An atypical case of bilateral optic neuritis after strabismus surgery under general anesthesia

INTRODUCTION

Strabismus surgery under general anesthesia is a common procedure with rare complications in the form of hemorrhage, infection, slipped muscle, lost muscle, scleral perforation, and anterior segment ischemia. We report a unique case of bilateral optic neuritis following squint surgery under general anesthesia in a 15-year-old girl.

METHODS

A 15-year-old girl presented with accommodative esotropia with V pattern. She underwent uneventful bilateral inferior oblique recession surgery under general anesthesia with Propofol 60 mg, Atracurium 30 mg, and Fentanyl 70 mcg. On the first post-operative day, the patient had an acute onset of temporal headache which was non-radiating. She responded to supportive treatment and was discharged. However, on the 7th postoperative day, she presented with a constant severe headache in the bitemporal region (left > right) for 3 days. She also experienced a painless diminution of vision for 2 days. There was no vomiting, fever, loose stools, diplopia, difficulty in breathing, peripheral sensation loss, generalized weakness, or bowel/bladder incontinence.

RESULTS

The best corrected visual acuity was 6/9 in right eye, and 6/9p in left eye with a relative afferent pupillary defect (RAPD) in the left eye. Both optic discs appeared hyperemic with blurred margins. Magnetic resonance imaging (MRI) of the brain and orbit showed hyperintensity along the intraorbital and intracanalicular parts of bilateral optic nerves on T2 weighted image suggesting bilateral optic neuritis. She received intravenous methylprednisolone pulse therapy followed by oral steroids and responded to the medical treatment with improvement in vision but developed steroid-induced glaucoma requiring medical management over several weeks.

DISCUSSION

Neuro-ophthalmic complication in the form of non-arteritic ischemic optic neuropathy has been reported after various ophthalmic surgeries, but bilateral optic neuritis has not been reported to date. This possibility should be kept in mind if any patient presents with similar symptoms. This report also highlights IOP monitoring in pediatric patients receiving systemic steroids to prevent loss of vision due to steroid-induced glaucoma.

ANGPTL7 and Its Role in IOP and Glaucoma

Purpose

Loss-of-function variants in the ANGPTL7 gene are associated with protection from glaucoma and reduced intraocular pressure (IOP). We investigated the role of ANGPTL7 in IOP homeostasis and its potential as a target for glaucoma therapeutics.

Methods

IOP, outflow facility, and outflow tissue morphology of Angptl7 knockout (KO) mice were assessed with and without dexamethasone (Dex). ANGPTL7 was quantified in conditioned media from human trabecular meshwork cells in response to Dex, in effluent from perfused human donor eyes, and in aqueous humor from human patients treated with steroids. Antibodies to ANGPTL7 were generated and tested in three-dimensional (3D) culture of outflow cells and perfused human donor eyes. Rabbits were injected intravitreally with a neutralizing antibody targeting ANGPTL7, and IOP was measured.

Results

IOP was significantly elevated, but outflow facility and outflow tissue morphology were not different between Angptl7 KO mice and littermates. When challenged with Dex, IOP increased in wild-type but not Angptl7 KO mice. In human samples, increased ANGPTL7 was seen in the aqueous humor of patients treated with steroids, regardless of glaucoma status. Using 3D culture, recombinant ANGPTL7 decreased, and ANGPTL7-blocking antibodies increased hydraulic conductivity. Significantly, outflow facility increased in human eyes treated ex vivo with ANGPTL7-blocking antibodies, and IOP decreased for 21 days in rabbits after a single injection of blocking antibodies.

Conclusions

Using multiple models, we have demonstrated that excess ANGPTL7 increases outflow resistance and IOP and that neutralizing ANGPTL7 has beneficial effects in both naïve and steroid-induced hypertensive eyes, thus motivating the development of ANGPTL7-targeting therapeutics for the treatment of glaucoma.

