Hydrogel intracorneal inlays for the correction of hyperopia: outcomes and complications after 5 years of follow-up

Surgical Technique to Treat Presbyopic Inlay-Associated Corneal Haze With Sequential Excimer Photoablation: A Case Series

PURPOSE

To describe an approach using sequential excimer laser ablation of the stromal surface of the corneal flap with or without subsequent excimer ablation to the stromal bed to reduce presbyopic inlay-associated corneal haze.

METHODS

Twelve patients who underwent KAMRA inlay (Acufocus) explantation due to corneal haze were included. The mean interval between explantation and the primary surgery (phototherapeutic keratotomy [PTK] to corneal flap) was 16.2 ± 29.7 months (range = 1 to 83 months). The corneal flap was lifted and laid on an evisceration spoon and an excimer laser was used to ablate the flap stroma by 30 to 40 µm depth. Subsequently, an excimer laser was used to ablate and treat the stromal bed following a second flap lift according to the manifest refraction, leaving a minimal residual stromal bed thickness of greater than 300 µm. For both procedures, mitomycin C 0.02% was applied to the stromal bed before the flap was replaced and a bandage contact lens applied.

RESULTS

Reductions in corneal haze were observed, following PTK to the corneal flap with or without photorefractive keratectomy (PRK) to the stromal bed, both clinically and on imaging. No significant changes in uncorrected distance visual acuity (P = .442) and corrected distance visual acuity (P = .565) were observed. Improvements were observed for both spherical equivalent refractive errors (P = .036) and corneal light backscatter (P = .019). There were significant improvements in spherical aberrations (P = .014) but no changes in total lower and higher order aberrations.

CONCLUSIONS

PTK to the corneal flap with or without subsequent stromal bed PRK is an effective technique in treating corneal haze following presbyopic inlay explantation. [J Refract Surg. 2023;39(9):639-646.].

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.

Association between dual sensory impairment and risk of mortality: a cohort study from the UK Biobank

BACKGROUND

Dual sensory impairment is affecting over 10% of older adults worldwide. However, the long-term effect of dual sensory impairment (DSI) on the risk of mortality remains controversial. We aim to investigate the impact of single or/and dual sensory impairment on the risk of mortality in a large population-based sample of the adult in the UK with 14-years of follow-up.

METHODS

This population-based prospective cohort study included participants aged 40 and over with complete records of visual and hearing functions from the UK Biobank study. Measurements of visual and hearing functions were performed at baseline examinations between 2006 and 2010, and data on mortality was obtained by 2021. Dual sensory impairment was defined as concurrent visual and hearing impairments. Cox proportional hazards regression models were employed to evaluate the impact of sensory impairment (dual sensory impairment, single visual or hearing impairment) on the hazard of mortality.

RESULTS

Of the 113,563 participants included in this study, the mean age (standard deviation) was 56.8 (8.09) years, and 61,849 (54.5%) were female. At baseline measurements, there were 733 (0.65%) participants with dual sensory impairment, 2,973 (2.62%) participants with single visual impairment, and 13,560 (11.94%) with single hearing impairment. After a follow-up period of 14 years (mean duration of 11 years), 5,992 (5.28%) participants died from all causes. Compared with no sensory impairment, dual sensory impairment was significantly associated with an estimated 44% higher hazard of mortality (hazard ratio: 1.44 [95% confidence interval, 1.11-1.88], p = 0.007) after multiple adjustments.

CONCLUSIONS

Individuals with dual sensory impairment were found to have an independently 44% higher hazard of mortality than those with neither sensory impairment. Timely intervention of sensory impairment and early prevention of its underlying causes should help to reduce the associated risk of mortality.

Biomaterials for Ophthalmic Applications

Ophthalmology is the branch of medicine that deals with diseases of the eye, the organ responsible for vision, and its attachments. Biomaterials can be made with different types of materials and can replace or improve a function or an organ, specifically the eye in the case of ophthalmic biomaterials. Biomaterials are substances that interact with biological systems for a medical purpose, either as a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a diagnostic agent, and have continued to improve over the years, leading to the creation of new biomaterials. With the arrival of new generations, biomaterials have succeeded in reducing complications and toxicity and improving biocompatibilities associated with older generations. With the aging population, eye problems are becoming more prevalent, and biomaterials have helped in recent years to improve or restore vision, improving the quality of life of many patients. This review focuses on the most clinically used ophthalmic biomaterials, including contact lenses, intraocular lenses, artificial tears, inlays and vitreous replacements. Tissue engineering is presented as a new tool that is able to be treat several ophthalmologic disorders.

Femtosecond laser-assisted implantation of corneal stroma lenticule for keratoconus

Purpose

To review recent progress, challenges, and future perspectives of stromal keratophakia for the treatment of advanced keratoconus.

Methods

We systematically reviewed the literature in the PubMed database, last update June 30, 2020. No language restriction was applied. The authors checked the reference lists of the retrieved articles to identify any additional study of interest.

Results

Several techniques have been proposed for the treatment of keratoconus in order to avoid or delay keratoplasty. This was primarily due to the lack of accessibility to donor corneas in many countries. The ease and predictability of the more advanced femtosecond lasers used to correct ametropias by stromal lenticule extraction lead to hypothesize that generated refractive lenticules could be implanted into corneal stromal layers to restore volume and alter the refractive properties of the cornea in patients with corneal ectasias. At the same time, new techniques for preservation, customization, and cellular therapy of the corneal stromal have been developed, directing to the valorization of otherwise discarded byproducts such as donor corneas unsuitable for either lamellar of penetrating keratoplasty.

Conclusions

Femtosecond laser-assisted stromal keratophakia could be a suitable therapeutic option for the treatment of corneal ectasias, especially in patients with advanced keratoconus, providing biomechanical support recovering the pachimetry to nearly normal value at the same time. The accuracy and predictability of the refractive outcome are yet a critical issue and the patient eligible for the procedure still has to be characterized.

