Journal of Refractive Surgery

Original Articles 

LASIK for Presbyopia Correction in Emmetropic Patients Using Aspheric Ablation Profiles and a Micro-monovision Protocol With the Carl Zeiss Meditec MEL 80 and VisuMax

Dan Z. Reinstein, MD, MA(Cantab), FRCSC, FRCOphth; Glenn I. Carp, MBBCh, FC Ophth(SA); Timothy J. Archer, MA(Oxon), DipCompSci(Cantab); Marine Gobbe, PhD, MSTOptom

Abstract

PURPOSE:

To evaluate the monocular and binocular visual outcomes of LASIK with an aspheric micro-mono-vision protocol in emmetropic patients with presbyopia.

METHODS:

A retrospective, noncomparative case series included 296 eyes from 148 consecutive emmetropic patients with presbyopia who were treated with LASIK-induced micro-monovision. The CRS-Master software was used to generate ablation profiles for the MEL 80 excimer laser (Carl Zeiss Meditec) and flaps were created using the VisuMax femtosecond laser (Carl Zeiss Meditec). The target refraction was plano for distance eyes (dominant eye) and between −1.00 and −1.88 diopters (D) for near eyes. Patients were followed for 1 year. Emmetropia was defined for inclusion as spherical equivalent refraction ⩾− 0.88 D, sphere ⩽+1.00 D, and cylinder ⩽1.25 D. Median patient age was 55 years (range: 44 to 65 years). Median follow-up was 12.9 months.

RESULTS:

Mean deviation from intended correction was +0.02±0.35 D, with 91% within ±0.50 D and 100% within ±1.00 D. Of distance eyes, 95% achieved uncorrected distance visual acuity (UDVA) of 20/20 or better and 100% achieved 20/32 or better. Binocularly, 98% of patients achieved UDVA of 20/20 or better and 100% achieved 20/32 or better; 96% achieved uncorrected near visual acuity of J2 and 99% could read J3 or better. No eyes lost 2 or more lines of corrected distance visual acuity. An average increase of 0.05 logMAR was noted in distance-corrected near visual acuity. A small increase occurred in mesopic contrast sensitivity (CSV-1000, VectorVision Inc) at 3 cycles per degree (cpd) (P=.016) and no change at 6, 12, or 18 cpd.

CONCLUSIONS:

This aspheric micro-monovision protocol was a well-tolerated and effective procedure for treating emmetropic patients with presbyopia.

From London Vision Clinic, London, United Kingdom (Reinstein, Carp, Archer, Gobbe); the Department of Ophthalmology, Columbia University Medical Center, New York, New York (Reinstein); and Centre Hospitalier National d’Ophtalmologie, Paris, France (Reinstein).

Dr Reinstein has a proprietary interest in the Artemis technology (ArcScan Inc, Morrison, Colorado) and is an author of patents related to VHF digital ultrasound administered by the Cornell Center for Technology Enterprise and Commercialization, Ithaca, New York. Dr Reinstein is a consultant for Carl Zeiss Meditec (Jena, Germany). The remaining authors have no proprietary or financial interest in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (D.Z.R., G.I.C., T.J.A., M.G.); data collection (D.Z.R., G.I.C., T.J.A.); analysis and interpretation of data (D.Z.R., T.J.A., M.G.); drafting of the manuscript (T.J.A.); critical revision of the manuscript (D.Z.R., G.I.C., M.G.); statistical expertise (T.J.A.)

Correspondence: Dan Z. Reinstein, MD, MA(Cantab), FRCSC, FRCOphth, London Vision Clinic, 138 Harley St, London W1G 7LA, United Kingdom. Tel: 44 207 224 1005; Fax: 44 207 224 1055; E-mail: dzr@londonvisionclinic.com

Received: February 02, 2012
Accepted: May 31, 2012

Abstract

PURPOSE:

To evaluate the monocular and binocular visual outcomes of LASIK with an aspheric micro-mono-vision protocol in emmetropic patients with presbyopia.

