Demographics, clinical interests, and ophthalmology skills confidence of medical student volunteers and non-volunteers in an extracurricular community vision screening service-learning program

BACKGROUND

Medical school curricular hours dedicated to ophthalmology are low and declining. Extracurricular ophthalmology activities, such as participation in community vision screenings, may serve an important adjunctive role in medical school curricula. The Johns Hopkins University (JHU) Vision Screening In Our Neighborhoods (ViSION) Program is an example of a voluntary medical student-directed community service-learning program.

METHODS

We used a mixed-methods cross-sectional approach, including an online survey and semi-structured interviews. JHU School of Medicine students enrolled in MD or MD/PhD programs during the 2019-2020 academic year were surveyed regarding demographics, career and service interests, involvement in ophthalmology-related activities, and confidence in their ophthalmology-related skills. Survey responses were compared between ViSION volunteers and non-volunteers using Fisher's exact chi-square tests. Semi-structured interviews were conducted via webconference with 8 prior or current ViSION volunteers and responses analyzed using inductive thematic analysis. Data were collected when ViSION volunteers were in variable stages of their medical education and involvement with the ViSION program.

RESULTS

A total of 118 medical students were included, representing an overall response rate of 24.6% of JHU medical students. ViSION volunteers reported greater involvement in ophthalmology-related research (42% vs. 4%, p < 0.001), intent to apply to ophthalmology residency programs (35% vs. 1%, p = 0.001), and confidence with multiple ophthalmology knowledge and clinical skill domains. In particular, ViSION volunteers were more likely to feel confident estimating cup-to-disc ratio using direct ophthalmoscopy (20% vs. 0%, p < 0.001). In open-ended survey and interview questions, most volunteers attributed at least some degree of their ophthalmology skill development and desire to pursue ophthalmology and public health careers to their ViSION experience.

CONCLUSIONS

Medical students who volunteered with a student-led community vision screening program were more likely to have a prior interest in ophthalmology than those who did not volunteer, but only 1/3 of volunteers planned to pursue a career in ophthalmology. Overall, volunteers reported higher confidence performing ophthalmology-related clinical skills, suggesting that student-led community vision screening programs may provide an important avenue for medical students to explore public health aspects of ophthalmology, while practicing ophthalmology exam skills and learning about common ophthalmic pathologies, regardless of their career intentions.

Electronically Monitored Corticosteroid Eye Drop Adherence after Trabeculectomy Compared to Surgical Success

OBJECTIVE

To compare electronically measured adherence with topical corticosteroid drops to outcomes of glaucoma surgery.

DESIGN

This prospective cohort study included eyes undergoing surgery from August 2019 to January 2021 and followed for up to 1 year.

PARTICIPANTS

All patients were recruited from the Glaucoma Center of Excellence at the Wilmer Eye Institute, Johns Hopkins. Eligible patients had either primary open angle or angle closure glaucoma, were ≥18 years old, and underwent either trabeculectomy (with or without cataract surgery) or tube-shunt implantation.

INTERVENTION

Patients were instructed on use of an eyedrop monitoring device (Kali Drop®), with knowledge that it would be used to record postoperative corticosteroid instillation in real time.

MAIN OUTCOMES

Adherence to a regimen of corticosteroid eye drops during the first 5 postoperative weeks; achievement of target intraocular pressure (IOP) at 6 weeks, 6 months to 1 year after surgery; and bleb morphology at 1 year.

RESULTS

Among 90 patients, adherence was 90 ± 14% overall and 81 ± 16% during q2h dosing. Target IOP was achieved at final visit (6 months or 1 year) in 81% (59/73) without reoperation. Eyes with a higher ratio of drops taken vs prescribed were significantly more likely to achieve target IOP at 6 months/1 year (p=0.05). Total adherence was better in younger persons, eyes with less field loss, and patients of one particular surgeon (p<0.03). Percent adherence during every 2 hours (q2h) dosing was higher in eyes with higher target IOP (p=0.01). No adherence outcome was significantly related to race, sex, bleb morphology, postoperative pain, or post-operative anterior chamber inflammation. Adherence values did not significantly correlate with adherence questionnaire data (predicted mean = 70 ± 17%, actual mean = 91 ± 13% adherent, p < 0.001).

