2019

: To describe the rationale, design, methodology and baseline characteristics of Fushun Diabetic Retinopathy Cohort Study (FS-DIRECT), a community-based prospective cohort study in patients with type 2 diabetes mellitus (T2DM) living in northeast China.: Patients with T2DM, aged 30 years and above from communities of Fushun city, Liaoning province, China, were recruited. The presence and severity of the diabetic retinopathy (DR) were determined by a modified Early Treatment Diabetic Retinopathy Study (ETDRS) retinopathy scale of 6 fields fundus photographs. Detailed ocular examinations and questionnaires were collated, in addition to blood and urine sample collection.: Of the 2224 subjects eligible for the FS-DIRECT, 2033 (91.4%) participated in the study. The majority of participants were female (58.9%), the average age was 62.1 ± 9.1 years. The overall prevalence rates of DR, non-proliferative DR, proliferative DR, diabetic macular edema, and vision-threatening retinopathy were 44.3%, 40.0%, 4.3%, 15.2%, and 12.3%, respectively. Compared to the patients without DR, patients with DR had lower income, an earlier onset of diabetes, a longer duration of diabetes, higher proportion of insulin use, higher fasting plasma glucose, HbA1c, systolic blood pressure, total cholesterol and high density lipoprotein, as well as a higher level of urine protein (all < .05).: The baseline data of FS-DIRECT showed a high prevalence of DR in a community of northeast China. Further investigation will provide key information about the risk factors, impact, and trends of DR in this region.

The nitric oxide - guanylyl cyclase-1 - cyclic guanylate monophosphate (NO-GC-1-cGMP) pathway has emerged as a potential pathogenic mechanism for glaucoma, a common intraocular pressure (IOP)-related optic neuropathy characterized by the degeneration of retinal ganglion cells (RGCs) and their axons in the optic nerve. NO activates GC-1 to increase cGMP levels, which are lowered by cGMP-specific phosphodiesterase (PDE) activity. This pathway appears to play a role in both the regulation of IOP, where reduced cGMP levels in mice leads to elevated IOP and subsequent RGC degeneration. Here, we investigated whether potentiation of cGMP signaling could protect RGCs from glaucomatous degeneration. We administered the PDE5 inhibitor tadalafil orally (10 mg/kg/day) in murine models of two forms of glaucoma - primary open angle glaucoma (POAG; GC-1 mice) and primary angle-closure glaucoma (PACG; Microbead Occlusion Model) - and measured RGC viability at both the soma and axon level. To determine the direct effect of increased cGMP on RGCs in vitro, we treated axotomized whole retina and primary RGC cultures with the cGMP analogue 8-Br-cGMP. Tadalafil treatment increased plasma cGMP levels in both models, but did not alter IOP or mean arterial pressure. Nonetheless, tadalafil treatment prevented degeneration of RGC soma and axons in both disease models. Treatment of whole, axotomized retina and primary RGC cultures with 8-Br-cGMP markedly attenuated both necrotic and apoptotic cell death pathways in RGCs. Our findings suggest that enhancement of the NO-GC-1-cGMP pathway protects the RGC body and axon in murine models of POAG and PACG, and that enhanced signaling through this pathway may serve as a novel glaucoma treatment, acting independently of IOP.

Glaucoma is a complex neurodegenerative disease with many clinical subtypes. Some of its rare forms include pigmentary glaucoma, uveitic glaucoma and congenital glaucoma. While they all share common features of progressive retinal ganglion cell (RGC) loss, optic nerve damage and corresponding visual field loss, the exact mechanisms underlying glaucomatous neuron loss are not clear. This has largely hindered the development of a real cure for this disease. Elevated intraocular pressure (IOP) is a known major risk factor of glaucoma; however, progressive degeneration of RGCs and axons can also be found in patients with a normal IOP, i.e., normal tension glaucoma (NTG). Interestingly, patients who carry the gain-of-function mutation of the pro-inflammatory gene TBK1 - tumor necrosis factor (TNF) receptor associated factor NF-κB activator (TANK) binding kinase 1 - are at increased risk to develop NTG. This finding suggests a causal link between neuroinflammatory processes and glaucoma. Various studies have reported the presence of neuroinflammatory responses by microglia, astrocytes and other blood-born immune cells in the optic nerve head (ONH) at early stages of experimental glaucoma. Inhibition of certain pro-inflammatory pathways, particularly those associated with microglial activation, appears to be neuroprotective. In this review, we will focus on the inflammatory responses, in particular the proposed roles of microglia, in the pathogenesis of glaucoma.