Open-Angle and Steroid-Induced Glaucoma in Patients With Retinitis Pigmentosa: A Dangerous Liaison

Previous studies have reported that patients with retinitis pigmentosa (RP) may develop open-angle and angle-closure glaucoma. We conducted a chart review of patients with RP. Two siblings with RP associated with a mutation in the PDE6B gene (c. 1540del, p.Leu514Trpfs*61) developed cystoid macular edema (CME) as part of the disease. For this reason, they both underwent intravitreal steroid injections. Both brothers developed steroid-induced glaucoma (SIG). Despite undergoing maximal medical therapy, they underwent seton implants to control their intraocular pressure. A third female patient with RP due to a mutation in the RPGR gene underwent cataract surgery. Topical steroids were prescribed and developed SIG. Increased intraocular pressure remains a complication of topical, injected, and systemic steroids. However, steroids may be needed to treat post-operatively and patients with CME. This case series unveils a complex association between RP and key comorbidities in these patients, with a focus on cataracts, glaucoma, and macular edema. Cataract surgery in patients with RP shows a link to the emergence of glaucoma, particularly in those with RPGR and PDE6B gene mutations, revealing a novel association with PDE6B mutations not previously documented. Furthermore, the paper explores a unique parallel with Schwartz-Matsuo syndrome, suggesting that patients with RP undergoing cataract surgery may develop increased intraocular pressure due to an outflow disturbance akin to Schwartz syndrome. This novel perspective deepens our understanding of the pathophysiological mechanisms governing intraocular pressure dynamics in patients with RP. To our knowledge, this is the first report of steroid-induced glaucoma in patients with RP due to mutations in the PDE6B gene. Intraocular pressure evaluation remains of utmost importance in the follow-up of patients with the disease.

Evaluation of clinical outcomes of raised intraocular pressure following intravitreal triamcinolone acetonide injection

Aim: To assess the incidence, risk factors, and treatment outcomes in intravitreal triamcinolone acetonide injection (IVTA) induced intraocular pressure rise and to compare IOP rise in 1-mg and 2-mg IVTA. Materials and methods: Prospective observational study conducted in all eyes receiving IVTA. Any pre-existing glaucoma and patients who received IVTA or dexamethasone implant in the last 6 months were excluded. Results: 9 between 61-70 years of age developed an IOP spike. The mean and standard deviation of age in years was 61.95 ± 8.70. Maximum eyes had ME due to Diabetic Retinopathy (53.3%). All cases of uveitic ME were reported to have an IOP spike. 2 out of 3 high myopic eyes and 1 eye with thyroid abnormality had an IOP spike. High IOP was found in 13 eyes, with more than 25 mm Hg rise in 4 eyes and more than 5 mm Hg rise from baseline IOP in 9 eyes. The mean and standard deviation of time taken for IOP raise (in days) was 46.39 ± 37.68. A total of 38 eyes received 1 mg of IVTA and the rest 22 received 2 mg of IVTA. 23.7% of 1 mg eyes experienced an IOP rise while it was 18.2% in eyes with 2 mg IVTA. The injection was repeated in 12 eyes and 41.7% developed an IOP spike among them. The independent "t" test results showed that there was a significant difference in the mean of IOP (Pre-injection) concerning the IOP rise (P=0.007*). 1 eye had IVTA crystals in the anterior chamber with raised IOP of 30 mm Hg. 1 out of 13 eyes with raised IOP needed 2 AGMs, the other 12 eyes responded well to 1 AGM. Discussion: IVTA is widely used in refractory cases of ME and steroid-induced glaucoma is the most common side effect of IVTA. To the best of our knowledge, there is a lack of literature on prospective studies on IVTA-associated risk factors, patterns of IOP elevation, and treatment outcomes. The pre-injection mean ± SD baseline IOP for uneventful eyes was 12.87±2.65 and the pre-injection mean IOP for eyes with IOP event was 15.23±2.89 (P=0.007*). Conclusion: We proposed that TA is an independent risk factor for post-intravitreal injection IOP spike. IVTA causes a maximum IOP spike at 1 to 2 months and has a protracted course that responds to anti-glaucoma medications. High baseline IOP, a repeated dose of IVTA, the presence of TA crystals in the anterior chamber, and high myopia were associated with significant IOP elevation. Abbreviations: ACD = Anterior chamber depth, AS = Anterior segment, AGM = Anti-glaucoma medications, ARMD = Age-related macular degeneration, BCVA = Best-corrected visual acuity, BRVO = Branch retinal vein occlusion, CCT = Central corneal thickness, CRVO = Central retinal vein occlusion, CME = Cystoid macular edema, CNVM = Choroidal neovascularization membrane, CSME = Clinically significant macular edema, DR = Diabetic retinopathy, ERM = Epiretinal membrane, IOP = Intraocular pressure, IGS = Irvine-Grass syndrome, GAGs = Glycosaminoglycans, IVTA = Intravitreal triamcinolone acetonide injection, ME = Macular edema, NVG = Neovascular glaucoma, OHT = Ocular hypertension, PDS = Pigment dispersion syndrome, PACG = Primary closed angle glaucoma, POAG = Primary open-angle glaucoma, PXF = Pseudoexfoliation, VA = Visual acuity, VEGF = Vascular endothelial growth factors, VH = Vonherick's grading, SD = Standard deviation, TA = Triamcinolone acetonide, TIGR = Trabecular meshwork inducible glucocorticoid response.

