened with time for the dominant eye, it improved for the non-dominant eye and binocularly through the years. For UNVA, there was a global loss of effectiveness through the years. This corresponds well with the progression of manifest refraction spherical equivalent from −0.17 ± 0.37 D at 1 year to +0.32 ± 0.51 D at 6 years for the dominant eye, and from −1.35 ± 0.56 D at 1 year to −0.86 ± 0.56 D at 6 years for the non-dominant eye. Refractive astigmatism was stable from 6 weeks of follow-up. The additional help of true accommodation will also decrease over time.

A good separation in the refractive outcome was observed between the dominant eye and the non-dominant eye for spherical equivalent corresponding to the planned micro-monovision. The dominant eye drove binocular UDVA and the non-dominant eye drove binocular UNVA. For UIVA, the dominant and non-dominant eyes crossed over at approximately 2 years postoperatively, but remained stable binocularly. This cross-over was due to the slow drift in refraction observed for both eyes. Until 1 year postoperatively, the dominant eye (slightly myopic and with moderate depth of focus) drove binocular UIVA (the non-dominant eye was more myopic with larger depth of focus), whereas at 6 years the dominant eye (slightly hyperopic and with moderate depth of focus) could no longer drive binocular UIVA, but the non-dominant eye (less myopic than at 1 year with larger depth of focus) covered the intermediate region better.

CDVA continued to improve during the 6-year follow-up, reaching preoperative levels, whereas CIVA and CNVA reached preoperative levels at 6 months of follow-up and remained stable thereafter. Corrected visual acuity was normal for both eyes at all distances and follow-up times. The dominant eye drove binocular CDVA and CIVA (likely due to the hybrid approach, inducing half of the spherical aberration in the dominant eye [inducing fewer detrimental effects in distance and intermediate vision], and the non-dominant eye binocular CNVA.

Pseudoaccommodation, measured as IVA and NVA with distance correction, reached at least preoperative levels and remained stable from 6 weeks postoperatively, except for DCNVA in the dominant eye (at 6 years worse than preoperative, and decreased 0.2 lines per year). The non-dominant eye drove binocular DCIVA and DCNVA (likely due to the hybrid approach, inducing twice as much spherical aberration in the non-dominant eye and higher gains in intermediate and near vision).

Asphericity was more prolate when measured with the OPD-Scan II than the values measured with the Pentacam. Postoperative asphericities were more prolate than preoperatively (indicating central myopia), with the non-dominant eye showing systematically more negative asphericities at all postoperative times, and a slight trend of losing hyperprolateness with time only measured by the OPD-Scan II (but not with the Pentacam, and also not confirmed by the spherical aberration).

Aberrations were induced across a 6-mm corneal diameter, but ocular aberrations could only be measured through the pupil so that the actual values of analysis diameter were in the range of 5.4 ± 0.2 mm (stable throughout time). Spherical aberration was more negative when measured with ocular aberrations than for corneal aberrations. Postoperative spherical aberration was more negative than preoperative (indicating central myopia), with the non-dominant eye showing systematically more negative values at all postoperative times (for both corneal and ocular spherical aberration), remaining (apparently) stable from 3 months of follow-up. The RMS HOAs increased, with the non-dominant eye showing systematically higher inductions HOA at all postoperative follow-up visits. Both the induction of spherical aberration (corneal or ocular, for the dominant eye or the non-dominant eye) and the postoperative ocular spherical aberration for the non-dominant eye were within −0.6 µm. This level has been reported previously as the maximum compromise between the gain in near visual acuity versus the loss in distance visual acuity,18 although newer assessments have suggested that with a 0.2-µm induction, there is a just noticeable impact in perceived image quality.19

The binocular defocus curve at 6 years of follow-up seems to lie between the preoperative and 1-year postoperative defocus curves. Actually, it seems thapt there was a (not significant) loss of visual acuity for shorter vergences compared to 1-year follow-up, despite the fact that spherical aberration (and HOA) was largely stable from 3 months of follow-up. This may indicate that for the long term, the micro-monovision component is more relevant in influencing the near visual performance of the patient than the induction of HOAs. Defocus curves contradict this: wider curves indicate pseudoaccommodation, which must be an HOA effect, so a decrease in near vision must be due to a decrease in true accommodation.