Sterile Excimer Laser Shaped Allograft Corneal Inlay for Hyperopia: One-year Clinical Results in 28 Eyes

Purpose: This study aimed to evaluate the one-year clinical results of an allograft corneal inlay (ACI) implantation in a case series of 28 hyperopic eyes of 16 patients.Methods: Patients with manifest refraction spherical equivalent (MRSE) between +1.00 and +6.00 D and having a cylindrical refraction of less than 1 D were included in this prospective study. The refractive powers of excimer laser-shaped ACIs were determined based on the refractive error of the individual subject's eyes. After the creation of a femtosecond flap, the inlays were centered on the pupillary axis. Visual acuities, refractive results, and other clinical findings were reported for the 6- and 12-month follow-up exams.Results: The mean age of the patients included in the study was 36.2 ± 12.4 years (range 22-65 years). The mean pre-operative MSRE of 3.6 ± 1.51 D decreased to 0.21 ± 0.56 D (P < .001). The uncorrected distance and near visual acuity increased from 0.33 ± 0.22 and 0.17 ± 0.13 to 0.75 ± 0.22 (P < .001) and 0.72 ± 0.19 (P < .001), respectively. The corrected distance visual acuity remained unchanged (pre-OP: 0.79 ± 0.22; post-OP: 0.80 ± 0.21; P = .916), and the corrected near visual acuity increased from 0.78 ± 0.22 to 0.84 ± 0.20 (P = .003). The mean K-value and central corneal thickness increased from 42.57 ± 0.81 D and 557.5 ± 43.0 µm to 44.8 ± 1.4 D (P < .001) and 597.1 ± 58.1 µm (P < .001), respectively. No significant postoperative complications such as diffuse lamellar keratitis, epithelial ingrowth, or decentralization were observed.Conclusion: Excimer laser-shaped ACI offers an alternative treatment modality for patients with hyperopia. Acceptable visual results and similar regression rates were observed with ACI implantation compared with other laser refractive procedures.

Correction of pseudophakic presbyopia using Lasik with aspheric ablation profiles and a micro-monovision protocol

PURPOSE

To evaluate the outcomes of Lasik with aspheric ablation profiles and a micro-monovision protocol for correction of presbyopia in pseudophakic patients.

PATIENTS AND METHODS

This study included 50 pseudophakic eyes of 25 patients. Full ophthalmic examination, dominant eye tests and tests for tolerance of anisometropia (1 or 2 diopters) were done preoperatively. All cases were treated by Lasik with laser-blended vision technique. The dominant eye corrected to plano, and the nondominant eye corrected with near add in the range from 1.50 to 2.00 diopters. Excimer laser ablation was done using the MEL90 with a 250-Hz pulse rate (Carl Zeiss Meditec, Jena, Germany, Triple-A profile, Lasik mode). The follow-up period was 6 months with visits at 1, 3 and 6 months postoperatively.

RESULTS

The mean postoperative uncorrected distant visual acuity at 1 month (0.74 ± 0.11) was significantly lower than the preoperative level (0.84 ± 0.14) (p < 0.001). But it improved at the 3rd (0.80 ± 0.09) and 6th months (0.82 ± 0.10) with no significant difference with the preoperative level (p = 0.344). The mean uncorrected near visual acuity was significantly higher at the 1st (2.94 ± 1.63 J), 3rd (2.95 ± 1.82 J) and 6th (2.92 ± 1.83 J) postoperative months than the preoperative level (2.26 ± 1.48 J) (p < 0.001). Insignificant change in stereopsis was found after surgery (p = 0.849). The micro-monovision was well tolerated (95.8%).

CONCLUSION

Lasik with aspheric ablation profiles and a micro-monovision protocol is an effective option for presbyopia correction in pseudophakic patients.

Refractive surgery beyond 2020

Refractive surgery refers to any procedure that corrects or minimizes refractive errors. Today, refractive surgery has evolved beyond the traditional laser refractive surgery, embodied by the popular laser in situ keratomileusis or 'LASIK'. New keratorefractive techniques such as small incision lenticule extraction (SMILE) avoids corneal flap creation and uses a single laser device, while advances in surface ablation techniques have seen a resurgence in its popularity. Presbyopic treatment options have also expanded to include new ablation profiles, intracorneal implants, and phakic intraocular implants. With the improved safety and efficacy of refractive lens exchange, a wider variety of intraocular lens implants with advanced optics provide more options for refractive correction in carefully selected patients. In this review, we also discuss possible developments in refractive surgery beyond 2020, such as preoperative evaluation of refractive patients using machine learning and artificial intelligence, potential use of stromal lenticules harvested from SMILE for presbyopic treatments, and various advances in intraocular lens implants that may provide a closer to 'physiological correction' of refractive errors.

Biology of keratorefractive surgery- PRK, PTK, LASIK, SMILE, inlays and other refractive procedures

The outcomes of refractive surgical procedures to improve uncorrected vision in patients-including photorefractive keratectomy (PRK), laser in-situ keratomileusis (LASIK), Small Incision Lenticule Extraction (SMILE) and corneal inlay procedures-is in large part determined by the corneal wound healing response after surgery. The wound healing response varies depending on the type of surgery, the level of intended correction of refractive error, the post-operative inflammatory response, generation of opacity producing myofibroblasts and likely poorly understood genetic factors. This article details what is known about these specific wound healing responses that include apoptosis of keratocytes and myofibroblasts, mitosis of corneal fibroblasts and myofibroblast precursors, the development of myofibroblasts from keratocyte-derived corneal fibroblasts and bone marrow-derived fibrocytes, deposition of disordered extracellular matrix by corneal fibroblasts and myofibroblasts, healing of the epithelial injury, and regeneration of the epithelial basement membrane. Problems with epithelial and stromal cellular viability and function that are altered by corneal inlays are also discussed. A better understanding of the wound healing response in refractive surgical procedures is likely to lead to better treatments to improve outcomes, limit complications of keratorefractive surgical procedures, and improve the safety and efficiency of refractive surgical procedures.

Confocal and Histological Features After Poly(Ethylene Glycol) Diacrylate Corneal Inlay Implantation

Purpose

To evaluate the in vivo biocompatibility of photopolymerized poly(ethylene glycol) diacrylate (PEGDA) intrastromal inlays in rabbit corneas.

Methods

Sixty-three eyes of 42 New Zealand rabbits were included. Manual intrastromal pockets were dissected in 42 eyes. PEGDA inlays were obtained using a specifically designed photomask and were inserted in the intrastromal pocket of 21 eyes (inlay group); the remaining 21 right eyes did not receive any implant (pocket-only group). Twenty-one eyes with no intervention were used as controls. In vivo confocal microscopy (IVCM) was performed at every visit. After 2 months, rabbits were sacrificed and corneas removed for histological analysis.

Results

Corneas remained clear in all but two animals, and five cases of corneal neovascularization were seen (P = 0.2). Inlays remained stable without evidence of lateral or anterior migration, and no other complications were observed. No changes in anterior and posterior keratocyte density (P = 0.3 and P = 0.1, respectively) or endothelial cell density (P = 0.23) were observed between groups during the study time by IVCM. On pathology samples, thinning of the epithelium over the inlay area and epithelial hyperplasia over the edges were observed. A polygonal empty space with no evidence of PEGDA hydrogel within the midstroma was seen in the inlay group. Keratocytes were normal in shape and number in the vicinity of the PEGDA implant area.