CONCLUSION

Adherence with frequent postoperative eye drops was high and can be successfully monitored remotely. Surgical success was greater among eyes with nearly ideal adherence and was poorer in older persons and those with more advanced glaucoma.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03402802.

Applicant Characteristics Associated with Glaucoma Fellowship Match from 2010 to 2017

PURPOSE

To describe trends in the glaucoma fellowship match results, glaucoma applicant characteristics, and applicant characteristics associated with matching.

DESIGN

Retrospective study.

PARTICIPANTS

Ophthalmology fellowship applicants participating in the San Francisco (SF) Match between 2010 and 2017.

METHODS

De-identified, individual applicant data provided by the San Francisco (SF) Match were used to describe glaucoma fellowship match trends and applicant characteristics between 2010 and 2017. Publicly available, conglomerate SF Match data were used to determine trends in the number of programs participating in the glaucoma fellowship match, as well as the number of positions offered and filled from 2014 to 2019. All trends analyses were performed using linear regression models on log-transformed response variables. Summary statistics for applicants who matched in glaucoma were compared with those who did not match. A multivariable logistic regression model was used to evaluate factors associated with matching in glaucoma fellowship.

MAIN OUTCOME MEASURES

Fellowship match status (matched in glaucoma vs. did not match in any ophthalmology subspecialty).

RESULTS

From 2010 to 2019, the number of matched glaucoma fellowship applicants increased from 54 to 77 (mean 3.3% per year, P = 0.001), and the proportion of applicants to any ophthalmology fellowship who matched in glaucoma increased from 13% to 15.5% (mean, 3% per year; P = 0.041). Compared with applicants who did not match in any specialty between 2010 and 2017, matched glaucoma applicants were more likely to have graduated from a top 10 residency program (10.7% vs. 4.5%, P < 0.001), U.S. medical school (93.1% vs. 39.1%, P < 0.001), or U.S. residency program (95.0% vs. 42.2%, P < 0.001), and complete more interviews (9 vs. 1, P < 0.001). After controlling for potential covariates, factors associated with increased odds of matching in glaucoma included graduating from a U.S. residency program (odds ratio [OR], 9.91; 95% confidence interval [CI], 5.45-18.03), applying to fewer programs (OR, 0.91; 95% CI, 0.88-0.93), and completing a greater number of interviews (OR, 1.49; CI, 1.39-1.60). United States Medical Licensing Examination (USMLE) Step scores were not associated with matching in glaucoma.

CONCLUSIONS

The number of applicants who matched in glaucoma fellowship increased from 2010 to 2019. Factors associated with matching in glaucoma were graduating from a U.S. residency program and completing more interviews.

ACR Appropriateness Criteria® Asymptomatic Patient at Risk for Coronary Artery Disease: 2021 Update

Coronary atherosclerotic disease is a leading cause of mortality and morbidity due to major cardiovascular events in the United States and abroad. Risk stratification and early preventive measures can reduce major cardiovascular events given the long latent asymptomatic period. Imaging tests can detect subclinical coronary atherosclerosis and aid initiation of targeted preventative efforts based on patient risk. A summary of available imaging tests for low-, intermediate-, and high-risk asymptomatic patients is outlined in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Syncope

Syncope and presyncope lead to well over one million emergency room visits in the United States each year. Elucidating the cause of syncope or presyncope, which are grouped together given similar etiologies and outcomes, can be exceedingly difficult given the diverse etiologies. This becomes more challenging as some causes, such as vasovagal syncope, are relatively innocuous while others, such as cardiac-related syncope, carry a significant increased risk of death. While the mainstay of syncope and presyncope assessment is a detailed history and physical examination, imaging can play a role in certain situations. In patients where a cardiovascular etiology is suspected based on the appropriate history, physical examination, and ECG findings, resting transthoracic echocardiography is usually considered appropriate for the initial imaging. While no imaging studies are considered usually appropriate when there is a low probability of cardiac or neurologic pathology, chest radiography may be appropriate in certain clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Home Self-tonometry Trials Compared with Clinic Tonometry in Patients with Glaucoma

PURPOSE

This study examined characteristics of intraocular pressure (IOP) as measured during home tonometry in comparison with in-clinic tonometry in patients with glaucoma.

