Steroid Response Following Dropless Cataract Surgery Using Subconjunctival Triamcinolone.

Purpose: To assess the rates of postoperative steroid response following dropless cataract surgery using a subconjunctival depot of triamcinolone versus conventional cataract surgery using topical prednisolone. Patients and Methods: We reviewed consecutive cataract surgery cases performed by a single surgeon to determine the likelihood of steroid response, defined as intraocular pressure (IOP) 50% above baseline or IOP > 24 mmHg postoperatively, excluding the first 72 hours. Logistic regression models were performed including baseline characteristics as exposures in the model and steroid response as the outcome. Main outcome measures were the proportion of eyes developing steroid response, risk factors for developing steroid response, and duration of steroid response. Results: Of the 150 dropless and 218 conventional cases, 26 eyes developed steroid response (15 dropless and 11 conventional cases [10% vs 5%, P=0.096]). Risk factors for steroid response included dropless surgery (OR=2.43, 95% CI=1.03-6.02], P=0.046) and prior diagnosis of glaucoma (OR=7.18, 95% CI=2.66-19.22], P<0.001). Baseline IOP, age, sex, race, and axial length did not increase risk for steroid response. Of the eyes with steroid response, more dropless cases had an IOP elevation ≥30 days (9/15 eyes vs 1/11 eyes; P=0.008), including one patient with refractory IOP elevation in the dropless group who required urgent bilateral trabeculectomy for IOP control. Conclusion: Dropless cataract surgery increases the risk of prolonged steroid response postoperatively. Patients with glaucoma have an increased risk of steroid response and may not be good candidates for dropless cataract surgery with subconjunctival triamcinolone.

Neurofilament Light Chain in Aqueous Humor as a Marker of Neurodegeneration in Glaucoma.

Purpose: Neurofilament light chain (NfL) is a neuronal cytoskeletal protein that has been identified as a marker of neurodegeneration in diseases of the central nervous system. In this study, we investigated whether NfL in the aqueous humor (AH) can serve as a marker of neurodegeneration in glaucoma in a racially diverse North American population. Design: Single-center, case-control study. Participants: We enrolled patients with various types and stages of glaucoma undergoing planned ophthalmic surgery as part of their routine care and compared them with patients without glaucoma undergoing phacoemulsification for age-related cataract. Methods: We collected AH from 39 glaucoma patients and 10 patients without glaucoma. AH NfL was quantified using the Single-Molecule Array (Simoa)® NF-light assay (Quanterix). Demographic information, such as age, body mass index, sex, and self-reported race, as well as clinical information, such as pre-operative intraocular pressure (IOP), maximum IOP, and number of pre-operative glaucoma medications, was obtained by reviewing the medical record. Main Outcome Measures: Levels of AH NfL. Results: In a model controlling for age and body mass index (BMI), NfL was significantly elevated in AH from glaucoma patients (mean: 429 pg/mL; standard deviation [SD]: 1136 pg/mL) compared to AH from patients without glaucoma (mean: 3.1 pg/mL; SD: 1.9 pg/mg): P = 0.002. Higher AH NfL was associated with higher maximum IOP (R = 0.44, P = 0.005), higher pre-operative IOP (R = 0.46, P = 0.003), and more pre-operative glaucoma medications (Rs = 0.61, P < 0.001). There was no association between AH NfL and Humphrey visual field mean deviation (R = -0.20, P = 0.220), retinal nerve fiber layer thickness as measured with optical coherence tomography (R = 0.07, P = 0.694), or glaucoma stage (Rs = 0.015, P = 0.935). Conclusion: Our findings suggest that AH NfL may have clinical utility as a marker of glaucomatous neurodegeneration.

Neurodegeneration Markers Galectin-3 and Apolipoprotein E Are Elevated in the Aqueous Humor of Eyes With Glaucoma.