Conclusions

Photopolymerized PEGDA intrastromal inlays have shown relatively good safety and stability in rabbit corneas. Inlays were biostable in the corneal environment and remained transparent during follow up.

Translational Relevance

The investigated PEGDA is promising for the development of biocompatible intrastromal implants.

Permavision intracorneal inlay after sixteen years. Regression of initial refractive hyperopia

According to the available scientific literature, 77 patients underwent Permavision inlay worldwide, between 2004 and 2007. This study reported about the use of Permavision intracorneal inlay to increase the central corneal curvature and to correct hyperopia. A 32-year-old male patient went to the Tecnolaser Clinic Vision ® facilities for a refractive study. Preoperative refraction without cycloplegia was +6.00 D in the right eye (RE) and +4.00 in the left eye (LE). The surgery was performed for both eyes on December 2, 2003. The Carriazo-Barraquer mechanical microkeratome (Moria) was used to create a 180 μm-thick corneal flap with a diameter of 8.5 mm. After lifting the flap, the corneal inlay was placed centrally above the pupil and the flap was re-positioned. In this case report, the patient reverted to the initial refractive situation. The first refractive regression appeared at twelve-month follow-up. After sixteen years, it was found a decrease in maximum corneal curvature, an increase in mean corneal densitometry percentage, and no important changes in the central corneal thickness. In the reported case, the cornea reverted to its original shape. In the scientific literature, this is the first case report of a non-explanted Permavision inlay after sixteen years.

Refractive surgery

Refractive surgery has evolved beyond laser refractive techniques over the past decade. Laser refractive surgery procedures (such as laser in-situ keratomileusis), surface ablation techniques (such as laser epithelial keratomileusis), and photorefractive keratectomy have now been established as fairly safe procedures that produce excellent visual outcomes for patients with low-to-moderate amounts of ametropia. Additionally, a broader selection of options are now available to treat a wider range of refractive errors. Small incision lenticule extraction uses a femtosecond laser to shape a refractive lenticule, which is removed through a small wound. The potential advantages of this procedure include greater tectonic strength and less dry eye. In the future, intracorneal implants could be used to treat hyperopia or presbyopia. Phakic intraocular implants and refractive lens exchange might be useful options in carefully selected patients for correcting high degrees of ametropia. Thus, physicians are now able to provide patients with the appropriate refractive corrective option based on the individual's risk-benefit profile.

Correction of hyperopia by intrastromal cutting and liquid filler injection

Correction of hyperopia requires an increase of the refractive power by steepening of the corneal surface. Present refractive surgical techniques based on corneal ablation (LASIK) or intrastromal lenticule extraction (SMILE) are problematic due to epithelial regrowth. Recently, it was shown that correction of low hyperopia can be achieved by implanting intracorneal inlays or allogeneic lenticules. We demonstrate a steepening of the anterior corneal surface after injection of a transparent, liquid filler material into a laser-dissected intrastromal pocket. We performed the study on ex-vivo porcine eyes. The increase of the refractive power was evaluated by optical coherence tomography (OCT). For a circular pocket, injection of 1 μl filler material increased the refractive power by +4.5 diopters. An astigmatism correction is possible when ellipsoidal intrastromal pockets are created. Injection of 2 μl filler material into an ellipsoidal pocket increased the refractive power by +10.9  dpt on the short and +5.1  dpt on the long axis. OCT will enable to monitor the refractive change during filler injection and is thus a promising technique for real-time dosimetry.

Histopathologic Analysis of Explanted KAMRA Corneal Inlays Demonstrating Adherent Fibroconnective Tissue Scar Formation

Objective

To investigate the histologic composition of opaque membranes associated with corneal intrastromal inlays implanted for the surgical treatment of presbyopia.

Methods

This is an observational case series of KAMRA corneal inlays explanted due to the presence of adherent opaque membranes associated with peri-inlay corneal stromal haze and sent for histopathologic analysis. Routine histology was performed in addition to immunohistochemical staining with myofibroblast and keratocyte markers.

Results

Eleven explanted inlay specimens were received, of which, after histologic processing, four demonstrated suf-ficient cellular material for histopathologic analysis. The opaque membranes surrounding the explanted inlays were composed of fibroconnective tissue, and myofibroblasts (positive for smooth muscle actin immunostain) were the predominant cell type. Immunostaining for the keratocyte marker CD34 was negative, confirming that the membranes were the result of a reactive scar-tissue formation process and not simply normal corneal stroma adherent to the explant.

Conclusions

Corneal inlay implantation can lead to the formation of an adherent fibroconnective tissue membrane, suggesting keratocyte-to-myofibroblast transdifferentiation and reactive fibroconnective tissue scar formation that could potentially impact visual potential. Prospective patients should be counseled regarding the risk of this complication, as this may be associated with some risk of incomplete reversibility of the procedure.

Corneal remodelling and topography following biological inlay implantation with combined crosslinking in a rabbit model

Implantation of biological corneal inlays, derived from small incision lenticule extraction, may be a feasible method for surgical management of refractive and corneal diseases. However, the refractive outcome is dependent on stromal remodelling of both the inlay and recipient stroma. This study aimed to investigate the refractive changes and tissue responses following implantation of 2.5-mm biological inlays with or without corneal collagen crosslinking (CXL) in a rabbit model. Prior to implantation, rotational rheometry demonstrated an almost two-fold increase in corneal stiffness after CXL. After implantation, haze gradually subsided in the CXL-treated inlays (p = 0.001), whereas the untreated inlays preserved their clarity (p = 0.75). In-vivo confocal microscopy revealed reduced keratocyte cell count at the interface of the CXL inlays at week 8. Following initial steepening, regression was observed in anterior mean curvature from week 1 to 12, being most prominent for the non-CXL subgroups (non-CXL: -12.3 ± 2.6D vs CXL: -2.3 ± 4.4D at 90 μm depth, p = 0.03; non-CXL: -12.4 ± 8.0D vs CXL: -5.0 ± 4.0D at 120 μm depth, p = 0.22). Immunohistochemical analysis revealed comparable tissue responses in CXL and untreated subgroups. Our findings suggest that CXL of biological inlays may reduce the time before refractive stabilization, but longer postoperative steroid treatment is necessary in order to reduce postoperative haze.

Refractive corneal inlay for presbyopia in emmetropic patients in Asia: 6-month clinical outcomes

Background

To evaluate the 6-month clinical outcomes of Flexivue Microlens refractive corneal inlay in emmetropic patients in Asia for the surgical compensation of presbyopia.

Methods

In this retrospective study, corneal inlay implantation was done using a femtosecond laser. The follow-up period was 6 months. Near/intermediate/distant visual acuities, refraction, keratometry, defocus curve, wavefront aberrations, contrast sensitivity, Scheimpflug corneal scanning, endothelial cell density, dry eye test, confocal microscopy scanning, and patient questionnaires were evaluated.

