Photorefractive Keratectomy and LASIK for the Correction of Hyperopia: 2-year Follow-up

Photorefractive Keratectomy: Technical Evolution, Refractive Outcomes, Corneal Wound Healing Response, and Complications

Photorefractive keratectomy (PRK) was the first excimer laser procedure developed to treat refractive errors. The safety and efficacy of PRK established it as one of the most performed corneal refractive procedures worldwide. With the introduction of laser in situ keratomileusis (LASIK), and more recently keratorefractive lenticule extraction (KLEx) procedures, many corneal surgeons favor these newer corneal procedures as the first choice due to faster visual rehabilitation and less discomfort during the early postoperative period. Importantly, however, PRK remains a viable alternative for most corneal refractive candidates and there are many situations in which PRK remains the refractive procedure of choice. This review addresses the technical evolution of PRK-mechanical epithelial debridement versus alcohol-assisted epithelial removal versus excimer laser-assisted epithelial debridement (transepithelial) PRK-and reports the PRK refractive outcomes compared to other keratorefractive laser procedures. The corneal wound response associated with each PRK technique and the indications, limitations, and complications of PRK are reviewed to aid refractive surgeons to best position PRK in their overall practice. [J Refract Surg. 2024;40(10):e754-e767.].

Lenticule Intrastromal Keratoplasty for the Correction of Iatrogenic High Hyperopia

PURPOSE

The aim of this study was to evaluate the safety, efficacy, and predictability of lenticule intrastromal keratoplasty (LIKE) for the correction of iatrogenic high hyperopia.

METHODS

Three patients (4 eyes) were referred to our department because of overcorrection of myopia induced by femtosecond laser-assisted in situ keratomileusis. All eyes exhibited hyperopia (between +4.00 and +8.00 D) and thin corneas ranging from 307 to 378 μm. Because of the regression of the use of laser ablation to correct high hyperopia and thin corneas, we initially adopted LIKE to correct iatrogenic high hyperopia in all 4 eyes. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, corneal topography, and anterior segment optical coherence tomography findings were recorded during each follow-up evaluation.

RESULTS

No postoperative complications, such as interface haze and opacification, were observed in the 4 eyes during each follow-up evaluation, with an average follow-up of 9.50 months. All eyes had significantly improved UDVA postoperatively. A total of 3 eyes achieved an UDVA of 20/25 or better while the other 1 eye had an UDVA of 20/40 postoperatively. In addition, 2 of the 4 eyes had a postoperative UDVA equal to or better than preoperative CDVA. No eyes lost any CDVA lines. All 4 eyes were within ±0.50 D of the spherical power (intended target of 0). The central corneal thickness and curvature of the anterior corneal surface in all 4 eyes increased postoperatively. Anterior segment optical coherence tomography revealed that the lenticule was transparent, with no wrinkles or offsets, during each follow-up evaluation.

CONCLUSIONS

LIKE for the correction of iatrogenic hyperopia has good efficacy and safety. Although an extremely thin cornea after overcorrection may not be suitable for hyperopic laser enhancement, LIKE is a good choice because of its good predictability and ability to restore the normal corneal structure.

Visual outcomes and corneal densitometry after allogenic and autologous lenticule intrastromal keratoplasty for the correction of moderate-to-high hyperopia

AIM

This study aimed to evaluate the visual outcomes and corneal densitometry (CD) after allogenic lenticule intrastromal keratoplasty (AL-LIKE) and autologous lenticule intrastromal keratoplasty (AU-LIKE) for the correction of moderate-to-high hyperopia.

METHODS

Ten subjects (14 eyes) underwent AL-LIKE and eight (8 eyes) underwent AU-LIKE. Patients were examined preoperatively and 1 day, 1 month, and 6 months postoperatively. The visual outcomes and CD for both surgical methods were evaluated.

RESULTS

No postoperative complications were observed with either method. The efficacy index was 0.85±0.18 and 0.90±0.33 in the AL-LIKE and AU-LIKE groups, respectively. The safety indices were 1.07±0.21 and 1.25±0.37 in the AL-LIKE and AU-LIKE groups, respectively. The CD values of the anterior, central, and posterior layers in the AL-LIKE group increased significantly at 1 day postoperatively (all P < 0.05). The CD values of the anterior and central layers remained significantly higher than the preoperative values at 6 months postoperatively (all P < 0.05). The CD values of the anterior layer in the AU-LIKE group increased significantly 1 day postoperatively (all P < 0.05) and decreased to preoperative values (all P > 0.05) 1 month postoperatively.

CONCLUSION

Both AL-LIKE and AU-LIKE exhibit good efficacy and safety in correcting hyperopia. However, AU-LIKE may have a smaller affected area and faster recovery time than those associated with AU-LIKE related to changes in corneal transparency.

Long-term results of hyperopic ablations using alcohol-assisted PRK and FS-LASIK: comparative study

PURPOSE

To evaluate the long-term visual and refractive outcomes of hyperopic excimer ablation using alcohol-assisted photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).

SETTING

American University of Beirut Medical Center, Beirut, Lebanon.

DESIGN

Retrospective, matched comparative study.

METHODS

Eyes that underwent alcohol-assisted PRK were compared to matched eyes that underwent FS-LASIK. All patients were followed up for at least 3 years after surgery. The refractive and visual outcomes of each group were compared at different postoperative time points. The main outcome measures were spherical equivalent deviation from target (SEDT), manifest refraction, and visual acuity.

RESULTS

83 eyes underwent alcohol-assisted PRK and 83 matched eyes underwent FS-LASIK. Preoperative manifest refraction spherical equivalent was 2.44 ± 1.18 diopters (D) and 2.20 ± 0.87 D ( P = .133) in the PRK and FS-LASIK groups, respectively. Preoperative manifest cylinder was -0.77 ± 0.89 D and -0.61 ± 0.59 D ( P = .175) for the PRK and LASIK groups, respectively. 3 years postoperatively, SEDT was 0.28 ± 0.66 D and 0.40 ± 0.56 D for the PRK and LASIK groups, respectively ( P = .222), whereas manifest cylinder was -0.55 ± 0.49 D and -0.30 ± 0.34 D for PRK and LASIK, respectively ( P < .001). The mean difference vector was 0.59 ± 0.46 for PRK and 0.38 ± 0.32 for LASIK ( P < .001). 13.3% of PRK eyes and 0% of LASIK eyes had >1 D of manifest cylinder ( P = .003).

CONCLUSIONS

Both alcohol-assisted PRK and FS-LASIK are safe and effective for the treatment of hyperopia. PRK induces slightly more postoperative astigmatism than LASIK. Larger optical zones and recently introduced ablation profiles that lead to a smoother ablation surface might improve the clinical results of hyperopic PRK.

Twelve-month outcomes of single-step transepithelial photorefractive keratectomy for moderate hyperopia and hyperopic astigmatism

BACKGROUND

Conventional mechanical or alcohol-assisted photorefractive keratectomy (PRK) techniques for correction of hyperopia and hyperopic astigmatism were associated with inconsistent results. The aim of this study is to evaluate the 12-month visual and refractive outcomes of the relatively new single-step transepithelial photorefractive keratectomy (TE-PRK) for moderate hyperopia and hyperopic astigmatism.

