Publications

2017

The function of the meibomian gland in the upper and lower eyelids is critical to maintaining homeostasis at the ocular surface. Highly specialized meibocytes within the gland must differentiate and accumulate intracellular lipid droplets that are released into the tear film following rupture of the cell membrane. Proteases and their inhibitors have been recognized as key players in remodeling extracellular matrices and promoting the normal integrity of glandular tissue. They modulate a wide range of biological processes, such as cell proliferation and differentiation, and can contribute to disease when aberrantly expressed. Deciphering the role of proteolytic activity in the meibomian gland offers an opportunity to gain a more comprehensive and fundamental understanding of the developmental, physiological, and pathological processes associated with this gland.
Bouffard MA, Caplan L, Torun N. Divergence Palsy due to Divalproex and Oxcarbazepine. Clin Neuropharmacol. 2017;

OBJECTIVE: This case series is the first to describe divergence palsy as an adverse effect of antiepileptic drug use. Diplopia is a common adverse effect of antiepileptic drugs, but no explanatory motility deficit has ever been reported. METHODS: We present 2 patients, 1 on oxcarbazepine and 1 on divalproex, each with a normal examination result between spells and divergency palsy when symptomatic. RESULTS: Discontinuation of the antiepileptic medication led to resolution of the episodes in both cases. Rechallenge with the offending agent after washout in one patient resulted in recurrence of diplopia and divergence palsy, both resolving after subsequent withdrawal of the antiepileptic. CONCLUSIONS: Antiepileptic drugs may cause divergence palsy.

Bujakowska K, Liu Q, Pierce E. Photoreceptor Cilia and Retinal Ciliopathies. Cold Spring Harb Perspect Biol. 2017;9(10).
Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, with analogous structures to those present in other nonmotile cilia. Deficient morphogenesis and/or dysfunction of photoreceptor sensory cilia (PSC) caused by mutations in a variety of photoreceptor-specific and common cilia genes can lead to inherited retinal degenerations (IRDs). IRDs can manifest as isolated retinal diseases or syndromic diseases. In this review, we describe the structure and composition of PSC and different forms of ciliopathies with retinal involvement. We review the genetics of the IRDs, which are monogenic disorders but genetically diverse with regard to causality.
Chen Q, Qiu F, Zhou K, Matlock G, Takahashi Y, Rajala R, Yang Y, Moran E, Ma JX. Pathogenic Role of MicroRNA-21 in Diabetic Retinopathy Through Down-Regulation of PPARα. Diabetes. 2017;

Fenofibrate, a specific agonist of peroxisome proliferator-activated receptor alpha (PPARα), displays robust therapeutic effects on diabetic retinopathy (DR) in type 2 diabetic patients. Our recent studies have shown that PPARα is down-regulated in the diabetic retina, which contributes to the pathogenesis of DR. However, the mechanism for diabetes-induced down-regulation of PPARα remains unknown. We investigated the role of microRNA-21 (miR-21) in regulating PPARα in DR. MiR-21 was over-expressed, while PPARα levels were decreased in the retina of db/db mice, a type 2 diabetic model. Such alterations were also observed in palmitate-treated retinal endothelial cells. MiR-21 targeted PPARα by inhibiting its mRNA translation. Knockout of miR-21 prevented the decrease of PPARα, alleviated microvascular damage, ameliorated inflammation and reduced cell apoptosis in the retina of db/db mice. Intravitreal injection of miR-21 inhibitor attenuated PPARα down-regulation and ameliorated retinal inflammation in db/db mice. Further, retinal miR-21 levels were increased, while PPARα levels were decreased in oxygen-induced retinopathy (OIR). Knockout of miR-21 prevented PPARα down-regulation and ameliorated retinal neovascularization and inflammation in OIR retinas. In conclusion, diabetes-induced over-expression of miR-21 in the retina is responsible, at least in part, for PPARα down-regulation in DR. Targeting miR-21 may represent a novel therapeutic strategy for DR.

PURPOSE: Obstructive meibomian gland dysfunction is a leading cause of ocular morbidity and its treatment remains a challenge. Meibomian gland probing was initially described in 2010. Here, the authors describe a modified technique, dynamic intraductal meibomian probing, which offers several advantages over the traditional approach including increased magnification, greater eyelid stabilization, enhanced anesthesia, and easier identification of gland orifices through the expression of meibum. METHODS: The authors conducted a retrospective chart review of 70 eyelids with treatment-resistant obstructive meibomian gland dysfunction undergoing dynamic intraductal meibomian probing between January 2013 and April 2015. RESULTS: Immediately after the procedure, 91.4% of cases experienced symptomatic improvement, and no complications were noted. CONCLUSIONS: Dynamic intraductal meibomian probing is an effective and safe treatment for obstructive meibomian gland dysfunction that is resistant to traditional therapies.