Importance: Gun violence represents a substantial public health issue, and firearm-related injuries rank second among the causes of injury-related deaths in children aged 0 to 17 years in the United States. Ocular trauma from firearm-related injuries can lead to devastating vision loss, but little is known to date about the specific demographics and characteristics of such injuries in children. Objective: To evaluate the epidemiologic pattern of pediatric firearm-related ocular injuries. Design, Setting, and Participants: This retrospective analysis used deidentified data from the National Trauma Data Bank, the largest national registry of hospitalized trauma cases in the United States. The firearm-related ocular injuries (n = 1972) of pediatric patients (defined as those younger than 21 years) hospitalized between January 1, 2008, and December 31, 2014, were analyzed. Statistical analyses were conducted from July 15, 2017, to June 15, 2019. Exposure: Firearm-related ocular trauma. Main Outcomes and Measures: Pediatric patients with firearm-related ocular injuries were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes and external causes of injury codes. Patient demographics (age, sex, and race/ethnicity), type of ocular injury, injury intent, geographic location, length of hospital admission, health insurance status, disposition at discharge, Injury Severity Score (ISS), and Glasgow Coma Scale (GCS) score were collected. Results: A total of 8715 firearm-related ocular injuries were identified. Of these injuries, 1972 (22.6%) occurred in pediatric patients, most of whom were male (1678 [85.1%]) and adolescents (1037 [52.6%]), with a mean (SD) age of 15.2 (5) years. Common locations of injury were home (761 [38.6%]) and street (490 [24.8%]). Mean (SD) hospital length of stay was 7.6 (12) days, ISS was 16 (13.1), and GCS score was 11 (5.1). The most common types of firearm-related ocular injuries were open wound of the eyeball (820 [41.6%]) and ocular adnexa (502 [25.5%]), orbital injuries or fractures (591 [30.0%]), and contusion of the eye or adnexa (417 [21.1%]). Patients aged 0 to 3 years had greater odds of unintentional injuries (odds ratio [OR], 4.41; 95% CI, 2.51-7.75; P < .001) and injuries occurring at home (OR, 5.39; 95% CI, 2.81-10.38; P < .001), and those aged 19 to 21 years had greater odds of assault injuries (OR, 2.17; 95% CI, 1.77-2.66; P < .001) and injuries occurring on the street (OR, 1.61; 95% CI, 1.3-1.98; P < .001). Black patients had the greatest odds of having injuries with assault intention (OR, 4.53; 95% CI, 3.68-5.59; P < .001), and white patients had the greatest likelihood for self-inflicted injury (OR, 7.1; 95% CI, 5.92-9.51; P < .001). Traumatic brain injury resulted mostly from self-inflicted trauma (OR, 5.99; 95% CI, 4.16-8.63; P < .001), as did visual pathway injuries (OR, 2.86; 95% CI, 1.95-4.20; P < .001). The inpatient mortality rate was 12.2%. Conclusions and Relevance: This study found that pediatric firearm-related ocular injuries from 2008 through 2014 were predominantly sight-threatening and associated with traumatic brain injury. If the possible risk factors, including sex, age, race/ethnicity, and injury intention, can be confirmed for 2015 through 2019, these findings may be useful in developing strategies to prevent pediatric firearm-related ocular injuries.

There is growing evidence that vascular dysfunction plays a role in the pathogenesis of glaucoma. The details of this relationship have remained elusive partially due to limitations in our ability to assess blood flow in the optic nerve. Optical coherence tomography angiography (OCTA) has emerged as a promising new technology well positioned to become the first clinically suitable test of optic nerve perfusion. OCTA uses the motion of red blood cells as an intrinsic contrast agent to create reproducible images of microvascular networks rapidly and non-invasively. A significant body of research regarding the use of OCTA in glaucoma has emerged in recent years. This review aims to provide an overview of the basic principles underlying OCTA technology, summarize the current literature regarding the application of OCTA in the management of glaucoma, and address the role of OCTA in explicating the vascular pathogenesis of glaucoma.