Purpose: Galectin-3 (Gal-3) and apolipoprotein E (APOE) are markers of activated microglia in neurodegenerative diseases of the central nervous system, whose targeting is protective in mouse models of glaucoma. In this study, we examined levels of Gal-3 and APOE in human aqueous humor (AH) and defined their clinical associations with glaucoma. Methods: We collected AH from 59 glaucoma patients and 15 controls at the start of planned ophthalmic surgery. Gal-3 and APOE levels were quantified by enzyme-linked immunosorbent assay. Total protein in AH was quantified by bicinchoninic acid assay. Significant associations between Gal-3, APOE, and clinical covariates were defined using univariate and multivariate linear regression models. Results: Gal-3 and APOE levels were significantly elevated in the AH of glaucoma patients compared to controls (P = 0.004 and P < 0.001, respectively). Gal-3 and APOE were positively correlated across the entire cohort (r = 0.65, P = 6.2E-9). No association was observed between Gal-3 and total protein or APOE and total protein (P = 0.35 and P = 0.50, respectively), indicating that their levels were not increased in glaucomatous AH due to nonspecific protein accumulation. Multivariate linear regression modeling revealed significant associations between Gal-3 and maximum recorded intraocular pressure (P = 0.009) and between APOE and number of past ophthalmic surgeries (P = 0.031). Conclusions: We demonstrate that Gal-3 and APOE are significantly elevated in the AH of eyes with glaucoma and are associated with a history of poorly controlled disease. Translational Relevance: Gal-3 and APOE in AH may inform clinical decision-making as quantifiable readouts of microglial activation in eyes with glaucoma.

Regulating microglial miR-155 transcriptional phenotype alleviates Alzheimer's-induced retinal vasculopathy by limiting Clec7a/Galectin-3+ neurodegenerative microglia.

Single cell RNA sequencing studies identified novel neurodegeneration-associated microglial (MGnD/DAM) subtypes activated around cerebral amyloid plaques. Micro-RNA (miR)-155 of the TREM2-APOE pathway was shown to be a key transcriptional regulator of MGnD microglial phenotype. Despite growing interest in studying manifestations of Alzheimer's disease (AD) in the retina, a CNS organ accessible to noninvasive high-resolution imaging, to date MGnD microglia have not been studied in the AD retina. Here, we discovered the presence and increased populations of Clec7a+ and Galectin-3+ MGnD microglia in retinas of transgenic APPSWE/PS1L166P AD-model mice. Conditionally targeting MGnD microglia by miR-155 ablation via the tamoxifen-inducible CreERT2 system in APPSWE/PS1L166P mice diminished retinal Clec7a+ and Galectin-3+ microglial populations while increasing homeostatic P2ry12+ microglia. Retinal MGnD microglia were often adhering to microvessels; their depletion protected the inner blood-retina barrier and reduced vascular amyloidosis. Microglial miR-155 depletion further limits retinal inflammation. Mass spectrometry analysis revealed enhanced retinal PI3K-Akt signaling and predicted IL-8 and Spp1 decreases in mice with microglia-specific miR-155 knockout. Overall, this study identified MGnD microglia in APPSWE/PS1L166P mouse retina. Transcriptional regulation of these dysfunctional microglia mitigated retinal inflammation and vasculopathy. The protective effects of microglial miR-155 ablation should shed light on potential treatments for retinal inflammation and vascular damage during AD and other ocular diseases.

The Prevalence of Autoimmune Diseases in Patients with Primary Open-Angle Glaucoma Undergoing Ophthalmic Surgeries.