Characteristics of Eyes Requiring Trabeculotomy for Glaucoma With Steroid Treatment: Atopic Dermatitis and Factors Affecting Surgical Outcomes

PURPOSE

The aim is to analyze the surgical outcomes of glaucomatous patients with steroid treatment and investigate the factors, including atopic dermatitis, associated with the surgical success rate.

MATERIALS AND METHODS

We retrospectively enrolled participants who required first trabeculotomy for glaucoma with steroid treatment between May 2005 and February 2018 and then compared the postoperative outcomes according to the history of atopic dermatitis or surgical procedures. Surgical success was defined as postoperative IOP ≤ 21 mmHg, ≥20% reduction from baseline, and absence of reoperation. The factors influencing the surgical success rates were investigated using mixed-effects Cox regression.

RESULTS

The study included 70 eyes of 46 patients (18 eyes of 12 patients with atopic dermatitis). Postoperative intraocular pressure was not significantly different between eyes with and without atopic dermatitis (12 months after the surgery: patients without atopic dermatitis, 15.4 ± 3.6 mmHg; patients with atopic dermatitis, 16.1 ± 3.9 mmHg; P = 0.65). Twelve months after the surgery, the number of postoperative medications was higher in patients with atopic dermatitis than in those without (2.8 ± 1.3 vs. 2.0 ± 1.7; P = 0.060). However, no significant differences were noted in surgical success rates between patients with atopic dermatitis and those without (P = 0.54). Mixed-effects Cox regression of surgical success rate indicated that only the number of preoperative medications significantly influenced surgical success (P = 0.03).

CONCLUSIONS

Regardless of the presence of atopic dermatitis, patients taking many preoperative glaucomatous medications might require reoperation.

Simvastatin Attenuates Glucocorticoid-Induced Human Trabecular Meshwork Cell Dysfunction via YAP/TAZ Inactivation

PURPOSE

Impairment of the trabecular meshwork (TM) is the principal cause of increased outflow resistance in the glaucomatous eye. Yes-associated protein (YAP) and transcriptional coactivator with PDZ binding motif (TAZ) are emerging as potential mediators of TM cell/tissue dysfunction. Furthermore, YAP/TAZ activity was recently found to be controlled by the mevalonate pathway in non-ocular cells. Clinically used statins block the mevalonate cascade and were shown to improve TM cell pathobiology; yet, the link to YAP/TAZ signaling was not investigated. In this study, we hypothesized that simvastatin attenuates glucocorticoid-induced human TM (HTM) cell dysfunction via YAP/TAZ inactivation.