DESIGN

Retrospective cross-sectional study of glaucoma patients who completed 1 week of self-tonometry at a single academic center.

PARTICIPANTS

Patients with glaucoma who completed home tonometry trials with the iCare HOME tonometer (iCare USA) for any reason.

METHODS

Home IOP measurements were compared with in-clinic tonometry performed during the 5 visits preceding home tonometry. Maximum daily IOP was correlated to time of day. Generalized estimating equations were used to evaluate patient characteristics and clinic-derived variables that predicted differences between home and clinic IOP.

MAIN OUTCOME MEASURES

IOP mean, maximum, minimum, range, standard deviation and coefficient of variation were compared between clinic and home tonometry. IOP mean daily maximum (MDM) and mean daily range were calulated to describe recurrent IOP spiking.

RESULTS

A total of 107 eyes from 61 patients were analyzed. Mean age was 63.2 years (standard deviation [SD], 14.0 years) and 59.0% were women. Mean clinic and home IOPs were 14.5 mmHg (SD, 4.7 mmHg) and 13.6 mmHg (SD, 5.1 mmHg). Home tonometry identified significantly higher maximum IOP, lower minimum IOP, and greater IOP range than clinic tonometry (P < 0.001). Maximum daily IOP occurred outside of clinic hours (8 am-5 pm) on 50% of days assessed and occurred between 4:30 am and 8 am on 24% of days. Mean daily maximum IOP exceeded maximum clinic IOP in 44% of patients and exceeded target IOP by 3 mmHg, 5 mmHg, or 10 mmHg in 31%, 15%, and 6% of patients, respectively. Patient characteristics that predicted significant deviations between MDM and mean clinic IOP or target IOP in multivariate models included younger age, male gender, and absence of prior filtering surgery.

CONCLUSIONS

Self-tonometry provides IOP data that supplements in-clinic tonometry and would not be detectable over daytime in-clinic diurnal curves. A subset of patients in whom home tonometry was ordered by their glaucoma clinician because of suspicion of occult IOP elevation demonstrated reproducible IOP elevation outside of the clinic setting. Such patients tended to be younger and male and not to have undergone previous filtering surgery.

The internal limiting membrane: Roles in retinal development and implications for emerging ocular therapies

Basement membranes help to establish, maintain, and separate their associated tissues. They also provide growth and signaling substrates for nearby resident cells. The internal limiting membrane (ILM) is the basement membrane at the ocular vitreoretinal interface. While the ILM is essential for normal retinal development, it is dispensable in adulthood. Moreover, the ILM may constitute a significant barrier to emerging ocular therapeutics, such as viral gene therapy or stem cell transplantation. Here we take a neurodevelopmental perspective in examining how retinal neurons, glia, and vasculature interact with individual extracellular matrix constituents at the ILM. In addition, we review evidence that the ILM may impede novel ocular therapies and discuss approaches for achieving retinal parenchymal targeting of gene vectors and cell transplants delivered into the vitreous cavity by manipulating interactions with the ILM.

An Algorithm for Ramp Up of Ophthalmic Elective Surgeries Post-COVID-19

Purpose: As ophthalmic elective surgeries resume amidst the COVID-19 pandemic, protocols for testing patients for SARS-CoV-2 is important due to the transmissibility of the virus. Here, we describe the protocol our institution has implemented for screening asymptomatic patients before proceeding to elective ophthalmic surgery. Methods: A retrospective chart review analyzed the number of elective surgeries, results of SARS-CoV-2 testing, and the effect of a positive result on surgery scheduling. Results: We display the screening protocol our institution used to test for SARS-CoV-2. Through its implementation, we found 2 asymptomatic patients who were positive for SARS-CoV-2 resulting in cancellation of their surgeries.  Conclusion: Because of the possibility of positive COVID-19 status in asymptomatic patients and the risk this poses to patients and staff, we recommend testing all asymptomatic patients for SARS-CoV-2 prior to elective surgeries.

