Complications of vitreoretinal surgery.Curr Opin Ophthalmol. 2020;31:167-173. [PMID: 32175941 DOI: 10.1097/ICU.0000000000000652]

Exploration of potential novel drug targets for diabetic retinopathy by plasma proteome screening

The aim of this study is to identify novel potential drug targets for diabetic retinopathy (DR). A bidirectional two-sample Mendelian randomization (MR) analysis was performed using protein quantitative trait loci (pQTL) of 734 plasma proteins as the exposures and clinically diagnosed DR as the outcome. Genetic instruments for 734 plasma proteins were obtained from recently published genome-wide association studies (GWAS), and external plasma proteome data was retrieved from the Icelandic Decoding Genetics Study and UK Biobank Pharma Proteomics Project. Summary-level data of GWAS for DR were obtained from the Finngen Consortium, comprising 14,584 cases and 202,082 population controls. Steiger filtering, Bayesian co-localization, and phenotype scanning were used to further verify the causal relationships calculated by MR. Three significant (p < 6.81 × 10-5) plasma protein-DR pairs were identified during the primary MR analysis, including CFH (OR = 0.8; 95% CI 0.75-0.86; p = 1.29 × 10-9), B3GNT8 (OR = 1.09; 95% CI 1.05-1.12; p = 5.9 × 10-6) and CFHR4 (OR = 1.11; 95% CI 1.06-1.16; p = 1.95 × 10-6). None of the three proteins showed reverse causation. According to Bayesian colocalization analysis, CFH (coloc.abf-PPH4 = 0.534) and B3GNT8 (coloc.abf-PPH4 = 0.638) in plasma shared the same variant with DR. All three identified proteins were validated in external replication cohorts. Our research shows a cause-and-effect connection between genetically determined levels of CFH, B3GNT8 and CFHR4 plasma proteins and DR. The discovery implies that these proteins hold potential as drug target in the process of developing drugs to treat DR.

Desired properties of polymeric hydrogel vitreous substitute

Vitreous replacement is a commonly employed method for treating a range of ocular diseases, including posterior vitreous detachment, complex retinal detachment, diabetic retinopathy, macular hole, and ocular trauma. Various clinical substitutes for vitreous include air, expandable gas, silicone oil, heavy silicone oil, and balanced salt solution. However, these substitutes have drawbacks such as short retention time, cytotoxicity, high intraocular pressure, and the formation of cataracts, rendering them unsuitable for long-term treatment. Polymeric hydrogels possess the potential to serve as ideal vitreous substitutes due to their structure-mimicking to natural vitreous and adjustable mechanical properties. Replacement with hydrogels as the tamponade can help maintain the shape of the eyeball, apply pressure to the detached retina, and ensure the metabolic transport of substances without impairing vision. This literature review examines the required properties of artificial vitreous, including the optical properties, rheological properties, expansive force action, and physiological and biochemical functions of chemically and physically crosslinked hydrogels. The strategies for enhancing the biocompatibility and injectability of hydrogels are also summarized and discussed. From a clinical ophthalmology perspective, this paper presents the latest developments in vitreous replacement, providing clinicians with a comprehensive understanding of hydrogel clinical applications, which offers guidance for future design directions and methodologies for hydrogel development.

Impact of COVID-19 pandemic on a world-wide private ophthalmic practice

Purpose

To assess the impact of the COVID-19 pandemic on a worldwide private ophthalmic practice.

Design

In this retrospective study, we reviewed the 2020 monthly outpatient and surgical volume of refractive, cataract, and retinal disease in Aier Eye clinics/hospitals of different regions, including the United States, Germany, Spain, Italy, and six major cities in China (Wuhan, Beijing, Shanghai, Shenyang, Urumqi and Yili). All of these data were compared to those of the same period of 2019.

