Suboptimal visual outcome after femto-LASIK ablation in a high myopic patient.

A 28-year-old nurse had an aberration-free femto-laser in situ keratomileusis (LASIK) performed for her myopia of -6.25 -0.50 × 096 and -6.75 -0.50 × 175 in the right and left eye, respectively. Corrected distance visual acuity (CDVA) preoperatively was 20/16. Preoperatively, there were no abnormalities on Scheimpflug imaging, and a pachymetry of 585 µm was measured in both eyes. Flap thickness was 115 µm. The patient was quite nervous during the surgery. Since the surgery, her uncorrected distance visual acuity (UDVA) and CDVA are suboptimal at 20/30 and 20/20 in the right eye, and 20/20 and 20/16 in the left eye. 3 months postoperatively, there is a stable manifest refraction of +0.25 -1.25 × 030 and +0.25 -0.00 × 0. The keratometric astigmatism in the Scheimpflug imaging is 1.2 diopter (D) × 114 and 0.4 D × 78 in the right and left eyes, respectively (FIgures 1 and 2). Thinnest pachymetry is 505 µm and 464 µm in the right and left eye, respectively. Her wavefront analysis shows refraction in a 6 mm zone of -0.99 -1.22 × 32 and -0.91 -0.36 × 136. The cycloplegic refraction is 1.25 -1.00 × 023 and +1.00 -0.25 × 006 (Figures 3 and 4). What is the cause of the suboptimal visual outcome in this case? What would be your treatment strategy to improve visual outcome?

Peripheral Vision in Patients Following Intraocular Lens Implantation: A Systematic Review and Meta-Analysis.

PURPOSE: To update the literature on peripheral optics and vision following intraocular lens (IOLs) implantation. METHODS: We investigated how current IOLs influence peripheral visual function, peripheral optical quality, and visual perception and performance, in patients following cataract surgery. Peripheral vision is described as vision outside the central foveal region of the eye (beyond 4-5° of eccentricity). We systematically searched PubMed, Cochrane Central Register of Controlled Trials, Embase, and gray literature for relevant references. Randomized controlled trials and observational studies were eligible for inclusion. Finally, 47 studies with a total of 5963 participants were eligible for this review, of which 15 were included in the meta-analysis. RESULTS: Regarding visual fields, the meta-analysis showed that the pooled estimate of mean deviation (MD) measured with perimetry tests (standard automated perimetry [SAP], short-wavelength automated perimetry [SWAP], and frequency doubling technology [FDT]) appears to be lower than the mean of healthy age-matched controls, regardless of IOL design. Results for pooled estimate show that localized defects (pattern standard deviation [PSD]) were higher than those in the healthy age-matched controls for FDT. We also collected evidence demonstrating that pseudophakia increases peripheral astigmatism and a myopic shift from 20° onward, leading to decreased peripheral image quality compared with that in phakic eyes. Patient-reported outcomes on peripheral vision showed a pooled score estimate of 95.19, indicating high satisfaction, and for the Steps & Stairs questions, a pooled score estimate at 0.23, indicating no to little difficulty seeing steps and stairs. CONCLUSIONS: Peripheral image quality is degraded in eyes after cataract surgery. Nevertheless, whether this degradation leads to impaired visual function in the periphery requires further investigation.

Ultrathin DSAEK versus DMEK - Review of systematic reviews.

The efficacy and safety of Descemet's membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) have been recently compared in several systematic reviews (SRs). The aim of this study was to assess the evidence quality of such SRs, in order to obtain a scientifically rigorous comparison between the two techniques. We performed a systematic review of SRs and meta-analyses comparing the efficacy and safety between UT-DSAEK and DMEK up to 24th March 2023, using 3 electronic databases (PubMed, Cochrane Library, Google Scholar) plus manual reference search. Specific outcomes analyzed included best-corrected visual acuity (BCVA), endothelial cell density (ECD), rebubbling rate, and other postoperative complications. Of 90 titles/abstracts screened, four SRs met the inclusion criteria. All SRs adequately analyzed potential bias of the included studies. One SR raised concern for potential literature search bias and two SRs have heterogeneity in some outcomes analyzed. All SRs found higher BCVA after DMEK, but one SR reported significant heterogeneity. All SRs found significant heterogeneity in ECD analysis, with one SR providing inconsistent analysis of this outcome. Three SRs analyzed rebubbling rates, favoring UT-DSAEK over DMEK. Three SRs concluded a higher overall complication rate after DMEK, although rebubbling may be a confounding factor. This systematic review clarifies the strengths and weaknesses of published SRs and reinforces the conclusion that DMEK leads to superior visual outcomes compared to UT-DSAEK, with the trade-off of higher rebubbling rates and possibly other postoperative complications. Studies with longer follow-up are needed to ascertain these differences between procedures.