METHODS:

A retrospective, noncomparative case series included 296 eyes from 148 consecutive emmetropic patients with presbyopia who were treated with LASIK-induced micro-monovision. The CRS-Master software was used to generate ablation profiles for the MEL 80 excimer laser (Carl Zeiss Meditec) and flaps were created using the VisuMax femtosecond laser (Carl Zeiss Meditec). The target refraction was plano for distance eyes (dominant eye) and between −1.00 and −1.88 diopters (D) for near eyes. Patients were followed for 1 year. Emmetropia was defined for inclusion as spherical equivalent refraction ⩾− 0.88 D, sphere ⩽+1.00 D, and cylinder ⩽1.25 D. Median patient age was 55 years (range: 44 to 65 years). Median follow-up was 12.9 months.

RESULTS:

Mean deviation from intended correction was +0.02±0.35 D, with 91% within ±0.50 D and 100% within ±1.00 D. Of distance eyes, 95% achieved uncorrected distance visual acuity (UDVA) of 20/20 or better and 100% achieved 20/32 or better. Binocularly, 98% of patients achieved UDVA of 20/20 or better and 100% achieved 20/32 or better; 96% achieved uncorrected near visual acuity of J2 and 99% could read J3 or better. No eyes lost 2 or more lines of corrected distance visual acuity. An average increase of 0.05 logMAR was noted in distance-corrected near visual acuity. A small increase occurred in mesopic contrast sensitivity (CSV-1000, VectorVision Inc) at 3 cycles per degree (cpd) (P=.016) and no change at 6, 12, or 18 cpd.

CONCLUSIONS:

This aspheric micro-monovision protocol was a well-tolerated and effective procedure for treating emmetropic patients with presbyopia.

From London Vision Clinic, London, United Kingdom (Reinstein, Carp, Archer, Gobbe); the Department of Ophthalmology, Columbia University Medical Center, New York, New York (Reinstein); and Centre Hospitalier National d’Ophtalmologie, Paris, France (Reinstein).

Dr Reinstein has a proprietary interest in the Artemis technology (ArcScan Inc, Morrison, Colorado) and is an author of patents related to VHF digital ultrasound administered by the Cornell Center for Technology Enterprise and Commercialization, Ithaca, New York. Dr Reinstein is a consultant for Carl Zeiss Meditec (Jena, Germany). The remaining authors have no proprietary or financial interest in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (D.Z.R., G.I.C., T.J.A., M.G.); data collection (D.Z.R., G.I.C., T.J.A.); analysis and interpretation of data (D.Z.R., T.J.A., M.G.); drafting of the manuscript (T.J.A.); critical revision of the manuscript (D.Z.R., G.I.C., M.G.); statistical expertise (T.J.A.)

Correspondence: Dan Z. Reinstein, MD, MA(Cantab), FRCSC, FRCOphth, London Vision Clinic, 138 Harley St, London W1G 7LA, United Kingdom. Tel: 44 207 224 1005; Fax: 44 207 224 1055; E-mail: dzr@londonvisionclinic.com

Received: February 02, 2012
Accepted: May 31, 2012

 

The treatment of presbyopia in emmetropic patients is currently one of the biggest challenges in refractive surgery and a number of different approaches have been used, including LASIK monovision,1 corneal multifocal ablation,2 corneal inlays,3–6 conductive keratoplasty,1 intrastromal femtosecond concentric rings,7,8 and refractive clear lens exchange with multifocal or accommodative intraocular lenses (IOL).9