Results

Overall, during the early stage (2020 January to 2020 April) of COVID-19 outbreak, the outpatient and surgical volume of three main type ocular diseases (refractive, cataract and retinal surgery) showed an obvious reduction and reached the bottom in February in China. The data from the United States, Germany, Spain and Italy revealed the same trend, but the visit count nadir occurred until April, which is consistent with the spread trend of COVID-19 disease around the world. The average change rates of surgery volume (refractive, cataract and retinal surgery) in Chinese centers are 5.59%, -26.38%, 11.76%. The change rates of refractive (REF) and cataract volumes (CAT) in the United States are -8.62% and -10.58%, in Germany are -13.71% and -20.49%, in Spain are 15.35% and 27.97%, in Italy are 30.43% and -22.64%. In addition, the optometry outpatient volumes keep going up since May, with an average increasing rate of 21.18%, ranging from 7.43% to 49.51%.

Conclusion

In conclusion, in this global chain of eye care units, the visit volumes of cataract, retinal and refractive changed significantly with the spread of COVID-19 pandemic. Among them, cataract surgery was the most affected sub-specialty, and refractive surgery and optometry volumes showed a potential growth in the near future. Therefore, medical institutions should make corresponding adjustments to the disease diagnosis and treatment strategies.

Incidence of and Risk Factors for Cataract in Anterior Uveitis

PURPOSE

To estimate the incidence/risk factors for cataract in noninfectious anterior uveitis.

DESIGN

Retrospective multicenter cohort study (6 US tertiary uveitis sites, 1978-2010).

METHODS

Data were harvested by trained expert reviewers, using protocol-driven review of experts' charts. We studied cataract incidence-newly reduced visual acuity worse than 20/40 attributed to cataract; or incident cataract surgery-in 3923 eyes of 2567 patients with anterior uveitis.

RESULTS

Cataract developed in 507 eyes (54/1000 eye-years, 95% CI 49-59). Time-updated risk factors associated with cataract included older age (≥65 vs <18 years: adjusted hazard ratio [aHR] 5.04, 95% CI 3.04-8.33), higher anterior chamber cell grade (P(trend)=0.001), prior incisional glaucoma surgery (aHR 1.86, 95% CI 1.10-3.14), band keratopathy (aHR 2.23, 95% CI 1.47-3.37), posterior synechiae (aHR 3.71, 95% CI 2.83-4.87), and elevated intraocular pressure ≥30 vs 6-20 mm Hg (aHR 2.57, 95% CI 1.38-4.77). Primary acute (aHR 0.59, 95% CI 0.30-1.15) and recurrent acute (aHR 0.74, 95% CI 0.55-0.98) had lower cataract risk than chronic anterior uveitis. Higher-dose prednisolone acetate 1%-equivalent use (≥2 drops/day) was associated with >2-fold higher cataract risk in eyes with anterior chamber cell grades 0.5+ or lower but was not associated with higher cataract risk in the presence of anterior chamber cells of grade 1+ or higher.

CONCLUSIONS

Cataract complicates anterior uveitis in ∼5.4/100 eye-years. Several fixed and modifiable risk factors were identified, yielding a point system to guide cataract risk minimization. Topical corticosteroids only were associated with increased cataract risk when anterior chamber cells were absent or minimally present, suggesting their use to treat active inflammation (which itself is cataractogenic) does not cause a net increase in cataract incidence.

Clinical Factors and Outcomes of Acute-Onset Endophthalmitis Following Small-Gauge Pars Plana Vitrectomy Surgery

BACKGROUND AND OBJECTIVES

Describe risk factors, findings, and outcomes of acute endophthalmitis (AE) following small-gauge pars plana vitrectomy (PPV).

PATIENTS AND METHODS

This was a retrospective single-center, nonrandomized study of post-PPV AE patients from 2013 to 2021. All received vitreous biopsy before treatment. Patients were divided into cohorts: 1) PPV within 3 days of diagnosis (Urgent-PPV), and 2) no urgent PPV (Other-treatment [Tx]). Main outcome was best-corrected visual acuity (BCVA) at 6 months.

RESULTS

Twenty-one patients were analyzed. Epiretinal membrane was most common indication for PPV (48%). Incidence was 0.074%. Culture-positive rate was 57%. For final BCVA, there was no significant (P = 0.85) difference between Urgent-PPV (median = 0.40 logMAR) and Other Tx cohorts (median = 0.35 logMAR). Sclerotomy wounds were not sutured in 71% of patients. Approximately 24% and 38% of patients analyzed had either no tamponade or partial tamponade, respectively.

