A Contemporary Risk Analysis of Iatrogenic Transmission of Creutzfeldt-Jakob Disease (CJD) via Corneal Transplantation in the United States.

BACKGROUND: Creutzfeldt-Jakob disease (CJD) is a rare, fatal, neurodegenerative prion disease potentially transmissible through corneal transplantation. While statistical analyses performed two decades ago estimated the overall prevalence of CJD in the corneal donor pool to be low, the recent significant increase in corneal transplants performed and deaths due to CJD in the U.S. warrants a contemporary risk analysis. METHODS: A literature review was conducted to determine the overall number of globally reported cases of CJD transmission through corneal transplantation. U.S. mortality and cornea donation data were utilized to estimate the age-stratified prevalence of undiagnosed, latent CJD in the cornea donor pool in 2018. A historical statistical analysis was performed to estimate the number of corneas from donors with latent CJD entering the U.S. donor pool for each year between 1979 and 2018. From these statistical analyses, risk factors of iatrogenic transmission were identified and summarized. RESULTS: Ten reported cases of iatrogenic transmission of CJD through corneal transplants were identified globally. In 2018, an estimated 3.8 corneas from donors with undiagnosed latent CJD potentially entered the pool of 111,703 transplant-intended corneas harvested from individuals aged 31-80. Between 1979 and 2018, an estimated 47 corneas may have entered the U.S. transplant-intended pool from donors with latent CJD aged 35 to 84. The advanced age of donors and a history of multiple transplants in recipients were both prominent risk factors for iatrogenic transmission. CONCLUSIONS: The 10 reported global cases of iatrogenic transmission likely under-represent the number of individuals with a coinciding history of death by CJD and prior corneal transplantation, as supported by our statistical analysis and lack of geographical diversity of reported cases. As effective screening methods develop and globalization of cornea transplantation broadens, it is of utmost importance that cornea transplantation history among victims of CJD should be investigated and reported.

Risks Posed to Corneal Transplant Recipients by COVID-19-Affected Donors.

The recent emergence of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its resultant human disease, COVID-19, will likely have a significant impact on the corneal tissue donor pool. Current recommendations from the United States and global eye bank associations call for the outright avoidance of tissues from donors recently infected with or exposed to COVID-19. This conservative recommendation is currently appropriate given the reported ocular sequelae, tear film viral detectability, and transmissibility of COVID-19. However, the rapidly increasing global prevalence and mortality of COVID-19 threatens the tenability of current tissue exclusion guidelines, and may necessitate their relaxation in the near future.

Long-term changes in keratometry and refraction after small aperture corneal inlay implantation.

PURPOSE: To assess longitudinal refractive, keratometric, and topographic changes following KAMRA small-aperture inlay implantation. DESIGN AND SETTING: Prospective study at a single site refractive surgery center. METHODS: Fifty patients underwent KAMRA small-aperture corneal inlay implantation for the correction of presbyopia. Uncorrected near visual acuity (UNVA), uncorrected distance visual acuity, manifest refractive spherical equivalent (MRSE), mean keratometry (Km), corneal topography, and surgically induced astigmatism vector analysis assessments were performed preoperatively and at 1, 3, 6, 12, 24, and 36 months postoperatively. RESULTS: The study comprises 50 eyes. An average shift of 0.15±0.63 D (range -1.63 to 2.00 D) occurred between preoperative baseline and 36 months. At 36 months, 54% of patients had hyperopic MRSE and 40% had myopic MRSE compared with baseline. Km was significantly elevated at all postoperative measurements compared with baseline, with the largest Km measured at 12 months. Eighty-six percent of patients had UNVA of 20/32 or better and 88% uncorrected distance visual acuity of 20/25 or better at 36 months. Longitudinal corneal topography revealed a pattern of corneal steepening over the body of the inlay and flattening over the aperture, correlating with a hyperopic shift. There was no significant surgically induced astigmatism. CONCLUSION: KAMRA inlay may cause an increase in Km compared with baseline. Corneal steepening may occur in a specific pattern with steepening over the inlay and flattening over the aperture. This topographic pattern causes a hyperopic shift, which may be relevant for subsequent procedures, such as cataract extraction.

Mechanisms of Optical Regression Following Corneal Laser Refractive Surgery: Epithelial and Stromal Responses.