We previously described the Laser Blended Vision (Carl Zeiss Meditec, Jena, Germany) technique in myopic10 and hyperopic populations11 that combines control of spherical aberration to increase depth of field with micro-monovision (anisometropia of 1.50 diopters [D] in the nondominant eye irrespective of age). In emmetropic patients, as the refractive error correction is small, inducing significant spherical aberration would require a multifocal ablation, but this has been shown to reduce quality of vision, such as decreased contrast sensitivity,12 increased glare and halos,12,13 and loss of corrected distance visual acuity (CDVA).14,15 Emmetropic presbyopic patients often have high expectations because they already have good distance vision and are not used to wearing glasses. Therefore, refractive accuracy and safety (both in terms of quantity and quality of vision) are paramount in these patients. For this reason, the Laser Blended Vision module uses a low degree of asphericity in emmetropic patients and relies more on the near vision afforded by micro-monovision together with the depth of field increase afforded by a change in spherical aberration.

The purpose of this study was to document the safety and efficacy of LASIK with the MEL 80 excimer laser and VisuMax femtosecond laser (Carl Zeiss Meditec) to treat emmetropic patients with presbyopia using an aspheric micro-monovision protocol.

Patients and Methods

This study was a retrospective, noncomparative case series including 160 consecutive emmetropic presbyopic patients undergoing LASIK between November 15, 2007 and June 9, 2010, at the London Vision Clinic, London, United Kingdom. Inclusion criteria were medically suitable for LASIK; no previous ocular, eyelid or orbital surgery; no visually significant cataract; emmetropic refraction in both eyes; distance-corrected near visual acuity (DCNVA) of J3 or worse in both eyes; CDVA 20/20 or better in both eyes; and minimum 1-year follow-up. An emmetropic refraction was defined as spherical equivalent refraction ⩾−0.88 D, manifest sphere ⩽+1.00 D, and manifest cylinder ⩽1.25 D. Informed consent and permission to use their data for analysis and publication were obtained from all patients.

Median follow-up after the primary treatment was 12.9 months. All patients who had not attended 1-year follow-up were contacted by telephone. Of these, 12 (7.5%) patients lived far from London or abroad and were unwilling to travel. These patients were classified as lost to follow-up and were excluded from the analysis. Of the 148 patients included for analysis, the last time point after the primary procedure was 6 months for 1.7% of eyes (n=5) and 1 year for the remaining 98.3% of eyes (n=293). Eyes for which the last time point was earlier than 1-year follow-up underwent retreatment at that time.

The following represents the standard treatment protocol for emmetropic presbyopic patients in our practice since August 1, 2003.

Preoperative Assessment

A full ophthalmologic examination was performed by an in-house optometrist as described previously.10,11

Micro-Monovision Assessment

The protocol used to determine the amount of induced myopic target, or “add,” to use in the nondominant eye has been described in detail previously.10,11 The age of the patient was not a consideration when choosing the add; rather an add of 1.50 D was used whenever possible and was reduced only if necessary until the patient reported no cross-blur (as defined previously10,11). The add was increased to >1.50 D only if the patient could not comfortably read J2. No contact lens monovision trials were performed. Patients were counseled to expect an adaptation period of at least 3 to 6 months and subjective cross-blur was recorded postoperatively using the following grading categories: none, slight, mild, moderate, and severe.

Surgical Procedure

All patients underwent bilateral simultaneous LASIK using the MEL 80 excimer laser and VisuMax femtosecond laser by one of two surgeons (D.Z.R. [63%], G.I.C [37%]). The CRS-Master software platform (Carl Zeiss Meditec) was used to generate the ablation profiles (version 2.1.6 until November 1, 2009, and version 2.3.0 after this date). Proprietary aspheric ablation profiles were used for all eyes, which incorporated a small amount of spherical aberration determined according to the patient’s age, preoperative spherical aberration, and the amount of refractive correction; the profiles were intended to control the induction of spherical aberration to a level that would provide an increased depth of field, but without affecting contrast sensitivity and quality of vision. Optical treatment zone diameters were 6.00 mm (in 17%), 6.50 mm (in 49%), and 7.00 mm (in 34%). Intended flap thickness was 90 μm in 23%, 95 μm in 0.7%, 100 μm in 44%, 110 μm in 16%, and 120 μm in 17% of eyes. Flap diameter was 8.4 mm in 65%, 8.9 mm in 9%, and 9.2 mm in 26% of eyes.