CONCLUSION

Tamponade agents and sclerotomy suturing may be important factors when evaluating post-small-gauge PPV-associated AE. Further studies are necessary for clarification. [Ophthalmic Surg Lasers Imaging Retina 2023;54:xx-xx.].

Intra- and post-operative risk of retinal breaks during vitrectomy for macular hole and vitreomacular traction

Background/Objective

To evaluate the development of intra- and post-operative retinal breaks after pars plana vitrectomy (PPV) for macular hole (MH) and/or vitreomacular traction (VMT).

Subjects/Methods

Medical records of patients who underwent PPV at Kellogg Eye Center between 1/1/2005–6/30/2018, were evaluated in three groups: group 1, MH/VMT (n = 136); group 2, epiretinal membrane (ERM) without VMT (n = 270); and group 3, diagnostic vitrectomy (DV) or vitreous opacities (n = 35). Statistical analyses were conducted using SAS.

Results

20.6% of patients with MH/VMT, 8.5% of patients with ERM, and 5.7% of patients with DV or vitreous opacities had either intra-operative or post-operative breaks. Indication of MH/VMT versus ERM was a significant predictor for this outcome (p = .0112). The incidence of retinal breaks was higher in operations using 23-gauge versus 25-gauge PPV (25.0% vs. 7.4%, p < .0001).

Conclusions

The presence of MH and/or VMT is a significant risk factor for retinal breaks from PPV, as is use of 23-gauge vitrectomy.

O-GlcNAc Modification and Its Role in Diabetic Retinopathy

Diabetic retinopathy (DR) is a leading complication in type 1 and type 2 diabetes and has emerged as a significant health problem. Currently, there are no effective therapeutic strategies owing to its inconspicuous early lesions and complex pathological mechanisms. Therefore, the mechanism of molecular pathogenesis requires further elucidation to identify potential targets that can aid in the prevention of DR. As a type of protein translational modification, O-linked β-N-acetylglucosamine (O-GlcNAc) modification is involved in many diseases, and increasing evidence suggests that dysregulated O-GlcNAc modification is associated with DR. The present review discusses O-GlcNAc modification and its molecular mechanisms involved in DR. O-GlcNAc modification might represent a novel alternative therapeutic target for DR in the future.

Screening for ocular candidiasis among patients with candidemia: Is it time to change practice?

Ocular candidiasis (OC) complicates ~10% of candidemia and carries potentially severe morbidity. There are conflicting recommendations about the need for routine funduscopic examinations of candidemic patients. Indirect funduscopy is accurate and safe in diagnosing OC, and positive findings change recommended treatment. However, conclusive evidence is lacking that treatment changes improve outcomes. Bringing perspectives as infectious diseases physicians and ophthalmologists, we review controversies about OC and endorse routine screening during candidemia. We acknowledge difficulties in obtaining inpatient ophthalmologic consults, and recommend studies evaluating digital fundus photography and tele-ophthalmology as an alternative to funduscopic examinations by ophthalmologists in asymptomatic patients.

Systemic and local immune responses to intraocular AAV vector administration in non-human primates

Positive clinical outcomes in adeno-associated virus (AAV)-mediated retinal gene therapy have often been attributed to the low immunogenicity of AAVs and immune privilege of the eye. However, several recent studies have shown potential for inflammatory responses. The current understanding of the factors contributing to inflammation, such as the pre-existence of serum antibodies against AAVs and their contribution to increases in antibody levels post-injection, is incomplete. The parameters that regulate the generation of new antibodies in response to the AAV capsid or transgene after intraocular injections are also insufficiently described. This study is a retrospective analysis of the pre-existing serum antibodies in correlation with changes in antibody levels after intraocular injections of AAV in non-human primates (NHPs) of the species Macaca fascicularis. In NHP serums, we analyzed the binding antibody (BAB) levels and a subset of these called neutralizing antibodies (NABs) that impede AAV transduction. We observed significantly higher pre-existing serum BABs against AAV8 compared with other serotypes and a dose-dependent increase in BABs and NABs in the serums collected post-injection, irrespective of the serotype or the mode of injection. Lastly, we were able to demonstrate a correlation between the serum BAB levels with clinical grading of inflammation and levels of transgene expression.