Factors Influencing Postgraduate Career Decisions of Ophthalmology Residents

Objective This study aims to identify factors that influence ophthalmology residents' decision to pursue fellowship training or to practice comprehensive ophthalmology after residency.

Design This is a cross-sectional study.

Methods An anonymous survey was sent to ophthalmology residents in the United States from the graduating class of 2018. The main outcome measure was the decision to seek fellowship training or to practice comprehensive ophthalmology. Information on demographics, residency program characteristics, and factors influencing career choices were collected.

Results The overall response rate was 24.0% (112/467). Among the 112 respondents, 88 (78.6%) matched into subspecialty training. Compared with residents entering comprehensive ophthalmology, there was a greater proportion of Asians (37.5 vs. 8.3%) and a smaller proportion of non-Hispanic whites (47.7 vs. 70.8%, p = 0.029) among residents pursuing fellowship training. Residents pursuing fellowships had fewer children (0.4 vs. 0.8, p = 0.049), had less debt (median debt ≤ $100,000 vs. > $200,000, p = 0.008), had more first-author publications (4.3 vs. 1.2, p< 0.001), decided on their postgraduate career path earlier (median time postgraduate second year [PGY2] versus postgraduate third year [PGY3], p = 0.016), and were more likely to plan to practice in an academic setting (51.1 vs. 29.2%, p< 0.001) and in an urban location (44.3 vs. 12.5%, p = 0.004). In a multiple logistic regression model, factors predictive of fellowship training included a desire to acquire special skills (odds ratio [OR] =4.39; 95% confidence intervals [CI]: 1.70–16.37) and work with new technology (OR = 2.92; 95% CI: 1.16–10.02). Factors that predicted a career in comprehensive ophthalmology were higher levels of educational debt (OR = 0.35; 95% CI: 0.12–0.77), a later timing of postgraduate decision (OR = 0.17; 95% CI: 0.02–0.65), and lifestyle considerations (OR = 0.13; 95% CI: 0.03–0.36). Gender, prestige, or perceived favorable job market was not significant factors.

Conclusion The majority of U.S. ophthalmology residents matched into fellowships. A desire to gain special skills and a desire to work with new technology were major factors influencing residents to seek fellowship training. Lifestyle considerations and educational debt were more important in the decision to choose a comprehensive ophthalmology career. Future research that includes more trainees and programs may minimize the selection bias issues present in this study.

Intraocular Pressure Following Prerandomization Glaucoma Medication Washout in the HORIZON and COMPASS Trials

PURPOSE

To assess the effectiveness of topical ocular hypotensive medications in patients with open-angle glaucoma and to identify factors associated with postwashout intraocular pressure (IOP) elevation.

DESIGN

Secondary analysis of prerandomization data from 2 prospective, multicenter, randomized clinical trials.

METHODS

Fourteen hundred subjects (1,400 eyes, 781 from the HORIZON study of the Hydrus micro-stent and 619 from the COMPASS study of the Cypass micro-stent) with primary open-angle glaucoma who were using 0-4 classes of topical IOP-lowering medication underwent Goldmann applanation tonometry before and after a protocol-defined washout period.

RESULTS

The mean (standard deviation) age was 70.7 (8.0) years and 55.6% were female. The change in IOP following washout for patients using 0 (n = 100), 1 (n = 705), 2 (n = 355), 3 (n = 214), or 4 (n = 26) medications was 0.2 (2.8), 5.7 (3.3), 6.9 (3.7), 8.8 (5.0), and 9.5 (4.1) mm Hg, respectively (P < .001, Kruskal-Wallis test). Postwashout IOP change was similar between the HORIZON and COMPASS cohorts. No difference in postwashout IOP change was detected among individual prostaglandin analogues in patients on monotherapy. A generalized linear model identified the following factors to be associated with greater IOP rise upon medication washout: greater number of glaucoma medications, higher unmedicated IOP, thinner central corneal thickness (CCT), lack of prior selective laser trabeculoplasty (SLT), and male sex.