Postoperative Evaluation

Patients were instructed to wear plastic shields while sleeping for 7 nights. Topical tobramycin 0.3%/dexamethasone 0.1% and ofloxacin 0.3% 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, 6, and 12 months using our standard protocol as described previously.10,11 Slit-lamp examination was performed at all postoperative follow-up visits and superficial punctuate keratitis was recorded using a six-grade classification system: none, trace, I–II (not visually significant), and III–V (visually significant). All postoperative examinations were conducted by one of seven in-house optometrists. Manifest refraction was performed based on a standardized protocol,16 and all optometrists had undergone refraction training with this protocol.

A retreatment was offered to all patients who could gain two lines of uncorrected distance visual acuity (UDVA) and patients with cylinder >0.75 D. Retreatments were performed once stability was demonstrated over a 2-month interval (stability was defined as no change in sphere within ±0.25 D and change in cylinder within ±0.50 D).

Statistical Analysis

Outcome measures were calculated according to the standardized graphs as originally defined by Waring.17–19 The outcomes were analyzed for the primary treatment and for final results after all treatments. For eyes that received retreatment, the refraction and vision at the time of retreatment were used for the primary outcome analysis. The mesopic contrast sensitivity was converted into log values before calculating statistics. The mean normalized mesopic contrast sensitivity ratio was calculated.20 Student paired t tests were used to assess the change in mesopic contrast sensitivity, and to compare UDVA, CDVA, DCNVA, and uncorrected near visual acuity (UNVA) (logMAR). Average pre- and postoperative spherical aberration was calculated for a 6-mm analysis zone using Optical Society of America (OSA) notation.21 Microsoft Excel 2007 (Microsoft Corp, Redmond, Washington) was used for data entry and statistical analysis.

Results

Two hundred ninety-six eyes from 148 consecutive patients (41% male, 59% female) were included in the final analysis. Median patient age was 55 years (range: 44 to 65 years). Table 1 shows descriptive statistics of the preoperative, intended, and attempted spherical equivalent refraction and the mean deviation from the intended spherical equivalent refraction after primary treatment and after all treatments grouped into distance and near eyes.

Mean Spherical Equivalent Refraction of Distance and Near Eyes Before and After Primary Treatment and All Treatments

Table 1: Mean Spherical Equivalent Refraction of Distance and Near Eyes Before and After Primary Treatment and All Treatments

Table 2 presents preoperative patient characteristics and target spherical equivalent refraction of the near eye. The right eye was dominant in 64% of patients.

Preoperative Patient Characteristics and Target Spherical Equivalent Refraction in the Near Eye

Table 2: Preoperative Patient Characteristics and Target Spherical Equivalent Refraction in the Near Eye

Figure 1 presents efficacy in terms of UDVA and UNVA before and after the primary treatment and after all treatments grouped into binocular and distance and near eyes monocularly. Figure 2 presents the standard graphs for reporting refractive surgery, with the UDVA efficacy histogram replaced by a histogram showing the change in lines of DCNVA (as the UDVA histogram is included in Figure 1). The attempted versus achieved scatterplot only includes data after all treatments. The stability plot includes data after the primary treatment only. The remaining four graphs include data after the primary treatment and after all treatments. Figure 3 presents the combined binocular distance and near visual acuity before and after all treatments. Figure 4 shows the defocus equivalent before and after all treatments for distance eyes only.

Cumulative histograms of uncorrected distance visual acuity (left column) and uncorrected near visual acuity (right column) for before (dark grey bars) and after the primary treatment (blue bars) and after all treatments (red bars), grouped into binocular (first row), distance eyes (second row), and near eyes (third row). The preoperative corrected distance visual acuity (light grey bars) is also shown for distance and near eyes.