METHODS

Primary HTM cells were seeded atop or encapsulated within bioengineered extracellular matrix (ECM) hydrogels. Dexamethasone was used to induce a pathologic phenotype in HTM cells in the absence or presence of simvastatin. Changes in YAP/TAZ activity, actin cytoskeletal organization, phospho-myosin light chain levels, hydrogel contraction/stiffness, and fibronectin deposition were assessed.

RESULTS

Simvastatin potently blocked pathologic YAP/TAZ nuclear localization/activity, actin stress fiber formation, and myosin light chain phosphorylation in HTM cells. Importantly, simvastatin co-treatment significantly attenuated dexamethasone-induced ECM contraction/stiffening and fibronectin mRNA and protein levels. Sequential treatment was similarly effective but did not match clinically-used Rho kinase inhibition.

CONCLUSIONS

YAP/TAZ inactivation with simvastatin attenuates HTM cell pathobiology in a tissue-mimetic ECM microenvironment. Our data may help explain the association of statin use with a reduced risk of developing glaucoma via indirect YAP/TAZ inhibition as a proposed regulatory mechanism.

A comparative analysis of surgical outcome in uveitic and non-uveitic steroid-induced glaucoma in children

Purpose

To compare outcomes of surgical management of uveitic glaucoma (UG) and steroid-induced glaucoma (SIG) in children in terms of intraocular pressure (IOP) control, visual acuity, and associations for failure.

Methods

This was a retrospective case-control study of consecutive UG (cases) and non-uveitic SIG (controls) in children <18 years of age who underwent surgery between January 2005 and December 2017.

Results

Primary trabeculectomy with mitomycin C (MMC) was performed in 12 cases (mean age: 9.2 ± 4.3 years) and 40 controls (mean age: 10.4 ± 3.7 years) (P = 0.33). Primary phaco-trabeculectomy with MMC was performed in 11 cases (mean age: 11.4 ± 4.7 years) and 16 controls (mean age: 10.4 ± 3.4 years) (P = 0.57). IOP control (P = 0.26), visual acuity (P = 0.97), number of glaucoma medications (P = 0.06), and survival rates (49% cases vs. 68% controls at 5 years; P = 0.22) were similar between the two groups following trabeculectomy. Survival rates in the phaco-trabeculectomy group at 5 years were 68% cases vs. 69% controls (P = 0.71). IOP was higher (P = 0.008) and visual acuity was worse (P = 0.02) in cases at the last visit. Associations for failure (univariate analysis) were younger age (OR: 6.29, 95% CL: 1.43, 27.67; P = 0.03) and male gender (OR: 4.79, 95% CL: 1.09, 20.97; P = 0.04). On multivariate analysis, younger age (OR: 11.985, 95% CL: 1.071, 134.153; P = 0.04) remained significant. Preoperative number of uveitic attacks was protective on univariate (OR: 0.75, 95% CL: 0.48, 1.15; P = 0.1) and multivariate analyses (OR: 0.49, 95% CL: 0.24, 0.09; P = 0.04).

Conclusion

Outcomes of trabeculectomy between cases and controls were similar in our series. However, phaco-trabeculectomy in pediatric uveitic eye group fared worse than eyes with SIG.