Results

The inlay implantation was performed in 21 eyes from June 2015 to April 2017. 6 months after surgery, the uncorrected near visual acuity of the operated eyes increased significantly from 0.55 ± 0.22 logMAR preoperatively to 0.25 ± 0.15 logMAR (p < 0.05) but mean bilateral uncorrected distant visual acuity did not change significantly (p = 0.90). Total higher-order aberration and spherical aberration increased, and the contrast sensitivity of the operated eyes decreased. Endothelial cell density and central corneal thickness did not change from preoperative values. Patient satisfaction for near vision was increased 6 months after implantation, and 50.0% of patients were independent of near spectacles. Explantation was done in 2 cases.

Conclusion

The Flexivue Microlens refractive corneal inlay was effective for improving near visual acuity at 6 months follow-up But proportion of spectacle independency and patient satisfaction were lower in this Korean population than in previous reports. Further study with a longer follow-up period is needed.

Flap Melting Over Corneal Inlay for Hyperopic Correction

PURPOSE

To report two cases of flap melting over corneal inlays for hyperopic correction several years after implantation.

METHODS

The corneal inlay (+6.00 diopters [D]; PermaVision intracorneal lens; Anamed Inc., Lake Forest, CA) was implanted underneath a LASIK flap in two patients.

RESULTS

Visual acuity and slit-lamp findings of both patients were stable for several years. At 9 years postoperatively, the first patient presented with a sudden loss of corrected distance visual acuity (CDVA) due to partial flap melting over the inlay while the surrounding anterior cornea showed opacification. The inlay was explanted immediately. Three years after explantation, CDVA returned to 1.0. Similarly, the second patient presented 11 years postoperatively with loss of vision, opacification, and partial flap melting. The inlay was explanted. Two years later, CDVA recovered.

CONCLUSIONS

Potentially severe biocompatibility issues of corneal inlays may occur even after several uneventful years. [J Refract Surg. 2018;34(11):775-778.].

Biological Lenticule Implantation for Correction of Hyperopia: An Ex Vivo Study in Human Corneas

PURPOSE

To evaluate changes in corneal tomography after stromal lenticule implantation ex vivo, with respect to the dependency of the lenticule thickness and implantation depth on the corneal curvature and the postoperative biomechanical strength at increased chamber pressure.

METHODS

Twenty-eight human donor corneas underwent pocket implantation of refractive stromal lenticules. Four groups were created by the combination of two implantation depths (110 and 160 µm) and two lenticule thicknesses (95 µm = 4.00 diopters [D], 150 µm = 8.00 D). Sagittal keratometry and total corneal refractive power (TCRP_{4mm,apex,zone}) were obtained for the front and back curvature with Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) at chamber pressures of 15 and 40 mm Hg.

RESULTS

The anterior curvature steepening was comparable between the 4.00 D and 8.00 D groups (P > .141), but more pronounced with 110 µm implantation depth (P < .038). The posterior curvature flattened significantly more after implantation of 8.00 D than 4.00 D lenticules (P < .002), but was similar at 110 and 160 µm implantation depths (P > .071). Average ΔTCRP for the 4.00 D and 8.00 D groups was 3.10 ± 0.60 and 5.30 ± 1.66 diopters (D) at 110-µm depth, respectively (P = .003), but 1.99 ± 0.79 and 3.36 ± 1.45 D at 160-µm depth, respectively (P = .066). The relative correction achieved was 66% to 78% at 110-µm depth and 42% to 50% at 160-µm depth, but similar when using 4.00 D and 8.00 D lenticules. Increased chamber pressure caused significant anterior and posterior curvature steepening after implantation in all four groups (P < .001), but not before implantation (P > .632).

CONCLUSIONS

The power of the implanted lenticule must be higher than the intended correction, and customized to the chosen implantation depth. Biomechanical strength seems to decrease after lenticule implantation. [J Refract Surg. 2018;34(4):245-252.].

Correction of presbyopia: An integrated update for the practical surgeon

Presbyopia results from loss or insufficiency of the eye's accommodative ability, and clinically manifests as the inability to focus near objects on the retina. It is one of the most common causes of visual impairment worldwide especially in adults of productive or working age. Various means of compensating for the loss of accommodative ability have been devised from optical tools such as spectacles and contact lenses, to topical medications and to surgical procedures. A comprehensive search on journal articles about topical and surgical correction of presbyopia was undertaken. The various techniques for presbyopia correction, as enumerated in these articles, are discussed in this paper with the addition of our personal experience and perspective on the future of these techniques.

Unilateral Keratectasia Treated with Femtosecond Fashioned Intrastromal Corneal Inlay

Purpose:

In this case report, we describe the surgical procedure of corneal inlay preparation and corneal pocket creation using a femtosecond laser system.

Case Report:

A 7-year-old girl who presented with unilateral paracentral corneal thinning underwent the surgical procedure of corneal inlay. Preoperatively, the refraction was +10.00-6.00 × 170. One month after the procedure, astigmatism and hyperopia were decreased and the refraction was +5.00-1.25 × 110.

Conclusion:

Femtosecond laser–assisted pocket creation for the implantation of corneal inlays offers accuracy of pocket parameters, enhancing predictability, resulting in better final outcomes, and improving the safety of the procedure.

Femtosecond laser-assisted in situ keratomileusis multifocal ablation profile using a mini-monovision approach for presbyopic patients with hyperopia

Purpose

To report the visual outcomes of the femtosecond laser-assisted multifocal aspheric corneal ablation profile using a mini-monovision approach and to evaluate if corneal multifocality was effective, and to report the relative benefits of this approach.

Patients and methods

Bilateral femtosecond laser-assisted in situ keratomileusis using a multifocal aspheric corneal ablation profile was performed on 19 hyperopic patients (38 eyes). They were divided into two groups based on eye dominance: dominant eye (DE) group targeting emmetropia and the nondominant eye (NDE) group targeting −0.5 D slight myopia. The uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), and retreatment rates were reported from baseline to 6 months.

Results

The UNVA, UIVA, and UDVA improved significantly in both groups (Kruskal–Wallis test, DE and NDE: P<0.00001, P<0.000005, and P=0.00001, respectively). Corrected distance visual acuity (CDVA) baseline was better in both groups in comparison to UDVA at 6 months (Wilcoxon test, DE: P<0.001, 95% confidence interval (CI) of the median 0.0–0.0 LogMAR and 0.1000–0.1218 LogMAR and NDE: P=0.010, 95% CI of the median 0.0–0.0 LogMAR and 0.00–0.10 LogMAR). There was a significant loss of lines between CDVA baseline and UDVA at 6 months in both groups (DE group: 68% of eyes lost one line or more; NDE group: 58% of eyes lost one line or more). The corrected near visual acuity baseline compared to UNVA at 6 months was not statistically important (Wilcoxon test, DE: P=0.8125, 95% CI of the median 0.0–0.0 LogMAR and 0.0–0.0 LogMAR and NDE: P=0.82, 95% CI of the median 0.0–0.0 LogMAR and 0.0–0.0 LogMAR). The comparison among the UDVA, UIVA, and UNVA between the two groups at baseline and during all follow-ups was not statistically important. Two cases from the DE group were retreated (6%).