Figure 1. Cumulative histograms of uncorrected distance visual acuity (left column) and uncorrected near visual acuity (right column) for before (dark grey bars) and after the primary treatment (blue bars) and after all treatments (red bars), grouped into binocular (first row), distance eyes (second row), and near eyes (third row). The preoperative corrected distance visual acuity (light grey bars) is also shown for distance and near eyes.

The standard graphs for reporting refractive surgery, with the uncorrected distance visual acuity (UDVA) efficacy histogram replaced by a histogram showing the change in lines of distance-corrected near vision acuity (as the UDVA histogram is already included in Figure 1). The attempted versus achieved scatterplot only includes data after all treatments and the linear regression equation and coefficient of determination (r2) are displayed. The stability plot only includes data after the primary treatment. The other four graphs include data after the primary treatment and after all treatments.

Figure 2. The standard graphs for reporting refractive surgery, with the uncorrected distance visual acuity (UDVA) efficacy histogram replaced by a histogram showing the change in lines of distance-corrected near vision acuity (as the UDVA histogram is already included in Figure 1). The attempted versus achieved scatterplot only includes data after all treatments and the linear regression equation and coefficient of determination (r2) are displayed. The stability plot only includes data after the primary treatment. The other four graphs include data after the primary treatment and after all treatments.

Combined distance and near binocular visual acuity before (blue data points) and after all treatments (red data points). Two ellipses are plotted to represent the mean and one standard deviation of the combined distance and near binocular visual acuity before (blue line) and after all treatments (red line). Distance vision is displayed on the x-axis, near vision is displayed on the y-axis and the number of patients with each combination of distance and near vision is represented by the relative size and darkness of the data points. Guidelines are plotted (orange dashed lines) to highlight 20/20 and 20/25 distance vision, and J2 and J5 near vision.

Figure 3. Combined distance and near binocular visual acuity before (blue data points) and after all treatments (red data points). Two ellipses are plotted to represent the mean and one standard deviation of the combined distance and near binocular visual acuity before (blue line) and after all treatments (red line). Distance vision is displayed on the x-axis, near vision is displayed on the y-axis and the number of patients with each combination of distance and near vision is represented by the relative size and darkness of the data points. Guidelines are plotted (orange dashed lines) to highlight 20/20 and 20/25 distance vision, and J2 and J5 near vision.

Histogram of defocus equivalent before and after all treatments for the distance eyes only.

Figure 4. Histogram of defocus equivalent before and after all treatments for the distance eyes only.

Table A (available as supplemental material in the PDF version of this article) shows the mean UDVA, CDVA, and DCNVA before and after the primary treatment and after all treatments grouped into binocular and distance and near eyes. Binocular UDVA was one line better than monocular UDVA of the distance eye in 23 (16%) patients, these were the same in 116 (78%) patients, and binocular UDVA was one line worse than monocular UDVA of the distance eye in 9 (6%) patients. The improvement of binocular UDVA compared to monocular UDVA of the distance eyes was statistically significant (P=.01).

Table 3 shows the incidence of cross-blur 3 months after the primary treatment and 1 year after all treatments.

Incidence of Cross-blur Postoperatively

Table 3: Incidence of Cross-blur Postoperatively

Of the eyes that lost one line of CDVA after all treatments, 18% were 20/12.5 preoperatively, 76% were 20/16 preoperatively, and 5% were 20/20 preoperatively; 99.3% (296/298) achieved CDVA 20/20 or better postoperatively.

Table 4 shows the mean normalized mesopic contrast sensitivity ratio before and after the primary treatment at 3, 6, 12, and 18 cycles per degree (cpd). There was a statistically significant improvement in mesopic contrast sensitivity at 3 cpd, and no statistically significant change at 6, 12, and 18 cpd.