Oculomotor synkinesis is the involuntary movement of the eyes or eyelids with a voluntary attempt at a different movement. The chemokine receptor CXCR4 and its ligand CXCL12 regulate oculomotor nerve development; mice with loss of either molecule have oculomotor synkinesis. In a consanguineous family with congenital ptosis and elevation of the ptotic eyelid with ipsilateral abduction, we identified a co-segregating homozygous missense variant (c.772G>A) in ACKR3, which encodes an atypical chemokine receptor that binds CXCL12 and functions as a scavenger receptor, regulating levels of CXCL12 available for CXCR4 signaling. The mutant protein (p.V258M) is expressed and traffics to the cell surface but has a lower binding affinity for CXCL12. Mice with loss of Ackr3 have variable phenotypes that include misrouting of the oculomotor and abducens nerves. All embryos show oculomotor nerve misrouting, ranging from complete misprojection in the midbrain, to aberrant peripheral branching, to a thin nerve, which aberrantly innervates the lateral rectus (as seen in Duane syndrome). The abducens nerve phenotype ranges from complete absence, to aberrant projections within the orbit, to a normal trajectory. Loss of ACKR3 in the midbrain leads to downregulation of CXCR4 protein, consistent with reports that excess CXCL12 causes ligand-induced degradation of CXCR4. Correspondingly, excess CXCL12 applied to ex vivo oculomotor slices causes axon misrouting, similar to inhibition of CXCR4. Thus, ACKR3, through its regulation of CXCL12 levels, is an important regulator of axon guidance in the oculomotor system; complete loss causes oculomotor synkinesis in mice, while reduced function causes oculomotor synkinesis in humans.

PURPOSE: To identify the molecular cause in five unrelated families with a distinct autosomal dominant ocular systemic disorder we called ROSAH syndrome due to clinical features of retinal dystrophy, optic nerve edema, splenomegaly, anhidrosis, and migraine headache. METHODS: Independent discovery exome and genome sequencing in families 1, 2, and 3, and confirmation in families 4 and 5. Expression of wild-type messenger RNA and protein in human and mouse tissues and cell lines. Ciliary assays in fibroblasts from affected and unaffected family members. RESULTS: We found the heterozygous missense variant in the ɑ-kinase gene, ALPK1, (c.710C>T, [p.Thr237Met]), segregated with disease in all five families. All patients shared the ROSAH phenotype with additional low-grade ocular inflammation, pancytopenia, recurrent infections, and mild renal impairment in some. ALPK1 was notably expressed in retina, retinal pigment epithelium, and optic nerve, with immunofluorescence indicating localization to the basal body of the connecting cilium of the photoreceptors, and presence in the sweat glands. Immunocytofluorescence revealed expression at the centrioles and spindle poles during metaphase, and at the base of the primary cilium. Affected family member fibroblasts demonstrated defective ciliogenesis. CONCLUSION: Heterozygosity for ALPK1, p.Thr237Met leads to ROSAH syndrome, an autosomal dominant ocular systemic disorder.

PURPOSE: To compare the efficacy, safety, and tolerability of waterfree cyclosporine formulation (CyclASol) at 2 concentrations (0.1% and 0.05% of cyclosporine [CsA]) to vehicle when applied twice daily for 16 weeks in patients with dry eye disease (DED). An open-label Restasis (Allergan, Irvine, CA) arm was included to allow a direct comparison with an approved therapy. DESIGN: An exploratory phase II, multicenter, randomized, vehicle-controlled clinical trial, double-masked between CyclASol and vehicle with an open-label comparator. PARTICIPANTS: Two hundred and seven eligible patients with a history of dry eye disease were randomized 1:1:1:1 to 1 of 4 treatment arms (CyclASol 0.05%, n = 51; CyclASol 0.1%, n = 51; vehicle, n = 52, and Restasis, n = 53). METHODS: After a 2-week run-in period with twice-daily dosing of Systane Balance (Alcon, Fort Worth, TX), patients were randomized to the respective treatment arm and dosed twice daily for 16 weeks. MAIN OUTCOME MEASURES: The study was set up to explore efficacy on a number of sign and symptom end points including total and subregion corneal fluorescein staining, conjunctival staining, visual analog scale (VAS) for dry eye symptoms VAS severity, and Ocular Surface Disease Index (OSDI) questionnaire. RESULTS: CyclASol showed a consistent reduction in corneal and conjunctival staining compared with both vehicle and Restasis over the 16-week treatment period, with an early onset of effect (at day 14). A mixed-effects model-based approach demonstrated that the CyclASol drug effect was statistically significant over vehicle (total corneal staining P < 0.1, central corneal staining P < 0.001, conjunctival staining P < 0.01). This model-based analysis suggests a significant CyclASol effect for OSDI as symptom parameter (P < 0.01). The numbers of ocular adverse events were low in all treatment groups. CONCLUSIONS: CyclASol showed efficacy, safety, and tolerability at 2 concentrations in moderate-to-severe DED. In a direct head-to-head against open-label Restasis, CyclASol was found to have an earlier onset of action, as early as after 2 weeks of treatment, in relieving the signs of DED, as measured by corneal and conjunctival staining. The central region of the cornea, an important area for visual function in dry eye sufferers, was shown to have the most benefit from treatment. Excellent safety, tolerability, and comfort profile supports this new CsA formulation as having a positive benefit-to-risk ratio.