Turalba A, Cakiner-Egilmez T, Payal A, Gonzalez-Gonzalez L, Chomsky A, Vollman D, Baze E, Lawrence M, Daly M. Outcomes after cataract surgery in eyes with pseudoexfoliation: Results from the Veterans Affairs Ophthalmic Surgery Outcomes Data Project. Can J Ophthalmol. 2017;52(1):61–68.

OBJECTIVE: To compare clinical outcomes of cataract surgery in eyes with and without pseudoexfoliation (PXF). DESIGN: Retrospective deidentified data analysis. PARTICIPANTS: A total of 123 PXF and 4776 non-PXF eyes of patients who underwent cataract surgery. METHODS: We compared data on visual acuity, Visual Function Questionnaire (VFQ)-based quality of life, and complications in PXF and non-PXF eyes from the Veterans Affairs (VA) Ophthalmic Surgery Outcomes Data Project across 5 VA medical centres. RESULTS: Pupillary expansion devices were used in 31 (25.2%) PXF cases and 398 (8.4%) non-PXF cases (p < 0.0001). Capsular tension rings were used in 6 (4.9%) PXF cases and 55 (1.2%) non-PXF cases (p < 0.004). The following complications occurred more frequently in PXF cases: zonular dehiscence without vitrectomy (4 [3.3%] PXF cases vs 40 [0.8%] non-PXF cases p = 0.02), persistent inflammation (28 [24.1%] vs 668 [14.5%]; p = 0.007), and persistent intraocular pressure elevation (5 [4.3%] vs 68 [1.5%]; p = 0.03). Best corrected visual acuity (BCVA) improved in both groups after 1 month, but 87 (83.7%) PXF cases achieved postoperative BCVA better than or equal to 20/40 compared to 3991 (93.8%) non-PXF cases (p = 0.0003). There was no significant difference in the postoperative composite VFQ scores between PXF (82.1 ± 16.9) and non-PXF cases (84.2 ± 16.8, p = 0.09). CONCLUSIONS: Several complications occurred more frequently in the PXF group compared to the non-PXF group, and fewer PXF cases achieved BCVA better than or equal to 20/40. Despite this, both groups experienced similar improvement in vision-related quality of life after cataract surgery.

Enterococci are ancient commensal bacteria that recently emerged as leading causes of antibiotic-resistant, hospital-acquired infection. Vancomycin-resistant enterococci (VRE) epitomize why drug-resistant enterococcal infections are a problem: VRE readily colonize the antibiotic-perturbed gastrointestinal (GI) tract where they amplify to large numbers, and from there, they infect other body sites, including the bloodstream, urinary tract, and surgical wounds. VRE are resistant to many antimicrobials and host defenses, which facilitates establishment at the site of infection and confounds therapeutic clearance. Having evolved to colonize the GI tract, VRE are comparatively ill adapted to the human bloodstream. A recent study by Honsa and colleagues (E. S. Honsa et al., mBio 8:e02124-16, 2017, https://doi.org/10.1128/mBio.02124-16) found that a strain of vancomycin-resistant Enterococcus faecium evolved antibiotic tolerance within the bloodstream of an immunocompromised host by activating the stringent response through mutation of relA Precisely how VRE colonize and infect and the selective pressures that led to the outgrowth of relA mutants are the subjects of ongoing research.

Wang R, Seifert P, Jakobs T. Astrocytes in the Optic Nerve Head of Glaucomatous Mice Display a Characteristic Reactive Phenotype. Invest Ophthalmol Vis Sci. 2017;58(2):924–932.

Purpose: Optic nerve head astrocytes, a subtype of white-matter astrocytes, become reactive early in the course of glaucoma. It was shown recently that in the DBA/2J mouse model of inherited glaucoma optic nerve astrocytes extend new longitudinal processes into the axon bundles before ganglion cell loss becomes apparent. The present study aims at testing whether this behavior of astrocytes is typical of early glaucomatous damage. Methods: Mice expressing green fluorescent protein in individual astrocytes were used to evaluate the early response of astrocytes in the glial lamina of the optic nerve head after increasing the IOP using the microbead occlusion method. Tissue sections from the glial lamina were imaged consecutively by confocal and electron microscopy. Results: Confocal and electron microscope images show that astrocytes close to the myelination transition zone in the hypertensive nerve heads extend new processes that follow the longitudinal axis of the optic nerve and invade axon bundles in the nerve head. Ultrastructurally, the longitudinal processes were largely devoid of subcellular organelles except for degenerating mitochondria. Conclusions: The longitudinal processes are a common feature of glaucomatous optic nerve astrocytes, whereas they are not observed after traumatic nerve injury. Thus, astrocytes appear to fine-tune their responses to the nature and/or timing of the injury to the neurons that they surround.