PURPOSE: To assess the prevalence of autoimmune disease (AiD) in patients with primary open-angle glaucoma (POAG) undergoing ophthalmic surgery. DESIGN: Retrospective, cross-sectional study. PARTICIPANTS: Patients with POAG undergoing any ophthalmic surgery and control subjects undergoing cataract surgery at the Massachusetts Eye and Ear from March 2019 to April 2020. METHODS: All available medical records with patient demographics, ocular, and medical conditions were reviewed. Differences in AiD prevalence were assessed and adjusted for covariates using multiple logistic regression. Additionally, a subgroup analysis comparing the POAG patients with and without AiD was performed. MAIN OUTCOME MEASURES: To assess the prevalence of AiD based on the American Autoimmune Related Diseases Association list. RESULTS: A total of 172 patients with POAG and 179 controls were included. The overall prevalence of AiD was 17.4% in the POAG group and 10.1% in the controls (P = 0.044); 6.4% of POAG patients and 3.4% of controls had more than 1 AiD (P = 0.18). The most prevalent AiDs in POAG group were rheumatoid arthritis (4.6%) and psoriasis (4.1%), which were also the most common in controls (2.8% each). In a fully adjusted multiple logistic regression analysis accounting for steroid use, having an AiD was associated with 2.62-fold increased odds of POAG relative to controls (95% confidence interval, 1.27-5.36, P = 0.009); other risk factors for POAG derived from the analysis included age (odds ratio [OR], 1.04, P = 0.006), diabetes mellitus (OR, 2.31, P = 0.008), and non-White ethnicity (OR, 4.75, P < 0.001). In a case-only analysis involving the eye with worse glaucoma, there was no statistical difference in visual field mean deviation or retinal nerve fiber layer (RNFL) thickness in POAG patients with AiD (n = 30) and without AiD (n = 142, P > 0.13, for both). CONCLUSIONS: A higher prevalence of AiD was found in POAG patients compared with control patients undergoing ophthalmic surgery. The presence of AiD was associated with increased risk for POAG after adjusting for covariates. Additional factors may have prevented a difference in RNFL thickness in POAG patients with and without AiD. Autoimmunity should be explored further in the pathogenesis of POAG.

CD163+ macrophages infiltrate axon bundles of postmortem optic nerves with glaucoma.

PURPOSE: Prior research in animal models has shown that macrophages and microglia play an important role in pathogenesis of glaucoma, but the phenotype and distribution of macrophages in human glaucomatous tissue have not been sufficiently characterized. METHODS: We analyzed H&E, CD68-, and CD163-immunostained slides from 25 formaldehyde-fixed, paraffin-embedded autopsy eyes: 12 control eyes and 13 eyes with glaucoma. The diagnosis of glaucoma was made based on a history of glaucoma as reported in the medical record and histological changes characteristic of glaucoma. Glaucoma cases and controls were matched in terms of age, sex, and race. RESULTS: Qualitative analysis of the conventional outflow pathway and the optic nerve revealed that all eyes contained CD163+ cells but a negligible number of CD68+ cells. CD163+ macrophages infiltrated the trabecular meshwork and surrounded Schlemm's canal of normal eyes and eyes with glaucoma, but the pattern was variable and qualitatively similar between groups. In optic nerves of control eyes, CD163+ macrophages were present at low levels and restricted to septa between axon bundles. In glaucomatous optic nerves, the number of CD163+ cells was increased both qualitatively and quantitatively (glaucoma 5.1 ± 0.6 CD163+ cells/mm2, control 2.5 ± 0.3 CD163+ cells/mm2, p < 0.001), with CD163+ cells infiltrating axon bundles in cases of both mild and severe diseases. CONCLUSIONS: The increase in CD163+ cell number in eyes with mild and severe glaucoma is the first demonstration of macrophage infiltration in glaucomatous human optic nerves. This finding supports a role for macrophages in glaucoma pathogenesis and progression.

Staying away from the optic nerve: a formula for modifying glaucoma drainage device surgery in pediatric and other small eyes.