PURPOSE: To determine the efficacy and complication rates of monocanalicular stents in the setting of canalicular lacerations. METHODS: A literature search was performed in May 2018 in the PubMed database to identify all English-language reports of monocanalicular stenting to address canalicular lacerations. Studies that did not include at least 10 patients with at least 3 months of follow-up evaluation after surgery were excluded. Ninety-nine articles were identified, and 15 of these met criteria for data abstraction and were included in this assessment. The panel methodologist (V.K.A.) evaluated the quality of evidence and assigned a level-of-evidence rating to each of these studies. RESULTS: All 15 studies were rated as level III evidence. Anatomic and functional success rates after surgery ranged from 68% to 100% and 79% to 100%, respectively. Stents were generally well tolerated, although extrusion rates varied from 0% to 29%. CONCLUSIONS: Only level III evidence was available, and studies were not powered to detect differences between groups for rare complications or failure. Monocanalicular stents seem to be efficacious and well tolerated in the management of canalicular lacerations. Potential complications include extrusion (most commonly), tube displacement, granuloma, ectropion, slit punctum, fistula, and infection. Further comparative studies would help to identify the optimal time for device removal and to directly compare monocanalicular with bicanalicular stents.

In Hybrid Foraging tasks, observers search for multiple instances of several types of target. Collecting all the dirty laundry and kitchenware out of a child's room would be a real-world example. How are such foraging episodes structured? A series of four experiments shows that selection of one item from the display makes it more likely that the next item will be of the same type. This pattern holds if the targets are defined by basic features like color and shape but not if they are defined by their identity (e.g., the letters p & d). Additionally, switching between target types during search is expensive in time, with longer response times between successive selections if the target type changes than if they are the same. Finally, the decision to leave a screen/patch for the next screen in these foraging tasks is imperfectly consistent with the predictions of optimal foraging theory. The results of these hybrid foraging studies cast new light on the ways in which prior selection history guides subsequent visual search in general.

PURPOSE: To highlight the histopathologic diagnostic challenges of small-cell predominant extranodal nasal-type natural killer/T-cell lymphoma (ENTNKT) of the orbit. METHODS: Retrospective chart review and histopathologic study with immunohistochemistry and in situ hybridization of 3 cases. RESULTS: Three cases of ENTNKT presented to the Mass Eye and Ear emergency room as orbital cellulitis over 1 year. The first case was unusual in that there was a predominance of small cells, giving the ENTNKT the histopathologic appearance of a nonmalignant inflammatory process. This challenging case is juxtaposed alongside 2 other cases, which exhibited the more typical lymphomatous microscopic appearance. DISCUSSION: ENTNKT can extend into the orbit from the adjacent sinuses or rarely arise primarily in the orbit. A diagnosis is typically made with a biopsy. Occasionally, however, the histopathologic diagnosis can be elusive when a predominance of small lymphomatous cells that are virtually indistinguishable from non-neoplastic inflammatory cells is present. Demonstration of CD56 positivity by immunostaining and in situ hybridization for Epstein-Barr virus are essential in confirming the diagnosis. CONCLUSIONS: ENTNKT should be considered both in the clinical and histopathologic differential diagnoses of orbital infections and idiopathic inflammations (pseudotumor).

