The normalizing effects of the CYP46A1 activator efavirenz on retinal sterol levels and risk factors for glaucoma in Apoj-/- mice.

Apolipoprotein J (APOJ) is a multifunctional protein with genetic evidence suggesting an association between APOJ polymorphisms and Alzheimer's disease as well as exfoliation glaucoma. Herein we conducted ocular characterizations of Apoj-/- mice and found that their retinal cholesterol levels were decreased and that this genotype had several risk factors for glaucoma: increased intraocular pressure and cup-to-disk ratio and impaired retinal ganglion cell (RGC) function. The latter was not due to RGC degeneration or activation of retinal Muller cells and microglia/macrophages. There was also a decrease in retinal levels of 24-hydroxycholesterol, a suggested neuroprotectant under glaucomatous conditions and a positive allosteric modulator of N-methyl-D-aspartate receptors mediating the light-evoked response of the RGC. Therefore, Apoj-/- mice were treated with low-dose efavirenz, an allosteric activator of CYP46A1 which converts cholesterol into 24-hydroxycholesterol. Efavirenz treatment increased retinal cholesterol and 24-hydroxycholesterol levels, normalized intraocular pressure and cup-to-disk ratio, and rescued in part RGC function. Retinal expression of Abcg1 (a cholesterol efflux transporter), Apoa1 (a constituent of lipoprotein particles), and Scarb1 (a lipoprotein particle receptor) was increased in EVF-treated Apoj-/- mice, indicating increased retinal cholesterol transport on lipoprotein particles. Ocular characterizations of Cyp46a1-/- mice supported the beneficial efavirenz treatment effects via CYP46A1 activation. The data obtained demonstrate an important APOJ role in retinal cholesterol homeostasis and link this apolipoprotein to the glaucoma risk factors and retinal 24-hydroxycholesterol production by CYP46A1. As the CYP46A1 activator efavirenz is an FDA-approved anti-HIV drug, our studies suggest a new therapeutic approach for treatment of glaucomatous conditions.

Rethinking Prophylactic Laser Peripheral Iridotomy in Primary Angle-Closure Suspects: A Review.

PURPOSE: To examine the generalizability, discuss limitations, and critically appraise recommendations on the management of primary angle-closure suspects (PACSs) that emerged as a result of recent randomized clinical trials challenging the widely accepted clinical practice of offering laser peripheral iridotomy (LPI) to PACS patients. To synthetize findings from these and other studies. DESIGN: Narrative review. SUBJECTS: Patients classified as PACS. METHODS: The Zhongshan Angle-Closure Prevention (ZAP)-Trial and the Singapore Asymptomatic Narrow Angle Laser Iridotomy Study (ANA-LIS) along with accompanying publications were reviewed. Epidemiologic studies reporting on the prevalence of primary angle-closure glaucoma and other precursor forms of the disease were also analyzed along with publications reporting on the natural course of the disease or studies reporting on outcomes after prophylactic LPI. MAIN OUTCOME MEASURES: Incidence of progression to more severe forms of angle closure. RESULTS: Patients recruited in recent randomized clinical trials are asymptomatic, do not have cataracts, may be younger, and have, on average, deeper anterior chambers depth compared with patients treated with LPI in clinics. CONCLUSIONS: The ZAP-Trial and ANA-LIS clearly represent the best available data on PACS management, additional parameters however may need to be considered when physicians face patients in clinic. PACS patients encountered at tertiary referral centers may represent more advanced cases with respect to ocular biometric parameters and may be at higher risk for disease progression compared with those recruited through population-based screening. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Proposed Mechanism of Long-Term Intraocular Pressure Lowering With the Bimatoprost Implant.