METHODS

This is a prospective interventional study. Forty-eight eyes of 30 patients with moderate hyperopia or hyperopic astigmatism with a cycloplegic spherical equivalent refraction (SEQ) between 2.0 and 4.5 diopters (D) underwent single-step StreamLight® TE-PRK using EX500 excimer laser (Alcon Laboratories, USA). The main outcome measures were recorded at 6 and 12 months postoperatively including assessment of logarithm of the minimum angle resolution (logMAR) uncorrected and corrected distance visual acuity (UDVA, CDVA), cycloplegic refraction, corneal topographic changes as well as post-PRK peripheral haze grading.

RESULTS

The mean preoperative cycloplegic SEQ was significantly reduced from 3.21 ± 0.61 D to 0.35 ± 0.04 D and 0.41 ± 0.04 D at 6 and 12 months, respectively (P < 0.001). The mean preoperative UDVA significantly improved from 0.53 ± 0.02 logMAR to 0.07 ± 0.01 logMAR and 0.08 ± 0.01 logMAR at 6 and 12 months, respectively (P < 0.001) while the mean preoperative logMAR CDVA showed non-significant change over time throughout the study (P = 0.135). At the end of the study, 41 eyes (85.4%) achieved UDVA of 20/25 or better and no eye lost any lines of CDVA. Thirty-eight eyes (79.1%) had a postoperative cycloplegic cylinder of 0.5 D or less at 12 months. The mean preoperative mean keratometry showed significant increase at 6 and 12 months postoperatively (P < 0.001) while there was no significant change between the two postoperative visits denoting topographic stability (P = 0.058). The mean postoperative Q value at 6 and 12 months showed a significant prolate shift (P < 0.001). No haze was observed in 62.5% and 85.4% of the enrolled eyes at 6 and 12 months, respectively.

CONCLUSIONS

Single-step StreamLight® TE-PRK for moderate hyperopia and hyperopic astigmatism achieved acceptable visual and refractive outcomes.

TRIAL REGISTRATION

(Clinicaltrials.gov): NCT05261685, 2 March 2022, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05261685.

Refractive Effect of Epithelial Remodelling in Myopia after Transepithelial Photorefractive Keratectomy

(1) Introduction: We analysed epithelial changes after the treatment of moderate myopia with transepithelial photorefractive keratectomy. (2) Materials and Methods: We used optical coherence tomography data and analysed changes in the stroma and epithelium after ablation. We aimed to ascertain how much epithelium hyperplasia occurred after TransPRK; for this, we used data from 50 eyes treated with TransPRK with the AMARIS 1050 Hz, with a minimum follow-up of 4 months. (3) Results: The measured epithelial changes corresponded to a less than 0.1 ± 0.2D of spherical effect, less than 0.2 ± 0.2D of astigmatic effect, and less than 0.5 ± 0.2D of comatic effect. (4) Conclusions: The changes in epithelial thickness after aberration-neutral transepithelial photorefractive keratectomy for moderate myopia were very small, indicating a low level of epithelial hyperplasia without resembling a regression-inducing lentoid.

Refractive Surgery for Older Children and Adults with Accommodative Esotropia: A Systematic Review

INTRODUCTION

Accommodative esotropia (AET) is characterized by an esodeviation of the eyes due to uncorrected hyperopia, deficient fusional divergence, or high accommodative convergence. Decreasing hyperopia would reduce accommodative convergence and strabismus. We sought to review the existing evidence regarding the outcomes of refractive surgery in patients with AET.

METHODS

A four-database search (Pubmed, ISI Web of Science, Cochrane, and Scopus) was performed from inception to March 2021 using the following MeSH terms: ("Refractive Surgical Procedures" OR "Keratomileusis, Laser In Situ" OR "Photorefractive Keratectomy" OR "Lens Implantation, Intraocular") AND ("Esotropia" OR "Accommodative Esotropia" OR "Refractive Esotropia" OR "Accommodative Strabismus"). No meta-analysis was performed due to studies' heterogeneity.

RESULTS

Twenty-eight studies including 22 case series enrolling 378 patients and 6 case reports enrolling 8 patients were selected among 185 original abstracts. In the case series, a total of 378 patients (726 eyes) were recruited with an age range of 8-52 years. All studies reported mean follow-up periods of at least 12 months. Photorefractive keratectomy was performed in 7 studies, laser-assisted in situ keratomileusis in 9 studies, laser-assisted sub-epithelial keratectomy was reported in 1 study, and 3 studies implanted intraocular lenses, including iris-fixated and collamer. Considering the adult patients with a preoperative corrected esodeviation ≤10 prism diopters (PD) (n = 129), all but 5 (3.9%) presented orthophoria or ≤10PD after refractive surgery. All children but 4 (4.5%) ended up with an esodeviation ≤10PD after surgery with those exceptions being in the range of 11-15PD. Six case reports were included in this review, comprising a total of 8 patients (16 eyes) with an age range of 7-34 years and a follow-up range of 4-48 months. Six case reports were included in this review, comprising a total of 8 patients (16 eyes) with an age range of 7-34 years and a follow-up range of 4-48 months.

CONCLUSION

Evidence produced so far points out that refractive surgery may be an alternative for spectacle correction for adults with AET ≤10PD. There is not enough evidence to recommend its use for patients under 18 years of age. The safety and predictability of these procedures for this purpose remains unclear as the selection criteria used for these patients are much different than the usual indications and there are no studies with long-term follow-up.

[Anatomical and morphometric features of anterior eye segment structures in hyperopia and the risk of developing primary angle-closure glaucoma]

PURPOSE

To study features of anatomical and morphometric parameters of the structures of anterior eye segment in young patients with moderate and high hyperopia in order to identify the signs of an increased risk of developing primary angle-closure glaucoma (PACG) and its acute attack.

MATERIAL AND METHODS

The study included 160 eyes (80 patients) with axial length (AL) of less than 23 mm. Patients with moderate or high hyperopia were divided into two groups according to their age ranges (the 1^st - 27 patients (54 eyes) under 40 years old; the 2^nd - 27 patients (54 eyes) of 41-50 years old, the comparison group - 26 patients (52 eyes) of 42-50 years old with the initial stage of PACG. AL of the eyes, anterior chamber (AC) depth in the central zone, lens thickness (LT) in the optical zone were measured using IOL Master 700 («Carl Zeiss Meditec AG», Germany). AC volume and peripheral AC depth were measured using rotating Scheimpflug camera Pentacam («Oculus», Germany).

RESULTS

While the average values of AL in patients of the 1^st and 2^nd groups were comparable, a statistically significant decrease in AC depth and a significant increase in LT were revealed in the 2^nd group. There was a statistically significant increase in LT, a decrease in peripheral AC depth and AC volume in the comparison group relative to the 2^nd group. In the 1^st group: in 2 eyes of one 38-year-old patient the maximum proximity of all 3 indices to the median values of the group of patients with PACG was found; in 4 eyes of two other patients (35 and 38 years old), a combination of small AC volume with increased LT or small AC volume with small AC on the periphery was noted.

