Association between blood-aqueous barrier disruption and extent of retinal detachment

Implications of Ocular Confounding Factors for Aqueous Humor Proteomic and Metabolomic Analyses in Retinal Diseases

Purpose

To assess the impact of ocular confounding factors on aqueous humor (AH) proteomic and metabolomic analyses for retinal disease characterization.

Methods

This study recruited 138 subjects (eyes): 102 with neovascular age-related macular degeneration (nAMD), 18 with diabetic macular edema (DME), and 18 with cataract (control group). AH samples underwent analysis using Olink Target 96 proteomics and Metabolon's metabolomics platform Data analysis included correlation, differential abundance, and gene-set analysis.

Results

In total, 756 proteins and 408 metabolites were quantified in AH. Total AH protein concentration was notably higher in nAMD (3.2-fold) and DME (4.1-fold) compared to controls. Pseudophakic eyes showed higher total AH protein concentrations than phakic eyes (e.g., 1.6-fold in nAMD) and a specific protein signature indicative of matrix remodeling. Unexpectedly, pupil-dilating drugs containing phenylephrine/tropicamide increased several AH proteins, notably interleukin-6 (5.4-fold in nAMD). Correcting for these factors revealed functionally relevant protein correlation clusters and disease-relevant, differentially abundant proteins across the groups. Metabolomics analysis, for which the relevance of confounder adjustment was less apparent, suggested insufficiently controlled diabetes and chronic hyperglycemia in the DME group.

Conclusions

AH protein concentration, pseudophakia, and pupil dilation with phenylephrine/tropicamide are important confounding factors for AH protein analyses. When these factors are considered, AH analyses can more clearly reveal disease-relevant factors.

Translational Relevance

Considering AH protein concentration, lens status, and phenylephrine/tropicamide administration as confounders is crucial for accurate interpretation of AH protein data.

Flare levels after intravitreal injection of brolucizumab for diabetic macular edema

PURPOSE

This study aimed to evaluate anterior flare intensity (AFI) after intravitreal injection of brolucizumab (IVBr) in patients with diabetic macular edema (DME), and to identify the factors associated with the change of AFI after IVBr.

METHODS

This prospective multicenter study was conducted at five sites in Japan for patients with DME who underwent a single IVBr. AFI and central retinal thickness (CRT) were measured using a laser flare meter and spectral-domain optical coherence tomography, respectively, at weeks 0 and 6.

RESULTS

Sixty-five patients (phakia, 37 eyes; pseudophakia, 28 eyes) were enrolled. Six weeks after IVBr, CRT and best-corrected visual acuity significantly improved (p < 0.0001). AFI (p = 0.0003) and age (p = 0.0054) were significantly higher in patients with pseudophakic eyes than those with phakic eyes. The AFI of the phakic eyes decreased after IVBr (p = 0.043). As the AFI before injection is higher (p = 0.0363) and the age is lower (p = 0.0016), the AFI decreases after IVBr. There was a significant positive correlation between the rates of change in CRT and AFI (p = 0.024).

CONCLUSION

After IVBr, AFI decreases in phakic eyes but not in pseudophakic eyes. The age, AFI and CRT before injection and changes of CRT are involved in the change in AFI after IVBr.

Presence of CoV-2 antibody in vitreous humor after Cov-2 infection

Purpose

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a life-threatening disease with largely unknown intraocular pathogenesis. Herein, we determined the presence of SARS-CoV-2-specific ribonucleic acid (RNA) and virus-associated antibodies in the vitreous humor of people who have recently recovered from SARS-CoV-2 infection.

Design

This cross-sectional study included 33 patients (33 eyes) who have recently recovered from SARS-CoV-2 infection. Vitreous humor and blood serum samples were tested for the SARS-CoV-2 RNA and virus-associated antibodies.

Results

Among 33 participants, blood serum and vitreous humor were all tested negative for SARS-CoV-2 RNA. SARS-CoV-2-specific IgM was detected in 87.88 % (29/33) patients in blood serum and 6.10 % (2/33) in vitreous humor; SARS-CoV-2-specific IgG was detected in 96.97 % (32/33) patient in blood serum and 81.82 % (27/33) in vitreous humor. Statistical significance was found for IgM expression between blood serum and vitreous humor (P < 0.01), while IgG was not (P = 0.11). The days after recovery were statistically longer both in IgM-positive blood serum samples group and IgG-positive vitreous humor samples group compared with negative samples of each group (P < 0.01). Additionally, no statistical difference could be detected in antibody expression in vitreous humor between different groups divided on the condition of the risk of blood-retina-barrier (BRB) failure (P = 0.49 for IgM; P = 0.37 for IgG).

Conclusion

After recovering from COVID-19, no SARS-CoV-2 RNA was detected in vitreous humor, but anti-CoV-2 IgM was detected in 6.1 % and IgG in approximately 80 % of vitreous humor samples of participants. We also found that the positivety rate of SARS-CoV-2-specific antibodies in the blood serum and vitreous humor were both correlated with the days after recovery since the infection.

LASER FLARE PHOTOMETRY IN PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT: An Evaluation of 2,487 Cases

PURPOSE

Exploratory analysis associated with the prospective, multicenter, randomized PRIVENT trial. To characterize the associations between laser flare photometry and anatomical and epidemiological features of rhegmatogenous retinal detachment (RRD).

METHODS

The authors measured laser flare values of all 3,048 prescreened patients excluding those with comorbidities. A mixed regression analysis evaluated the strength of the influencing factors like age, sex, lens status, and presence and extent of RRD on laser flare.