PURPOSE: To provide guidelines for safe implantation of glaucoma drainage devices (GDDs) in small and pediatric eyes to avoid contact between the optic nerve (ON) and the posterior edge of the GDD plate. METHODS: We developed a formula for calculating limbus-to-ON distance to estimate the available "real estate" for GDD placement in small eyes. The formula was validated using eyes of pediatric decedents undergoing clinical autopsy, with axial lengths (AL) of 15-24 mm. For each autopsy eye, we measured AL, anterior chamber depth, corneal diameter, and limbus-to-ON distances for the four eye quadrants. The main outcome measure was the degree of agreement between measured and calculated limbus-to-ON distances. RESULTS: A total of 15 autopsy eyes were divided into derivation (n = 10) and validation (n = 5) groups. A formula was derived to estimate superotemporal limbus-to-ON distance (DST) using AL and corneal diameter data. Linear regression showed excellent correlation between the measured DST and AL (R2 = 0.98). There was excellent agreement between measured and calculated limbus-to-ON values for all four eye quadrants (R2 range, 0.92-0.98). CONCLUSIONS: Our formula accurately predicts limbus-to-ON distances across a wide range of clinically relevant ALs. Based on this information, GDD surgery in small eyes can be adjusted by positioning the GDD closer to the limbus or by trimming the posterior edge of the GDD plate. To our knowledge, this is the first set of guidelines developed to promote safe implantation of GDDs in small eyes.

Low cerebrospinal fluid protein in prepubertal children with idiopathic intracranial hypertension.

PURPOSE: To evaluate a clinical observation that prepubertal children with idiopathic intracranial hypertension (IIH) have low cerebrospinal fluid (CSF) protein levels compared to healthy children and pubertal patients with IIH. METHODS: The medical records of prepubertal and pubertal IIH patients and controls seen in the pediatric neuro-ophthalmology clinic at Duke between 2003 and 2013 were retrospectively reviewed. The control group consisted of children who had normal intracranial pressure on lumbar puncture performed to evaluate for headaches or anomalous-looking optic nerves. The records were analyzed with attention to demographic characteristics, clinical presentation, course, and lumbar puncture results. RESULTS: A total of 23 prepubertal children with IIH (age range, 0.75-13 years), 16 pubertal patients with IIH (age range, 13-21 years), and 12 controls (age range 3-14 years) were included. CSF analysis revealed that prepubertal children with IIH had significantly lower CSF protein levels (17.3 ± 5.7 mg/dL) compared to pubertal subjects with IIH (23.4 ± 8.4 mg/dL; P = 0.019) or healthy controls (23.5 ± 6.4 mg/dL; P = 0.011). Furthermore, 9 of 23 prepubertal IIH patients (39%) had abnormally low CSF protein level (<15 mg/dL), compared to zero pubertal IIH patients (P = 0.005) and zero controls (P = 0.015). Acetazolamide increased CSF protein level in 100% of patients who underwent repeat lumbar puncture after starting the medication (average increase, 10.3 ± 6.6 mg/dL). CONCLUSIONS: Low CSF protein level may have diagnostic utility as a biomarker for prepubertal IIH. Furthermore, this finding suggests that some cases of prepubertal IIH may be caused by CSF overproduction rather than decreased CSF resorption.

Glia promote local synaptogenesis through UNC-6 (netrin) signaling in C. elegans.

Neural circuits are assembled through the coordinated innervation of pre- and postsynaptic partners. We show that connectivity between two interneurons, AIY and RIA, in Caenorhabditis elegans is orchestrated by a pair of glial cells that express UNC-6 (netrin). In the postsynaptic neuron RIA, the netrin receptor UNC-40 (DCC, deleted in colorectal cancer) plays a conventional guidance role, directing outgrowth of the RIA process ventrally toward the glia. In the presynaptic neuron AIY, UNC-40 (DCC) plays an unexpected and previously uncharacterized role: It cell-autonomously promotes assembly of presynaptic terminals in the immediate vicinity of the glial cell endfeet. These results indicate that netrin can be used both for guidance and local synaptogenesis and suggest that glial cells can function as guideposts during the assembly of neural circuits in vivo.