Conclusion

Use of this multifocal aspheric corneal ablation profile in patients with hyperopic presbyopia significantly improved UDVA, UIVA, and UNVA. This improvement was due to created multifocality of the cornea. The mini-monovision seems not to affect UDVA, UIVA, and UNVA between the two groups. The retreatment rates at the 6-month evaluation were significantly less in our study when compared with other studies. This method seems to improve UDVA, UIVA, and UNVA but could result in a significant statistical difference between CDVA baseline and UDVA at 6 months that leads to loss of lines in distance vision. Despite promising results, this is a preliminary evaluation of this new profile, and a larger number of eyes are needed to verify visual outcomes, retreatment rates, and safety.

Bifocal refractive corneal inlay implantation to improve near vision in emmetropic presbyopic patients

PURPOSE

To evaluate the safety and effectiveness of the Flexivue Microlens corneal inlay for the improvement of near vision in emmetropic presbyopic patients.

SETTING

Ophthalmology Department, Misericordia e Dolce Hospital, Prato, Italy.

DESIGN

Prospective interventional case series.

METHODS

Corneal inlay implantation was performed in nondominant eyes using a 150 kHz femtosecond laser (iFS). Refraction, uncorrected (UNVA) and corrected (CNVA) near visual acuities, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, slitlamp evaluation, wavefront aberrometry, photopic and mesopic contrast sensitivity, anterior segment optical coherence tomography, endothelial cell density, and central corneal thickness measurements were assessed preoperatively and at each postoperative visit.

RESULTS

The study evaluated 81 eyes. In 26 eyes, the mean preoperative UNVA and UDVA were 0.76 logMAR and 0.00 logMAR, respectively, compared with 0.10 logMAR and 0.15 logMAR, respectively, 36 months postoperatively. Sixteen (62%) of 26 treated eyes lost more than 1 line of UDVA, and 5 (19%) lost more than 2 lines of UDVA. Two eyes (8%) lost more than 1 line of CDVA at 36 months. The mean binocular UDVA was 0.00 logMAR preoperatively and 0.02 logMAR at 36 months. The mean spherical aberration increased after surgery. Statistically significant differences in the mean mesopic and photopic contrast sensitivities at higher spatial frequencies were found between treated eyes and nontreated eyes. Explantation was performed in 6 treated eyes because of halos, glare, and a reduced UDVA.

CONCLUSION

The corneal inlay might be a safe and effective method of improving UNVA in emmetropic presbyopic patients.

FINANCIAL DISCLOSURE

Dr. Fantozzi is a member of the Presbia medical advisory board. No other author has a financial or proprietary interest in any material or method mentioned.

Advances in femtosecond laser technology

Femtosecond laser technology has become widely adopted by ophthalmic surgeons. The purpose of this study is to discuss applications and advantages of femtosecond lasers over traditional manual techniques, and related unique complications in cataract surgery and corneal refractive surgical procedures, including: LASIK flap creation, intracorneal ring segment implantation, presbyopic treatments, keratoplasty, astigmatic keratotomy, and intrastromal lenticule procedures.

Hydrogel Inlay for Presbyopia: Objective and Subjective Visual Outcomes

PURPOSE

To evaluate changes in visual performance and ocular optical quality after implantation of a corneal hydrogel inlay as a treatment for presbyopia.

METHODS

A Raindrop Near Vision Inlay (ReVision Optics, Lake Forest, CA) was implanted monocularly on the stromal bed of a femtosecond laser-assisted generated corneal flap of non-dominant eyes of 22 patients with emmetropic presbyopia (preoperative spherical equivalent range: -0.50 to 1.00 diopters). Efficacy was determined by measuring near and distance visual acuities and ocular aberrations, and satisfaction was assessed by a patient questionnaire.

RESULTS

The preoperative monocular uncorrected near visual acuity of the inlay inserted eye was 20/129 ± 1 Snellen (range: 20/135 to 20/61 Snellen) and improved to 20/35 ± 2 Snellen (range: 20/61 to 20/20 Snellen) (P < .01) at 6 months postoperatively. The monocular uncorrected distance visual acuity of the eye receiving the inlay was 20/25 ± 2 Snellen (range: 20/50 to 20/20 Snellen) preoperatively and 20/25 ± 1 Snellen (range: 20/50 to 20/20 Snellen) at 6 months postoperatively (P =.257). According to the questionnaire responses, 82% of patients were satisfied. This was despite near glasses needs remaining in 13.6% of the cohort and the presence of glare and a decrease in night vision in approximately 40% of patients. The primary spherical aberration coefficient Z4(0) changed from positive to negative values in all patients (P < .01). However, the point spread function showed no significant change.

CONCLUSIONS

Hydrogel corneal inlays improve uncorrected near visual acuity in patients with presbyopia with only moderate effect on visual quality. However, the satisfaction with this therapy was relatively lower in these Korean patients than that reported previously in Western patients.

The evolution of corneal and refractive surgery with the femtosecond laser

The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.

Long-term outcomes after monocular corneal inlay implantation for the surgical compensation of presbyopia

PURPOSE

To evaluate long-term outcomes of small-aperture corneal inlay implantation for the surgical compensation of presbyopia.

SETTING

Paracelsus Medical University, Salzburg, Austria.

DESIGN

Prospective interventional cohort study.

METHODS

Monocular implantation of a Kamra small-aperture inlay (model ACI7000) (1.6 mm central aperture) was performed in emmetropic presbyopic eyes. The preoperative and postoperative parameters included monocular and binocular uncorrected (UDVA) and corrected (CDVA) distance visual acuities, uncorrected intermediate visual acuity (UIVA), and uncorrected (UNVA) and corrected (CNVA) near visual acuities; refraction; patient satisfaction; and complications.