QoV scores at 6 years were comparable to preoperative scores for all questionnaire items, and the previously reported halos and blurred vision symptoms at 1 year resolved at 6 years. NAVQ scores assessing patient satisfaction with near functional vision improved for all items from preoperative scores, but the scores for reading small print, medicine and food packaging, bank statements, writing letters, and conducting near work worsened from 1 year postoperatively (confirming the UNVA and defocus curve findings). There may be potential adjustments in the surgical goals or some other approach to remedy this complication. Surgeons may decide to increase the monovision effect (−0.90 D in this study) to −1.25 or −1.50 D to further strengthen near visual acuity; alternative options could be to increase the depth of focus (+2.20 D for the non-dominant eye in this study) to +2.50 or +2.75 D (at the expense of a longer adaptation time for the recovery of UDVA). Both alternatives could be equally combined with near vision training.

Leydolt et al.20 showed that near vision training made patients more independent of reading glasses. This was done by comparing a “motivated” group (instructed not to use reading glasses for at least 3 months) to a “control” group. On questioning the patients with a questionnaire, which was also done in an observer-masked fashion, it was found that the motivated group reported significantly better scores for near vision tasks without glasses. Additionally, the motivated group had a proportion of 40% (8 patients) who never used glasses at the 1-year interview compared with none in the control group. The authors concluded that either impeding the use of reading glasses in the first months after surgery or motivation enhances near visual performance and results in a higher degree of spectacle independence. Therefore, studies that examine presbyopia treatment strategies, such as accommodating intraocular lenses, corneal presbyopic ablations, or multifocal intraocular lenses, should not underestimate this “placebo” effect of patient motivation that is present all the time. Whether this effect holds for longer terms (6 years in our cohort) remains unclear. But this may be reinforced with training strategies.4

All re-treatments performed between 6 months and 1 year after the initial treatment were reported previously.10 One late re-treatment was bilaterally performed after 6 years postoperatively (hyperopic photorefractive keratectomy in both eyes of 1 patient; the non-dominant eye was emmetropic, the dominant eye was hyperopic), but no re-treated eyes required a second re-treatment.

Many clinical studies have evaluated various surgical techniques to treat presbyopia; however, the current developments throughout the corneal presbyopic correction spectrum indicate a converging trend toward hybrid techniques. These hybrid modifications include: Supracor (TECHNOLAS Perfect Vision GmbH),21 PresbyMAX (reduced multifocality in the dominant eye combined with full multifocality and monovision in the non-dominant eye),10 Intracor (full correction in the dominant eye combined with multifocality and monovision in the non-dominant eye),22 KAMRA (AcuFocus, Inc.) (full correction in the dominant eye combined with pinhole based extended depth-of-focus and monovision in the non-dominant eye),23 Presbyond (Carl Zeiss Meditec AG) laser blended vision (moderate multifocality in both eyes combined with monovision in the non-dominant eye),24 and refractive corneal inlays (eg, Raindrop from ReVision Optics; now withdrawn from the market).25

Methods depending only on the depth of focus might have difficulty creating more than 1.50 D of range of focus, providing spectacle independence. In contrast, models combining monovision with depth of focus may provide a higher near vision independence. Because presbyopia increases with age, a wide range of near vision shall be an asset in such cases. In addition, the difference in the depth of focus between the near and far eye provides the patient with a wider binocular range of focus for an enhanced intermediate vision.

Corneal topography and aberrometry revealed an induction of negative spherical aberrations in corneal and ocular spherical aberrations, associated with an increase in the RMS HOAs. Furthermore, QoV responses revealed a recovery to preoperative (using corrective glasses) levels for all items, including improvement in terms of halos and blurred vision postoperatively compared to the patient responses at 1-year follow-up. The presented clinical outcomes are based on 6 years of clinical follow-up, which is considered long-term in refractive surgery. However, presbyopia increases with age. Therefore, even longer follow-up periods could shed light on the durability of performance during further degradation of accommodation.

Other techniques reported long-term outcomes, but all were shorter than 6 years. This includes intrastromal femtosecond laser presbyopia (3 years, showing a refractive progression of 0.13 D per year),22 intracorneal pinhole inlays (5 years),23,26 or conductive keratoplasty (3 years, showing a refractive progression of 0.13 D per year)27. From our cohort, as well as previous reports for other techniques, it seems that 0.13 D per year is a reasonable estimate of the presbyopic progression at the considered ages (in our case approximately 51 years old at the time of treatment). Further, it seems that this presbyopic progression is not truly a corneal regression, but lenticular changes (corneal curvature did not change postoperatively in our cohort, or with conductive keratoplasty27).