Corneal Endothelial Cell Cultures from Organotypic Preservation of Older Donor Corneas Are Suitable for Advanced Cell Therapy.

INTRODUCTION: The purpose of this work was to evaluate the in vitro growth capacity and functionality of human corneal endothelial cells (hCEC) expanded from corneas of elderly (>60 years) donors that were preserved using an organotypic culture method (>15 days, 31°C) and did not meet the clinical criteria for keratoplasty. METHODS: Cell cultures were obtained from prior descemetorhexis (≥10 mm) and a controlled incubation with collagenase type I followed by recombinant trypsin. Cells were seeded on coated plates (fibronectin-albumin-collagen I) and cultures were expanded using the dual supplemented medium approach (maintenance medium and growth medium), in the presence of a 10 µm Rho-associated protein kinase inhibitor (Y-27632). Cell passages were obtained at culture confluency (∼2 weeks). A quantitative colorimetric WST-1 cell growth assay was performed at different time points of the culture. Morphometric analysis (area assessment and circularity), immunocytochemistry (ZO-1, Na+/K+-ATPase α, Ki67), and transendothelial electrical resistance (TEER) were performed on confluent monolayers. RESULTS: There was no difference between the cell growth profiles of hCEC cultures obtained from corneas older than 60 years, whether preserved cold or cultivated organotypic corneas. Primary cultures were able to maintain a certain cell circularity index (around 0.8) and morphology (hexagonal) similar to corneal endothelial mosaic. The ZO-1 and Na+/K+-ATPase pump markers were highly positive in confluent cell monolayers at 21 days after isolation (passage 0; P0), but significantly decreased in confluent monolayers after the first passage (P1). A weak expression of Ki67 was observed in both P0 and P1 monolayers. The P0 monolayers showed a progressive increase in TEER values between days 6 and 11 and remained stable until day 18 of culture, indicating a state of controlled permeability in monolayers. The P1 monolayers also showed some functional ability but with decreased TEER values compared to monolayers at P0. CONCLUSIONS: Our results indicate that it is possible to obtain functional hCEC cultures in eye banks, using simplified and standardized protocols, from older donor corneas (>60 years of age), previously preserved under organotypic culture conditions. This tissue is more readily available in our setting, due to the profile of the donor population or due to the low endothelial count (<2,000 cells/mm2) of the donated cornea.

Descemet's Membrane Endothelial Keratoplasty for Corneal Endothelial Failure Secondary to Three Types of Phakic Intraocular Lens - Retrospective Study.

Purpose: To analyze the outcomes of Descemet's membrane endothelial keratoplasty (DMEK) for corneal endothelial failure secondary to phakic intraocular lens implantation (PIOL) at a reference center for corneal transplantation in Spain. Design: Retrospective, single-surgeon case series. Methods: Single-center analysis of patients who underwent DMEK for PIOL-related corneal decompensation between July 2011 and July 2020 with at least 6 months of follow-up postoperatively. Primary outcome was final best-corrected visual acuity (BCVA, logMAR) compared to pre-DMEK BCVA. Secondary outcomes analyzed included post-DMEK refractive spherical equivalent, endothelial cell loss (%ECL), and graft failure. Results: Sixteen eyes (14 patients) underwent DMEK for PIOL-related corneal decompensation. Mean (SD) time to PIOL explantation was 9.3 (5.0) years, and median (P25-P75) time between PIOL explantation and DMEK surgery was 3 (2-4) months. Median pre-DMEK BCVA was 0.80 (1.08-0.60) logMAR. A statistically significant improvement in BCVA was observed 1 month after DMEK (p = 0.001), and median final BCVA was 0.15 (0.0-0.35) logMAR (p = 0.002). Mean %ECL was 55.6 (18.7) % at 2-year follow-up and 61.7 (11.7) % in eyes with over 4 years of follow-up. Two eyes required re-bubbling (12.5%), one of which ended in primary graft failure (6.2%) and one eye had late endothelial graft failure (LEGF) at 4-year follow-up (1/15 grafts, 6.7%). Conclusion: In patients with PIOL-related corneal decompensation, DMEK leads to good and clinically significant refractive and visual outcomes in the medium-long term, with a good safety profile. Prospective studies are encouraged to ascertain whether these cases are at increased risk of accelerated endothelial cell loss and LEGF.