Purpose: The purpose of this study was to evaluate the effects of pharmacologically relevant bimatoprost and bimatoprost free acid (BFA) concentrations on matrix metalloproteinase (MMP) gene expression in cells from human aqueous outflow tissues. Methods: MMP gene expression by human trabecular meshwork (TM), scleral fibroblast (SF), and ciliary muscle (CM) cells exposed to 10 to 1000 µM bimatoprost or 0.1 to 10 µM BFA (intraocular concentrations after intracameral bimatoprost implant and topical bimatoprost dosing, respectively) was measured by polymerase chain reaction array. Results: Bimatoprost dose-dependently upregulated MMP1 and MMP14 mRNA in all cell types and MMP10 and MMP11 mRNA in TM and CM cells; in TM cells from normal eyes, mean MMP1 mRNA levels were 62.9-fold control levels at 1000 µM bimatoprost. BFA upregulated MMP1 mRNA only in TM and SF cells, to two- to three-fold control levels. The largest changes in extracellular matrix (ECM)-related gene expression by TM cells derived from normal (n = 6) or primary open-angle glaucoma (n = 3) eyes occurred with 1000 µM bimatoprost (statistically significant, ≥50% change for 9-11 of 84 genes on the array, versus 1 gene with 10 µM BFA). Conclusions: Bimatoprost and BFA had differential effects on MMP/ECM gene expression. Dramatic upregulation in MMP1 and downregulation of fibronectin, which occurred only with bimatoprost at high concentrations observed in bimatoprost implant-treated eyes, may promote sustained outflow tissue remodeling and long-term intraocular pressure reduction beyond the duration of intraocular drug bioavailability. Variability in bimatoprost-stimulated MMP upregulation among cell strains from different donors may help explain differential long-term responses of patients to bimatoprost implant.

α-Synuclein modulates fibronectin expression in the trabecular meshwork independent of TGFß2.

α-Synuclein (α-Syn) is implicated in Parkinson's disease (PD), a neuromotor disorder with prominent visual symptoms. The underlying cause of motor dysfunction has been studied extensively, and is attributed to the death of dopaminergic neurons mediated in part by intracellular aggregation of α-Syn. The cause of visual symptoms, however, is less clear. Neuroretinal degeneration due to the presence of aggregated α-Syn has been reported, but the evidence is controversial. Other symptoms including those arising from primary open angle glaucoma (POAG) are believed to be the side-effects of medications prescribed for PD. Here, we explored the alternative hypothesis that dysfunction of α-Syn in the anterior eye alters the interaction between the actin cytoskeleton of trabecular meshwork (TM) cells with the extracellular matrix (ECM), impairing their ability to respond to physiological changes in intraocular pressure (IOP). A similar dysfunction in neurons is responsible for impaired neuritogenesis, a characteristic feature of PD. Using cadaveric human and bovine TM tissue and primary human TM cells as models, we report two main observations: 1) α-Syn is expressed in human and bovine TM cells, and significant amounts of monomeric and oligomeric α-Syn are present in the AH, and 2) primary human TM cells and human and bovine TM tissue endocytose extracellular recombinant monomeric and oligomeric α-Syn via the prion protein (PrPC), and upregulate fibronectin (FN) and α-smooth muscle actin (α-SMA), fibrogenic proteins implicated in POAG. Transforming growth factor ß2 (TGFß2), a fibrogenic cytokine implicated in ∼50% cases of POAG, is also increased, and so is RhoA-associated coiled-coil-containing protein kinase 1 (ROCK-1). However, silencing of α-Syn in primary human TM cells reduces FN, α-SMA, and ROCK-1 in the absence or presence of over-expressed active TGFß2, suggesting modulation of FN and ROCK-1 independent of, or upstream of TGFß2. These observations suggest that extracellular α-Syn modulates ECM proteins in the TM independently or via PrPC by activating the RhoA-ROCK pathway. These observations reveal a novel function of α-Syn in the anterior eye, and offer new therapeutic options.

Restoration of Vision in Severe, Cicatricial, Ocular Surface Disease With the Boston Keratoprosthesis Type II.