The depth of focus acts as a useful marker, but some studies consider acuity at a typical near vision distance as a more suitable metric that is closely related to patient expectations and concerns.28 Our analysis and results indicate significant success in presbyopic treatments using the hybrid bi-aspheric micro-monovision ablation profile, which is safe and efficacious. The postoperative outcomes indicate improvements in binocular vision at far, intermediate, and near distances with improved contrast sensitivity. An 8% re-treatment rate should be considered to increase satisfaction levels, with a 3% reversal rate.

References

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Preoperative Demographics

CharacteristicMean ± SDRange
Age (y)51 ± 345 to 55
SEQ (D)−0.57 ± 1.98−6.75 to +2.00
Cylinder (D)0.58 ± 0.570.00 to 2.25
Average K-readings (D)42.80 ± 1.5039.50 to 45.40
CDVA20/16 ± 320/20 to 20/13
Add (D)1.76 ± 0.361.00 to 2.50
Colvard pupillometry (mm)5.8 ± 0.84 to 7.5
Planned OZ (mm)6.6 ± 0.36 to 7

Follow-up Rates

CharacteristicPreoperativePostoperative

6-Week3-Month6-Month1-Year6-Year
Patients (n)323030272819
Eyes (n)646060545638
Follow-up rate (%)100%94%94%84%88%59%

QoV Questionnaire

QoVItemFrequencySeverityBothersomeness



Preop1Y6YPaPbPreop1Y6YPaPbPreop1Y6YPaPb
1Glare0.5 ± 0.70.7 ± 0.80.5 ± 0.6.10.300.5 ± 0.70.9 ± 0.90.7 ± 0.9.40.400.5 ± 0.70.7 ± 0.80.6 ± 0.7.40.40
2Halos0.3 ± 0.41.0 ± 0.70.3 ± 0.5.40.0050.3 ± 0.51.1 ± 0.90.4 ± 0.7.50.010.3 ± 0.40.9 ± 1.00.3 ± 0.4.40.004
3Starbursts0.5 ± 0.70.6 ± 0.70.4 ± 0.6.30.500.5 ± 0.70.6 ± 0.70.4 ± 0.6.20.300.4 ± 0.50.4 ± 0.90.2 ± 0.4.10.40
4Hazy vision0.2 ± 0.40.4 ± 0.60.1 ± 0.3.10.100.2 ± 0.40.4 ± 0.70.2 ± 0.4.20.200.2 ± 0.40.4 ± 0.70.1 ± 0.3.10.10
5Blurred vision0.6 ± 0.71.3 ± 1.00.6 ± 0.5.40.100.6 ± 0.71.4 ± 1.10.6 ± 0.5.40.080.5 ± 0.71.3 ± 1.10.4 ± 0.5.20.03
6Distortion0.1 ± 0.20.1 ± 0.30.1 ± 0.2.20.200.1 ± 0.20.1 ± 0.30.1 ± 0.2.20.200.1 ± 0.20.1 ± 0.30.1 ± 0.2.20.20
7Multiple images0.1 ± 0.20.5 ± 0.80.1 ± 0.2.50.050.1 ± 0.20.5 ± 0.80.1 ± 0.2.50.050.1 ± 0.20.5 ± 0.80.1 ± 0.2.50.05
8Fluctuations0.5 ± 0.60.9 ± 0.70.6 ± 0.6.40.400.6 ± 0.81.0 ± 0.80.6 ± 0.6.20.200.6 ± 0.80.9 ± 0.80.5 ± 0.6.10.20
9Focusing difficulties0.9 ± 0.61.3 ± 0.71.0 ± 0.0.20.300.9 ± 0.61.2 ± 0.71.0 ± 0.3.20.200.9 ± 0.61.1 ± 0.90.9 ± 0.4.10.40
10Depth perception0.4 ± 0.50.5 ± 0.60.5 ± 0.6.40.400.3 ± 0.50.5 ± 0.60.5 ± 0.7.40.300.4 ± 0.60.5 ± 0.60.5 ± 0.6.40.40
Rasch score33 ± 547 ± 636 ± 4.30.1028 ± 541 ± 531 ± 4.30.0530 ± 542 ± 729 ± 5.10.10

