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Presbyopia, the physiological change in near vision that develops with ageing, gradually affects individuals older than 40 years and is a growing cause of visual disability due to ageing demographics of the global population. The routine use of computers and 'smartphones', combined with the affluence of the 'baby boomers' generation has set high standards for near vision correction. Corneal inlays are a relatively new treatment modality that is effective at compensating for presbyopia. The dimensions of these devices vary from 2 to 3.8 mm in diameter and 5 to 32 μm in thickness. They are implanted in the anterior corneal stroma of the non-dominant eye, most commonly, in a femtosecond laser created corneal pocket. They improve near vision by increasing the depth of focus, creating a hyper-prolate region of increased central cornea power or providing a refractive add power. This article reviews the literature on the efficacy and safety of corneal inlays.

Majid Moshirfar,1– 3 Chap-Kay Lau,4 Nicholas A Chartrand,4 Mark T Parsons,4 Seth Stapley,5 Nour Bundogji,2 Yasmyne C Ronquillo,1 Steven H Linn,1 Phillip C Hoopes1 1Hoopes Vision Research Center, Hoopes Vision, Draper, UT, USA; 2John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA; 3Utah Lions Eye Bank, Murray, UT, USA; 4University of Arizona, College of Medicine-Phoenix, Phoenix, AZ, USA; 5Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USACorrespondence: Majid Moshirfar, Medical Director Hoopes Vision Research Center, Hoopes Vision Research Center, 11820 S. State St. #200, Draper, UT, 84020, USA, Tel +1 801-568-0200, Fax +1 801-563-0200, Email cornea2020@me.comPurpose: To evaluate 10 years of KAMRA corneal inlay explantation and associated visual outcomes.Patients and Methods: Single-site retrospective chart review of 22 cases of AcuFocus KAMRA Inlay (ACI7000PDT) explantation (range 1 week– 1 year). Uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity (CDVA), and manifest refraction at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year post-explantation were reviewed.Results: The explantation rate was 8.2% across 10 years. All patients underwent KAMRA explantation due to dissatisfaction with their vision including blurry near vision, impaired night vision, decreased vision in dim lighting, streaks or halos, haze, and double vision. Mean UDVA pre-implant was − 0.01± 0.13 logMAR (logarithm of the minimal angle of resolution), 0.30± 0.22 logMAR pre-explant, and 0.16± 0.15 logMAR post-explant (n=20). Mean UNVA pre-implant was 0.37± 0.09 logMAR, 0.38± 0.13 logMAR pre-explant, and 0.42± 0.21 logMAR post-explant (n=20). Mean CDVA pre-implant was − 0.01± 0.04 logMAR and 0.05± 0.11 logMAR post-explant (n=17). Mean CDVA pre-explant was 0.04± 0.07 logMAR and 0.04± 0.11 logMAR post-explant (n=19). Significant differences were observed between pre-implant and post-explant UDVA (p=0.009), and between pre-explant and post-explant UDVA (p=0.02). All patients (100%) had 20/20 or better CDVA pre-implant but decreased to 73.7% post-explant. Sixty percent (12/20) of the patients lost UDVA Snellen acuity lines post-explant. MRSE was − 0.31± 0.29 D pre-implant and +0.26± 0.77 D post-explant (p=0.007) with note of a hyperopic shift. The hyperopic shift in 31.6% (6/19) of patients did not resolve after explantation. Post-explant residual corneal haze occurred in 72.7% (16/22) of patients.Conclusion: Although the KAMRA corneal inlay is a removable device, patients may experience residual corneal haze, hyperopic shift, and deficits in UDVA after explantation compared to pre-implantation UDVA.Keywords: presbyopia, cornea, small aperture inlay, KAMRA, explantation

Presbyopia may represent the largest segment of refractive errors that is without an established and effective refractive surgery treatment. Corneal Inlays are materials (synthetic or allogenic) implanted in the stroma of patients' corneas to improve presbyopia. These inlays, introduced into the United States in 2015 via the small-aperture corneal inlay (KAMRATM, SightLife Surgical/CorneaGen, Seattle, Washington, United States), were met with an initial wave of enthusiasm. Subsequent models like the shape-changing corneal inlay (RAINDROPTM, Revision Optics, Lake Forest, California, United States) offered excellent results for patients, but longer-term research raised questions about patient safety. At the time of this article, no synthetic corneal inlays are available in the United States for the correction of presbyopia. Other options for presbyopia correction include allograft corneal inlays, trifocal synthetic corneal inlays, pharmacologic therapies, scleral incisions or additive techniques and PresbyLASIK. Presently, allograft inlays consist of corneal lenticules removed from patients undergoing Small Incision Lenticule Extraction (SMILE). We will review corneal inlays and other alternative procedures that may provide effective and predictable treatments for patients with presbyopia. [ABSTRACT FROM AUTHOR]

Shehzad Anjam Naroo, Paramdeep Singh Bilkhu Ophthalmic Research Group, School of Life & Health Sciences, Aston University, Birmingham, UK Abstract: The treatment of presbyopia has been the focus of much scientific and clinical research over recent years, not least due to an increasingly aging population but also the desire for spectacle independence. Many lens and nonlens-based approaches have been investigated, and with advances in biomaterials and improved surgical methods, removable corneal inlays have been developed. One such development is the KAMRA™ inlay where a small entrance pupil is exploited to create a pinhole-type effect that increases the depth of focus and enables improvement in near visual acuity. Short- and long-term clinical studies have all reported significant improvement in near and intermediate vision compared to preoperative measures following monocular implantation (nondominant eye), with a large proportion of patients achieving Jaeger (J) 2 to J1 (~0.00 logMAR to ~0.10 logMAR) at the final follow-up. Although distance acuity is reduced slightly in the treated eye, binocular visual acuity and function remain very good (mean 0.10 logMAR or better). The safety of the inlay is well established and easily removable, and although some patients have developed corneal changes, these are clinically insignificant and the incidence appears to reduce markedly with advancements in KAMRA design, implantation technique, and femtosecond laser technology. This review aims to summarize the currently published peer-reviewed studies on the safety and efficacy of the KAMRA inlay and discusses the surgical and clinical outcomes with respect to the patient’s visual function. Keywords: presbyopia, refractive surgery, implants, cornea

Presbyopia is a growing problem in view of an aging global population and increasingly patients desire spectacle-free solutions to address this condition. Surgically implanted corneal inlays have been the topic of renewed research efforts in the past several years as a treatment option for presbyopia, with several approaches being used to modify the refractive properties of the cornea and enhance near vision. In this review we discuss historical approaches to corneal inlay surgery, critically appraise the current generation of presbyopia-correcting corneal inlays and their associated complications and consider the future prospects for emerging corneal inlay technologies that aim address the shortcomings of currently available inlays. • Presbyopia correction is a growing problem and the demand for spectacle-free outcomes is increasing. • Corneal inlay surgery offers the potential for minimally invasive and reversible correction of presbyopia. • Contemporary inlays have improved biocompatibility and outcomes but complications limit surgeon and patient acceptance. • Novel inlays with improved biocompatibility may overcome the limitations of current generation inlays. [ABSTRACT FROM AUTHOR]