PURPOSE: The centenarian population is growing and ophthalmic plastic surgeons are providing care to an increasing number of elderly patients. Outcomes of centenarians have not been previously studied in the ophthalmic plastic surgery literature. The goal of the current review was to examine the baseline characteristics, surgical problems, and outcomes of this select group of patients. METHODS: A retrospective chart review was performed. Patients who underwent ophthalmic plastic surgery at age 100 or older between January 2000 and June 2016 by a member of the New England Oculoplastics Society were included in the study. RESULTS: Fifteen patients met inclusion criteria. The majority (66%) were female. More than half (60%) presented with a surgical problem of an urgent nature. Most disorders involved the lacrimal system or eyelids, and many were the result of trauma or infection. There were no cases of orbital tumor or thyroid eye disease. There were no surgical or anesthesia-related complications. Most patients (80%) had no documented history of dementia, and only 1 was diabetic. Notably, 33% of patients presented with no light perception vision in at least 1 eye. CONCLUSIONS: Ophthalmic plastic surgery can be performed safely in select patients 100 years of age and older. Formal prospective studies are needed to improve surgical care in this group.

Corneal neurotization is an innovative surgical approach for restoring corneal sensation, whereby the sensory functions of a normal donor nerve are rerouted to an anesthetic cornea. Many variations upon this basic surgical principal have been introduced and have proven successful in ameliorating corneal sensation in patients. It is unclear whether one surgical approach is superior to another, as each has advantages and disadvantages. Surgical approaches differ in the donor nerve selected and in whether a nerve graft is required. Surgical techniques have varied in the location, number and extent of incisions, methods of nerve coaptation, the number of surgeons required, the equipment and materials utilized and the duration of the procedure. The current review provides an overview of developments in this nascent field. A review of all peer-reviewed publications on corneal neurotization was performed. The various approaches to corneal neurotization are compared and discussed. The least morbid, simplest, most expedient and successful surgical approaches will ultimately become the most utilized.

PURPOSE: Novel cancer immunotherapies, called immune checkpoint inhibitors, have demonstrated clinical efficacy in the treatment of squamous cell carcinomas of the head and neck. Tissue expression of programmed cell death 1 ligand 1 (PD-L1) and programmed cell death 1 ligand 2 (PD-L2) has been shown to predict tumor response to these drugs. We examine the expression of prognostic immune biomarkers, PD-L1 and PD-L2, in invasive ocular surface squamous neoplasia. DESIGN: Retrospective case series. METHODS: Eighteen cases of ocular surface or ocular adnexal invasive squamous cell carcinomas were identified in pathology case files of the Massachusetts General Hospital/Massachusetts Eye and Ear Infirmary and at the Wills Eye Hospital accessioned between January 1, 2014 and January 1, 2017. Immunohistochemical staining for PD-L1, PD-L2, CD8, and p16 was performed and graded in a standardized fashion. RESULTS: PD-L1 and PD-L2 were expressed on tumor cells to varying degrees, and also on some stromal cells and endothelial cells. Stromal and endothelial cell expression was also seen in control conjunctival specimens. Tumor expression of PD-L1 and PD-L2 was present on the cell membranes. All 18 (100%) of the tumors expressed PD-L1: 7 (39%) expressed a high level, 3 (17%) expressed a medium level, and 8 (44%) expressed a low level. Only 9 (50%) tumors expressed PD-L2 and it was at a low level. The expression of PD-L1 in tumor cells correlated with the presence of CD8-positive cytotoxic T lymphocytes among tumor cells (P < .01) and with the presence of CD8-positive cells in the surrounding stroma (P = .04). CONCLUSIONS: A subset of ocular invasive conjunctival squamous carcinomas express high levels of PD-L1 and CD8 and therefore may respond therapeutically to immune checkpoint inhibition.