CONCLUSION

Significant differences in terms of LT, peripheral AC depth and AC volume were found between age-comparable (41-50 years old) healthy individuals with short eyes and patients with initial PACG. In 11% of the eyes of healthy patients with hyperopia aged 21 to 40 years, there was a combination of two or three of the studied morphometric signs, which may indicate the risk of developing PACG.

Bilateral Refractive Lens Exchange With Trifocal Intraocular Lens for Hyperopia in Patients Younger Than 40 Years: A Case-Control Study

PURPOSE

To evaluate visual outcomes, satisfaction, and spectacle independence in non-presbyopic hyperopic patients who underwent bilateral refractive lens exchange with a trifocal intraocular lens (IOL) and to compare them with presbyopic hyperopic patients.

METHODS

In this retrospective study, patients younger than 40 years underwent bilateral refractive lens exchange with a diffractive trifocal IOL (FineVision Micro F; PhysIOL SA) for hyperopia with at least 3 months of follow-up. A control group of patients older than 50 years was matched by axial length, sex, and follow-up. Safety, efficacy, predictability, patient satisfaction, and spectacle independence were evaluated.

RESULTS

One hundred thirty-three patients (average age = 36.94 ± 2.91 years; range = 21.50 to 40 years) were included in this study. After a mean follow-up of 8.83 ± 5.69 months (range = 2.75 to 77.63 months), the safety and efficacy indexes and predictability within ±1.00 diopters (D) were 1.02%, 0.98%, and 99.62%, respectively, which was not different from the control group (P > .05). No intraoperative complications were recorded. The only postoperative complication was posterior capsule opacification in 21 eyes (7.89%), which was similar to the control group (P > .05). Ninety-seven percent of patients in each group expressed that they were satisfied and all of them in each group reported that they did not use spectacles for distance, intermediate, or near vision.

CONCLUSIONS

Refractive lens exchange and trifocal IOL implantation for hyperopia in patients without presbyopia provided the same good visual outcomes as in presbyopic patients with a high rate of patient satisfaction and spectacle independence. [J Refract Surg. 2021;37(8):524-531.].

Causes for Rejection of Keratorefractive Surgery in a Central Indian Population

Aim

To identify the reasons for refusing refractive surgery in patients visiting for spectacle-free vision.

Methodology

Medical records of 296 patients who presented for keratorefractive surgery (KRS) from June 2017 to April 2020 at a tertiary eye care center in central India (Government Medical College and Hospital, Nagpur, Maharashtra, India) were reviewed. Demographic details of all the patients and parameters obtained during workup of a case presented for KRSs were captured in an Excel^® sheet and analyzed statistically.

Results

Of the 296 patients who presented for KRS during the study period, 86 (29.1%) patients were denied KRS. The mean pachymetry in the right eye was 505 μm ± 10 μm (range 520-485 μm) and 502 μm ± 7 μm (511-490 μm) in the left eye. Suboptimal corneal thickness (n = 28, 32.6%) was the most common reason for rejection. Other reasons for not recommending the procedure were high myopia (n = 20, 23.3%), spectacle not stable (n = 16, 18.6%), and keratoconus (n = 11, 12.8%). Collagen vascular diseases (n = 3, 3.5%) and anxiety about the procedure (n = 2, 2.3%) were causes unrelated to the procedure. No correlation was observed between corneal thickness and degree of myopia (r = 0.014, p = 0.66).

Conclusion

Patients presenting for KRS exhibit various problems. Meticulous preoperative evaluation is most important for long-term visual outcome. Suboptimal corneal thickness, high myopia, unstable spectacle correction, and keratoconus were the common reasons for not performing KRS in the study population.

[Regression and ablation profiles in corneal refractive surgery]

Regression after corneal refractive surgery is a complex phenomenon which seems inevitable. The choice of surgical technique has very little influence on regression for low myopia or myopic astigmatism. However, LASIK and SMILE are the two techniques of choice in the correction of high myopia. LASIK is also better for the correction of hyperopia, hyperopic astigmatism and mixed astigmatism. Intraoperatively, the choice of a wide optical zone and adherence to a thick residual stromal bed provide stability. Regression may also be reduced by modulating anti-inflammatory therapy, treating dry eye, and using mitomycin C in PKR. In all cases, obtaining keratometry during patient follow-up helps to identify the cause of the regression. The objective of this review is to synthesize recent data from the literature on regression in refractive surgery as a function of the ablation profiles used.

Comparison of Visual Outcome After Hyperopic LASIK Using a Wavefront-Optimized Platform Versus Other Excimer Lasers in the Past Two Decades

Introduction

Laser-assisted in-situ keratomileusis (LASIK) for the correction of hyperopia and hyperopic astigmatism is challenging and has been less studied than for the correction of myopia and myopic astigmatism. The aim of this study was to analyze the refractive outcomes of LASIK in hyperopia and hyperopic astigmatic eyes using a wave-front optimized laser platform (the Allegretto EX500 laser) and perform a historical comparison with other excimer lasers within the past two decades.

Methods

A one-center (Tertiary Refractive Center, Draper, Utah), retrospective, non-comparative study was conducted on 379 eyes treated with LASIK for hyperopia and hyperopic astigmatism. The data retrieved on these eyes were analyzed using uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and spherical equivalents. A literature search of excimer platforms in use in the past 20 years and a comparison of US Federal Drug Administration-approved platforms for hyperopia were performed.

Results

At 3 and 12 months postoperatively, 142 (66%) and 81 (69%) eyes had a UDVA of 20/20 or better and 207 (96%) and 114 (97%) eyes had a UDVA of 20/40 or better, respectively. The mean refractive spherical equivalent was − 0.52 ± 0.78 D at 3 months and − 0.46 ± 0.79 D at 12 months. At 12 months, 181 (96%) eyes achieved a spherical equivalent within ± 1.00 D of the intended target. Studies published before 2005 reported lower rates of UDVA 20/20 or better (32%) compared to those published after (68%); however, this discrepancy was less evident for UDVA 20/40 or better. A similar trend towards improved accuracy was noted in the literature with postoperative manifest refractive spherical equivalent within ± 0.50 D before and after 2005.

Conclusion

There has been significant improvement in safety, efficacy, stability, and accuracy of LASIK treatment for hyperopia and hyperopic astigmatism within the past two decades. Newer excimer lasers meet industry standards and in particular, the Allegretto EX500 used in this study exceeded industry standards.