Selective laser trabeculoplasty for steroid-induced ocular hypertension following endothelial keratoplasty

Purpose: To examine the safety and efficacy of selective laser trabeculoplasty (SLT) in patients responding to topical steroids with elevated intraocular pressure following endothelial keratoplasty.Methods: Patients that underwent Descemet Membrane Endothelial Keratoplasty (DMEK) or Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) were offered SLT as first-line therapy if they presented with steroid response and met inclusion criteria. Patient demographics, best-corrected visual acuity (BCVA), steroid and glaucoma regimens were recorded before and after SLT.Results: Twelve eyes of 8 patients were recruited to the study. All patients demonstrated a reduction in IOP and only one patient remained on anti-glaucoma drops after SLT. The mean (±SD) reduction in IOP following SLT was 8.8 (±4.9) mmHg (p < 0.0001). BCVA remained stable and no adverse events following treatment were observed.Conclusions: SLT may be a safe and effective treatment option that reduces topical antihypertensive burden while allowing continuance of corticosteroids in steroid-responsive eyes at high risk of rejection following endothelial keratoplasty. Larger randomized studies are needed to compare SLT efficacy with topical medication in this patient group and to review any impact on graft survival and glaucoma progression.

Optogenetic Modulation of Intraocular Pressure in a Glucocorticoid-Induced Ocular Hypertension Mouse Model

Purpose

Steroid-induced glaucoma is a common form of secondary open angle glaucoma characterized by ocular hypertension (elevated intraocular pressure [IOP]) in response to prolonged glucocorticoid exposure. Elevated IOP occurs with increased outflow resistance and altered trabecular meshwork (TM) function. Recently, we used an optogenetic approach in TM to regulate the 5-phosphatase, OCRL, which contributes to regulating PI(4,5)P2 levels. Here, we applied this system with the aim of reversing compromised outflow function in a steroid-induced ocular hypertension mouse model.

Methods

Elevated IOP was induced by chronic subconjunctival dexamethasone injections in wild-type C57Bl/6j mice. AAV2 viruses containing optogenetic modules of cryptochrome 2 (Cry2)-OCRL-5ptase and CIBN-GFP were injected into the anterior chamber. Four weeks after viral expression and dexamethasone exposure, IOP was measured by tonometer and outflow facility was measured by perfusion apparatus. Human TM cells were treated with dexamethasone, stimulated by light and treated with rhodamine-phalloidin to analyze actin structure.

Results

Dexamethasone treatment elevated IOP and decreased outflow facility in wild-type mice. Optogenetic constructs were expressed in the TM of mouse eyes. Light stimulation caused CRY2-OCRL-5ptase to translocate to plasma membrane (CIBN-CAAX-GFP) and cilia (CIBN-SSTR3-GFP) in TM cells, which rescued the IOP and outflow facility. In addition, aberrant actin structures formed by dexamethasone treatment were reduced by optogenetic stimulation in human TM cells in culture.

Conclusions

Subcellular targeting of inositol phosphatases to remove PIP2 represents a promising strategy to reverse defective TM function in steroid-induced ocular hypertension.

Translational Relevance

Targeted modulation of OCRL may be used to decrease steroid-induced elevated IOP.

Pathophysiology and management of glaucoma and ocular hypertension related to trauma

Ocular trauma is a significant cause of blindness worldwide, particularly if associated with glaucoma. Direct damage from blunt or penetrating trauma, bleeding, inflammation, lens-related problems, orbital and brain vascular pathologies related to trauma, and chemical injuries may increase intraocular pressure and lead to traumatic glaucoma. Treatment may be as simple as eliminating the underlying cause in some conditions or management can be challenging, depending on the mechanism of damage. If proper management is not undertaken, visual outcomes can be poor. We discuss a broad spectrum of trauma-related mechanisms of intraocular pressure elevation, as well as their management.

Steroid-induced glaucoma: Epidemiology, pathophysiology, and clinical management

Glucocorticoids are a class of anti-inflammatory drugs commonly used to treat various ocular and systemic conditions. Although the role of glucocorticoids in the treatment of numerous serious inflammatory diseases is pivotal, their prolonged use may increase intraocular pressure resulting in steroid-induced glaucoma. We provide a detailed update on steroid-induced glaucoma as a preventable cause of blindness in the adult and pediatric population and describe its epidemiology, social impact, and risk factors. Furthermore, we explore the propensity of different steroids to increase the intraocular pressure, the role of different routes of steroid administration, dosage and duration of treatment, as well as the clinical features, genetics, and management of steroid-induced glaucoma.