Mean Normalized Mesopic Contrast Sensitivity Ratio Before and After the Primary Treatment

Table 4: Mean Normalized Mesopic Contrast Sensitivity Ratio Before and After the Primary Treatment

The following complications were experienced. Intraoperative epithelial defects occurred in 12 (4.1%) eyes, of which 5 eyes gained 1 line of CDVA and 7 eyes had no change in CDVA after the primary treatment. Table B (available as supplemental data in the PDF version of this article) presents the percentage of eyes with superficial punctate keratitis before and 1 year after the primary treatment. One (0.3%) eye had visually significant superficial punctate keratitis at 1 year. Two (0.7%) cases of suction loss occurred during the creation of the flap interface. Both cases were managed using the standard repair mode to reapply the contact glass, resulting in normal flaps with no bed irregularities as confirmed intraoperatively.

In accordance with our retreatment policy and definition of stability, the retreatment rate was 11.8% (35/296 eyes), of which 14 (40%) were for distance eyes and 21 (60%) for near eyes. Of the 28 patients who underwent a retreatment, 7 (25%) received bilateral retreatments. The mean requested increase in myopic spherical equivalent refraction of the near eye was −0.27 D (range: −0.13 to −0.38 D). No patients required the myopic refraction of the near eye to be reduced from target. No patients requested the distance and near eyes be switched.

Table 5 shows the mean spherical aberration before and after the primary treatment, and the change in spherical aberration grouped by distance and near eyes.

Change in Spherical Aberration*

Table 5: Change in Spherical Aberration

Discussion

This aspheric micro-monovision protocol in a population of emmetropic presbyopic patients achieved results similar to those previously reported for myopic10 and hyperopic populations.11 Uncorrected binocular visual acuity of 20/20 at distance and J3 at near was achieved in 99% of patients with no loss of CDVA or contrast sensitivity.

The aspheric micro-monovision protocol was well tolerated, with only five (3.4%) patients who did not tolerate anisometropia of −1.50 D and just one (0.7%) patient who did not tolerate −1.25 D on preoperative screening. Also, no patient requested the target spherical equivalent refraction of the near eye be reduced, nor did any patient request both eyes be corrected for distance vision after the primary treatment. The tolerance was similar to that observed in a hyperopic population11 but better than that observed in a myopic population, where 12% of patients did not tolerate anisometropia of −1.00 D.10 However, the myopic population was younger (median 49 years) than both the hyperopic (median 56 years) and emmetropic (median 55 years) populations. In the myopic population, all but one of the patients, who could only tolerate −0.75 D in the near eye, were younger than 49 years of age, whereas the majority of patients older than 54 years could tolerate −1.50 D in the near eye. This suggests that patients with mild presbyopia are less tolerant to a larger degree of anisometropia than patients with advanced presbyopia, which agrees with previous reports.22 The tolerance to micro-monovision was also monitored by recording subjective cross-blur. Although mild/moderate cross-blur was observed in 35 (24%) patients at 3 months, only 10 (7%) patients reported mild/moderate cross-blur at 1 year, demonstrating that the neural adaptation process takes <3 months in most patients, but can take up to ⩾1 year in a few patients.

Another interesting finding in this study was that the average DCNVA increased by 0.05 log units (approximately half a line) in both the distance and near eyes. This appears to demonstrate a small increase in depth of field despite only a small degree of asphericity used in the ablation profile. Alternatively, this could be a systematic effort–related bias.

Femtosecond LASIK monovision has been reported previously with the EC-5000 excimer laser (NIDEK Co Ltd, Gamagori, Japan) and IntraLase FS30 (Abbott Medical Optics, Santa Ana, California), although only the nondominant eye was treated using a target refraction of −1.50 D.1 Mean UNVA was J3 compared with J1.5 in the present study. The study by Ayoubi et al1 also reported results of monovision using conductive keratoplasty; spherical equivalent refraction regressed by 1.04 D (65%) over 18 months and induced average cylinder of 1.04 D, resulting in a mean UNVA of J5.5.