PURPOSE: To assess clinical outcomes of patients with severe, cicatricial ocular surface disease (OSD) implanted with the currently marketed design of the Boston keratoprosthesis type II (BK2). DESIGN: Retrospective cohort study. METHODS: Records of consecutive patients undergoing BK2 implantation from June 2009 to March 2021 were assessed for postoperative visual acuity, postoperative complications, device replacement, and additional surgeries. RESULTS: Fifty-six eyes of 53 patients with a mean follow-up of 45.8 months (range, 0.2-134.7 months) were included. Stevens-Johnson syndrome/toxic epidermal necrolysis was the most common indication (49.1%), followed by mucous membrane pemphigoid (39.6%) and other OSD (11.3%). Visual acuity improved from logMAR 2.2 ± 0.5 preoperatively to 1.5 ± 1.2 at final follow-up. Of 56 eyes, 50 saw ≥20/200 at some point postoperatively. Of the eyes with a follow-up of more than 5 years, 50.0% retained a visual acuity of ≥20/200 at their final follow-up. The most common complications over the entire postoperative course (mean ∼4 years) were de novo or worsening glaucoma (41.1%), choroidal effusions (30.3%), retinal detachment (25.0%), and end-stage glaucoma (25.0%). In a univariate analysis, patients who experienced irreversible loss of ≥20/200 visual acuity were more likely to have been previously implanted with an older design of BK2, less likely to be on preoperative systemic immunosuppressive therapy, and less likely to have undergone concurrent glaucoma tube implantation, compared to patients who retained ≥20/200 acuity (P < .04 for all). CONCLUSIONS: Advances in device design and postoperative care have made implantation of BK2 a viable option for corneal blindness in the setting of severe cicatricial OSD.

Effect of SPARC Suppression in Mice, Perfused Human Anterior Segments, and Trabecular Meshwork Cells.

Purpose: Secreted protein, acidic and rich in cysteine (SPARC) elevates intraocular pressure (IOP), increases certain structural extracellular matrix (ECM) proteins in the juxtacanalicular trabecular meshwork (JCT), and decreases matrix metalloproteinase (MMP) protein levels in trabecular meshwork (TM) endothelial cells. We investigated SPARC as a potential target for lowering IOP. We hypothesized that suppressing SPARC will decrease IOP, decrease structural JCT ECM proteins, and alter the levels of MMPs and/or their inhibitors. Methods: A lentivirus containing short hairpin RNA of human SPARC suppressed SPARC in mouse eyes and perfused cadaveric human anterior segments with subsequent IOP measurements. Immunohistochemistry determined structural correlates. Human TM cell cultures were treated with SPARC suppressing lentivirus. Quantitative reverse transcriptase polymerase chain reaction (PCR), immunoblotting, and zymography determined total RNA, relative protein levels, and MMP enzymatic activity, respectively. Results: Suppressing SPARC decreased IOP in mouse eyes and perfused human anterior segments by approximately 20%. Histologically, this correlated to a decrease in collagen I, IV, and VI in both the mouse TM and human JCT regions; in the mouse, fibronectin was also decreased but not in the human. In TM cells, collagen I and IV, fibronectin, MMP-2, and tissue inhibitor of MMP-1 were decreased. Messenger RNA of the aforementioned genes was not changed. Plasminogen activator inhibitor 1 (PAI-1) was upregulated in vitro by quantitative PCR and immunoblotting. MMP-1 activity was reduced in vitro by zymography. Conclusions: Suppressing SPARC decreased IOP in mice and perfused cadaveric human anterior segments corresponding to qualitative structural changes in the JCT ECM, which do not appear to be the result of transcription regulation.

Morphologic and Cellular Changes Induced by Selective Laser Trabeculoplasty.