[Application of corticosteroid eye drops for allergic eye diseases in children]

The prevalence of allergic diseases has been increasing recently. Allergy has various symptoms. Allergic eye diseases (seasonal and perennial allergic conjunctivitis, vernal keratoconjunctivitis, atopic keratoconjunctivitis, giant papillary conjunctivitis, contact blepharoconjunctivitis) are common in atopic patients. Treatment options for allergic conjunctivitis include local and systemic antihistamines, mast cell stabilizers, dual-action agents, vasoconstrictors and corticosteroids. Treatment seems easy, but inappropriate therapy - in extreme cases - can lead to vision loss. Corticosteroid eyedrops provide effective relief of symptoms, however, their use is limited due to their severe side effects. Both steroid-induced cataract and steroid-induced glaucoma are dangerous for vision. The characteristics, frequency and risks of these side effects have been studied widely in adults, but there are very few studies focused on children. According to the present studies, the side effects of topically administered corticosteroids appear more often in children than in adults. Orv Hetil. 2019; 160(9): 329-337.

ILUVIEN® technology in the treatment of center-involving diabetic macular edema: a review of the literature

Diabetic macular edema (DME) is one of the major causes of blindness, caused primarily by hyperglycemia and results from multiple pathological processes mostly secondary to increased levels of VEGF and other inflammatory cytokines. DME management includes control of systemic risk factors together with laser photocoagulation, frequent intraocular injections of anti-VEGF agents and steroids implants. Recent adoption of novel alternative drug delivery options has led to the development of sustained release ocular implants with longer duration of action with less injection frequency. This article will review the pharmacology and clinical data in terms of efficacy, safety and benefits of the sustained release steroid implants in treatment of DME with special emphasis on the fluocinolone acetonide ILUVIEN^® implant.

Transforming growth factor β2 (TGFβ2) signaling plays a key role in glucocorticoid-induced ocular hypertension

Elevation of intraocular pressure (IOP) is a serious adverse effect of glucocorticoid (GC) therapy. Increased extracellular matrix (ECM) accumulation and endoplasmic reticulum (ER) stress in the trabecular meshwork (TM) is associated with GC-induced IOP elevation. However, the molecular mechanisms by which GCs induce ECM accumulation and ER stress in the TM have not been determined. Here, we show that a potent GC, dexamethasone (Dex), activates transforming growth factor β (TGFβ) signaling, leading to GC-induced ECM accumulation, ER stress, and IOP elevation. Dex increased both the precursor and bioactive forms of TGFβ2 in conditioned medium and activated TGFβ-induced SMAD signaling in primary human TM cells. Dex also activated TGFβ2 in the aqueous humor and TM of a mouse model of Dex-induced ocular hypertension. We further show that Smad3^-/- mice are protected from Dex-induced ocular hypertension, ER stress, and ECM accumulation. Moreover, treating WT mice with a selective TGFβ receptor kinase I inhibitor, LY364947, significantly decreased Dex-induced ocular hypertension. Of note, knockdown of the ER stress-induced activating transcription factor 4 (ATF4), or C/EBP homologous protein (CHOP), completely prevented Dex-induced TGFβ2 activation and ECM accumulation in TM cells. These observations suggested that chronic ER stress promotes Dex-induced ocular hypertension via TGFβ signaling. Our results indicate that TGFβ2 signaling plays a central role in GC-induced ocular hypertension and provides therapeutic targets for GC-induced ocular hypertension.