Outcomes of cystoid macular edema following Descemet's membrane endothelial keratoplasty in a referral center for keratoplasty in Spain: retrospective study.

The aim of this study was to analyze the outcomes of eyes with visually significant cystoid macular œdema (vs-CMO) after Descemet membrane endothelial keratoplasty (DMEK) in a referral center for keratoplasty in Spain. We conducted a retrospective, single-surgeon case series of eyes that developed post-DMEK vs-CMO performed between January 2011 and December 2020. Data collected included: indication for DMEK; biometric data; ocular comorbidities; past medical history; time to detection of vs-CMO after DMEK (T, weeks); best-corrected visual acuity (BCVA, logMAR) and central retinal thickness (CRT, µm) at diagnosis of vs-CMO, after resolution of CMO, and at last follow-up; and management strategy. Main outcomes analyzed were incidence of vs-CMO, improvement in BCVA and CRT after treatment of vs-CMO. Of 291 consecutive DMEK surgeries, 14 eyes of 13 patients (4.8%) developed vs-CMO. Five patients (38.5%) had history of CMO, and 28.6% of eyes had ophthalmic comorbidities. Median (P25-P75) T was 4 (3-10) weeks. Treatment success was observed in 12/13 eyes (92.3%), two of which required second-line treatment. In successful cases (median time-to-resolution 3.0 (2.0-3.5) months), median BCVA improved from 0.60 (0.40-0.80) logMAR to 0.30 (0.15-0.40) logMAR (p = 0.002) after treatment, and median CRT improved from 582.5 (400.0-655.0) µm to 278.0 (258.0-294.0) µm (p = 0.005). In our study, we found a 4.8% rate of post-DMEK vs-CMO, with most cases occurring in the first 3 months after surgery. Good functional and anatomical outcomes are expected in most eyes, without treatment-related complications or implications in graft outcomes. Additional studies are encouraged to determine a standardized protocol for post-DMEK vs-CMO.

Ten-year outcomes of pseudophakic mini-monovision correction of hyperopic presbyopia.

PURPOSE: To evaluate long-term efficacy, safety, and spectacle independence after the treatment of hyperopic presbyopia with pseudophakic mini-monovision using standard monofocal intraocular lenses (IOLs) after bilateral cataract surgery. SETTING: Private practice in Barcelona, Spain. DESIGN: Retrospective, noncomparative case series. METHODS: Patients with hyperopic presbyopia underwent bilateral cataract surgery with pseudophakic mini-monovision using standard monofocal IOLs between 2008 and 2018. Main outcomes analyzed were uncorrected distance visual acuity (UDVA), uncorrected near distance visual acuity (UNVA), and rates of spectacle independence at postoperative day 1 (POD1), months 1, 6 and 12, and at 5 and 10 years (Y10) postoperatively. RESULTS: The study enrolled 463 patients. Both UDVA and UNVA significantly improved postoperatively ( P < .05). The mean binocular UDVA improved from 0.47 ± 0.3 logMAR preoperatively to 0.096 ± 0.14 at POD1 to 0.16 ± 0.2 at Y10 ( P = .0033). The binocular UNVA was 0.05 logMAR at Y10, whereas in preoperative visits, all patients needed spectacles. The mean UDVA for the dominant eye ≤0.20 logMAR was achieved in 84.29% at the Y10. Self-reported and measured complete spectacle independence for near vision was achieved in 79.61% of patients at POD1 and 71.92% at Y10 postoperatively. For distance, respectively, in 86.29% of patients at POD1 and 78.43% at Y10. The achieved results were stable. No serious events were reported, as well as no photic phenomena. CONCLUSIONS: Pseudophakic mini-monovision in hyperopic presbyopes is a safe, effective, and low-cost approach for the long-term correction of presbyopia. It significantly reduces spectacle dependence and fulfils patients' expectations after bilateral cataract surgery.

Photorefractive keratectomy after DMEK for corneal decompensation by phakic IOL.