Purpose: Selective laser trabeculoplasty is a safe and effective procedure for reducing IOP, but its mechanism of action is not fully elucidated. We evaluated the morphologic and cellular changes as well as DNA synthesis after SLT treatment of human trabecular meshwork (TM) tissue explants. Methods: Corneoscleral rim tissues that underwent SLT treatment were compared to control segments that had no laser treatment. Light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to assess cell morphology. The Click-iT 5-ethynyl-2'-deoxyuridine (EdU) imaging kit was used to compare DNA synthesis/cell proliferation with a confocal microscope. All tissues were assessed for vitality. Results: SLT treatment does not reveal notable cell damage in the juxtacanalicular (JCT) region, but mildly disrupts superficial trabecular beams and uveal TM, ablates TM endothelial cells from the undamaged beams as detected by both LM and TEM. This superficial destruction was not observed in some SLT treatment spots on higher magnification by SEM. SLT treatment increased mitotic activity and DNA synthesis near the lining of Schlemm's canal after several days. Conclusion: SLT treatment disrupts endothelial cells in the corneoscleral TM and causes superficial ultrastructural changes to the uveal TM. SLT treatment also shows a trend towards dynamic time-dependent changes in (DNA synthesis) with an increase in mitotic activity at 7 days cell proliferation.

Long-term Outcomes from the HORIZON Randomized Trial for a Schlemm's Canal Microstent in Combination Cataract and Glaucoma Surgery.

PURPOSE: To present the 5-year results of the HORIZON trial comparing cataract surgery (CS) combined with an intracanalicular microstent with CS alone. DESIGN: Prospective, multicenter, controlled randomized clinical trial. PARTICIPANTS: Patients with cataract and primary open-angle glaucoma treated with 1 or more glaucoma medications, washed-out diurnal intraocular pressure (DIOP) of 22 to 34 mmHg, and no prior incisional glaucoma surgery. METHODS: Eyes were randomized 2:1 to receive a Hydrus Microstent (HMS; Ivantis, Inc) or no stent after successful CS. MAIN OUTCOME MEASURES: Intraocular pressure (IOP), glaucoma medication use, repeat glaucoma surgery, visual acuity, visual field, procedure-related adverse events, and corneal endothelial cell counts. RESULTS: Three hundred sixty-nine eyes were randomized to HMS treatment, and 187 eyes were randomized to CS only. Study groups were well matched for preoperative IOP, medication use, washed-out DIOP, and glaucoma severity. Five-year follow-up was completed in 80% of patients. At 5 years, the HMS group included a higher proportion of eyes with IOP of 18 mmHg or less without medications than the CS group (49.5% vs. 33.8%; P = 0.003), as well as a greater likelihood of IOP reduction of 20% or more without medications than the CS group (54.2% vs. 32.8%; P < 0.001). The number of glaucoma medications was 0.5 ± 0.9 in the HMS group and 0.9 ± 0.9 in the CS group (P < 0.001), and 66% of eyes in the HMS group were medication free compared with 46% in the CS group (P < 0.001). The cumulative risk of incisional glaucoma surgery was lower in the HMS group (2.4% vs. 6.2%; P = 0.027, log-rank test). No clinical or statistically significant differences were found in the rate of endothelial cell loss from 3 to 60 months between the HMS and CS alone groups (P = 0.261). CONCLUSIONS: The addition of a Schlemm's canal microstent in conjunction with CS was safe, resulted in lowered IOP and medication use, and reduced the need for postoperative incisional glaucoma filtration surgery compared with CS after 5 years. Long-term presence of the implant did not affect the corneal endothelium adversely.

The role of trabeculectomy in the era of minimally invasive glaucoma surgery.

PURPOSE OF REVIEW: This review discusses recent findings in surgical management of glaucoma, focusing on trabeculectomy and minimally invasive glaucoma surgery (MIGS). We discuss how the role these procedures play in conjunction with phacoemulsification. RECENT FINDINGS: New findings of the Primary Trab Vs Tube study and findings regarding the Hydrus, Xen 45, Kahook dual blade, Ab-interno Canaloplasty and head-to-head MIGS studies are summarized. SUMMARY: Patients with glaucoma greatly benefit from combining cataract surgery with a MIGS procedure that can be tailored to disease severity and medication use. Certain MIGS combined with phacoemulsification in severe and refractory glaucoma can potentially delay incisional glaucoma, although trabeculectomy- mitomycin C (MMC) still remains the best option in certain patient populations. We provide an update in the MIGS treatment paradigm based on newer, stronger evidence.