Incidence of cataract surgeries in people with and without Alzheimer's disease

PURPOSE

To investigate the incidence of cataract surgeries in relation to Alzheimer's disease (AD) diagnosis and to compare it with that in people without AD.

METHODS

The MEDALZ-study includes community-dwelling Finnish persons who received clinically verified AD diagnoses (n = 70718) during 2005-2011 and a matched comparison cohort without AD (n = 70718). The cataract surgeries were identified from the Care Register for Healthcare (1996-2015) using NOMESCO surgical procedure codes CJE (10,15,20,25,99), CJF (00,10,20,30,40,45,50,55,99) and CJG (00,05,10,15,20,25,99). The incidence rates for surgeries per 100 person-years were calculated from 10 years before to 3 years after the index date (date of AD diagnosis from the Special Reimbursement Register).

RESULTS

25 763 cataract procedures were performed on persons with AD and 26 254 on persons without AD during the follow-up. The incidence of surgery increased similarly in both groups before the index date of AD diagnosis, and the rate of surgery was similar in people with and without AD (3.5 and 3.3/100 person-years, respectively). The incidence diminished steeply in the AD group already one year after the index date, whereas the slow increase continued in the non-AD group. After the index date, the rates were 3.7 and 4.7/100 person-years in people with and without AD.

CONCLUSION

The diminishing surgery rate very soon after AD diagnosis is concerning. The stigma of AD diagnosis may lead to fewer referrals to surgery, although these patients are expected to benefit from surgery.

High molecular weight hyper-branched PCL-based thermogelling vitreous endotamponades

Vitreous endotamponades play essential roles in facilitating retina recovery following vitreoretinal surgery, yet existing clinically standards are suboptimal as they can cause elevated intra-ocular pressure, temporary loss of vision, and cataracts while also requiring prolonged face-down positioning and removal surgery. These drawbacks have spurred the development of next-generation vitreous endotamponades, of which supramolecular hydrogels capable of in-situ gelation have emerged as top contenders. Herein, we demonstrate thermogels formed from hyper-branched amphiphilic copolymers as effective transparent and biodegradable vitreous endotamponades for the first time. These hyper-branched copolymers are synthesised via polyaddition of polyethylene glycol, polypropylene glycol, poly(ε-caprolactone)-diol, and glycerol (branch inducing moiety) with hexamethylene diisocyanate. The hyper-branched thermogels are injected as sols and undergo spontaneous gelation when warmed to physiological temperatures in rabbit eyes. We found that polymers with an optimal degree of hyper-branching showed excellent biocompatibility and was able to maintain retinal function with minimal atrophy and inflammation, even at absolute molecular weights high enough to cause undesirable in-vivo effects for their linear counterparts. The hyper-branched thermogel is cleared naturally from the vitreous through surface hydrogel erosion and negates surgical removal. Our findings expand the scope of polymer architectures suitable for in-vivo intraocular therapeutic applications beyond linear constructs.

Cellular targets in diabetic retinopathy therapy

Despite the existence of treatment for diabetes, inadequate metabolic control triggers the appearance of chronic complications such as diabetic retinopathy. Diabetic retinopathy is considered a multifactorial disease of complex etiology in which oxidative stress and low chronic inflammation play essential roles. Chronic exposure to hyperglycemia triggers a loss of redox balance that is critical for the appearance of neuronal and vascular damage during the development and progression of the disease. Current therapies for the treatment of diabetic retinopathy are used in advanced stages of the disease and are unable to reverse the retinal damage induced by hyperglycemia. The lack of effective therapies without side effects means there is an urgent need to identify an early action capable of preventing the development of the disease and its pathophysiological consequences in order to avoid loss of vision associated with diabetic retinopathy. Therefore, in this review we propose different therapeutic targets related to the modulation of the redox and inflammatory status that, potentially, can prevent the development and progression of the disease.

