Addressing Technical Failures in a Diabetic Retinopathy Screening Program.

Purpose: Diabetic retinopathy (DR) is a preventable cause of blindness detectable through screening using retinal digital photography. The Irish National Diabetic Retina Screening (DRS) programme, Diabetic RetinaScreen, provides free screening services to patients with diabetes from aged 12 years and older. A technical failure (TF) occurs when digital retinal imaging is ungradable, resulting in delays in the diagnosis and treatment of sight-threatening disease. Despite their impact, the causes of TFs, and indeed the utility of interventions to prevent them, have not been extensively examined. Aim: Primary analysis aimed to identify factors associated with TF. Secondary analysis examined a subset of cases, assessing patient data from five time points between 2019 and 2021 to identify photographer/patient factors associated with TF. Methods: Patient data from the DRS database for one provider were extracted for analysis between 2018 and 2022. Information on patient demographics, screening results, and other factors previously associated with TF were analyzed. Primary analysis involved using mixed-effects logistic regression models with nested patient-eye random effects. Secondary analysis reviewed a subset of cases in detail, checking for causes of TF. Results: The primary analysis included a total of 366,528 appointments from 104,407 patients over 5 years. Most patients had Type 2 diabetes (89.2%), and the overall TF rate was 4.9%. Diabetes type and duration, dilate pupil status, and the presence of lens artefacts on the camera were significantly associated with TF. The Secondary analysis identified the primary cause of TF was found to be optically dense cataracts, accounting for over half of the TFs. Conclusion: This study provides insight into the causes of TF within the Irish DRS program, highlighting cataracts as the primary contributing factor. The identification of patient-level factors associated with TF facilitates appropriate interventions that can be put in place to improve patient outcomes and minimize delays in treatment and diagnosis.

The Role of the Ophthalmic Genetics Multidisciplinary Team in the Management of Inherited Retinal Degenerations-A Case-Based Review.

(1) Background: Inherited retinal degenertions are rare conditions which may have a dramatic impact on the daily life of those affected and how they interact with their environment. Coordination of clinical services via an ophthalmic genetics multidisciplinary team (OG-MDT) allows better efficiency of time and resources to reach diagnoses and facilitate patient needs. (2) Methods: This clinical case series was conducted by a retrospective review of patient records for patients enrolled in the Target 5000 programme and managed by the OG-MDT, at the Mater Hospital Dublin, Ireland (n = 865) (3) Results: Herein we describe clinical cases and how the use of the OG-MDT optimizes care for isolated and syndromic IRD pedigrees. (4) Conclusions: this paper demonstrates the benefits of an OG-MDT to patients with IRDs resulting in the holistic resolution of complex and syndromic cases. Furthermore, we demonstrate that this format can be adopted/developed by similar centres around the world, bringing with it the myriad benefits.

Usher Syndrome on the Island of Ireland: A Genotype-Phenotype Review.

Purpose: Usher syndrome (USH) is a genetically heterogeneous group of autosomal recessive (AR) syndromic inherited retinal degenerations (IRDs) representing 50% of deaf-blindness. All subtypes include retinitis pigmentosa, sensorineural hearing loss, and vestibular abnormalities. Thorough phenotyping may facilitate genetic diagnosis and intervention. Here we report the clinical/genetic features of an Irish USH cohort. Methods: USH patients were selected from the Irish IRD registry (Target 5000). Patients were examined clinically (deep-phenotyping) and genetically using a 254 IRD-associated gene target capture sequencing panel, USH2A exon, and whole genome sequencing. Results: The study identified 145 patients (24.1% USH1 [n = 35], 73.8% USH2 [n = 107], 1.4% USH3 [n = 2], and 0.7% USH4 [n = 1]). A genetic diagnosis was reached in 82.1%, the majority (80.7%) being MYO7A or USH2A genotypes. Mean visual acuity and visual field (VF) were 0.47 ± 0.58 LogMAR and 31.3° ± 32.8°, respectively, at a mean age of 43 years. Legal blindness criteria were met in 40.7%. Cataract was present in 77.4%. ADGRV1 genotypes had the most VF loss, whereas USH2A patients had greater myopia and CDH23 had the most astigmatism. Variants absent from gnomAD non-Finnish Europeans and ClinVar represented more than 20% of the variants identified and were detected in ADGRV1, ARSG, CDH23, MYO7A, and USH2A. Conclusions: USH is a genetically diverse group of AR IRDs that have a profound impact on affected individuals and their families. The prevalence and phenotype/genotype characteristics of USH in Ireland have, as yet, gone unreported. Understanding the genotype of Irish USH patients may guide clinical and genetic characterization facilitating access to existing/novel therapeutics.