Antibiotic prophylaxis of postoperative endophthalmitis after cataract surgery: results of the 2021 ASCRS member survey.

In an online survey of >1200 global cataract surgeons, 66% were using intracameral (IC) antibiotic prophylaxis. This compared with 50% and 30% in the 2014 and 2007 surveys, respectively. Irrigation bottle infusion and intravitreal injection was each used by only 5% of respondents. For IC antibiotics, vancomycin was used by 6% in the United States (52% in 2014), compared with 83% for moxifloxacin (31% in 2014). Equal numbers used compounded moxifloxacin or the Vigamox bottle as the source. There was a decrease in respondents using preoperative (73% from 85%) and postoperative (86% from 97%) topical antibiotic prophylaxis; the latter was not used by 24% of surgeons injecting IC antibiotics. Reasons cited by those not using IC antibiotics include mixing/compounding risk (66%) and being unconvinced of the need (48%). However, 80% believe having a commercially approved IC antibiotic is important; if reasonably priced, this would increase adoption of IC prophylaxis to 93%.

Advances in medical therapy for glaucoma.

PURPOSE OF REVIEW: To discuss a new class of medication that has recently become available for the treatment of glaucoma; as well as share insights into developments in glaucoma medicine administration which has the potential to revolutionize medical therapy for glaucoma. RECENT FINDINGS: Newly available eye drops, netarsudil 0.02% and latanoprostene bunod 0.024%, are improving aqueous outflow through the conventional outflow tract. Other new developments in medical glaucoma are focused on alternative methods for sustained glaucoma medication delivery. SUMMARY: Newer medications may be able to extend the duration of medically controlled glaucoma, delaying or possibly eliminating the need of glaucoma surgery for some patients. Alternative methods of delivery for glaucoma medications may be a key factor in improving outcomes with currently available medications.

Three-Year Findings of the HORIZON Trial: A Schlemm Canal Microstent for Pressure Reduction in Primary Open-Angle Glaucoma and Cataract.

PURPOSE: To report 3-year outcomes of the HORIZON study comparing cataract surgery (CS) with Hydrus Microstent (Ivantis, Inc) implantation versus CS alone. DESIGN: Multicenter randomized clinical trial. PARTICIPANTS: Five hundred fifty-six eyes from 556 patients with cataract and primary open-angle glaucoma (POAG) treated with 1 or more glaucoma medication, washed out diurnal intraocular pressure (IOP) of 22 to 34 mmHg, and no prior incisional glaucoma surgery. METHODS: After phacoemulsification, eyes were randomized 2:1 to receive a Hydrus Microstent or no stent. Follow-up included comprehensive eye examinations through 3 years. MAIN OUTCOME MEASURES: Outcome measures included IOP, medical therapy, reoperation rates, visual acuity, adverse events, and changes in corneal endothelial cell counts. RESULTS: Three hundred sixty-nine eyes were randomized to microstent treatment and 187 to CS only. Preoperative IOP, medication use, washed-out diurnal IOP, and glaucoma severity did not differ between the two treatment groups. At 3 years, IOP was 16.7 ± 3.1 mmHg in the microstent group and 17.0 ± 3.4 mmHg in the CS group (P = 0.85). The number of glaucoma medications was 0.4 ± 0.8 in the microstent group and 0.8 ± 1.0 in the CS group (P < 0.001), and 73% of microstent group eyes were medication free compared with 48% in the CS group (P < 0.001). The microstent group included a higher proportion of eyes with IOP of 18 mmHg or less without medications compared with the CS group (56.2% vs. 34.6%; P < 0.001), as well as IOP reduction of at least 20%, 30%, or 40% compared with CS alone. The cumulative probability of incisional glaucoma surgery was lower in the microstent group (0.6% vs. 3.9%; hazard ratio, 0.156; 95% confidence interval, 0.031-0.773; P = 0.020). No difference was found in postoperative corneal endothelial cell loss between groups. No procedure- or device-related serious adverse events resulting in vision loss occurred in either group. CONCLUSIONS: Combined CS and microstent placement for mild to moderate POAG is safe, more effective in lowering IOP with fewer medications, and less likely to result in further incisional glaucoma filtration surgery than CS alone at 3 years.