PURPOSE: To provide the first description of photorefractive keratectomy (PRK) for the correction of mild residual refractive error after Descemet membrane endothelial keratoplasty (DMEK). METHODS: Case report. RESULTS: A 45 year-old woman presenting with phakic intraocular lens (PIOL)-related corneal decompensation underwent staged DMEK surgery following PIOL explantation and cataract surgery. Eighteen months after DMEK, uncorrected distance visual acuity (UDVA) was 20/60 and best-corrected visual acuity (BCVA) was 20/22, with a stable refraction. The patient requested refractive surgery to decrease spectacle dependance, and wavefront-optimized PRK was performed. At last follow-up observation thirty-three months after PRK (54 months after DMEK surgery), UDVA was 20/20, the cornea remained clear without signs of rejection or endothelial failure, and the endothelial cell loss rate was not accelerated after PRK. CONCLUSION: Since long-term visual and refractive stability can be expected after DMEK, PRK may be a particular safe and effective approach for the correction of mild residual refractive errors after DMEK. However, we consider that surgeons must exercise caution when considering keratorefractive surgery in these eyes due to postoperative changes in corneal curvature and thickness, and further studies are encouraged.

Acute corneal allograft rejection following SARS-CoV-2 vaccination-A systematic review.

All documented cases of acute corneal allograft rejection following SARS-CoV-2 vaccination were examined, to characterize possible risk factors and graft outcomes. Comprehensive search (4 electronic databases: PubMed, CENTRAL, ClinicalTrials.gov, Google Scholar, plus manual search in articles' reference lists) until March 1st 2022 to identify studies reporting acute corneal allograft rejection following SARS-CoV-2 vaccination; study protocol was developed in line with PRISMA statement. We analysed demographics, allograft type, rejection prophylaxis regime at the time of vaccination, transplantation-to-vaccination time (G-Vt), vaccination-to-immune reaction onset time (V-Rt), management, best-corrected visual acuity before and after rejection, and graft survival. Of 169 titles/abstracts screened, 16 studies (n  = 36 eyes) met the inclusion criteria. Fourteen eyes (38.9%) had received >1 graft, and 11.1% of cases had history of immune reactions; 52.9% of cases occurred after the first dose. Median (P25-P75) G-Vt was 48 (10-78) months; median V-Rt was 9 (7-14) days. In eyes with resolved rejection, median time-to-resolution was 3 (1-4) weeks. Four eyes (11.1%) had partial resolution of corneal decompensation, and 5 grafts (13.9%) failed. Acute corneal allograft rejection after SARS-CoV-2 vaccination is a rare event, but may occur any time post-keratoplasty. Early recognition and prompt, aggressive treatment is warranted to optimize vision and graft survival. Well-known risk factors for rejection may be confounding factors, including the high proportion of cases with a history of previous grafts and the rejection prophylaxis regimes at the time of vaccination. Increasing immunosuppressants in the peri-vaccination period may decrease the risk of immune reactions, especially in high-risk cases.

DMEK for the treatment of interface fluid syndrome secondary to failed DSAEK graft: A case report and review of the literature.

Purpose: To report a case of Descemet membrane endothelial keratoplasty (DMEK) for the management of post-laser in situ keratomileusis (LASIK) interface fluid syndrome (IFS) secondary to failed Descemet stripping automated endothelial keratoplasty (DSAEK) graft, and to provide a literature review on endothelial keratoplasty (EK) for this indication. Observations: A 52-year-old patient presented with LASIK interface fluid accumulation and a non-functioning primary DSAEK graft. Past ophthalmic history was relevant for: (1) phakic intraocular lens (PIOL) implantation with later refinement by LASIK; (2) combined PIOL explantation and refractive lens exchange due to accelerated endothelial cell loss (ECL); (3) primary DSAEK due to corneal decompensation.A secondary EK graft (DMEK) was performed, and the patient was prospectively followed for 6 months (M6). DMEK surgery was uneventful, without postoperative graft detachment. Corneal clearing and resolution of interface fluid accumulation occurred during the first postoperative month. Best-corrected visual acuity (BCVA) improved from 20/800 Snellen to 20/25 Snellen at 3-month follow-up, remaining stable at M6. Due to a persistent rise in intraocular pressure (IOP), the patient underwent uneventful non-penetrating deep sclerectomy 2 months after DMEK, with controlled IOP and without accelerated ECL. Conclusions and Importance: DMEK is feasible, effective, and safe in the management of IFS in cases where corneal endothelial failure plays a major role, even in complex eyes with previous EK grafts. Aggressive postoperative IOP control is warranted to decrease the risk of interface fluid recurrence and damage to the optic nerve. Studies with larger patient numbers are encouraged to ascertain the role of EK for this indication.