Multifocal ablation profiles have been described, but currently no published reports exist regarding their use in emmetropic presbyopes. However, published studies using multifocal ablation profiles in hyperopic and myopic patients show a reduction in quality of vision, including decreased contrast sensitivity,12 increased glare and halos,12,13 and loss of CDVA.14,15

Pinhole intracorneal inlays are designed to increase the depth of field based on the principle of pinhole optics to restore near and intermediate acuity without significantly impacting distance vision, with the most common being the KAMRA (AcuFocus Inc, Irvine, California). The first generation KAMRA inlay (ACI-7000, AcuFocus Inc) was 10-μm thick with 1600 microperforations.4,23,24 The design and materials were then improved (ACI-7000PDT, AcuFocus Inc) to reduce the thickness to 5 μm and increase the number of c 8400.5,6 The results of the published studies using the KAMRA corneal inlay4–6,23,24 are included in Table C (available as supplemental material in the PDF version of this article). The binocular UNVA was comparable to the present study, although the results with the new ACI-7000PDT were slightly worse (Waring6 reported mean UNVA between J2 and J3, logMAR 0.14). The potential advantage of corneal inlays is that UDVA of at least 20/32 is retained in the eye treated for near vision, whereas only 16% of near eyes in the present study could achieve 20/32. However, binocular UDVA is similar with both techniques and the inlay population reported by Yilmaz et al4,23 showed that binocular UDVA decreased from 100% 20/20 to 73% 20/20 between 1 and 4 years. On the other hand, micro-monovision relies on the natural process of binocular neural summation and achieves excellent binocular vision despite comparatively blurred distance vision in the near eye. This may be partly explained by the fact that even the small refractive error has been corrected in the distance eye in the present study (as demonstrated by the defocus equivalent analysis in Figure 4), but needs to be confirmed by further study. The safety of corneal inlays is not yet comparable to LASIK, with a 4% to 6% loss of two lines of CDVA reported in two studies5,24 and a significant decrease in contrast sensitivity in the two studies that reported contrast sensitivity data.6,24

Refractive intracorneal inlays are also being used to treat presbyopic patients. The first refractive corneal inlays (Permavision; Anamed Inc, Anaheim, California) were associated with poor refractive predictability and loss of CDVA.25 More recent models have improved the design, such as the Flexivue Microlens (Presbia, Los Angeles, California),26 the PresbyLens (ReVision Optics Inc, Lake Forest, California), and the Invue Lens (Biovision AG, Bruggs, Switzerland). Using the Invue Lens in a population of emmetropic patients with presbyopia, binocular UDVA was 20/20 or better in 20% of patients and 20/25 or better in all patients, and binocular UNVA was J2 or better in 76% and J3 or better in 98% of patients.27 No eyes lost more than one line of CDVA; however, there was a decrease in contrast sensitivity.

Refractive lens exchange has also been used as a treatment for emmetropic presbyopes by combining clear lens extraction with multifocal or accommodating IOLs to address myopic and hyperopic refractive errors, including presbyopia, and simultaneously eliminating the need for cataract surgery in the future.9 The outcomes reported in the study of 46 eyes by Alfonso et al9 were good with mean UDVA of 20/21, mean UNVA of J1.5, and no loss of 2 lines of CDVA. However, refractive lens exchange removes all residual accommodation and intraocular surgery introduces the risk of potentially catastrophic complications, such as the 0.07% risk of endophthalmitis, 1% to 6% risk of macular edema, 0.04% risk of suprachoroidal hemorrhage, 0.25% to 0.41% risk of retinal detachment, and 7% to 31% risk of posterior capsular opacification.28 This seems a large risk to introduce for 50- to 60-year-old patients with good distance vision when less than half are likely to undergo cataract surgery during their lifetime.29