CONCLUSIONS

Cessation of glaucoma medications results in a dose-dependent IOP increase in treated open-angle glaucoma patients. Two independent clinical trial cohorts exhibit similar levels of IOP elevation upon washout, using standardized methodology to estimate real-world medication effectiveness. Thicker CCT and history of SLT may predict reduced response to IOP lowering medications.

A method to quantify regional axonal transport blockade at the optic nerve head after short term intraocular pressure elevation in mice

Axonal transport blockade is an initial step in retinal ganglion cell (RGC) degeneration in glaucoma and targeting maintenance of normal axonal transport could confer neuroprotection. We present an objective, quantitative method for assessing axonal transport blockade in mouse glaucoma models. Intraocular pressure (IOP) was elevated unilaterally in CD1 mice for 3 days using intracameral microbead injection. Longitudinal sections of optic nerve head (ONH) were immunofluorescently labeled for myelin basic protein (MBP) and amyloid precursor protein (APP), which is transported predominantly orthograde by neurons. The beginning of the myelin transition zone, visualized with the MBP label, was more posterior with elevated IOP, 288.8 ± 40.9 μm, compared to normotensive control eyes, 228.7 ± 32.7 μm (p = 0.030, N = 6 pairs). Glaucomatous regional APP accumulations in retina, prelaminar ONH, unmyelinated ONH, and myelinated optic nerve were identified by objective qualification of pixels with fluorescent intensity greater than the 97.5th percentile value of control eyes (suprathreshold pixels). This method segregated images with APP blockade from those with normal transport of APP. The fraction of suprathreshold pixels was significantly higher following IOP elevation than in normotensive controls in the unmyelinated ONH and myelinated nerve regions (paired analyses, p = 0.02 and 0.003, respectively, N = 12), but not in retina or prelaminar ONH (p = 0.91 and 0.08, respectively). The mean intensity of suprathreshold pixels was also significantly greater in glaucoma than in normotensive controls in prelaminar ONH, unmyelinated ONH and myelinated optic nerve (p = 0.01, 0.01, 0.002, respectively). Using this method, subconjunctival glyceraldehyde, which is known to worsen long-term RGC loss with IOP elevation, also produced greater APP blockade, but not statistically significant compared to glaucoma alone. Systemic losartan, which aids RGC axonal survival in glaucoma, reduced APP blockade, but not statistically significant compared to glaucoma alone. The method provides a short-term assessment of axonal injury for use in initial tests of neuroprotective therapies that may beneficially affect RGC transport in animal models of glaucoma.

ACR Appropriateness Criteria® Chest Pain-Possible Acute Coronary Syndrome

Chest pain is a frequent cause for emergency department visits and inpatient evaluation, with particular concern for acute coronary syndrome as an etiology, since cardiovascular disease is the leading cause of death in the United States. Although history-based, electrocardiographic, and laboratory evaluations have shown promise in identifying coronary artery disease, early accurate diagnosis is paramount and there is an important role for imaging examinations to determine the presence and extent of anatomic coronary abnormality and ischemic physiology, to guide management with regard to optimal medical therapy or revascularization, and ultimately to thereby improve patient outcomes. A summary of the various methods for initial imaging evaluation of suspected acute coronary syndrome is outlined in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Aqueous Flow Measured by Fluorophotometry in the Mouse

PURPOSE

A fluorophotometer designed to measure aqueous flow in murine eyes was tested with artificial fluorescein chambers and in live mice with different anesthesia regimens, aqueous flow suppressants, and an anterior chamber cannulation method.