NAVQ Questionnaire

NAVQItemPreop1Y6YPaPb
1Reading small print, such as newspaper articles, items on a menu, telephone directories?1.9 ± 1.00.3 ± 0.50.7 ± 0.8.0003.01
2Reading labels/instructions/ingredients/prices, such as on medicine bottles, food packaging?2.2 ± 1.00.4 ± 0.51.1 ± 0.9.002.002
3Reading your post/mail, such as electric bills, greeting cards, bank statements, letters from friends and family?1.9 ± 1.10.1 ± 0.30.4 ± 0.6.0000009.03
4Writing and reading your own writing, such as greeting cards, notes, letters, filling in forms, checks, signing your name?1.6 ± 1.00.0 ± 0.00.2 ± 0.4.0000002.02
5Seeing the display and keyboard on a computer or calculator?1.8 ± 0.90.3 ± 0.50.4 ± 0.6.00008.09
6Seeing the display and keyboard on a mobile or fixed telephone?2.0 ± 1.00.2 ± 0.40.6 ± 0.7.00009.06
7Seeing objects close to you and engaging in your hobbies, such as playing card games, gardening, seeing photographs?1.6 ± 0.90.0 ± 0.20.2 ± 0.4.000000005.08
8Seeing objects close to you in poor or dim light?1.8 ± 0.90.6 ± 0.60.8 ± 0.8.00006.08
9Maintaining focus for prolonged near work?1.5 ± 0.90.4 ± 0.60.6 ± 0.7.0001.3
10Conducting near work without spectacles?1.8 ± 1.10.2 ± 0.40.6 ± 0.9.0002.04
11Overall Score3.3 ± 0.31.1 ± 0.31.7 ± 0.5.0002.05
Rasch Score62 ± 715 ± 528 ± 7.000003.01
Authors

From Bergman Oogzorg, Naarden, The Netherlands (MHAL); the Department of Ophthalmology, Princess of Wales Hospital, Bridgend, United Kingdom (CM); the School of Health Professions, Plymouth University, Plymouth, United Kingdom (PJB); the School of Life and Health Sciences, Aston University, Birmingham, United Kingdom (JSW); SCHWIND eye-tech-solutions, Kleinostheim, Germany (SV, SA-M); Experimental Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Heidelberg, Germany (SV); and Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany (SV).

Dr. Luger's institution received reimbursement of travel expenses to present a preliminary version of this work in Paris during the Congress of the ESCRS 2019 and receives reimbursement of travel expenses for activities outside this work. Dr. McAlinden received remuneration from SCHWIND eye-tech-solutions for his involvement in this study (consulting fee or honorarium; fees for participation in review activities such as statistical analysis; payment for writing or reviewing the manuscript); outside this work, he has received personal fees in the past 36 months from Bausch & Lomb, Ora, STAAR Surgical, AcuFocus, targomed GmbH, Yoshida Eye Institute, University of Michigan, CORD LLC, RxSight, Sight Glass Vision, Alcon, Novartis, ClarVista, Ophtec, Wenzhou Medical University, Ludwig-Maximilians-University, Bayer, European Society of Cataract and Refractive Surgeons (ESCRS), Perfect Lens, Eye Center Vista Alpina, PowerVision, Eye and Vision Journal, Pharmerit, Carl Zeiss Meditec, Allergan, Thea Pharmaceuticals, Santen, and Glaukos. Dr. Buckhurst's institution receives research grants unrelated to this work by Bausch & Lomb, Rayner, and Menicontur. Dr. Wolffsohn is on the board of the Tear Film and Ocular Surface Society, International Myopia Institute, is a conference consultant of the British Contact Lens Association, has received payment for lectures including service on speaker's bureaus/advisory boards by Alcon, Allergan, British Contact Lens Association, Johnson and Johnson, and Novartis, receives royalties from Elsevier for a book on low vision and ocular imaging, receives travel/accommodations/meeting expenses unrelated to activities listed by Shire, and receives stock options (by him and his institution) in Eyoto (spin out company of the University but no financial benefit at the current time and not related to this project), and his institution receives research grants unrelated to this work by Alcon, Allergan, Johnson and Johnson, Novartis, Visioncare Research, and Innovate UK. Mr. Verma is an employee of SCHWIND eye-tech-solutions, Kleinostheim, Germany. Dr. Arba-Mosquera is an employee of SCHWIND eye-tech-solutions, Kleinostheim, Germany, and is the inventor of several patents owned by SCHWIND eye-tech-solutions.

AUTHOR CONTRIBUTIONS

Study concept and design (MHAL, JSW, SA-M); data collection (MHAL); analysis and interpretation of data (MHAL, CM, PJB, JSW, SV, SA-M); writing the manuscript (SA-M); critical revision of the manuscript (MHAL, CM, PJB, JSW, SV); statistical expertise (CM, SA-M); administrative, technical, or material support (JSW, SA-M)

Correspondence: Michiel H.A. Luger, MD, Gooimeer 11, 1411 DE Naarden, The Netherlands. E-mail: M.Luger@bergmanclinics.nl

Received: November 04, 2019
Accepted: January 02, 2020

10.3928/1081597X-20200102-01

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