[Refractive surgery for hyperopia]

Hyperopia is a refractive error in which light is focused behind, instead of on, the retina. Clear vision can be obtained by accommodation, but in the long run, this results in eye strain. Hyperopia can be classified as low [≤2.00 diopters (D)], moderate (2.00-4.00 D) and high (>4.00 D). Detailed preoperative evaluation is necessary and essential to obtain good postoperative results. Various surgical techniques can be proposed to correct this ametropia. The main techniques used act either by modifying the corneal curvature with the Excimer laser or by implanting a phakic intraocular lens. The anatomical peculiarities of the hyperopic eye (small corneal diameter, short axial length, narrow anterior chamber or large kappa angle) make refractive surgery for hyperopia a considerable challenge. Large optical ablation zones now allow correction of high hyperopia by reducing the risks of optical aberrations and regression. The patient must be informed and understand the postoperative course, which differs from that of surgery for myopia.

Femtosecond-LASIK outcomes using the VisuMax®-MEL® 80 platform for hyperopia and hyperopic astigmatism refractive surgery

The present study evaluated the efficacy, the safety and the predictability of the Femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) procedure for hyperopia and hyperopic astigmatism. We retrospectively analyzed the postoperative 12-month evolution of 593 eyes with hyperopia and hyperopic astigmatism that underwent Femto-LASIK treatment. The procedure was predictable and effective. No eye lost 2 lines of corrected distance visual acuity (CDVA), demonstrating a safety profile of the procedure. Nine percent of the eyes gained at least one line of CDVA. The accuracy of the spherical equivalent after 12 months was 74% within ±1.0 diopter (D) of emmetropia. The refractive outcomes were stable during the follow-up period. There were no significant complications during the procedure. Femto-LASIK using the VisuMax^®-MEL^® 80 platform was demonstrated to be a suitable option to correct selected cases of hyperopia and hyperopic astigmatism. A longer follow-up period is required to better assess the refractive results and to detect any further regression.

The relationship between patient age and residual refractive error after uneventful laser in situ keratomileusis for moderate-to-high hyperopia

PURPOSE

To determine if the manifest sphero-cylindrical residual refractive error, at various time points over a 12-month postop period after laser in situ keratomileusis (LASIK) was associated with patient age at time of surgery.

METHODS

Patients with moderate to high hyperopia (3.00-7.00 DS) and astigmatism ⩽2 DC underwent LASIK using Wavelight Allegretto Eye Q (400 Hz). Treatments were centered on corneal vertex, flaps were made with Moria M2 mechanical microkeratome. Pre-and postoperative uncorrected and corrected distant visual acuity, best corrected spherical equivalent (SEQ) were measured. Measurements were taken at 1 week, 1, 3, 6, and 12 months after the surgery. Target refraction was emmetropia. Total of 161 patients were treated. In binocular cases, data from the right eyes were included for analysis. In this article, we report on refraction data only. Raw data were subjected to several permutations to elicit any links between refractive outcomes and patient age.

RESULTS

The key findings were as follows y = postop SEQ (diopters), x = patient age (years), ln(x) = natural logarithm of patient age: At 1 month, y = x[0.049 -0.011.ln(x)] (R = -0.205, p = 0.001, n = 161). At 3 months, y = x[0.077 -0.017.ln(x)] (R = -0.355, p < 0.001, n = 161). At 6 months, y = x[0.088 -0.020.ln(x)] (R = -0.382, p < 0.001, n = 161). At 12 months, y = x[0.093 -0.021.ln(x)] (R = -0.409, p < 0.001, n = 161). There was no significant association between x and y at 1 week (p > 0.05).

CONCLUSION

Residual postop refractive error after LASIK for hyperopia has a logarithmic association with patient age at time of surgery. In younger patients there is tendency toward undercorrection, the opposite occurs in older patients and this persists 1 year after treatment.

Preliminary effects of treating the half of high latent hyperopia on refractive and visual results of femtosecond laser-assisted in situ keratomileusis in subjects with hyperopia

BACKGROUND

To evaluate the preliminary effects of treating the half of high latent hyperopia on refractive and visual outcomes of femtosecond laser-assisted in situ keratomileusis (LASIK) in young subjects with hyperopia.

METHODS

This non-randomized comparative study includes 120 eyes of 60 subjects who underwent femtosecond LASIK to correct hyperopia. Group 1 (n = 60) includes subjects with ≤ 1D algebraic difference (DRSE) between cycloplegic (CRSE) and manifest (MRSE) refraction spherical equivalents and was treated by entering manifest refraction values. Group 2 includes subjects with > 1D DRSE and was treated by entering the mean manifest and cycloplegic refraction values. Refractive and subjective outcomes obtained at the 1-, 3-, and 6-month postoperative visits were compared.

RESULTS

The mean age of the subjects was 26.2 ± 3.5 and 26.2 ± 5.2 years for Group 1 and Group 2, respectively. The male-to-female ratios were 10/10 in both groups. Demographic values of the groups were similar (p > 0.05). Preoperative MRSE values were similar (p = 0.924), while CRSE and DRSE values were significantly higher in Group 2 (p < 0.001). At the 1- and 3-month postoperative visits, MRSE was higher and uncorrected distance visual acuity (UDVA) was lower in Group 2 (p < 0.001). Subjective visual parameters and quality of vision scores were also worse in Group 2 during these visits (p < 0.001); however, at the 6-month visit, all outcomes for Group 2 improved, and MRSE, UDVA, some subjective visual parameters, and quality of vision scores became similar between groups (p > 0.05).

CONCLUSION

At the 6-month visit after treating the half of > 1D latent hyperopia with femtosecond LASIK, refractive and visual outcomes like MRSE, UDVA, subjective visual parameters, and quality of vision scores become similar to those obtained in ≤ 1D latent hyperopia.

Stability of corneal topography and aberrometry after hyperopic laser in situ keratomileusis with a 500-Hz excimer laser platform: A 3-year follow-up study

PURPOSE

The aim of this study is to analyze the long-term stability of the corneal topography, the functional optical zone, and the refractive stability throughout 3 years following laser in situ keratomileusis surgery for hyperopia using a 500-Hz excimer laser system.

METHODS

This retrospective consecutive observational case series study comprised 66 eyes that underwent laser in situ keratomileusis to correct hyperopia with a postoperative follow-up of 3 years. Laser in situ keratomileusis procedures were performed using the SCHWIND Amaris 500-Hz excimer laser. Main outcomes measured were stability of the functional optical zone at corneal topography and corneal aberrometry.

RESULTS

Statistically significant differences were found in simulated keratometry (K2 (steep meridian) and Km (mean keratometry)) between 3 and 36 months postoperatively (p ⩽ 0.01); these differences disappeared at 12 and 36 months (p ⩾ 0.18). No statistically significant changes were observed in the horizontal and vertical diameter of the functional optical zone throughout the whole follow-up (p ⩾ 0.07). A statistically significant difference was found in the spherical aberration between 3 and 36 months (p = 0.02); this difference disappeared when compared between 12 and 36 months (p = 0.72). Statistically significant correlations were detected between the vertical functional optical zone and coma root mean square (r = -0.510, p < 0.01) and between the vertical functional optical zone and spherical aberration (r = 0.441, p = 0.02) 36 months after surgery.

CONCLUSION

Following 3 years of hyperopic laser in situ keratomileusis with a 500-Hz Amaris excimer laser, keratometry, functional optical zone, and corneal aberrations remain stable from 1 year after surgery. Topographical regression is not observed in hyperopic laser in situ keratomileusis with this excimer laser technology from 1 year after surgery.