Heat treatment of soluble proteins isolated from human cataract lens leads to the formation of non-fibrillar amyloid-like protein aggregates

The loss of crystallins solubility with aging and the formation of amyloid-like aggregates is considered the hallmark characteristic of cataract pathology. The present study was carried out to assess the effect of temperature on the soluble lens protein and the formation of protein aggregates with typical amyloid characteristics. The soluble fraction of lens proteins was subjected for heat treatment in the range of 40-60 °C, and the nature of protein aggregates was assessed by using Congo red (CR), thioflavin T (ThT), and 8-anilinonaphthalene-1-sulfonic acid (ANS) binding assays, circular dichroism (CD), Fourier-transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). The heat-treated protein samples displayed a substantial bathochromic shift (≈15 nm) in the CR's absorption maximum (λ_max) and increased ThT and ANS binding. The heat treatment of lens soluble proteins results in the formation of nontoxic, β-sheet rich, non-fibrillar, protein aggregates similar to the structures evident in the insoluble fraction of proteins isolated from the cataractous lens. The data obtained from the present study suggest that the exposure of soluble lens proteins to elevated temperature leads to the formation of non-fibrillar aggregates, establishing the role of amyloid in the heat-induced augmentation of cataracts pathology.

Retinal detachment during COVID-19 era: a review of challenges and solutions

Background

Since the beginning of the Coronavirus disease 2019 (COVID-19) pandemic, there have been obstacles in the proper diagnosis and management of many diseases. We evaluated the changes in retinal detachment (RD) presentation and surgery during the COVID-19 pandemic and propose solutions to minimize the detrimental effects of lockdown on RD diagnosis.

Materials and methods

PubMed, Embase, Scopus, Web of Science, and Google Scholar were searched for relevant articles with the keywords “Retinal detachment” AND “Coronavirus OR COVID-19 OR SARS OR MERS.”

Results

The COVID-19 lockdown was associated a 53–66% reduction in RD presentation. The decrease in the rate of macula-on RD, the increase in the mean duration of symptoms, and the rise in the number of patients with proliferative vitreoretinopathy were all suggestive of a delayed presentation of RD. Moreover, a drop of 56–62% in RD repair surgeries was observed. However, the most frequently performed ophthalmic surgery changed from cataract surgery in April 2019 to RD repair in April 2020. Using phacovitrectomy instead of vitrectomy alone can reduce the number of operations in ophthalmology centers, decrease the use of personal protective equipment by 50%, and cut costs per patient by 17–20%. Also, developing a well-organized telemedicine system can decrease unnecessary visits and delayed presentations.

Conclusion

Delay in RD presentation and surgery is associated with a poorer prognosis. Optimizing the guidelines of RD management and developing a well-organized telemedicine system can minimize the impact of lockdown on RD management.

Trehalose Inhibits the Heat-Induced Formation of the Amyloid-Like Structure of Soluble Proteins Isolated from Human Cataract Lens

The age-dependent loss of solubility and aggregation of crystallins constitute the pathological hallmarks of cataract. Several biochemical and biophysical factors are responsible for the reduction of crystallins' solubility and formation of irreversible protein aggregates, which display amyloid-like characteristics. The present study reports the heat-induced aggregation of soluble proteins isolated from human cataract lenses and the formation of amyloid-like structures. Exposure of protein at 55 °C for 4 h resulted in extensive (≈ 60%) protein aggregation. The heat-induced protein aggregates displayed substantial (≈ 20 nm) redshift in the wavelength of maximum absorption (λ_max) of Congo red (CR) and increase in Thioflavin T (ThT) fluorescence emission intensity, indicating the presence of amyloid-like structures in the heat-induced protein aggregates. Subsequently, the addition of trehalose resulted in substantial inhibition of heat-induced aggregation and the formation of amyloid-like structure. The ability of trehalose to inhibit the heat-induced aggregation was found to be linearly dependent upon its concentration used. The optimum effect was observed in the presence of 30-40% (w/v) trehalose where the aggregated was found to be reduced from 60 to 30%. The present study demonstrated the ability to trehalose to inhibit the protein aggregation and interfere with the formation of amyloid-like structures.

Vitreoretinal Surgery in the Post-Lockdown Era: Making the Case for Combined Phacovitrectomy

The coronavirus disease (COVID-19) pandemic has significantly limited the capacity of healthcare systems to provide elective services like cataract surgery. Cataract formation is a frequent complication after pars plana vitrectomy. In this paper, we review the pros and cons of combined phacovitrectomy as opposed to sequential surgery in the post-pandemic era. In particular, we discuss the patient-level visual benefits and societal economic advantages of this procedure.