Liposomal Ozonated Oil in Ocular Infections: A Review of Preclinical and Clinical Studies, Focusing on Its Antiseptic and Regenerative Properties.

Ozonated oil has shown antimicrobial, anti-inflammatory and regenerative properties that make it useful in the prevention of infectious diseases and also as an adjuvant in wound-healing management. This review brings together most aspects of the use of liposomal ozonated oil for ocular infections and regeneration of the ocular surface. A search was performed in PubMed, Medline, Web of Science and Cochrane Library for studies published by June 2021. Search terms were combined to sort out papers on the properties and use of ozonated oil in ocular infections. A total of 25 publications were selected for this review on the composition, mechanism of action, restorative action, and preclinical and clinical studies of liposomal ozonated oil focused on ocular infections. In patients with complicated corneal pathology, liposomal ozonated oil has been found to restore corneal ulcers and improve keratitis. In patients with ocular pathologies involving inflammation and infections, liposomal ozonated oil has been found to improve and almost completely restore the signs of vernal, granulomatous and even adenoviral conjunctivitis. Liposomal ozonated oil has also been found to be effective in reducing ocular microbial flora. In conclusion, liposomal ozonated oil has an antiseptic and regenerative effect on corneoconjunctival tissues. It has demonstrated efficacy and safety profile for its use in ocular infections and can be considered as a suitable supportive strategy both alone and combined with other antimicrobial agents.

Long-term efficacy and safety profiles of iris-fixated foldable anterior chamber phakic intraocular lens implantation in eyes with more than 10 years of follow-up.

PURPOSE: To evaluate the long-term efficacy, safety, predictability, and stability of a foldable anterior chamber phakic intraocular lens (pIOL) (Artiflex) implantation in eyes with more than 10 years of follow-up. SETTING: Instituto de Microcirugía Ocular, Barcelona, Spain. DESIGN: Retrospective study. METHODS: Patients who underwent Artiflex pIOL implantation during 2008 to 2011 and with more than 10 years of follow-up were included. Variables analyzed were as follows: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, spherical equivalent (SE), endothelial cell count (ECC), and intraocular pressure (IOP) preoperatively and at 1 month, 1 year, 5 years, and the final follow-up. Descriptive statistics were performed and results reported following the Standard for Reporting Refractive Surgery Outcomes. RESULTS: 76 eyes (40 patients) were analyzed, and the mean follow-up was 10.67 ± 0.64 years. The mean preoperative SE was -8.26 ± 2.47 diopters (D), and the mean preoperative cylinder was -0.95 ± 0.86 D. At the final follow-up, efficacy and safety indices were 0.82 and 1.11, respectively. In total, 58 eyes (76%) achieved a UDVA of ≥20/40. 30 eyes (39%) gained ≥1 line of CDVA, and no eye lost ≥2 lines of CDVA. At the final follow-up, 46 (61%) and 58 (76%) eyes were within ±0.50 D and ±1.00 D of attempted SE correction, respectively. 72 eyes (95%) had ≤1.00 D of postoperative astigmatism, and 46 eyes (61%) were within ±15 degrees from the intended correction axis. At the last visit, a statistically significant myopic progression of -0.56 ± 0.83 D was observed ( P = .01). The mean ECC loss at the final follow-up was 12.2 ± 12.5%. IOP remained stable. Two eyes (2.63%) developed cataract after 10.3 years. CONCLUSIONS: Long-term results demonstrated that Artiflex pIOL implantation was effective, predictable, stable, and safe.

Long-term efficacy and safety profiles after posterior chamber phakic intraocular lens implantation in eyes with more than 10 years of follow-up.