Secreted protein acidic and rich in cysteine (SPARC) knockout mice have greater outflow facility.

PURPOSE: Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that regulates intraocular pressure (IOP) by altering extracellular matrix (ECM) homeostasis within the trabecular meshwork (TM). We hypothesized that the lower IOP previously observed in SPARC -/- mice is due to a greater outflow facility. METHODS: Mouse outflow facility (Clive) was determined by multiple flow rate infusion, and episcleral venous pressure (Pe) was estimated by manometry. The animals were then euthanized, eliminating aqueous formation rate (Fin) and Pe. The C value was determined again (Cdead) while Fin was reduced to zero. Additional mice were euthanized for immunohistochemistry to analyze ECM components of the TM. RESULTS: The Clive and Cdead of SPARC -/- mice were 0.014 ± 0.002 µL/min/mmHg and 0.015 ± 0.002 µL/min/mmHg, respectively (p = 0.376, N/S). Compared to the Clive = 0.010 ± 0.002 µL/min/mmHg and Cdead = 0.011 ± 0.002 µL/min/mmHg in the WT mice (p = 0.548, N/S), the Clive and Cdead values for the SPARC -/- mice were higher. Pe values were estimated to be 8.0 ± 0.2 mmHg and 8.3 ± 0.7 mmHg in SPARC -/- and WT mice, respectively (p = 0.304, N/S). Uveoscleral outflow (Fu) was 0.019 ± 0.007 µL/min and 0.022 ± 0.006 µL/min for SPARC -/- and WT mice, respectively (p = 0.561, N/S). Fin was 0.114 ± 0.002 µL/min and 0.120 ± 0.016 µL/min for SPARC -/- and WT mice (p = 0.591, N/S). Immunohistochemistry demonstrated decreases of collagen types IV and VI, fibronectin, laminin, PAI-1, and tenascin-C within the TM of SPARC -/- mice (p < 0.05). CONCLUSIONS: The lower IOP of SPARC -/- mice is due to greater aqueous humor outflow facility through the conventional pathway. Corresponding changes in several matricellular proteins and ECM structural components were noted in the TM of SPARC -/- mice.

Outflow Facility Effects of 3 Schlemm's Canal Microinvasive Glaucoma Surgery Devices.

PURPOSE: To study the effect of 3 Schlemm's canal (SC) microinvasive glaucoma surgery (MIGS) devices on outflow facility. DESIGN: Paired comparisons, randomized design, baseline-controlled study. PARTICIPANTS: Thirty-six pairs of dissected anterior segments from donated human eye bank eyes without glaucoma were studied. A baseline measurement was collected from each eye to serve as its control. METHODS: Using a constant pressure perfusion method, outflow facility was measured in paired eyes from human donors. Measurements were made at perfusion pressures of 10 mmHg, 20 mmHg, 30 mmHg, and 40 mmHg. Outflow facility was measured before (baseline control) and after the implantation of an SC glaucoma drainage device or sham procedure. Three sets of experiments were carried out comparing 1 and 2 iStent Trabecular Micro-Bypass Stents and 2 iStent Inject implants with the Hydrus Microstent. MAIN OUTCOME MEASURES: Change in outflow facility from baseline or contralateral eye. RESULTS: After Hydrus placement, the outflow facility increased from 0.23±0.03 µl/minute per millimeter of mercury at baseline to 0.38±0.03 µl/minute per millimeter of mercury (P < 0.001). The percent increase in outflow facility was 79±21% for the Hydrus and 11±16% for the 2 iStent Inject devices, a difference that was significant (P = 0.018). Outflow facility with 1 iStent (0.38±0.07 µl/minute per millimeter of mercury) was greater than baseline (0.28±0.03 µl/minute per millimeter of mercury; P = 0.031). The 1 iStent showed a greater increase in outflow facility from baseline (0.10±0.04 µl/minute per millimeter of mercury) compared with the sham procedure (-0.08±0.05 µl/minute per millimeter of mercury; P = 0.042). No other significant differences were found. CONCLUSIONS: The longer the MIGS device, and thus the more SC that it dilates, the greater the outflow facility.