Photorefractive keratectomy influences the angle of ocular deviation in strabismus patients with hyperopia

PURPOSE

To evaluate refractive, binocular vision and ocular alignment outcomes of photorefractive keratectomy (PRK) for the treatment of hyperopia in esotropic patients.

METHODS

Medical charts of hyperopic patients with full or partial accommodative esotropia (FAE or PAE) or consecutive exotropia (CE) undergone PRK from 2011 to 2014 were reviewed. The primary outcome was to assess the efficacy of PRK in improving ocular alignment. The secondary outcomes were the assessments of uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent (SE) and stereoacuity.

RESULTS

Sixty-four eyes of 32 hyperopic patients were included. Three patients were affected by FAE, 24 by PAE and 5 by CE. All FAE patients and 4 PAE patients underwent only PRK; the remaining 25 patients underwent PRK plus strabismus surgery. After PRK, the mean corrected esodeviation decreased significantly in the overall esotropic population [7.15 ± 9.42 prism diopters (PD) vs. 5.04 ± 8.83 PD; p = 0.03] and in particular in the group with small-angle esodeviation (< 20 PD). Conversely, the only 2 patients with an angle of strabismus ≥ 20 PD as well as all CE patients did not show any postoperative variation of the deviation angle. Mean preoperative BCVA did not differ from postoperative UCVA (p = 0.19), while the mean postoperative SE decreased significantly after PRK (p < 0.0001).

CONCLUSIONS

Our study confirmed that PRK eliminates the accommodative component of the deviation. In addition, this procedure seems to reduce or eliminate also the non-accommodative component of esodeviation (especially in small-angle deviation), thus suggesting to postpone strabismus surgery after PRK when esotropia and hyperopia coexist.

Induction of Controlled Wound Healing with PMMA Segments in the Deep Stroma in Corneas of Hens

Purpose

Polymethylmethacrylate (PMMA) segments are normally used in additive surgery to treat both corneal ectasia post laser-assisted in situ keratomileusis and keratoconus. The aim of this work was to develop an experimental animal model to induce wound healing in the deep stroma in corneas of hens.

Methods

PMMA segments were implanted in the right eyes of 40 adult hens without suture in the wound incision. Animals were randomized for 5 time points to histopathology study (1, 3, 15, 30, and 90 days) being clinically evaluated during the experiment.

Results

Thirty-four eyes (85%) had a successful clinical outcome and intraoperative mistakes occurred in 6 eyes (15%), including anterior chamber perforation resulting in abscess (1), excess of lamellar dissection with segment migration (3), and peripheral incisions evolving with neovascularization (2). At 24 hours, all the epithelial injuries were completed in integrity, but a persistent stromal incision, with a fish mouth form, was observed until day 15. Corneal edema disappeared at the fifth day. Haze, keratocyte cell death, keratocyte proliferation, myofibroblast differentiation, and new matrix production were observed in length around the segment.

Conclusions

Wound healing was induced in the deep corneal stroma by means of PMMA segment implantation in a new animal model developed in hens.

Outcomes of retreatment after hyperopic laser in situ keratomileusis

PURPOSE

To evaluate the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) retreatment in eyes with hyperopia.

SETTING

Multicenter refractive surgery centers and University Hospital, Germany.

DESIGN

Retrospective case series.

METHODS

This multicenter study included hyperopic patients with a preoperative difference between cycloplegic and manifest refraction of 1.00 diopter (D) or less who had LASIK retreatment based on manifest refraction. The refractive outcome was analyzed according to standard graphs for reporting the efficacy, predictability, and safety of refractive surgery.

RESULTS

One hundred thirteen eyes of 113 consecutive hyperopic patients were enrolled. Efficacy (P < .001) and safety (P = .004) were statistically significantly improved by retreatment without being negatively influenced by preoperative manifest spherical equivalent (SE), manifest cylinder, or keratometry. In cases still showing a trend toward undercorrection, retreatment resulted in 88 eyes (78.0%) being within ±0.50 D of the attempted correction. The optical zone (OZ) diameter of the retreatment did not correlate with efficacy, predictability, or safety.

CONCLUSIONS

Retreatment after hyperopic LASIK resulted in high efficacy, predictability, and safety outcomes. The efficacy and safety of the retreatment were not affected by preoperative manifest SE, manifest cylinder, keratometry, or OZ diameter.

Outcomes of photorefractive keratectomy following laser in situ keratomileusis: a cohort study

OBJECTIVE

To analyze the outcomes of photorefractive keratectomy (PRK) on residual myopia and hyperopia post-laser in situ keratomileusis (LASIK) and to compare these results with PRK on eyes without previous laser refractive surgery.

DESIGN

Retrospective comparative cohort study.

PARTICIPANTS

Patients undergoing PRK between 2006 and 2010 were reviewed.

METHODS

Patients were divided into 4 groups, myopic or hyperopic PRK post-LASIK (mPRK-PL and hPRK-PL, respectively) and myopic or hyperopic PRK on corneas without previous laser refractive surgery (mPRK and hPRK, respectively). Uncorrected and corrected distance visual acuity, mean refractive spherical equivalent (MRSE), and mean keratometry and aberrations (total, higher order [HOA], coma, trefoil, and spherical aberration) were recorded at months 3 and 6 postoperatively, as were complications and attempted versus achieved MRSE.

RESULTS

Thirty-three eyes of 25 patients who underwent PRK post-LASIK (21 eyes of 14 patients for hPRK-PL and 12 eyes of 11 patients for mPRK-PL) and 35 eyes of 21 patients who underwent PRK on virgin eyes (11 eyes of 8 patients for hPRK and 24 eyes of 13 patients for mPRK) were included in the study. The only significant differences in outcomes were found to be HOA at 3 months for hPRK-PL as compared with both hPRK and mPRK. Achieved MRSE was significantly different from expected MRSE for hPRK-PL at 3 months postoperatively. No haze- or flap-related complications were observed.

CONCLUSION

Outcomes of PRK were not different in myopic and hyperopic corrections post-LASIK by 6 months or when compared with PRK in virgin eyes. HOA may render hPRK-PL results less predictable early in the postoperative period.

Role of preoperative cycloplegic refraction in LASIK treatment of hyperopia

BACKGROUND

Previous studies have suggested that, to improve refractive predictability in hyperopic LASIK treatments, preoperative cycloplegic or manifest refraction, or a combination of both, could be used in the laser nomogram. We set out to investigate (1) the prevalence of a high difference between manifest and cycloplegic spherical equivalent in hyperopic eyes preoperatively, and (2) the related predictability of postoperative keratometry.

METHODS

Retrospective cross-sectional data analysis of consecutive treated 186 eyes from 186 consecutive hyperopic patients (mean age 42 [±12] years) were analyzed. Excimer ablation for all eyes was performed using a mechanical microkeratome (SBK, Moria, France) and an Allegretto excimer laser platform. Two groups were defined according to the difference between manifest and cycloplegic spherical equivalent which was defined as ≥1.00 diopter (D); the data was analyzed according to refractive outcome in terms of refractive predictability, efficacy, and safety.