RESULTS

From September 4, 2006, to May 21, 2007, a small-aperture inlay (1.6 mm central aperture) was implanted in 32 emmetropic presbyopic eyes. The mean binocular uncorrected visual acuities improved as follows: UNVA from Jaeger (J) 6 ± 1.2 lines (∼20/50) to J2 ± 1.8 lines (∼20/25) (P < .001) and UIVA from 0.2 logMAR ± 1.3 lines (∼20/32) to 0.1 logMAR ± 1.3 lines (∼20/25) (P = .04). The UDVA decreased from -0.2 logMAR ± 0.2 lines (∼20/12.5) to -0.1 logMAR ± 0.6 lines (∼20/16) (P < .001). At 60 months, 74.2% of patients had a UNVA of J3 (∼20/32) or better, 87.1% had a UIVA of 0.2 logMAR (∼20/32) or better, and 93.5% had a UDVA of 0.0 logMAR (∼20/20) or better. One inlay was removed after 36 months because of patient dissatisfaction with vision after a hyperopic shift in the surgical eye, with no loss of CDVA or CNVA 2 years after removal.

CONCLUSION

Long-term results of monocular corneal inlay implantation indicate increased UNVA and UIVA and slightly compromised UDVA in emmetropic presbyopic eyes.

FINANCIAL DISCLOSURE

Dr. Grabner was reimbursed for travel expenses from Acufocus. Dr. Riha is a consultant to Acufocus. No other author has a financial or proprietary interest in any material or method mentioned.

Preloaded refractive-addition corneal inlay to compensate for presbyopia implanted using a femtosecond laser: one-year visual outcomes and safety

PURPOSE

To report the results of the Icolens corneal inlay 12 months after implantation.

SETTING

Department of Refractive Surgery, Mater Private Hospital, Dublin, Ireland.

DESIGN

Prospective case series.

METHODS

The inlay was implanted in the nondominant eye of emmetropic patients through a femtosecond laser-created corneal pocket.

RESULTS

The mean uncorrected near visual acuity (UNVA) in the surgical eye (n = 52) improved from N18/N24 preoperatively to N8 postoperatively (P = .000); all patients had a UNVA of N16 or better and 9 (17%), of N5 or better. The uncorrected distance visual acuity (UDVA) in the surgical eye increased from 0.05 logMAR ± 0.12 (SD) preoperatively to 0.22 ± 0.15 logMAR postoperatively (P = .000). There was a mean loss of 1.67 ± 1.77 lines of UDVA (P = .000). Binocularly, there was a mean gain of 0.48 ± 1.16 lines of UDVA postoperatively (P = .000), with 22 patients (42%) gaining more than 1 line. The mean loss of corrected distance visual acuity postoperatively was 1.78 ± 1.04 lines (P = .000). There was no significant change in corneal topography or endothelial cell count. On the satisfaction survey, 90% of patients reported being happy ("yes" or "rather yes") with the overall procedure in general. Eleven implants were explanted because of minimal improvement in UNVA. No significant adverse events were reported throughout the study.

CONCLUSION

The new refractive-addition corneal inlay effectively corrected presbyopia in emmetropic presbyopic patients.

FINANCIAL DISCLOSURE

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

Implantable inlay devices for presbyopia: the evidence to date

By 2020, it is estimated that 2.1 billion people will be presbyopic, and the demand for spectacle independence in this group is growing. This review article provides an overview of the three commercially available corneal inlays for the correction of presbyopia. Safety, efficacy, visual outcomes, and complications are analyzed for all three inlays according to published peer-reviewed data.

Two target locations for corneal inlay implantation combined with laser in situ keratomileusis

PURPOSE

To compare the visual acuity outcomes between 2 target locations for corneal inlay implantation with concurrent laser in situ keratomileusis (LASIK) to compensate for presbyopia.

SETTING

Shinagawa LASIK Center, Tokyo, Japan.

DESIGN

Retrospective cohort study.

METHODS

Bilateral LASIK was performed simultaneously with inlay implantation in the nondominant eye. The preoperative and 6-month postoperative uncorrected distance (UDVA) and uncorrected near (UNVA) visual acuities were evaluated. Patients were divided into the following 2 groups based on the pupil center to Purkinje reflex distance (Pp-Pk): small (≤300 μm) and large (>300 μm). Each group was divided into subgroups according to the distance of the inlay center to the Purkinje reflex (I-Pk) or to the midpoint between the pupil center and Purkinje reflex (I-M). The inlay position was classified as 0 to 100 μm, 101 to 200 μm, 201 to 300 μm, and 301 to 400 μm from the Purkinje reflex and from the midpoint.

RESULTS

Of 1008 patients, 992 were available for postoperative follow-up. The UDVA and UNVA improved in both subgroups with all inlay positions (P < .0001). There were no statistically significant differences in UDVA or UNVA within or between the small Pp-Pk group and the large Pp-Pk group (P > .05). The Spearman rank-order correlation showed weak associations between the inlay distance and visual acuity.

CONCLUSION

The amount of inlay decentration had no influence on postoperative visual acuity.

FINANCIAL DISCLOSURE

Dr. Tomita is a consultant to Acufocus, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Morphologic study of the cornea by in vivo confocal microscopy and optical coherence tomography after bifocal refractive corneal inlay implantation

PURPOSE

To evaluate the biocompatibility of the Flexivue Microlens intracorneal inlay based on healing of corneal wounds and analysis of corneal structural features using in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT).

SETTING

Ophthalmology Department, Misericordia e Dolce Hospital, Prato, Italy.

DESIGN

Case series.

METHODS

The intracorneal inlay was inserted in a stromal pocket created in the nondominant eye of emmetropic presbyopic patients using a femtosecond laser. In vivo confocal microscopy and AS-OCT examinations were performed preoperatively and 1, 6, and 12 months postoperatively.

RESULTS

The mean follow-up was 7.6 months. In the early postoperative period, IVCM showed intense cellular activity in the stroma around the inlay, edema, inflammation, and degenerative material deposition but normal regularity after 12 months. Anterior segment OCT showed a regular planar shape of the corneal pocket in all eyes. The mean of the side-cut angles was 30.7 degrees. The mean difference between the measured and planned pocket depth was 9.77 μm. At 1 month, hyperreflective areas beneath the inlay and microfolds were observed in 21 of the 52 eyes. After 12 months, the anterior segment profile was regular and interface pocket reflectivity decreased over time. Six patients had inlay removal postoperatively (3 before 6 months; 3 before 12 months); after removal, IVCM and AS-OCT showed clear corneas without signs of irregularity.

CONCLUSION

In vivo confocal microscopy and AS-OCT analysis showed that the inlay elicited a low-level wound-healing response in its immediate vicinity with no alteration in the corneal structures.

FINANCIAL DISCLOSURE

Dr. M. Fantozzi is a member of the Presbia medical advisory board. No other author has a financial or proprietary interest in any material or method mentioned.

Confocal microscopy evaluation of the corneal response following AcuFocus KAMRA inlay implantation

PURPOSE

To describe the corneal appearance on confocal microscopy after AcuFocus KAMRA Inlay (AcuFocus, Inc., Irvine, CA) implantation and evaluate the visual acuity compared to the confocal microscopy data.

