Inlays and the cornea Fenner, Beau J.; Moriyama, Aline Silveira; Mehta, Jodhbir S.
Experimental eye research,
April 2021, 2021-Apr, 2021-04-00, 20210401, Volume:
205
Journal Article
Peer reviewed
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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Purpose: 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 + or - 0.13 logMAR (logarithm of the minimal angle of resolution), 0.30 + or - 0.22 logMAR pre-explant, and 0.16 + or - 0.15 logMAR post-explant (n=20). Mean UNVA pre-implant was 0.37 + or - 0.09 logMAR, 0.38 + or - 0.13 logMAR pre-explant, and 0.42 + or - 0.21 logMAR post-explant (n=20). Mean CDVA pre-implant was -0.01 + or - 0.04 logMAR and 0.05 + or - 0.11 logMAR post-explant (n=17). Mean CDVA pre-explant was 0.04 + or - 0.07 logMAR and 0.04 + or - 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 + or - 0.29 D pre-implant and +0.26 + or - 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
To provide a side-by-side analysis of the summary of safety and effectiveness data (SSED) submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia.
SSED reports ...submitted to the FDA for KAMRA and Raindrop were compared with respect to loss of corrected distance visual acuity (CDVA), adverse event rates, induction of astigmatism, retention of contrast sensitivity, stability of manifest refractive spherical equivalent (MRSE), and achieved monocular uncorrected near visual acuity (UNVA) at 24mo.
Totally 442/508 of KAMRA patients and 344/373 Raindrop patients remained enrolled in the clinical trials at 24mo. The proportion of KAMRA and Raindrop patients who lost ≥2 lines of CDVA at 24mo was 3.4% and 1%, respectively. The adverse event rate was comparable between the devices. No significant inductions of astigmatism were noted. Both technologies induced a transient myopic shift in MRSE followed by a hyperopic shift and subsequent stabilization. Totally 87% of KAMRA and 98% of Raindrop patients attained a monocular UNVA of J5 (20/40) or better at 24mo, 28% of KAMRA and 67% of Raindrop patients attained a monocular UNVA of J1 (20/20) or better at 24mo.
Both devices can be considered safe and effective, however, the results of corneal inlay implantation are mixed, and long-term patient satisfaction will likely depend on subjective expectations about the capabilities of the inlays. Variability in surgical technique and postoperative care within and between the two clinical trials diminishes the comparative power of this article.
This Special Issue aimed to explore the cutting-edge advancements in vision science, optometry, and ocular surface research. In an era marked by rapid technological progress, there is an imperative ...to understand how innovations in diagnostic tools, treatment protocols, and computational models are reshaping our understanding of ocular health and vision care. We invited contributions that delved into novel methodologies, uncovered new aspects of ocular physiology, or offered fresh perspectives on the management of eye conditions.
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. Keywords: corneal inlay, corneal onlay, SMILE, PEARL, PresbyLASIK, refractive surgery, KAMRA, raindrop, flexivue, corneal allografts, presbyopic allogenic refractive lenticule
The purpose of this study was to report visual prognosis after explantation of a small-aperture corneal inlay used for the treatment of presbyopia. This is a retrospective case series conducted at a ...single site in Draper, Utah, USA (Hoopes Vision). Medical records of 176 patients who had received a small-aperture corneal inlay (KAMRA™, AcuFocus Inc., Irvine, CA, USA) were reviewed. Patients who had undergone explantation of the device were identified. Uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity (CDVA), and manifest refraction spherical equivalent (MRSE) were measured pre-implantation, post-implantation, pre-explantation, and post-explantation of the inlay. Ten eyes from ten patients were included in this study. The explantation rate was 5.7% over 31 months, with blurry vision as the most common complaint. After explantation, six patients achieved pre-implantation UDVA, and six achieved pre-implantation UNVA. Eight of nine patients who underwent final manifest refraction achieved pre-operative CDVA. All patients had residual donut-shaped corneal haze in the stroma at the previous position of the inlay. All patients experienced improvement in haze with 20% experiencing complete resolution. The degree of stromal haze was not related to the duration of implantation. Of the subset of patients who underwent explantation of their small-aperture corneal inlay, there was persistent loss of CDVA in 10%. The majority of patients experienced some level of residual stromal haze, which may contribute to deficits in UNVA and CDVA in few patients. A hyperopic shift induced by the corneal inlay may contribute to the blurry vision these patients experienced; there was a reduction of this shift post-explantation. While this device is removable, patients should expect some post-explantation changes such as residual haze with a small subset experiencing persistent deficits in CDVA.
To evaluate the effect of femtosecond laser and excimer laser on an intracorneal inlay (KAMRA
) implanted in animal models.
Femtosecond laser was used to create corneal intrastromal pockets at 250μm ...depth in five porcine eyes. Four intact KAMRA inlays, examined by slit-lamp biomicroscopy and light microscopy, were implanted in the pocket of four eyes. A standard LASIK flap was created above each implanted inlay in the four eyes using a femtosecond laser with flap thicknesses of 150μm, 130μm, 110μm and 90μm. In the fifth porcine eye, a LASIK flap was created using femtosecond laser at 110μm depth, and a fifth inlay was then implanted in the 250μm pocket. Excimer laser ablation was performed under the flap targeting a -3.00 refraction. The inlay was then explanted, examined and reimplanted in the same pocket followed by a second similar excimer laser ablation.
Significant burn, shrinkage and distortion of microholes were noted in all the first four inlays following the femtosecond laser flap creation at all the various flap thicknesses. The damage was noted to be more prominent as the distance between the flap and inlay decreased. No apparent effect was noted on the fifth inlay following repeated excimer laser ablations.
Unlike excimer laser, femtosecond laser appears to be hazardous and damaging to the intracorneal KAMRA inlay when applied above it.
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