RESULTS

In 24 eyes (13 %), a preoperative difference of ≥1.00D between manifest spherical equivalent and cycloplegic spherical equivalent (= MCD) occurred. With increasing preoperative MCD, the postoperative achieved spherical equivalent showed hyperopic regression after 3 months. There was no statistically significant effect of age (accommodation) or optical zone size on the achieved spherical equivalent.

CONCLUSIONS

A difference of ≥1.00D occurs in about 13 % of hyperopia cases. We suggest that hyperopic correction should be based on the manifest spherical equivalent in eyes with preoperative MCD <1.00D. If the preoperative MCD is ≥1.00D, treatment may produce manifest undercorrection, and therefore we advise that the patient should be warrned about lower predictability, and suggest basing conclusions on the arithmetic mean calculated from the preoperative manifest and cycloplegic spheres.

No change in anterior chamber dimensions after femtosecond LASIK for hyperopia

Objective:

To compare the changes in anterior chamber volume (ACV), anterior chamber depth (ACD) and anterior chamber angle (ACA) before and 6 months after femtosecond laser in situ keratomileusis (LASIK) for hyperopia using the Pentacam HR device.

Methods:

A total of 24 eyes of 24 consecutive hyperopic patients undergoing femtosecond LASIK were examined preoperatively and 6 months postoperatively. Anterior chamber volume; ACDs in the central, superior, inferior, nasal, and temporal quadrants; and ACA were measured using the Pentacam HR device. Comparisons of preoperative versus postoperative values were performed using paired Student t test. Linear regression analysis was performed to evaluate correlations between ACV change, central ACD change, age, and attempted maximum ablation depth.

Results:

Preoperative and postoperative mean ACVs were 153.6 and 158.2 μL, respectively. Preoperative and postoperative mean ACDs were 2.81, 2.28, 2.53, 2.16, and 2.61 mm, and 2.84, 2.31, 2.54, 2.16, and 2.65 mm, respectively. Preoperative and postoperative mean ACAs were 33.3° and 32.0°, respectively. There were not statistically significant differences in ACV, ACDs, and ACA from preoperatively to 6 months after femtosecond LASIK (all P>0.05). The change of central ACD was correlated significantly with age at 6 months postoperatively (R²=0.18, P=0.039).

Conclusions:

Anterior chamber profiles, including ACV, ACA, and central and peripheral ACDs did not significantly change after femtosecond LASIK for hyperopia.

[Safety of the automated microkeratome for Sub-Bowman's Keratomileusis on the flat cornea]

INTRODUCTION

Use of the One Use-Plus SBK (Sub-Bowman's Keratomileusis) automated microkeratome (Moria, Antony, France) has been shown to be safe, predictable and comfortable for the creation of thin corneal flaps with a smooth and regular stromal bed.

PURPOSE

To evaluate the use of the Moria One Use-Plus SBK (Moria, Antony, France) automated microkeratome on corneas with 180°-keratometry under 40 diopters (D).

METHODS

We retrospectively studied cases that underwent SBK whose 180°-keratometry was under 40 D. We separated the cases between 39 and 40 D and those less than 39 D. The preoperative data, the procedure and the postoperative outcomes were analyzed. The Moria One Use-Plus SBK microkeratome with the 90-micron head was used for all cases.

RESULTS

Among the 2883 eyes that underwent SBK LASIK over the past six years, 80 eyes (2.77%) had a preoperative topographical 180°-keratometry of less than 40 D: 63 eyes (2.19%) between 39 and 40 D and 17 eyes (0.59%) between 38 and 39 D (38.13-38.97 D). The spherical equivalent was between -3.50 D (-2.25 sph -2.50 cyl. at 175°) and+6.00 D (+5.50 sph +1.00 cyl. at 85°). Fifty-eight eyes (72.5%) had hyperopia and/or hyperopic astigmatism; 18 eyes (22.5%) had mixed astigmatism; and 4 eyes (5%) had myopia and/or myopic astigmatism. Twenty-six eyes (32%) had a history of strabismus. Thirteen patients (27.66%) had a history of amblyopia. The "-1" ring was used in all cases, with a 7.5 stop (14%) or 8 stop (86%). The procedure went uneventfully in all cases with a stable vacuum between 117 and 123 mm Hg. The nasal hinge and the stromal bed were normal in size in all cases and sufficient to perform the photoablation laser safely with an optical zone between 6.00 and 7.00 millimeters. There were no intraoperative nor immediate postoperative complications: free cap 0%; incomplete flap 0%; button hole 0%; epithelial erosion 0%; bleeding 0%; irregular stromal bed 0%. Postoperative complications: flap displacement 0%; punctate keratitis: 8%; LASIK retreatments: 12%; safety: 100% (no loss of lines of visual acuity).

DISCUSSION

Corneas with a topographical 180°-keratometry under 40 D are a very small percentage of the total eyes that undergo LASIK (SBK). Those with a 180°-keratometry under 39 D are even more infrequent. Due to the characteristics of the flat cornea, the percentage of hyperopia is much larger in than in the general LASIK group. In addition, the percentage with a history of strabismus and amblyopia is higher.

CONCLUSION

The Moria One Use-Plus SBK microkeratome is an excellent device that allows the easy creation of thin corneal flaps and regular and smooth corneal beds, safely and predictably even in extremely flat corneas without complications. The safety, efficacy and predictability are quite comparable to the general LASIK group.

[Laser Blended Vision for presbyopia: Results after 3 years]

PURPOSE

Retrospective study of the first 173 patients with presbyopia who underwent LASIK with a non-linear aspheric ablation profile and micro-monovision for the correction of presbyopia with myopia, astigmatism, hyperopia or emmetropia: Laser Blended Vision(®) Program by Carl Zeiss Meditec(®) (Jena, Germany).

METHODS

We retrospectively studied the first consecutive 173 patients with presbyopia who underwent LASIK with the wavefront-guided Laser Blended Vision(®) Program by Zeiss(®) in our Excimer Laser Zeiss Mel-80 by Carl Zeiss Meditec(®) (Jena, Germany) over the last three years in our clinic (Optima Laser Clinic, Valence, Spain). The program has a non-linear aspheric ablation profile that increases the spherical aberration in both eyes. A slight myopia of -1.5 diopters (D) in the non-dominant eye is also programmed. We analysed the results and patient satisfaction. The patients were separated into two groups: less than 50 years old and 50 years or more. Follow-up was from 1 to 28 months. We also separated two groups: follow-up under 12 months and follow-up of 12 months or more. We analysed the efficacy, safety and predictability of the procedure.