Detailed analysis of an enriched deep intronic ABCA4 variant in Irish Stargardt disease patients.

Over 15% of probands in a large cohort of more than 1500 inherited retinal degeneration patients present with a clinical diagnosis of Stargardt disease (STGD1), a recessive form of macular dystrophy caused by biallelic variants in the ABCA4 gene. Participants were clinically examined and underwent either target capture sequencing of the exons and some pathogenic intronic regions of ABCA4, sequencing of the entire ABCA4 gene or whole genome sequencing. ABCA4 c.4539 + 2028C > T, p.[= ,Arg1514Leufs*36] is a pathogenic deep intronic variant that results in a retina-specific 345-nucleotide pseudoexon inclusion. Through analysis of the Irish STGD1 cohort, 25 individuals across 18 pedigrees harbour ABCA4 c.4539 + 2028C > T and another pathogenic variant. This includes, to the best of our knowledge, the only two homozygous patients identified to date. This provides important evidence of variant pathogenicity for this deep intronic variant, highlighting the value of homozygotes for variant interpretation. 15 other heterozygous incidents of this variant in patients have been reported globally, indicating significant enrichment in the Irish population. We provide detailed genetic and clinical characterization of these patients, illustrating that ABCA4 c.4539 + 2028C > T is a variant of mild to intermediate severity. These results have important implications for unresolved STGD1 patients globally with approximately 10% of the population in some western countries claiming Irish heritage. This study exemplifies that detection and characterization of founder variants is a diagnostic imperative.

Electrophysiology-Guided Genetic Characterisation Maximises Molecular Diagnosis in an Irish Paediatric Inherited Retinal Degeneration Population.

Inherited retinal degenerations (IRDs) account for over one third of the underlying causes of blindness in the paediatric population. Patients with IRDs often experience long delays prior to reaching a definitive diagnosis. Children attending a tertiary care paediatric ophthalmology department with phenotypic (i.e., clinical and/or electrophysiologic) evidence suggestive of IRD were contacted for genetic testing during the SARS-CoV-2-19 pandemic using a "telegenetics" approach. Genetic testing approach was panel-based next generation sequencing (351 genes) via a commercial laboratory (Blueprint Genetics, Helsinki, Finland). Of 70 patient samples from 57 pedigrees undergoing genetic testing, a causative genetic variant(s) was detected for 60 patients (85.7%) from 47 (82.5%) pedigrees. Of the 60 genetically resolved IRD patients, 5% (n = 3) are eligible for approved therapies (RPE65) and 38.3% (n = 23) are eligible for clinical trial-based gene therapies including CEP290 (n = 2), CNGA3 (n = 3), CNGB3 (n = 6), RPGR (n = 5) and RS1 (n = 7). The early introduction of genetic testing in the diagnostic/care pathway for children with IRDs is critical for genetic counselling of these families prior to upcoming gene therapy trials. Herein, we describe the pathway used, the clinical and genetic findings, and the therapeutic implications of the first systematic coordinated round of genetic testing of a paediatric IRD cohort in Ireland.

Usher syndrome type IV: clinically and molecularly confirmed by novel ARSG variants.

Usher syndrome (USH) is an autosomal recessively inherited disease characterized by sensorineural hearing loss (SNHL) and retinitis pigmentosa (RP) with or without vestibular dysfunction. It is highly heterogeneous both clinically and genetically. Recently, variants in the arylsulfatase G (ARSG) gene have been reported to underlie USH type IV. This distinct type of USH is characterized by late-onset RP with predominantly pericentral and macular changes, and late onset SNHL without vestibular dysfunction. In this study, we describe the USH type IV phenotype in three unrelated subjects. We identified three novel pathogenic variants, two novel likely pathogenic variants, and one previously described pathogenic variant in ARSG. Functional experiments indicated a loss of sulfatase activity of the mutant proteins. Our findings confirm that ARSG variants cause the newly defined USH type IV and support the proposed extension of the phenotypic USH classification.