Effect of prostaglandin analogs: Latanoprost, bimatoprost, and unoprostone on matrix metalloproteinases and their inhibitors in human trabecular meshwork endothelial cells.

Bimatoprost, latanoprost, and unoprostone are prostaglandin F2α analogs (PGAs) and are used to lower intraocular pressure. We investigated the free acid effects of these three prostaglandin analogs: bimatoprost, latanoprost, and unoprostone on human matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMP) in the trabecular meshwork (TM) cells. Immunoblot results show that all three PGAs generally increased MMPs-1,9 and TIMPs-4. Additionally, bimatoprost and latanoprost both increased MMP-3 and TIMP-2, while unoprostone had an indeterminate effect on both. Zymography results show that all three PGAs except unoprostone increased intermediate MMP-1 activity while bimatoprost and latanoprost increased MMP-9 activity. Together, these data suggest that the balance between MMPs and TIMPs correlate to the relative intraocular pressure lowering effectiveness observed in clinical studies of these PGAs.

TGFß2-Hepcidin Feed-Forward Loop in the Trabecular Meshwork Implicates Iron in Glaucomatous Pathology.

Purpose: Elevated levels of transforming-growth-factor (TGF)-ß2 in the trabecular meshwork (TM) and aqueous humor are associated with primary open-angle glaucoma (POAG). The underlying mechanism includes alteration of extracellular matrix homeostasis through Smad-dependent and independent signaling. Smad4, an essential co-Smad, upregulates hepcidin, the master regulator of iron homeostasis. Here, we explored whether TGF-ß2 upregulates hepcidin, implicating iron in the pathogenesis of POAG. Methods: Primary human TM cells and human and bovine ex vivo anterior segment organ cultures were exposed to bioactive TGF-ß2, hepcidin, heparin (a hepcidin antagonist), or N-acetyl carnosine (an antioxidant), and the change in the expression of hepcidin, ferroportin, ferritin, and TGF-ß2 was evaluated by semiquantitative RT-PCR, Western blotting, and immunohistochemistry. Increase in reactive oxygen species (ROS) was quantified with dihydroethidium, an ROS-sensitive dye. Results: Primary human TM cells and bovine TM tissue synthesize hepcidin locally, which is upregulated by bioactive TGF-ß2. Hepcidin downregulates ferroportin, its downstream target, increasing ferritin and iron-catalyzed ROS. This causes reciprocal upregulation of TGF-ß2 at the transcriptional and translational levels. Heparin downregulates hepcidin, and reduces TGF-ß2-mediated increase in ferritin and ROS. Notably, both heparin and N-acetyl carnosine reduce TGF-ß2-mediated reciprocal upregulation of TGF-ß2. Conclusions: The above observations suggest that TGF-ß2 and hepcidin form a self-sustained feed-forward loop through iron-catalyzed ROS. This loop is partially disrupted by a hepcidin antagonist and an anti-oxidant, implicating iron and ROS in TGF-ß2-mediated POAG. We propose that modification of currently available hepcidin antagonists for ocular use may prove beneficial for the therapeutic management of TGF-ß2-associated POAG.

Comparative corneal endothelial cell toxicity of differing intracameral moxifloxacin doses after phacoemulsification.