Laser vision correction is a safe and effective method of reducing spectacle dependence. Photorefractive Keratectomy (PRK), Laser In Situ Keratomileusis (LASIK), and Small-Incision Lenticule Extraction (SMILE) can accurately correct myopia, hyperopia, and astigmatism. Although these procedures are nearing optimization in terms of their ability to produce a desired refractive target, the long term cellular responses of the cornea to these procedures can cause patients to regress from the their ideal postoperative refraction. In many cases, refractive regression requires follow up enhancement surgeries, presenting additional risks to patients. Although some risk factors underlying refractive regression have been identified, the exact mechanisms have not been elucidated. It is clear that cellular proliferation events are important mediators of optical regression. This review focused specifically on cellular changes to the corneal epithelium and stroma, which may influence postoperative visual regression following LASIK, PRK, and SMILE procedures.

Ectasia following small-incision lenticule extraction (SMILE): a review of the literature.

PURPOSE: Four cases of corneal ectasia after small-incision lenticule extraction (SMILE) have been reported. In this review, we provide an overview of the published literature on corneal ectasia after SMILE and risk factors associated with this complication. METHODS: Case reports were identified by a search of seven electronic databases for pertinent heading terms between 2011 and July 2017. We identified patient characteristics and surgical details including preoperative topography, central corneal thickness, and anterior keratometry (Km). Residual stromal bed (RSB) values not reported were computed using VisuMax ReLEx SMILE software Version 2.10.10. Preoperative ectasia risk was measured using the Randleman Ectasia Risk Score System (ERSS). Percent tissue alteration was calculated for each patient as described by Santhiago et al. RESULTS: Seven eyes of four patients developed corneal ectasia post SMILE. Two patients had abnormal topography in both eyes. One patient had abnormal topography in one eye. Only one patient was noted to have normal topography in both eyes and later developed ectasia in one eye in the absence of any known risk factors. The mean Randleman ectasia risk score was 4±3 (range: 1-8). The mean calculated percent tissue altered (PTA) was 38%±6% (range: 30%-47%). CONCLUSION: A majority of reported ectasia cases occurred in patients with subclinical keratoconus. These conditions may be exacerbated by SMILE and should be considered absolute contraindications to the procedure. Three patients were identified to have high risk based on the ERSS, and one patient exhibited a PTA ≥40%. We formulated a modification to the current calculation of PTA that takes into account the differences in tissue altered between SMILE and laser in situ keratomileusis (LASIK). More studies are needed to fully quantify the risk of ectasia. For now, we propose adopting the same exclusion criteria used for LASIK in the SMILE procedure until more specific metrics have been validated.

Comparison of FDA safety and efficacy data for KAMRA and Raindrop corneal inlays.

AIM: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Corneal Hydrops Secondary to Intrastromal Corneal Ring Intrusion into the Anterior Chamber 7 Years after Implantation: A Case Report.

INTRODUCTION: This report describes the first known case of late-onset intrusion of an intrastromal ring segment into the anterior chamber due to posterior migration of a ring segment. To our knowledge, intrastromal ring segment penetration has only been shown to occur in the intraoperative or immediate postoperative period. We postulate that the perforation in this case is due to progressive thinning of the cornea, possibly in combination with habitual eye rubbing. CASE REPORT: A 44-year-old man presented with acute corneal hydrops related to penetration of Descemet's membrane and endothelium by an intrastromal ring segment implanted 7 years prior. Removal of the ring segment resulted in an anterior chamber fistula that directed fluid through the ring segment tunnel to the ocular surface. Leakage of aqueous humor was successfully controlled, and corneal edema gradually resolved. CONCLUSION: This case indicates the need for long term monitoring of ring segment proximity to the posterior corneal surface, especially in patients with ectatic ocular conditions and/or habitual eye rubbing behavior.

Case of Presumed Transient Light-Sensitivity Syndrome After Small-Incision Lenticule Extraction.

PURPOSE: To report the first presumed case of transient light-sensitivity syndrome (TLSS) after small-incision lenticule extraction (SMILE). METHODS: A 27-year-old male patient was treated for severe photophobic symptoms occurring 7 weeks after undergoing a bilateral SMILE procedure. His comprehensive ocular examination was unremarkable and his visual acuity was unaffected. Treatment was a month-long tapering dose of topical steroids. RESULTS: Photophobic symptoms fully resolved after steroid treatment. TLSS related to SMILE mirrors TLSS after laser in situ keratomileusis in both onset and steroid responsiveness. CONCLUSIONS: TLSS is a rare and minor complication of SMILE. Photophobic symptoms associated with post-SMILE TLSS are fully responsive to topical corticosteroids.