Clinical and Genetic Re-Evaluation of Inherited Retinal Degeneration Pedigrees following Initial Negative Findings on Panel-Based Next Generation Sequencing.

Although rare, inherited retinal degenerations (IRDs) are the most common reason for blind registration in the working age population. They are highly genetically heterogeneous (>300 known genetic loci), and confirmation of a molecular diagnosis is a prerequisite for many therapeutic clinical trials and approved treatments. First-tier genetic testing of IRDs with panel-based next-generation sequencing (pNGS) has a diagnostic yield of ≈70-80%, leaving the remaining more challenging cases to be resolved by second-tier testing methods. This study describes the phenotypic reassessment of patients with a negative result from first-tier pNGS and the rationale, outcomes, and cost of second-tier genetic testing approaches. Removing non-IRD cases from consideration and utilizing case-appropriate second-tier genetic testing techniques, we genetically resolved 56% of previously unresolved pedigrees, bringing the overall resolve rate to 92% (388/423). At present, pNGS remains the most cost-effective first-tier approach for the molecular assessment of diverse IRD populations Second-tier genetic testing should be guided by clinical (i.e., reassessment, multimodal imaging, electrophysiology), and genetic (i.e., single alleles in autosomal recessive disease) indications to achieve a genetic diagnosis in the most cost-effective manner.

Irish National Diabetic RetinaScreen Programme: report on five rounds of retinopathy screening and screen-positive referrals. (INDEAR study report no. 1).

OBJECTIVE: To study the uptake of annual diabetic retinopathy screening and study the 5-year trends in the detection of screen-positive diabetic retinopathy and non-diabetes-related eye disease in a cohort of annually screened individuals. DESIGN: Retrospective retinopathy screening attendance and retinopathy grading analysis. SETTING: Community-based retinopathy screening centres for the Diabetic RetinaScreen Programme. PARTICIPANTS: 171 557 were identified by the screening programme to be eligible for annual diabetic retinopathy screening. 120 048 individuals over the age of 12 consented to and attended at least one screening appointment between February 2013 to December 2018. MAIN OUTCOME MEASURES: Detection rate per 100 000 of any retinopathy, screen-positive referrable retinopathy and nondiabetic eye disease. RESULTS: Uptake of screening had reached 67.2% in the fifth round of screening. Detection rate of screen-positive retinopathy reduced from 13 229 to 4237 per 100 000 screened over five rounds. Detection of proliferative disease had reduced from 2898 to 713 per 100 000 screened. Non-diabetic eye disease detection and referral to treatment centres increased almost eightfold from 393 in round 1 to 3225 per 100 000 screened. The majority of individuals referred to treatment centres for ophthalmologist assessment are over the age of 50 years. CONCLUSIONS: Screening programme has seen a reduced detection rate both screen-positive retinopathy referral in Ireland over five rounds of screening. Management of nondiabetic eye diseases poses a significant challenge in improving visual outcomes of people living with diabetes in Ireland.

Target 5000: a standardized all-Ireland pathway for the diagnosis and management of inherited retinal degenerations.

INTRODUCTION: Inherited retinal degenerations (IRD) are rare genetic disorders with > 300 known genetic loci, manifesting variably progressive visual dysfunction. IRDs were historically underserved due to lack of effective interventions. Many novel therapies will require accurate diagnosis (phenotype and genotype), thus an efficient and effective pathway for assessment and management is required. METHODS: Using surveys of existing practice patterns and advice from international experts, an all-Ireland IRD service (Target 5000) was designed. Detailed phenotyping was followed by next generation genetic sequencing in both a research and accredited laboratory. Unresolved pedigrees underwent further studies (whole gene/whole exome/whole genome sequencing). Novel variants were interrogated for pathogenicity (cascade screening, in silico analysis, functional studies). A multidisciplinary team (MDT; ophthalmologists, physicians, geneticists, genetic counsellors) reconciled phenotype with genotype. A bespoke care plan was created for each patient comprising supports, existing interventions, and novel therapies/clinical trials. RESULTS AND DISCUSSION: Prior to Target 5000, a significant cohort of patients were not engaged with healthcare/support services due to lack of effective interventions. Pathogenic or likely pathogenic variants in IRD-associated genes were detected in 62.3%, with 11.6% having variants of unknown significance. The genotyping arm of Target 5000 allowed a 42.73% cost saving over independent testing, plus the value of MDT expertise/processing. Partial funding has transferred from charitable sources to government resources. CONCLUSION: Target 5000 demonstrates efficacious and efficient clinical/genetic diagnosis, while discovering novel IRD-implicated genes/variants and investigating mechanisms of disease and avenues of intervention. This model could be used to develop similar IRD programmes in small/medium-sized nations.