METHODS

Two hours following topical fluorescein application, one group of CD-1 mice was anesthetized with ketamine/xylazine, 2,2,2-tribromoethanol, or ketamine alone. Cornea and anterior chamber fluorescein concentrations were measured periodically for 60 to 90 minutes by fluorophotometric scans to calculate aqueous flow. Later, a subgroup of mice underwent aqueous flow measurement by anterior chamber cannulation. A third group was treated with timolol, dorzolamide, and vehicle in a crossover manner 1 hour prior to fluorophotometric scans.

RESULTS

Aqueous flow with ketamine/xylazine anesthesia (0.09 ± 0.05 μL/min, mean ± SD, n = 24) was slower than with tribromoethanol or ketamine alone (P < 0.001). Timolol reduced aqueous flow from 0.20 ± 0.07 μL/min to 0.07 ± 0.03 μL/min (P = 0.001) under tribromoethanol anesthesia and from 0.14 ± 0.03 μL/min to 0.10 ± 0.02 μL/min (P = 0.004) under ketamine anesthesia but not under ketamine/xylazine anesthesia. Dorzolamide reduced aqueous flow from 0.09 ± 0.03 to 0.06 ± 0.03 μL/min (P = 0.04) under ketamine/xylazine anesthesia. Aqueous flow by anterior chamber cannulation (0.20 ± 0.13 μL/min) was greater (P = 0.05) than by fluorophotometry (0.09 ± 0.07 μL/min).

CONCLUSIONS

A new noninvasive fluorophotometric method detected effects of general anesthesia and known aqueous suppressants on aqueous flow in mice. Aqueous flow measured by fluorophotometry was slower than by cannulation, and was technically easier with less variability. The mouse fluorophotometer is useful for repeated measurements of aqueous flow in the murine eye making crossover and longitudinal studies possible.

Time-Lapse Retinal Ganglion Cell Dendritic Field Degeneration Imaged in Organotypic Retinal Explant Culture

Purpose

To develop an ex vivo organotypic retinal explant culture system suitable for multiple time-point imaging of retinal ganglion cell (RGC) dendritic arbors over a period of 1 week, and capable of detecting dendrite neuroprotection conferred by experimental treatments.

Methods

Thy1-YFP mouse retinas were explanted and maintained in organotypic culture. Retinal ganglion cell dendritic arbors were imaged repeatedly using confocal laser scanning microscopy. Maximal projection z-stacks were traced by two masked investigators and dendritic fields were analyzed for characteristics including branch number, size, and complexity. One group of explants was treated with brain derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF) added to the culture media. Changes in individual dendritic fields over time were detected using pair-wise comparison testing.

Results

Retinal ganglion cells in mouse retinal explant culture began to degenerate after 3 days with 52.4% surviving at 7 days. Dendritic field parameters showed minimal change over 8 hours in culture. Intra- and interobserver measurements of dendrite characteristics were strongly correlated (Spearman rank correlations consistently > 0.80). Statistically significant (P < 0.001) dendritic tree degeneration was detected following 7 days in culture including: 40% to 50% decreases in number of branch segments, number of junctions, number of terminal branches, and total branch length. Scholl analyses similarly demonstrated a significant decrease in dendritic field complexity. Treatment of explants with BDNF+CNTF significantly attenuated dendritic field degeneration.

Conclusions

Retinal explant culture of Thy1-YFP tissue provides a useful model for time-lapse imaging of RGC dendritic field degeneration over a course of several days, and is capable of detecting neuroprotective amelioration of dendritic pruning within individual RGCs.

Stem cell therapy for glaucoma: possibilities and practicalities

Glaucoma is a progressive, neurodegenerative, optic neuropathy in which currently available therapies cannot always prevent, and do not reverse, vision loss. Stem cell transplantation may provide a promising new avenue for treating many presently incurable degenerative conditions, including glaucoma. This article will explore the various ways in which transplantation of stem or progenitor cells may be applied for the treatment of glaucoma. We will critically discuss the translational prospects of two cell transplantation-based treatment modalities: neuroprotection and retinal ganglion cell replacement. In addition, we will identify specific questions that need to be addressed and obstacles to overcome on the path to clinical translation, and offer insight into potential strategies for approaching this goal.