High levels of proinflammatory cytokines have been associated with a loss of tissue function in ocular autoimmune diseases, but the basis for this relationship remains poorly understood. Here we investigate a new role for tumor necrosis factor α in promoting N-glycan-processing deficiency at the surface of the eye through inhibition of N-acetylglucosaminyltransferase expression in the Golgi. Using mass spectrometry, complex-type biantennary oligosaccharides were identified as major N-glycan structures in differentiated human corneal epithelial cells. Remarkably, significant differences were detected between the efficacies of cytokines in regulating the expression of glycogenes involved in the biosynthesis of N-glycans. Tumor necrosis factor α but not IL-1β had a profound effect in suppressing the expression of enzymes involved in the Golgi branching pathway, including N-acetylglucosaminyltransferases 1 and 2, which are required for the formation of biantennary structures. This decrease in gene expression was correlated with a reduction in enzymatic activity and impaired N-glycan branching. Moreover, patients with ocular mucous membrane pemphigoid were characterized by marginal N-acetylglucosaminyltransferase expression and decreased N-glycan branching in the conjunctiva. Together, these data indicate that proinflammatory cytokines differentially influence the expression of N-glycan-processing enzymes in the Golgi and set the stage for future studies to explore the pathophysiology of ocular autoimmune diseases.

The system of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated endonucleases (Cas) has been utilized for genome editing with great accuracy and high efficiency in generating gene knockout, knockin, and point mutations in eukaryotic genomes. However, traditional CRISPR/Cas9 technology introduces double-stranded DNA breaks (DSBs) at a target locus as the first step to make gene corrections, which easily results in undesired mutations. Thus, it is necessary to develop new methods for correcting the unwanted mutations. In this review, we summarize the recent developments and a new approach to genome and base editing by using CRISPR/Cas9. This methodology renders a conversion of one target base into another, for example, C to T (or G to A), and A to G (or T to C) without producing DSBs, requiring a donor DNA template, or generating excessive insertions and deletions. Furthermore, CRISPR/Cas9-derived base editing also improves efficiency in repairing point mutations in the genome.

We previously demonstrated that β6 knockout mice showed impaired wound repair in corneal debridement and keratectomy wounds. In the current investigation, we continued our examination of integrin αvβ6 in order to determine if it was required for the initiation of wound healing in a corneal wound model that normally heals in a fibrotic manner. A full-thickness corneal incision was made in C57BL/6 J wild type (WT) and C57BL/6-Itgb6 KO (β6) mice. The mice were observed at 3, 7, 14, and 28 days post-incision. The morphology of corneal restoration was observed in tissue sections stained with hemotoxilin and eosin (H&E). In addition, indirect-immunofluorescence (IF) was performed on sections and/or whole mounts to evaluate the immunolocalization of α-smooth muscle actin (SMA) and thrombospondin-1 (TSP-1). H&E staining revealed that the corneas in β6 mice healed slower than those in WT mice, with an obvious delay in the restoration of the stromal matrix and epithelium. In sections at 3 and 7 days, SMA and TSP-1 were greatly reduced in the β6 mice as compared to WT, but peaked at 28 days after incision. Whole mount SMA IF results were consistent with those from sections. Therefore, the initiation of fibrosis was inhibited by the lack of αvβ6; however, there appeared to be an alternate mechanism that initiated fibrosis 7-14 days later. Localization of TSP-1 correlated with expression of SMA whether wound healing was delayed or initiated immediately after wounding.

Meibomian gland dysfunction (MGD) is the leading cause of dry eye and proposed treatments are based on disease severity. Our purpose was to establish reliable morphologic measurements of meibomian glands for evaluating MGD severity. This retrospective, cross-sectional study included 100 MGD patients and 20 controls. The patients were classified into dry eye severity level (DESL) 1-4 based on symptoms and clinical parameters including tear-film breakup time, ocular staining and Schirmer I. The gland loss, length, thickness, density and distortion were analyzed. We compared the morphology between patients and controls; examined their correlations to meibum expressibility, quality, and DESL. Relative to controls, the gland thickness, density and distortion were elevated in patients (p < 0.001 for all tests). The area under the receiver operating characteristic curve was 0.98 (95% confidence interval [CI], 0.96-1.0) for gland loss, and 0.96 (CI 0.91-1.0) for gland distortion, with a cutoff value of six distorted glands yielding a sensitivity of 93% and specificity of 97% for MGD diagnosis. The gland distortion was negatively correlated to the meibum expressibility (r = -0.53; p < 0.001) and DESL (r = -0.22, p = 0.018). In conclusion, evaluation of meibomian gland loss and distortion are valuable complementary clinical parameters to assess MGD status.