METHODS

Twelve eyes of 12 patients implanted with one of three models of the AcuFocus KAMRA Inlay (ACI 7000, 7000T, and 7000PDT) were prospectively evaluated by confocal microscopy 6 months after implantation. Additionally, 4 eyes of 4 patients explanted during the follow-up period were evaluated.

RESULTS

Among the eyes implanted, mean epithelial thickness was 54.6 ± 22 μm. The subbasal nerve plexus was detected in 10 patients. The corneal nerves per unit area were 2.73 ± 2.1 sprouts/mm(2). The branch pattern was found in 8 patients. The mean keratocyte density value was 540 ± 210 cells/mm(2). A low grade of keratocyte activation was found in all patients. Among the eyes explanted, the mean wound healing opacity was 1,092.75 ± 1,877.35 μm/pixel.

CONCLUSIONS

The corneal tolerance to the KAMRA Inlay appeared to be good. The inlay modified the normal structure of the corneal layer, but it was not associated with severe complications of the eye. Keratocyte activation was the finding most associated with a negative visual outcome. Confocal microscopy can be useful to evaluate the long-term evolution of the corneal layer changes following KAMRA Inlay implantation.

Accuracy and stability of hyperopic treatments

PURPOSE OF REVIEW

Treatment of hyperopia presents greater challenges than treatment of myopia for multiple reasons, including the fact that hyperopia tends to progress with age and becomes more symptomatic with the loss of accommodation.

RECENT FINDINGS

Despite these issues, surgeons have multiple options to treat hyperopia successfully. Modern laser vision correction has high success rates for most patients and performs acceptably in the presence of high hyperopia or high cylinder. Early studies combining excimer laser treatment with collagen cross-linking (CXL) suggest that this may improve refractive stability. Recent studies have also described femtosecond lenticule extraction and use of a solid-state laser in place of the excimer. In addition to cornea-based treatment, long-term studies of a hyperopic phakic intraocular lens have shown excellent visual outcomes and good safety. Cross-linking is increasingly being applied to the hyperopia that follows radial keratotomy.

SUMMARY

The established treatments for hyperopia continue to accumulate evidence supporting their safety and efficacy. The next step forward in treatment may arise from combining these treatments with CXL to stabilize the cornea long-term.

Developments in the correction of presbyopia II: surgical approaches

PURPOSE

To discuss the various static and dynamic surgical approaches which attempt to give presbyopes good vision at far, intermediate and near viewing distances.

CONTENT

Static methods broadly adopt the same optical techniques as those used in presbyopic contact lens correction and aim to satisfy the needs of the presbyope by increasing binocular depth-of-focus, often using monovision as well as simultaneous-imagery. Dynamic methods generally attempt to make use of at least some of the still-active elements of the accommodation system. They include procedures which are supposed to modify the relative geometry of the ciliary muscle and lens, or which reduce the stiffness of the presbyopic lens either by replacing it with other natural or man-made material or by subjecting it to femtosecond laser treatment. Alternatively the natural lens may be replaced by some form of intraocular lens which changes power as a result of forces derived from the still-active ciliary muscle, zonule and capsule, or other sources.

CONCLUSIONS

At present, multifocal intraocular lenses appear to offer the most consistent and reliable surgical approach to surgical presbyopic correction. They have obvious advantages in convenience and stability over optically-similar, simultaneous-image presbyopic contact lenses but this must be balanced against their relative inflexibility in cases of patient dissatisfaction. Dynamic methods remain largely experimental. Although some approaches show promise, as yet no method has demonstrated a reliable, long-term ability to correct distance refractive error and to appropriately change ocular power in response to changes in viewing distance over the normal range of interest.

LASIK following small incision lenticule extraction (SMILE) lenticule re-implantation: a feasibility study of a novel method for treatment of presbyopia

Presbyopia remains a major visual impairment for patients, who have previously undergone laser refractive correction and enjoyed unaided distance vision prior to the onset of presbyopia. Corneal stromal volume restoration through small incision lenticule extraction (SMILE) lenticule re-implantation presents an opportunity for restoring the patients’ non-dominant eye to previous low myopia to achieve a monovision. In this study, we investigated the feasibility of performing LASIK after lenticule re-implantation as a method to create presbyopic monovision. A -6.00D SMILE correction was performed in 9 rabbit eyes. The lenticules were cryopreserved for 14 days and re-implanted. Five weeks later, 3 of these eyes underwent LASIK for -5.00D correction (RL group); 3 underwent LASIK flap creation, which was not lifted (RN); and no further procedures were performed on the remaining 3 eyes. These groups were compared with 3 eyes that underwent standard LASIK for a -5.00D correction (LO); 3 that underwent creation of non-lifted flap (LN); and 3 non-operated eyes. Rabbits were euthanized 1 day post-surgery. Tissue responses were analyzed by immunohistochemistry, slit lamp and in vivo confocal microscopy (IVCM). Intrastromal irregularities and elevated reflectivity levels of the excimer-ablated plane were observed on slit lamp and IVCM, respectively in the RL group. The results were comparable (P = 0.310) to IVCM findings in the LO group. RL and LO groups showed similar fibronectin expression levels, number of CD11b-positive cells (P = 0.304) and apoptotic cells (P = 0.198). There was no difference between the RN and LN groups in reflectivity levels (P = 0.627), fibronectin expression levels, CD11b-positive cells (P = 0.135) and apoptotic cells (P = 0.128). LASIK can be performed following lenticule re-implantation to create presbyopic monovision. The tissue responses elicited after performing LASIK on corneas that have undergone SMILE and subsequent lenticule re-implantation are similar to primary procedure.

Small-aperture corneal inlay implantation to treat presbyopia after laser in situ keratomileusis

PURPOSE

To evaluate the visual outcomes after implantation of a Kamra small-aperture corneal inlay into a femtosecond-created corneal pocket to treat presbyopia in patients who had previous laser in situ keratomileusis (LASIK).

SETTING

Private center, Tokyo, Japan.

DESIGN

Prospective interventional case series.

METHODS

Post-LASIK presbyopic patients had inlay implantation into a corneal pocket created by a femtosecond laser at a depth of 200 μm or 250 μm a minimum of 80 μm below the previous LASIK flap interface in the nondominant eye. Uncorrected and corrected distance visual acuities, near visual acuity, and a patient questionnaire on satisfaction, the use of reading glasses, and visual symptoms were evaluated.