PURPOSE: To determine whether intracameral moxifloxacin 500 µg is noninferior to 250 µg for central endothelial cell loss (ECL) after phacoemulsification. SETTING: Aravind Eye Care System. DESIGN: Prospective masked randomized study. METHODS: Eyes with bilateral nuclear cataracts, central endothelial cell density (ECD) of more than 2000 cells/mm, and ECD not differing between eyes by more than 200 cells/mm underwent phacoemulsification at least 14 days apart. Intraoperatively, the first eye was randomized to receive either a 500 or 250 µg dose of moxifloxacin intracamerally and received the other dose for the second-eye surgery. Postoperative course was monitored at 1 day, 1 week, 1 month, and 3 months. Preoperative and 30-day and 90-day postoperative central ECD was determined by a reading center for a masked analysis of ECL at 3 months postoperatively. RESULTS: Fifty eyes of 25 patients (aged 48 to 69 years) underwent uneventful surgery and had normal postoperative courses. The point estimate (PE) and 95% CI for the mean difference in % ECL between the 500 µg and 250 µg doses at 3 months postoperatively was 0.8% (-5.8%, 7.4%). Upon identifying and removing 2 outliers, noninferiority was proven with a mean difference of the PE, -2.2% (CI, -6.5%, 2.1%). CONCLUSIONS: Clinical and corneal endothelial cell were comparable in this study population for the 250 µg and 500 µg doses of intracameral moxifloxacin. Both doses were well tolerated clinically, supporting the use of the higher dose for improved antimicrobial coverage for the prevention of postoperative endophthalmitis.

A Prospective Randomized Trial Comparing Hydrus and iStent Microinvasive Glaucoma Surgery Implants for Standalone Treatment of Open-Angle Glaucoma: The COMPARE Study.

PURPOSE: To compare the efficacy of different microinvasive glaucoma surgery (MIGS) devices for reducing intraocular pressure (IOP) and medications in open-angle glaucoma (OAG). DESIGN: Prospective, multicenter, randomized clinical trial. PARTICIPANTS: One hundred fifty-two eyes from 152 patients aged 45 to 84 years with OAG, Shaffer angle grade III-IV, best-corrected visual acuity (BCVA) 20/30 or better, and IOP 23 to 39 mmHg after washout of all hypotensive medications. Eyes with secondary glaucoma other than pseudoexfoliative or pigmentary glaucoma, angle closure, previous incisional glaucoma surgery, or any significant ocular pathology other than glaucoma were excluded. INTERVENTION: Study eyes were randomized 1:1 to standalone MIGS consisting of either 1 Hydrus Microstent (Ivantis, Inc, Irvine, CA) or 2 iStent Trabecular Micro Bypass devices (Glaukos Inc, San Clemente, CA). Follow-up was performed 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. MAIN OUTCOME MEASURES: Within-group and between-group differences in IOP and medications at 12 months and complete surgical success defined as freedom from repeat glaucoma surgery, IOP 18 mmHg or less, and no glaucoma medications. Safety measures included the frequency of surgical complications, changes in visual acuity, slit-lamp findings, and adverse events. RESULTS: Study groups were well matched for baseline demographics, glaucoma status, medication use, and baseline IOP. Twelve-month follow-up was completed in 148 of 152 randomized subjects (97.3%). At 12 months, the Hydrus had a greater rate of complete surgical success (P < 0.001) and reduced medication use (difference = -0.6 medications, P = 0.004). More Hydrus subjects were medication free at 12 months (difference = 22.6% P = 0.0057). Secondary glaucoma surgery was performed in 2 eyes in the 2-iStent group (3.9%) and in none of the Hydrus eyes. Two eyes in the Hydrus group and 1 in the 2-iStent group had BCVA loss of ≥2 lines. CONCLUSION: Standalone MIGS in OAG with the Hydrus resulted in a higher surgical success rate and fewer medications compared with the 2-iStent procedure. The 2 MIGS devices have similar safety profiles.