RESULTS

Seventy-nine male and 94 female patients between 42 and 69 years old were studied, for a total of 337 eyes. Only eight patients (4.62%) were between 42 and 44; 55 (31.79%) were between 45 and 49; 110 patients (63.58%) were 50 years or more. Nine patients underwent the surgery in the non-dominant eye only. Twelve (6.94%) patients were emmetropic (0.5 or less spherical equivalent), 42 (24.28%) were myopic or myopic astigmatic, and 119 (68.79%) were hyperopic or hyperopic astigmatic. One hundred and thirty-six patients (78.61%) had pre-operative near vision between J4 and J10. One hundred and seventy-one patients (98.84%) had post-operative near vision between J1 and J3; 150 (86.7%) had J1 (efficacy). Post-operative visual acuity without correction for distance was 20/20 or better in 159 patients (91.91%) (binocular). The predictability within 0.5 D was 87.86%. Safety 99.7% (336/337 eyes): one eye of a diabetic patient lost two lines BCVA. A total of 93.64% were satisfied with the procedure, 2.89% used eye-glasses for certain activities, 1.73% reported dry eye, 0.58% reported a nonspecific lack of adaptation, and there were no serious complications; 3.47% did not achieve their expectations. Twenty-four patients (13.87%) needed an enhancement, 18 of them (75.5%) for only one eye, with 88.89% of these being the non-dominant eye. Forty-nine patients (28.32%) had over 12 months follow-up, with 95.92% still satisfied.

CONCLUSIONS

Laser Blended Vision(®) is an excellent option, well tolerated, stable and effective for patients with presbyopia and myopia, astigmatism, hyperopia or emmetropia, also avoiding an intraocular procedure.

Correction of moderate to high hyperopia with an implantable collamer lens: medium-term results

PURPOSE

To evaluate the medium-term results of phakic posterior chamber implantable collamer lens implantation to correct moderate and high hyperopia.

METHODS

In this retrospective study, patients were treated for hyperopia with the Visian Implantable Collamer Lens (ICH model V3; STAAR Surgical AG, Nidau, Switzerland). Examined parameters were manifest refraction spherical equivalent, uncorrected distance visual acuity, corrected distance visual acuity, vault, anterior chamber depth, anterior chamber angle width, endothelial cell density, intraocular pressure, patient satisfaction, and complications.

RESULTS

The mean age of 15 patients (28 eyes) was 28 years (range: 18 to 36 years), with a mean follow-up period of 3.6 years (range: 3 to 6 years). The mean manifest refraction spherical equivalent decreased from +6.30 ± 1.42 diopters (D) (range: +4.25 to +8.50 D) preoperatively to -0.37 ± 0.56 D (range: -1.25 to +1.00 D) at 3 years postoperatively. The mean uncorrected distance visual acuity improved from 0.77 ± 0.38 logMAR (range: 0.16 to 1.30 logMAR) to 0.20 ± 0.17 logMAR (range: 0.00 to 0.48 logMAR) at the 3-year follow-up. Postoperatively, 62% of eyes gained one line of corrected distance visual acuity or remained unchanged. The mean vault reduced from 367.1 ± 253.6 μm (range: 70.0 to 1,190.0 μm) at 1 month postoperatively to 283.6 ± 210.0 μm (range: 75.0 to 915.0 μm) at the last follow-up visit (P = .005). The mean preoperative anterior chamber depth and anterior chamber angle width also decreased at the last follow-up visit (P = .037 and < .0001, respectively). The mean endothelial cell loss was 4.91% (P = .089). No serious complications occurred. Thirteen (87%) patients were satisfied with the outcomes and no patient was dissatisfied.

CONCLUSIONS

Implantation of a posterior chamber implantable collamer lens is a safe, effective, predictable, and stable method for the correction of moderate and high hyperopia in highly selected patients. No case of cataract or anterior subcapsular opacities formation was recorded in relation to the decrease of vault over the studied period and low vault in some eyes.

Change in keratometry after myopic laser in situ keratomileusis and photorefractive keratectomy

PURPOSE

To compare the change in keratometry (K), spherical equivalent (SE), and visual acuity after myopic laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

SETTING

Academic tertiary care center.

DESIGN

Retrospective review.

METHODS

The postoperative K, SE, and uncorrected and corrected distance visual acuities were measured 6 months, 9 months, 1 year, 2 years, 3 years, 4 to 5 years, 6 to 7 years, and 8+ years postoperatively. A difference (Δ) for each variable was calculated from its 6-month postoperative baseline. The rates of change were grouped based on the magnitude of myopic correction (0.00 to 2.99 diopters [D]; 3.00 to 5.99 D; 6.00 to 8.99 D), type of surgery (LASIK versus PRK), and age (<34 years; 34 to 45 years; >45 years).

RESULTS

Statistically significant differences were found in the rates of change between low and moderate corrections to high corrections for ΔKavg (P=.0472 and P=.0091, respectively) and ΔSE (both P<.0001). Statistically significant differences were found in the rate of change in ΔKavg between all 3 ages groups (P=.0330, P=.0051, and P<.0001) and in ΔSE between ages less than 34 years and 34 to 45 years to ages over 45 years (P=.0158 and P=.0015, respectively). There was no significant difference in the rate of change in ΔKavg and ΔSE between LASIK and PRK (P=.3599 and P=.9403, respectively).

CONCLUSION

There was keratometric and refractive regression for myopic LASIK, with the rate of regression depending on treatment magnitude and age.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Laser in situ keratomileusis for high hyperopia (>5.0 diopters) using optimized aspheric profiles: efficacy and safety

PURPOSE

To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) for high hyperopia using an excimer laser and optimized aspheric profiles.

SETTING

Vissum Corporation and Miguel Hernández University, Alicante, Spain, and Research Institute of Ophthalmology, Giza, Egypt.

DESIGN

Case series.

METHODS

Eyes of patients with high hyperopia or hyperopic astigmatism (spherical equivalent [SE] ≥ 5.64 diopters [D]) had uneventful LASIK with an aspheric optimized ablation profile centered on the corneal vertex using an Amaris 500 kHz excimer laser and a femtosecond platform for flap creation with a temporal hinge.

RESULTS

There was a significant improvement in uncorrected distance visual acuity 3 months postoperatively (P<.01), with no significant changes afterward (P=.72). At 6 months, the corrected distance visual acuity (CDVA) remained unchanged or improved in 90.48% of eyes; 2 eyes (9.52%) lost 2 lines of logMAR CDVA. The postoperative SE was within ± 0.50 D of emmetropia in 70.37% of eyes. The LASIK enhancement rate at the end of the follow-up was 29.4%. Significant induction of corneal primary spherical aberration and coma was found with 6.0 mm pupils (P<.01). The safety index was 0.94 and the efficacy index, 0.85.

CONCLUSION

Laser in situ keratomileusis for high hyperopia using optimized aspheric profiles requires further improvement in terms of safety but was still an effective and a predictable procedure.

One-year results of excimer laser in situ keratomileusis for hyperopia

PURPOSE

To evaluate the visual and refractive results of hyperopic LASIK.

SETTING

Clínica Baviera Instituto Oftalmológico Europeo, Madrid, Spain.