Prevalence of Steroid-Induced Cataract and Glaucoma in Chronic Obstructive Pulmonary Disease Patients Attending a Tertiary Care Center in India

PURPOSE

Exposure to corticosteroids is known to be associated with an increased risk of cataract and glaucoma. This study was undertaken to determine the prevalence of steroid-induced cataract and glaucoma in patients with chronic obstructive pulmonary disease (COPD) and to assess a dose-response relationship between them.

DESIGN

This was a prospective observational study.

METHODS

We identified all COPD patients aged 50 years or older, with minimum steroid exposure of 4 months and on inhaled corticosteroids from March 2014 to March 2015. Average daily dose of inhaled corticosteroids was defined as low (1-250 µg), medium (251-500 µg), and high (501-1000 µg) using fluticasone propionate equivalents.

RESULTS

We screened 405 COPD patients, of which 48 were dropouts. We identified 58 cataract and 14 glaucoma patients with a prevalence of 16.24% and 3.92%, respectively. We also observed a dose-response relationship with the highest prevalence of cataract (39.6%) and glaucoma (42.8%) at daily doses of 501-1000 µg fluticasone propionate equivalents.

CONCLUSIONS

It is evident that higher doses and longer duration of inhaled corticosteroid in COPD patients are associated with a higher prevalence of cataract and glaucoma.

Bioengineered glaucomatous 3D human trabecular meshwork as an in vitro disease model

Intraocular pressure (IOP) is mostly regulated by aqueous humor outflow through the human trabecular meshwork (HTM) and represents the only modifiable risk factor of glaucoma. The lack of IOP-modulating therapeutics that targets HTM underscores the need of engineering HTM for understanding the outflow physiology and glaucoma pathology in vitro. Using a 3D HTM model that allows for regulation of outflow in response to a pharmacologic steroid, a fibrotic state has been induced resembling that of glaucomatous HTM. This disease model exhibits HTM marker expression, ECM overproduction, impaired HTM cell phagocytic activity and outflow resistance, which represent characteristics found in steroid-induced glaucoma. In particular, steroid-induced ECM alterations in the glaucomatous model can be modified by a ROCK inhibitor. Altogether, this work presents a novel in vitro disease model that allows for physiological and pathological studies pertaining to regulating outflow, leading to improved understanding of steroid-induced glaucoma and accelerated discovery of new therapeutic targets. Biotechnol. Bioeng. 2016;113: 1357-1368. © 2015 Wiley Periodicals, Inc.

Dexamethasone Stiffens Trabecular Meshwork, Trabecular Meshwork Cells, and Matrix

PURPOSE

Treatment with corticosteroids can result in ocular hypertension and may lead to the development of steroid-induced glaucoma. The extent to which biomechanical changes in trabecular meshwork (TM) cells and extracellular matrix (ECM) contribute toward this dysfunction is poorly understood.

METHODS

Primary human TM (HTM) cells were cultured for either 3 days or 4 weeks in the presence or absence of dexamethasone (DEX), and cell mechanics, matrix mechanics and proteomics were determined, respectively. Adult rabbits were treated topically with either 0.1% DEX or vehicle over 3 weeks, and mechanics of the TM were determined.

RESULTS

Treatment with DEX for 3 days resulted in a 2-fold increase in HTM cell stiffness, and this correlated with activation of extracellular signal-related kinase 1/2 (ERK1/2) and overexpression of α-smooth muscle actin (αSMA). Further, the matrix deposited by HTM cells chronically treated with DEX is approximately 4-fold stiffer, more organized, and has elevated expression of matrix proteins commonly implicated in glaucoma (decorin, myocilin, fibrillin, secreted frizzle-related protein [SFRP1], matrix-gla). Also, DEX treatment resulted in a 3.5-fold increase in stiffness of the rabbit TM.