PURPOSE: To evaluate long-term efficacy, safety, predictability, and stability of a posterior chamber phakic intraocular lens (Visian implantable collamer lens [ICL]) in eyes with ≥10 years of follow-up. SETTING: Instituto de Microcirugía Ocular, Barcelona, Spain. DESIGN: Retrospective study. METHODS: Eyes undergoing ICL implantation from 2008 to 2011 with ≥10 years of follow-up were included. Variables analyzed were preoperative, 1-month, 1-year, 5-year, and last follow-up uncorrected distance (UDVA) and corrected distance visual acuity (CDVA), manifest refraction, spherical equivalent (SE), endothelial cell count (ECC), and intraocular pressure (IOP). Descriptive statistics were performed and results reported following the Standard for Reporting Refractive Surgery Outcomes. RESULTS: 45 eyes (26 patients) were analyzed; the mean follow-up 11.35 ± 1.30 years. The mean preoperative SE was -10.06 ± 3.40 diopters (D) and the mean preoperative cylinder -1.55 ± 1.45 D. At the last follow-up, efficacy and safety indices were 0.79 and 1.12, respectively. In total, 32 eyes (71%) achieved an UDVA of ≥20/40. 22 eyes (49%) gained ≥1 line of CDVA, and 2 eyes (4%) lost ≥2 lines of CDVA. At the final follow-up, 19 eyes (42%) and 29 eyes (64%) were within ±0.50 D and ±1.00 D of attempted SE correction, respectively. 31 eyes (69%) had ≤1.00 D of postoperative astigmatism, and 29 eyes (74%) were within ±15 degrees from the intended correction axis. At the last visit, a statistically significant myopic progression of -0.75 ± 1.20 D was observed ( P = .01). ECC loss at the last follow-up was 9.85 ± 11.35%. IOP remained stable. There were no intraoperative complications. 3 eyes (7%) developed cataract after 10 years. CONCLUSIONS: The long-term results demonstrated that ICL was effective, predictable, stable, and safe.

Laser-integrated real-time OCT in anterior segment procedures.

Intraoperative optical coherence tomography (OCT) was so far only available as a microscope-integrated or handheld device. Recently, this technology has been integrated into a femtosecond (FS) laser. This pilot study analyzed the potential of intraoperative imaging using OCT during FS-assisted procedures of the anterior eye segment. Therefore, intraoperatively acquired videos using FS-integrated intraoperative OCT (laser-integrated [LI] OCT) in 14 patients (Victus, Bausch & Lomb) were analyzed in different surgical procedures. The results showed that all surgical steps could be successfully visualized by LI-OCT. LI-OCT added important information regarding the depth and location of the incisions and dissection planes. Moreover, dynamic processes could be observed in real-time. LI-OCT represents a new imaging technology that makes it possible to visualize intraoperative steps during FS-assisted surgery. In the future, automatic image analysis based on artificial intelligence could be helpful to detect complications at an early stage and to automatically stop the laser process in relevant constellations.

Whole anterior segment and retinal swept source OCT for comprehensive ocular screening.

Whole eye visualization and morphometry are of high relevance in clinical practice. However, most standard ophthalmic OCT instruments are dedicated either to retinal or to anterior segment imaging. We demonstrate a swept source optical coherence tomography system (SS-OCT) that images both the whole anterior segment and the retina alternately using a single source and detector. A pilot population was imaged with the proof of concept prototype. We demonstrate the clinical potential of whole eye OCT screening for the description and early detection of relevant clinical features in the anterior segment and retina of several patients.

Secondary Endothelial Keratoplasty-A Narrative Review of the Outcomes of Secondary Corneal Endothelial Allografts.

BACKGROUND: We review the literature on the efficacy and safety outcomes of secondary Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK). METHODS: Literature search of English-written publications up to September 27, 2020 in PubMed database, using the terms "endothelial keratoplasty" in combination with keywords "secondary" or "repeat." In addition, we manually searched the references of the primary articles. RESULTS: Twenty-seven studies (n = 651 eyes) were retained and reviewed, including 10 studies on repeat DSEK, 8 studies on repeat DMEK, 6 studies of DMEK following DSEK, and 3 studies of DSEK after failed DMEK. All studies reported significant improvement in visual acuity after secondary endothelial keratoplasty (EK). Twelve studies compared visual outcomes between primary and secondary EK, reporting conflicting findings. Sixteen studies reported endothelial cell loss rates after secondary EK, and only 1 study reported significantly increased endothelial cell loss rates compared with primary EK. Allograft rejection episodes occurred in 1.8% of eyes (range, 0%-50%). Six studies compared complication rates between primary and secondary EK eyes, and only 1 study found a higher median number of complications. However, 2 studies reported higher regraft failure rates compared with primary EK eyes. CONCLUSIONS: Secondary EK is surgically feasible and renders significant visual improvement after failed primary EK, although it is not clear whether visual outcomes and allograft survival are comparable with primary EK, raising the question of whether secondary EK eyes are "low risk" as primary EK eyes. Further larger, prospective studies are encouraged to obtain additional quality data on secondary corneal endothelial allotransplantation.