Factors associated with non-attendance in the Irish national diabetic retinopathy screening programme (INDEAR study report no. 2).

AIMS: We aimed to determine the patient and screening-level factors that are associated with non-attendance in the Irish National Diabetic Retinal screening programme (Diabetic RetinaScreen). To accomplish this, we modelled a selection of predictors derived from the historical screening records of patients with diabetes. METHODS: In this cohort study, appointment data from the national diabetic retinopathy screening programme (RetinaScreen) were extracted and augmented using publicly available meteorological and geospatial data. A total of 653,969 appointments from 158,655 patients were included for analysis. Mixed-effects models (univariable and multivariable) were used to estimate the influence of several variables on non-attendance to screening appointments. RESULTS: All variables considered for analysis were statistically significant. Variables of note, with meaningful effect, were age (OR: 1.23 per decade away from 70; 95% CI: [1.22-1.24]), type 2 diabetes (OR: 1.10; 95% CI: [1.06-1.14]) and socio-economic deprivation (OR: 1.12; 95% CI: [1.09-1.16]). A majority (52%) of missed appointments were from patients who had missed three or more appointments. CONCLUSIONS: This study is the first to outline factors that are associated with non-attendance within the Irish national diabetic retinopathy screening service. In particular, when corrected for age and other factors, patients with type 2 diabetes had higher rates of non-attendance. Additionally, this is the first study of any diabetic screening programme to demonstrate that weather may influence attendance. This research provides unique insight to guide the implementation of an optimal and cost-effective intervention strategy to improve attendance.

Surgical management of non-syndromic ectopia lentis.

AIM: To compare whether aphakic contact lenses or secondary iris-claw intraocular lenses are superior in the refractive management post-pars plana vitreolensectomy in a pedigree with an FBN1 mutation causing non-syndromic ectopia lentis (NSEL) with retinal detachment (RD). METHODS: Eight affected individuals had pars plana vitreolensectomy for bilateral ectopia lentis (EL). Twelve eyes of 6 patients had secondary iris-claw intraocular lenses inserted and 4 eyes of 2 patients were managed with contact lenses. Rhegmatogenous retinal detachment (RRD) was treated when necessary. Pre- and post-operative assessment included visual acuity, endothelial cell count and dilated fundal examination. RESULTS: Macula-on RRD was present in all individuals >18y, 64% (7/11 eyes) presenting post-vitreolensectomy with 57% having bilateral non-synchronous RRD. Surgical aphakia was managed with iris-fixated intraocular lenses (IOL group, n=6), or contact lenses (CL group, n=2). Visual acuity ≥0.3 logMAR (driving standard) was achieved in 75% of IOL group eyes and 25% of the CL group eyes. Mean loss of corneal endothelial cell count in the IOL group was 4% at 2y post-operative. CONCLUSION: In this cohort, refractive management with iris-claw IOLs provided superior outcomes to contact lenses and the authors recommend this as the optimal refractive correction in EL patients.

A FBN1 variant manifesting as non-syndromic ectopia lentis with retinal detachment: clinical and genetic characteristics.

BACKGROUND/OBJECTIVES: Fibrillin-1 (FBN1) mutations cause connective tissue dysgenesis the main ocular manifestation being ectopia lentis (EL), which may be syndromic or non-syndromic. We describe a pedigree with a FBN1 mutation causing non-syndromic EL with retinal detachment (RRD) and their management. SUBJECTS/METHODS: Patients with familial EL with RRD were invited to participate (vitreoretinopathy branch of Target 5000, the Irish inherited retinal degeneration study). All patients signed full informed consent. The study was approved by the Institutional Review Board of the Mater Hospital, Dublin and abided by the Declaration of Helsinki. RESULTS: Seven adults were affected with bilateral EL. All subjects had RRD with bilateral non-synchronous RRD in 57%. CONCLUSIONS: The FBN1 variant described herein confers an increased risk of both EL and RRD and can now be upgraded to 'pathogenic' ACMG status.