RESULTS

The study enrolled 223 eyes (223 patients) with a mean age of 53.6 years (range 44 to 65 years) and a mean manifest spherical equivalent of -0.18 diopter (D) (range -1.00 to +0.50 D). The mean uncorrected distance visual acuity in the operated eye decreased 1 line from 20/16 preoperatively to 20/20 6 months postoperatively (P<.001). The mean uncorrected near visual acuity improved 4 lines from Jaeger (J) 8 to J2 (P<.001). At 6 months, significant improvements were observed in patient dependence on reading glasses and patient satisfaction with vision without reading glasses.

CONCLUSION

The 6-month results suggest that implantation of a small-aperture inlay in post-LASIK presbyopic patients improves near vision with a minimal effect on distance vision, resulting in high patient satisfaction and less dependence on reading glasses.

FINANCIAL DISCLOSURE

Drs. Tomita and Waring are consultants to Acufocus, Inc. Dr. Tomita is a consultant to Ziemer Group AG. No other author has a financial or proprietary interest in any material or method mentioned.

Removability of a small aperture intracorneal inlay for presbyopia correction

PURPOSE

To evaluate the safety of the corneal inlay removal procedure and the reversibility of visual acuities, corneal topography, and corneal biomicroscopy changes in a series of cases.

METHODS

Ten cases implanted with one of three versions of the AcuFocus Kamra Inlay (ACI 7000, 7000T, and 7000PDT; AcuFocus, Inc., Irvine, CA) were followed for a minimum of 6 months after corneal inlay removal.

RESULTS

The reason for removal was related to subjective dissatisfaction with visual symptoms (8 of 10 patients) such as night glare, photophobia, starburst, blurry vision, and halos. One case of removal was related to inadvertent thin flap and the final case was related to insufficient near vision. Mean uncorrected distance visual acuity (UDVA) and uncorrected near visual acuity (UNVA) was 0 ± 0.1 logMAR (Snellen 20/20) and 0.5 ± 0.2 logMAR (Snellen 20/40), respectively, preoperatively and 0.1 ± 0.1 logMAR (Snellen 20/25) and 0.5 ± 0.1 logMAR (Snellen 20/63), respectively, 6 months after corneal inlay removal. Mean corrected distance visual acuity (CDVA) and corrected near visual acuity (CNVA) was 0 ± 0.1 logMAR (Snellen 20/20) and 0 ± 0.1 logMAR (Snellen 20/20), respectively, preoperatively and 0 ± 0.1 logMAR (Snellen 20/20) and 0.1 ± 0.1 logMAR (Snellen 20/25), respectively, 6 months after corneal inlay removal. Mean root mean square (RMS) higher-order aberration (HOA) was 0.50 ± 0.12 (range: 0.30 to 0.70) preoperatively and 0.69 ± 0.14 (range: 0.48 to 0.95) 6 months after corneal inlay removal (P < .8). Weak positive correlation was found between Δt Implant-Removal (Δt I-R), RMS spherical, coma, and HOA at 6 months (Δt I-R vs RMS spherical was r = 0.2, r(2) = 0.5, P < .7; Δt I-R vs RMS coma was r = 0.8, r(2) = 0.6, P < .3; and Δt I-R vs HOA r = 0.8; r(2) = 0.6, P < .9).

CONCLUSION

This study suggests that after removal of the corneal inlay, corneal topography and corneal aberrometry are not permanently affected. In more than 60% of patients, CNVA, CDVA, UNVA, and UDVA were similar to the preoperative value.

Reversible femtosecond laser-assisted myopia correction: a non-human primate study of lenticule re-implantation after refractive lenticule extraction

LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap. Correction of refractive error is achieved by the resulting change in the curvature of the cornea and is limited by central corneal thickness, as a thin residual stromal bed may result in biomechanical instability of the cornea. A recently developed alternative to LASIK called Refractive Lenticule Extraction (ReLEx) utilizes solely a femtosecond laser (FSL) to incise an intrastromal refractive lenticule (RL), which results in reshaping the corneal curvature and correcting the myopia and/or astigmatism. As the RL is extracted intact in the ReLEx, we hypothesized that it could be cryopreserved and re-implanted at a later date to restore corneal stromal volume, in the event of keratectasia, making ReLEx a potentially reversible procedure, unlike LASIK. In this study, we re-implanted cryopreserved RLs in a non-human primate model of ReLEx. Mild intrastromal haze, noted during the first 2 weeks after re-implantation, subsided after 8 weeks. Refractive parameters including corneal thickness, anterior curvature and refractive error indices were restored to near pre-operative values after the re-implantation. Immunohistochemistry revealed no myofibroblast formation or abnormal collagen type I expression after 8 weeks, and a significant attenuation of fibronectin and tenascin expression from week 8 to 16 after re-implantation. In addition, keratocyte re-population could be found along the implanted RL interfaces. Our findings suggest that RL cryopreservation and re-implantation after ReLEx appears feasible, suggesting the possibility of potential reversibility of the procedure, and possible future uses of RLs in treating other corneal disorders and refractive errors.

Correction of presbyopia with a small aperture corneal inlay

PURPOSE

To assess the efficacy of a small aperture corneal inlay (KAMRA, AcuFocus Inc) to improve near vision in emmetropic presbyopes.

METHODS

Prospective, nonrandomized, multicenter clinical trial in presbyopic emmetropes aged 45 to 60 years. A small corneal pocket or flap was created in the nondominant eye by femtosecond laser or mechanical microkeratome, and the inlay (N=507) placed on the stromal bed. Uncorrected visual acuity was measured for the implanted eye at near (40 cm), intermediate (80 cm), and distance (20 ft) using ETDRS charts with the Optec 6500 Vision Tester (Stereo Optical Inc) at the preoperative, and 1-, 3-, 6-, 9-, 12-, and 18-month postoperative examinations. Contrast sensitivity (CS) was measured with best distance correction in the implanted eye using the Optec system and FACT chart under photopic (85 cd/m(2)) and mesopic (3 cd/m(2)) conditions preoperatively and at 1-year follow-up.

RESULTS

Mean patient age was 52.87±3.64 years. Monocular mean uncorrected near visual acuity was J8 (0.482±0.925 logMAR) preoperatively, J3 (0.185±0.848 logMAR) at 1 month (n=506, P<.0001), and J2 (0.139±0.851 logMAR) at 18 months (n=99, P<.0001). Mean uncorrected intermediate visual acuity was 20/35 (0.239±0.837 logMAR) preoperatively and 20/26 (0.139±0853 logMAR) at 18 months (P<.0001). Mean uncorrected distance visual acuity (UDVA) was 20/20 (0.011±0.890 logMAR) at 18 months. Photopic (P<.001) and mesopic (P<.0001) monocular contrast sensitivities were within the range of the normal population at 1 year.

CONCLUSIONS

The KAMRA corneal inlay improved near visual acuity with minimal impact on UDVA or mesopic contrast sensitivity in the implanted eye.