DISCUSSION

This integrated approach clearly demonstrates that DEX treatment increases TM cell stiffness concurrent with elevated αSMA expression and activation of the mitogen-activated protein kinase (MAPK) pathway, stiffens the ECM in vitro along with upregulation of Wnt antagonists and fibrotic markers embedded in a more organized matrix, and increases the stiffness of TM tissues in vivo. These results demonstrate glucocorticoid treatment can initiate the biophysical alteration associated with increased resistance to aqueous humor outflow and the resultant increase in IOP.

Activated αvβ3 integrin regulates αvβ5 integrin-mediated phagocytosis in trabecular meshwork cells

PURPOSE

To investigate the roles of αvβ3 and αvβ5 integrins in phagocytosis in human trabecular meshwork (HTM) cells.

METHODS

Immunofluorescence microscopy and FACS analysis were used to determine levels of αvβ3 and αvβ5 integrins in TM tissue and cultures of normal and immortalized TM cells. Phagocytosis was measured using pHrodo-labeled S. aureus bioparticles followed by FACS analysis. The role of αvβ5 integrin in phagocytosis was evaluated by knocking down αvβ5 integrin expression with siRNA against the human β5 gene. Signaling from focal adhesion kinase (FAK) was blocked using FAK inhibitor 14. The role of αvβ3 integrins in phagocytosis was determined by treating HTM cells with dexamethasone (DEX) or ethanol (EtOH) and by generating stable cell lines that overexpressed either wild type (WT) or constitutively active (CA) β3 integrin subunit.

RESULTS

Both TM tissue and cell lines expressed αvβ3 and αvβ5 integrins. Knockdown of αvβ5 integrin reduced phagocytosis by ∼60% and FAK inhibition significantly reduced phagocytosis up to 84%, in a dose-dependent manner. DEX treatment increased αvβ3 integrin expression in HTM cells but reduced phagocytosis by ∼50% compared with untreated and EtOH-treated cells. The CA β3 integrin-expressing cell line showed increased αvβ3 integrin levels and decreased phagocytosis by ∼50% compared with the control.

CONCLUSIONS

The αvβ5 integrin-FAK-mediated pathway regulates phagocytosis in TM cells and this pathway is inhibited by activation of αvβ3 integrins. This suggests that changes in integrin expression and activity may be responsible for alterations in phagocytosis observed in steroid induced glaucoma.

Development of ocular hypertension and persistent glaucoma after intravitreal injection of triamcinolone

Purpose

This study evaluates intraocular pressure (IOP) elevation secondary to intravitreal injection of triamcinolone acetonide (IVTA) and discusses its management.

Methods

The records of 175 patients who underwent IVTA treatment and regular eye examinations in the period 2003–2006 were reviewed. One hundred and twenty-two of these patients were included in the study, of which 147 eyes that received IVTA (4 mg/0.1 ml) were followed for at least 9 months. Mean IOPs observed after IVTA injection as well as IOP elevations defined as moderate (≥5 mm Hg), important (≥10 mm Hg) and severe (>25 mm Hg) during the follow-up period were evaluated and compared statistically.

Results

Overall, the mean IOPs following IVTA injection were statistically significantly higher than the preinjection IOP (15.8 ± 2.6), after the first hour (17.7 ± 2.9), the first week (18.7 ± 4.1), the first month (19.6 ± 6.2), the second month (19.1 ± 6.1), the third month (18.0 ± 4.1), the sixth month (17.3 ± 4.0), and the ninth month (17.0 ± 2.7), but not after the first day (16.3 ± 7.6). Important IOP elevations were observed mostly in the first (17.7%) and second months (10.2%). In 40 (27.7%) eyes, topical antiglaucomatous therapy was needed and 7 later required surgical intervention to lower the IOP. Of the remaining 33 eyes, topical treatment was continued in 14 (9.5%) because of IOPs ≥20 mm Hg.

Conclusion

The persistence of IOP elevation beyond the IVTA clearance period and the development of intractable secondary glaucoma requiring surgical intervention substantiate the need for careful consideration of IVTA indication and follow-up.