Rhegmatogenous retinal detachments: primary reattachment rates and visual outcomes over a 4-year period.

BACKGROUND AND AIMS: To describe rhegmatogenous retinal detachment surgery in a Dublin tertiary referral centre over a 4-year period and to examine factors predictive of surgical and anatomical success. METHODS: A retrospective study was performed by reviewing the surgical log and the charts of patients who underwent a primary retinal detachment repair in a specialist centre over a 4-year period between 2012 and 2015. We excluded exudative and tractional cases. Multiple parameters were recorded including macular status, visual acuity, type of procedure, complications and visual and anatomical outcomes at 6 months post operation. Primary reattachment rate was calculated alongside change in visual acuity. Chi-square testing and analysis of variance were utilized to determine the effect which lens status, macular status, extent of breaks and type of procedure had on outcome and visual success. RESULTS: A total of 613 primary rhegmatogenous retinal detachment repairs were performed over the 4-year period. Our primary reattachment rate was calculated to be 88.58% (annual range 85.25-91.30%) with a perioperative complication rate of 2.94%. We noted a statistical significant improvement in VA with a median logMAR VA of 1.0 at presentation to 0.5 at 6 months post procedure. Macular status (chi-square test p = 0.15, X2 = 2.072) and lens status (chi-square test p = 0.2974, X2 = 1.086) had no statistical effect on the final anatomical outcome. However, eyes with giant retinal tears were more likely to redetach than those without (chi-square test p = 0.0069, X2 = 7.3). There was no statistical significant difference in the proportion of eyes achieving visual success by surgery category (one-way ANOVA analysis p = 0.501). CONCLUSIONS: This is the first study of its kind in Ireland and will help surgeons benchmark their results against international standards in the future. Accurate recording of logMAR acuity and intraoperative complications is imperative to assist with prospective studies.

Early Subretinal Allograft Rejection Is Characterized by Innate Immune Activity.

Successful subretinal transplantation is limited by considerable early graft loss despite pharmacological suppression of adaptive immunity. We postulated that early innate immune activity is a dominant factor in determining graft survival and chose a nonimmunosuppressed mouse model of retinal pigment epithelial (RPE) cell transplantation to explore this. Expression of almost all measured cytokines by DH01 RPE cells increased significantly following graft preparation, and the neutrophil chemoattractant KC/GRO/CINC was most significantly increased. Subretinal allografts of DH01 cells (C57BL/10 origin) into healthy, nonimmunosuppressed C57BL/6 murine eyes were harvested and fixed at 1, 3, 7, and 28 days postoperatively and subsequently cryosectioned and stained. Graft cells were detected using SV40 large T antigen (SV40T) immunolabeling and apoptosis/necrosis by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Sections were also immunolabeled for macrophage (CD11b and F4/80), neutrophil (Gr1 Ly-6G), and T-lymphocyte (CD3-ɛ) infiltration. Images captured with an Olympus FV1000 confocal microscope were analyzed using the Imaris software. The proportion of the subretinal bolus comprising graft cells (SV40T+) was significantly (p < 0.001) reduced between postoperative day (POD) 3 (90 ± 4%) and POD 7 (20 ± 7%). CD11b+, F4/80+, and Gr1 Ly-6G+ cells increased significantly (p < 0.05) from POD 1 and predominated over SV40T+ cells by POD 7. Colabeling confocal microscopic analysis demonstrated graft engulfment by neutrophils and macrophages at POD 7, and reconstruction of z-stacked confocal images confirmed SV40T inside Gr1 Ly-6G+ cells. Expression of CD3-ɛ was low and did not differ significantly between time points. By POD 28, no graft cells were detectable and few inflammatory cells remained. These studies reveal, for the first time, a critical role for innate immune mechanisms early in subretinal graft rejection. The future success of subretinal transplantation will require more emphasis on techniques to limit innate immune-mediated graft loss, rather than focusing exclusively on suppression of the adaptive immune response.

Bullous Variant of Central Serous Chorioretinopathy: Expansion of Phenotypic Features Using Multimethod Imaging.