Neodymium:YAG laser posterior capsulotomy in eye with an intrastromal inlay.

We report intraoperative issues, patient outcomes, and lessons learned from inadvertently contacting a Kamra corneal inlay with a neodymium:YAG (Nd:YAG) laser during a routine capsulotomy procedure for posterior capsule opacification. We also present scanning electron microscopic and histopathologic images from a series of 4 inlays implanted in postmortem porcine eyes that were purposely contacted with an Nd:YAG laser. Our capsulotomy patient developed a clinically insignificant and transient corneal opacity accompanied by mild blanching on the inlay. Modeling this scenario in porcine corneas demonstrated the potential for carbon particle liberation into the overlying stroma, damage to the inlay body, and fusion of inlay nutrition holes.

Stereoacuity after small aperture corneal inlay implantation.

PURPOSE: The aim of this study was to compare stereoacuity before and after KAMRA corneal inlay implantation for the correction of presbyopia. PATIENTS AND METHODS: This is a prospective study of 60 patients who underwent KAMRA inlay implantation. Patients were examined before and 6 months after surgery for stereoacuity, uncorrected distance visual acuity (UDVA), and uncorrected near visual acuity (UNVA). RESULTS: The mean stereoacuity before surgery was 29.5±28.1 arcsec (range: 20-200) and at 6 months was 29.8±26.4 arcsec (range: 20-200). The decline in stereoacuity was not statistically significant. At 6 months follow-up, UDVA was 20/25 or better in all 60 patients and UNVA was J2 (20/25) or better in 51 (85%) patients. CONCLUSION: There is no significant change in stereoacuity following KAMRA inlay implantation. The KAMRA inlay is a good treatment option for improving near vision in presbyopic patients while preserving stereoacuity and distance vision.

Short-term visual result after simultaneous photorefractive keratectomy and small-aperture cornea inlay implantation.

PURPOSE: To report the short-term results of simultaneous photorefractive keratectomy (PRK) and small-aperture cornea inlay implantation (KAMRA) surgery in treating presbyopia. METHODS: Simultaneous PRK and KAMRA inlay surgery was performed on 21 patients from July 2015 to March 2016. Follow-up exams were conducted at 1, 3, and 6 months postoperatively. Our patients were also divided preoperatively into three categories: myopic, hyperopic, and emmetropic. Over the 6-month period, the main outcome measures were uncorrected near visual acuity (UNVA), changes in best-corrected distance visual acuity, and mean spherical equivalent refraction. RESULTS: At 6-month follow-up, 83% (10/12) of patients had a monocular UNVA of 20/40 or better, and 75% had a binocular UNVA of 20/40 (J5) or better. At 6 months, the overall mean refractive spherical equivalent (MRSE) was -0.60 D (±0.42 standard deviation [SD], range: -1.38 to -0.13) with a mean change of -0.43 D (±1.19 SD, range: -1.5 to 2.63) compared to preoperative data. Overall, 91% (10/11) of patients were within a ±0.5 D range of our target -0.75 D for KAMRA use. One-hundred percent (5/5) of the hyperopes, 50% (1/2) of emmetropes, and 100% (4/4) of myopes met the targeted range. At 6 months, the MRSE for the hyperopic subgroup (n=5) was 0.33 D (±0.20 SD), the MRSE for the emmetropic subgroup (n=2) was -1.19 D (±0.19 SD), and the MRSE for the myopic subgroup (n=4) was -0.66 D (±0.36 SD). CONCLUSION: Based on preliminary results and a small sample size, it seems that simultaneous PRK and KAMRA is effective and predictable. There are multiple advantages in performing simultaneous PRK and KAMRA including a shorter recovery time and less steroid use than the two surgeries performed separately.

Rainbow glare after laser-assisted in situ keratomileusis: a review of literature.

This article reviews the current literature pertaining to rainbow glare (RG), including incidence rate, clinical presentation, etiology, prognosis, and management. RG is a rare optical complication of femtosecond laser-assisted in situ keratomileusis that results in patients seeing an array of spectral bands surrounding point sources of light under mesopic and scotopic conditions. The mechanism is thought to be a consequence of the formation of a transmissive diffraction grating on the posterior surface of the corneal flap created by the FS laser. RG has a good prognosis and is usually self-limiting. Persistent RG with concomitant residual refractive error may warrant lifting the flap and photoablating the posterior surface of the flap. Patients with persistent RG and no residual refractive error should be considered candidates for phototherapeutic keratectomy on the posterior flap surface.