Recently, a new technique has been suggested in which a series of concentric cylindrical ring cuts are created intrastromally using a femtosecond laser to induce a central steepening to improve near vision (INTRACOR; Technolas Perfect Vision GmbH, Munich, Germany).7,8 The study by Ruiz et al7 reported mean UNVA of J1.5 at 6 months; however, 2 (2.4%) eyes lost 2 lines CDVA. A prospective study by Holzer et al8 reported mean logMAR UNVA of 0.26 (between J2 and J3) and a loss of one line of CDVA in 42% and two lines of CDVA in 8.3% of eyes. At this stage, UNVA and safety do not compare with the other treatment modalities, the long-term stability of the central induced steepening is unknown, contrast sensitivity and quality of vision have been reported to be reduced,30 refractive error cannot be corrected simultaneously, and a retreatment is not currently possible.

This aspheric micro-monovision protocol achieved functional binocular uncorrected distance and near vision without compromising safety in terms of CDVA or contrast sensitivity, while enabling simultaneous correction of even small refractive errors; a combination that has not been demonstrated with any other presbyopic treatment option.

References

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Mean Spherical Equivalent Refraction of Distance and Near Eyes Before and After Primary Treatment and All Treatments

Parameter Spherical Equivalent Refraction (Mean±SD [Range]) (D)
Eyes
Distance Near
Preoperative +0.25±0.43 (−0.88 to +1.00) +0.24±0.48(−0.88 to +1.00)
Intended after primary treatment −0.01±0.04 (−0.13 to 0.00) −1.52±0.09 (−1.88 to −1.00)
Attempted +0.26±0.43 (−0.88 to +1.00) +1.76±0.49 (+0.63 to +2.75)
After primary treatment +0.04±0.34 (−0.75 to +1.13) −1.46±0.42 (−2.50 to −0.38)
Difference between eyes after primary treatment 1.50±0.48 (0.38 to 3.13)
Intended after all treatments −0.01±0.04 (−0.13 to 0.00) −1.53±0.11 (−1.88 to −1.00)
1 year after all treatments −0.01±0.26 (−0.75 to +0.75) −1.49±0.40 (−2.50 to −0.50)
Difference between eyes 1 year after all treatments 1.48±0.44 (0.38 to 2.50)

Preoperative Patient Characteristics and Target Spherical Equivalent Refraction in the Near Eye

Parameter Mean±SD (Range)
Cylinder (D) 0.44±0.31 (0.00 to 1.25)
Corneal thickness (μm) 546.1±29.8 (484 to 673)
Pupil diameter* (mm)
  Scotopic 5.40±0.75 (3.36 to 7.50)
  Mesopic 4.57±0.73 (3.01 to 6.79)
Keratometry (D) 43.20±1.30 (39.40 to 47.50)

Target SE (D) No. of Patients (%)

−1.00 1 (0.7)
−1.25 5 (3.4)
−1.38 1 (0.7)
−1.50 117 (79.1)
−1.63 18 (12.2)
−1.75 7 (4.7)
−1.88 1 (0.7)

Incidence of Cross-blur Postoperatively


No. of Eyes (%)
3 Months After Primary Treatment (n=148) 1 Year After All Treatments (n=148)
None 86 (58) 114 (77)
Trace 27 (18) 24 (16)
Mild 25 (17) 5 (3)
Moderate 10 (7) 5 (3)
Severe 0 (0) 0 (0)

Mean Normalized Mesopic Contrast Sensitivity Ratio Before and After the Primary Treatment

CPD Preoperative Postoperative PValue
3 0.95 0.96 .016*
6 0.95 0.95 .669
12 0.97 0.96 .270
18 0.94 0.92 .530

Change in Spherical Aberration*

Eyes Preop After Primary Treatment Change in SA
Distance 0.14±0.13 (−0.19 to 0.49) 0.07±0.15 (−0.32 to 0.60) −0.08±0.10 (−0.36 to 0.24)
Near 0.15±0.12 (−0.18 to 0.44) −0.13±0.15 (−0.51 to 0.37) −0.29±0.11 (−0.53 to 0.00)

10.3928/1081597X-20120723-01

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