PURPOSE: To define the phenotypic characteristics of the bullous variant of central serous chorioretinopathy (CSC) using multimethod imaging. DESIGN: Retrospective, observational case series. PARTICIPANTS: Twenty-one eyes of 14 patients with bullous retinal detachment resulting from CSC (bullous CSC group) and 122 eyes of 84 patients with chronic CSC without bullous retinal detachment (nonbullous CSC group). METHODS: We performed a retrospective review of clinical and multimethod imaging data of patients who sought treatment from the authors with bullous retinal detachment resulting from CSC between January 2010 and November 2015. Multimethod imaging comprised color photography, fluorescein angiography, fundus autofluorescence, and high-resolution optical coherence tomography. Consecutive cases of chronic CSC without bullous retinal detachment, seen during the same period, comprised a comparative group. MAIN OUTCOME MEASURES: Qualitative and quantitative characteristics of the choroid, retinal pigment epithelium, and retina were compared between the 2 groups. RESULTS: Mean age of the bullous CSC group was 53.8 years. There was no difference in age, visual acuity, corticosteroid use, or the proportion of white patients and men between the 2 groups (all P > 0.132). Peripheral nonperfusion occurred only in eyes with bullous retinal detachment (38% of cases). Retinal pigment epithelial tears were seen in 95% of eyes in the bullous group and none of the eyes in the nonbullous CSC group. The bullous CSC group demonstrated a greater number of pigment epithelial detachments (PEDs) and more eyes demonstrated PEDs with internal hyperreflectivity (both P < 0.016). Mean subfoveal choroidal thickness in the bullous CSC group (463.1±83.1 µm) was not different compared with that of the nonbullous CSC group (400.6±100.6 µm; P = 0.993). More eyes in the bullous CSC group demonstrated hyperreflectivity around large choroidal vessels and at the level of the choriocapillaris on OCT (P < 0.001). Retinal folds and subretinal fibrin were identified in a greater proportion of eyes in the bullous CSC group (both P < 0.001). CONCLUSIONS: Bullous retinal detachment is a rare manifestation of chronic CSC and is characterized by a unique constellation of phenotypic and multimethod imaging features.

Management of ganciclovir-resistant cytomegalovirus retinitis in HIV infection in the era of antiretroviral therapy.

The incidence of cytomegalovirus retinitis has decreased significantly since the advent of antiretroviral therapy. However, it remains an important problem in both the developed and developing worlds. Furthermore, long-term antiviral suppression is associated with a significant increase in viral resistance. We present the case of a 46-year-old man who developed cytomegalovirus retinitis one year after being diagnosed with HIV. While he initially demonstrated an excellent clinical response to ganciclovir, his cytomegalovirus viral load remained persistently elevated. Over the subsequent years, his virus developed ganciclovir resistance with a concomitant deterioration in his visual acuity. He responded poorly to salvage therapy with foscarnet and cidofovir. This case highlights the ongoing difficulty of managing cytomegalovirus disease nearly two decades into the era of antiretroviral therapy and underlines the need to develop new treatment strategies.

DFPE, partially fluorinated ether: a novel approach for experimental intravitreal tamponade.

PURPOSE: To evaluate decafluoro-di-n-pentyl ether (DFPE) as a vitreous tamponade by examining ocular tolerance in rabbits' eyes. METHODS: Thirteen rabbits were divided into 4 groups after mechanical vitrectomy and were followed up to 12 months. The tamponade remained in the eye for 6 months in group 1 (DFPE) and Group 3 (DFPE and silicone oil) and for 12 months in group 2 (DFPE). Group 4 served as control. RESULTS: In groups 1, 2, and 3, dispersion of the fluid appeared 2 weeks postoperatively. Posterior subcapsular cataracts appeared in rabbits' eyes with large fills of DFPE (>50%). Histologic findings in groups 1 and 2 showed no detectable change in outer nuclear layer thickness. Except for some vacuolations, the inner retina was well preserved in all injected rabbits' eyes. On the electroretinography of injected rabbits' eyes, there was no effect on the a wave amplitude and b wave implicit time, but the b wave amplitude was elevated with statistical significance (P < 0.001) at 1, 3, and 6 months postoperatively but with no statistical significance (P > 0.05) after that period when compared with group 4 and unoperated fellow rabbits' eyes of each group. CONCLUSION: Decafluoro-di-n-pentyl ether demonstrated minimum adverse effects in retinal rabbits; further studies are needed before clinical use as short-term tamponade.