RESULTS

Rhegmatogenous retinal detachment was more frequent in men (65.8%) than in women (34.2%, P < 0.001) and in right (52%) than in left eyes (48%, P = 0.045). Phakic RRD affected less quadrants and was less likely to be associated with macula-off status than pseudophakic RRD (48.4% vs. 58.0% macula off, 23% vs. 31% ≥3 quadrants, P < 0.001). Laser flare of affected eyes was significantly higher compared with fellow eyes (12.6 ± 15.2 vs. 8.3 ± 7.4 pc/ms, P < 0.001). The factors age, sex, lens status, presence of RRD, and the number of quadrants affected were independent influencing factors on laser flare. R 2 was 0.145 for phakic and 0.094 for pseudophakic eyes.

CONCLUSION

The results indicate that there may be more factors affecting laser flare than previously assumed. This might limit flare as predictive value for PVR and retinal redetachment.

Blood-Aqueous Barrier Disruption in Penetrating and Posterior Lamellar Keratoplasty: Implications for Clinical Outcome

BACKGROUND

The blood-aqueous barrier (BAB) separates immunoprivileged tissue of the eye from the blood circulation. Disruption of the BAB is therefore a risk factor for rejection after keratoplasty.

PURPOSE

The present work provides a review of the work of our group and others on BAB disruption in penetrating and posterior lamellar keratoplasty and its implications for clinical outcome.

METHODS

A PubMed literature search was performed to generate a review paper.

RESULTS

Laser flare photometry provides an objective and reproducible method to assess the integrity of the BAB. Studies of the flare after penetrating and posterior lamellar keratoplasty demonstrate a mostly regressive disruption of the BAB in the postoperative course, which is influenced in extent and duration by multiple factors. Persistently elevated flare values or an increase in flare after initial postoperative regeneration may indicate an increased risk of rejection.

DISCUSSION

In case of persistent or recurrent elevated flare values after keratoplasty, intensified (local) immunosuppression may potentially be useful. This could become important in the future, especially for the monitoring of patients after high-risk keratoplasty. Whether an increase of the laser flare is a reliable early indicator of an impending immune reaction after penetrating or posterior lamellar keratoplasty has to be shown in prospective studies.

The Blood-ocular Barriers and their Dysfunction: Anatomy, Physiology, Pathology

Complex barriers comprise the blood-aqueous (BAB) and the blood-retinal barrier (BRB), and separate anterior and posterior eye chambers, vitreous body, and sensory retina from the circulation. They prevent pathogens and toxins from entering the eye, control movement of fluid, proteins, and metabolites, and contribute to the maintenance of the ocular immune status. Morphological correlates of blood-ocular barriers are tight junctions between neighboring endothelial and epithelial cells, which function as gatekeepers of the paracellular transport of molecules, thereby limiting their uncontrolled access to ocular chambers and tissues. The BAB is composed of tight junctions between endothelial cells of the iris vasculature, endothelial cells of Schlemm's canal inner wall, and cells of the nonpigmented ciliary epithelium. The BRB consists of tight junctions between endothelial cells of the retinal vessels (inner BRB) and epithelial cells of the retinal pigment epithelium (outer BRB). These junctional complexes respond rapidly to pathophysiological changes, thus enabling vascular leakage of blood-derived molecules and inflammatory cells into ocular tissues and chambers. Blood-ocular barrier function, which can be clinically measured by laser flare photometry or fluorophotometry, is compromised in traumatic, inflammatory, or infectious processes, but also frequently contributes to the pathophysiology of chronic diseases of the anterior eye segment and the retina, as exemplified by diabetic retinopathy and age-related macular degeneration.

Lens status and degree of lens opacity influence laser flare photometry (objective tyndallometry)

PURPOSE

Objective tyndallometry using laser flare photometry can be utilized e.g., in management of uveitis. Previous studies showed a significant difference in flare values between pseudophakic and phakic eyes. We investigate a potential association between the degree of lens opacification and flare value in a large cohort phakic eyes.

METHODS

Retrospective, non-interventional single center study. Laser flare values of 460 healthy fellow eyes from two large cohorts (primary rhegmatogenous retinal detachment (RRD), macular holes (MH)) were correlated with lens status, degree of lens opacity, and age.

RESULTS

Out of 460 patients (mean age 64.6 ± 11.2, 57% male) 30.4% were pseudophakic (70.2 ± 10.9) and 69.6% phakic, of which 47.8% showed a clear lens (57.3 ± 9.1), 43.2% an mild cataract (65.2 ± 9.0) and 9.0% a moderate cataract (73.5 ± 9.0).In pseudophakia, flare (8.14 ± 4.6 pc/ms) was significantly higher compared to phakia (6.4 ± 3.9 pc/ms; p < 0.001). In phakic eyes, flare values increased significantly with increasing lens opacity (clear lens 5.3 ± 2.8 pc/ms; mild cataract 7.0 ± 4.0 pc/ms; moderate cataract 9.5 ± 6.1 pc/ms; p < 0.001). In clear lenses and mild cataract, age correlated significantly with flare (two-sided, p < 0.001, clear lenses R = 0.3; mild cataract R = 0.4). In clear lenses, flare values increased with age by 0.09 per year, in mild cataract by 0.17 (regression coefficients). No significant correlation was found between age and flare value in moderate cataract and pseudophakic eyes.

CONCLUSION

The level of objective tyndallometry seems to be dependent on lens status, degree of lens opacity and age. These factors should therefore be taken into account when interpreting laser flare values in the future.