METHODS

This retrospective consecutive noncomparative observational study evaluated hyperopic LASIK results over 1 year. Outcomes included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), cycloplegic refraction, and corneal topography. Surgery was performed using an MEL 80-G excimer laser. Results were analyzed by preoperative spherical equivalent (SE) (Group 1: <or=+3.50 diopters [D]; Group 2: >or=+3.60 D).

RESULTS

The mean UDVA improved from 0.50 +/- 0.3 (SD) to 0.90 +/- 0.2 in Group 1 and from 0.50 +/- 0.3 to 0.80 +/- 0.2 in Group 2 and the mean CDVA, from 0.86 +/- 0.2 to 0.93 +/- 0.1 and from 0.80 +/- 0.2 to 0.90 +/- 0.2, respectively. The mean cycloplegic SE improved from +2. 5+/- 0.8 to +0.1 +/- 0.5 in Group 1 and from +4.5 +/- 0.6 to +0.4 +/- 0.6 in Group 2; 70.9% of eyes and 63.3% of eyes, respectively, were within +/-0.50 D of emmetropia. Postoperatively, 92.8% of eyes in Group 1 and 87.8% in Group 2 maintained or gained 1 or more lines of CDVA; 1.7% and 4.0%, respectively, lost 2 or more lines. The safety index was 1.1 in both groups and the efficacy index, 1.01 in Group 1 and 0.98 in Group 2. The enhancement rate was 20.0% and 18.4%, respectively.

CONCLUSION

Excimer laser LASIK was safe and effective for treating hyperopia up to +6.25 D with no further loss of CDVA lines after enhancement.

Mitomycin C in corneal refractive surgery

Mitomycin C has played a deciding role in the current revival of excimer laser surface ablation techniques. We review the literature regarding mechanism of action of mitomycin C, histological effects on the cornea, and indications, dose, exposure time, and toxicity of mitomycin C in corneal refractive surgery. Mitomycin C is an alkylating agent with cytotoxic and antiproliferative effects that reduces the myofibroblast repopulation after laser surface ablation and, therefore, reduces the risk of postoperative corneal haze. It is used prophylactically to avoid haze after primary surface ablation and therapeutically to treat pre-existing haze. There is no definite evidence that establishes an exact diopter limit or ablation depth at which to apply prophylactic mitomycin C. It is usually applied at a concentration of 0.2mg/ml (0.02%) for 12 to 120 seconds over the ablated stroma, although some studies suggest that lower concentrations (0.01%, 0.002%) could also be effective in preventing haze when treating low to moderate myopia. This dose of mitomycin C has not been associated with any clinically relevant epithelial corneal toxicity. Its effect on the endothelium is more controversial: two studies report a decrease in endothelial cell density, but the majority of reports suggest that the endothelium is not altered. Regarding mitomycin C's effect on keratocyte population, although animal studies report keratocyte depletion after its use, longer follow-up suggested that the initial keratocyte depletion does not persist over time.

LASIK for hyperopic astigmatism and presbyopia using micro-monovision with the Carl Zeiss Meditec MEL80 platform

PURPOSE

To evaluate the monocular and binocular outcomes of LASIK for a micro-monovision protocol for the correction of hyperopic astigmatism and presbyopia.

METHODS

A prospective non-comparative case series included 258 eyes of 129 consecutive patients with hyperopic astigmatism and presbyopia who were treated with LASIK-induced micro-monovision. The CRS-Master software was used to generate ablation profiles for the Carl Zeiss Meditec MEL80 excimer laser. The target refraction was piano for distance eyes (dominant eye) and between -1.00 and -1.50 diopters (D) for near eyes. Patients were followed for 1 year.

RESULTS

Mean attempted spherical equivalent refraction (SE) correction was +2.54+/-1.16 D (range: +0.25 to +5.75 D). Mean attempted cylinder was -0.52+/-0.49 D (range: -0.00 to -3.25 D). Median age was 56 years (range: 44 to 66 years). Median follow-up was 12.5 months (range: 3.3 months [early retreatment] to 18.2 months). The retreatment rate was 22%. Outcome measures after all treatments were as follows. Mean deviation from the intended SE correction was +0.09+/-0.48 D, with 79% of eyes within +/-0.50 D and 95% within +/-1.00 D. The cylinder correction ratio was 1.23+/-0.63 and the error ratio was 0.67+/-0.65. Of the distance eyes, 86% achieved uncorrected visual acuity of 20/20 and 100% achieved 20/40. Binocularly, 95% of patients achieved 20/20 and 100% achieved 20/40. Eighty-one percent of patients could read J2 and 100% could read J5. Binocularly, 95% of patients achieved 20/20 and could read J5. No eyes lost 2 or more lines of best spectacle-corrected visual acuity. A statistically significant increase was noted in contrast sensitivity at 3 and 6 cycles per degree (cpd), with no reduction at 12 and 18 cpd. The average change in refraction between 3 months and 1 year was +0.11+/-0.36 D with a change of >1.00 D in 2.6% of eyes.

CONCLUSIONS

This hyperopic micro-monovision protocol was a well-tolerated and effective procedure for treating patients with presbyopia in moderate to high hyperopia with corrections ranging up to +5.75 D. Contrast sensitivity was improved and the distance vision of near eyes was found to contribute positively to binocular distance vision compared to distance eyes monocularly.

Corneal aberrations and objective visual quality after hyperopic laser in situ keratomileusis using the Esiris excimer laser

PURPOSE

To evaluate the changes in visual performance and ocular optical quality after hyperopic laser in situ keratomileusis (LASIK) using the Esiris excimer laser (Schwind eye-tech-solutions).

SETTING

Vissum-Instituto Oftalmológico de Alicante, Alicante, Spain.

METHODS

Excimer laser surgery was performed with the Esiris laser in 51 eyes of 29 patients with hyperopia or hyperopic astigmatism. The follow-up was 6 months. Changes in visual acuity, refraction, and corneal and ocular wavefront aberrations (6.0 mm pupil) were recorded and analyzed.

RESULTS

The mean preoperative sphere was +4.45 diopters (D)+/-1.08 (SD) (range +2.50 to +7.25 D) and the mean preoperative cylinder, -0.55+/-0.36 D (range 0.00 to 1.00 D). Ten eyes (19.61%) had a LASIK enhancement during the follow-up for the correction of the residual refractive error and were excluded from the refractive analysis. Of the 41 remaining eyes, 95.12% had the same or improved distance best spectacle-corrected visual acuity (BSCVA) 6 months after surgery; 90.25% had no change or a gain of lines of near BSCVA. Moreover, 80.50% of eyes were within +/-0.50 D of emmetropia. Regarding corneal aberrations, statistically significant changes were observed in higher-order aberrations (HOAs), coma-like aberrations, and the primary spherical aberration coefficient Z(4,0), which changed from positive to negative values (all P<.01). Regarding total ocular aberrations, statistically significant changes were observed in total and higher-order root-mean-square values (P<.01).

CONCLUSIONS

Hyperopic LASIK using the Esiris excimer laser for the correction of 2nd-order aberrations was safe and effective. Ocular and corneal HOAs increased significantly postoperatively.