Identification of retinal ganglion cell neuroprotection conferred by platelet-derived growth factor through analysis of the mesenchymal stem cell secretome

The development of neuroprotective strategies to attenuate retinal ganglion cell death could lead to novel therapies for chronic optic neuropathies such as glaucoma. Intravitreal transplantation of mesenchymal stem cells slows retinal ganglion cell death in models of optic nerve injury, but the mechanism of action remains unclear. Here we characterized the neuroprotective effects of mesenchymal stem cells and mesenchymal stem cell-derived factors in organotypic retinal explant culture and an in vivo model of ocular hypertensive glaucoma. Co-culture of rat and human bone marrow-derived mesenchymal stem cells with retinal explants increased retinal ganglion cell survival, after 7 days ex vivo, by ∼2-fold and was associated with reduced apoptosis and increased nerve fibre layer and inner plexiform layer thicknesses. These effects were not demonstrated by co-culture with human or mouse fibroblasts. Conditioned media from mesenchymal stem cells conferred neuroprotection, suggesting that the neuroprotection is mediated, at least partly, by secreted factors. We compared the concentrations of 29 factors in human mesenchymal stem cell and fibroblast conditioned media, and identified 11 enriched in the mesenchymal stem cell secretome. Treatment of retinal explants with a cocktail of these factors conferred retinal ganglion cell neuroprotection, with factors from the platelet-derived growth factor family being the most potent. Blockade of platelet-derived growth factor signalling with neutralizing antibody or with small molecule inhibitors of platelet-derived growth factor receptor kinase or downstream phosphatidylinositol 3 kinase eliminated retinal ganglion cell neuroprotection conferred by mesenchymal stem cell co-culture. Intravitreal injection of platelet-derived growth factor -AA or -AB led to profound optic nerve neuroprotection in vivo following experimental induction of elevated intraocular pressure. These data demonstrate that mesenchymal stem cells secrete a number of neuroprotective proteins and suggest that platelet-derived growth factor secretion in particular may play an important role in mesenchymal stem cell-mediated retinal ganglion cell neuroprotection. Furthermore, platelet-derived growth factor may represent an independent target for achieving retinal ganglion cell neuroprotection.

Myocilin mediates myelination in the peripheral nervous system through ErbB2/3 signaling

The glaucoma-associated gene, myocilin, is expressed in ocular and non-ocular tissues including the peripheral nervous system, but its functions in these tissues remain poorly understood. We demonstrate that in sciatic nerve, myocilin is expressed in Schwann cells with high concentrations at the nodes of Ranvier. There, myocilin interacts with gliomedin, neurofascin, and NrCAM, which are essential for node formation and function. Treatment of isolated dorsal root ganglion cultures with myocilin stimulates clustering of the nodal proteins neurofascin and sodium channel Nav1.2. Sciatic nerves of myocilin null mice express reduced levels of several myelin-associated and basal membrane proteins compared with those of wild-type littermates. They also demonstrate reduced myelin sheath thickness and partial disorganization of the nodes. Myocilin signaling through ErbB2/3 receptors may contribute to these observed effects. Myocilin binds to ErbB2/ErbB3, activates these receptors, and affects the downstream PI3K-AKT signaling pathway. These data implicate a role for myocilin in the development and/or maintenance of myelination and nodes of Ranvier in sciatic nerve.

Myocilin stimulates osteogenic differentiation of mesenchymal stem cells through mitogen-activated protein kinase signaling

Myocilin is a secreted glycoprotein that is expressed in ocular and non-ocular tissues. Mutations in the MYOCILIN gene may lead to juvenile- and adult-onset primary open-angle glaucoma. Here we report that myocilin is expressed in bone marrow-derived mesenchymal stem cells (MSCs) and plays a role in their differentiation into osteoblasts in vitro and in osteogenesis in vivo. Expression of myocilin was detected in MSCs derived from mouse, rat, and human bone marrow, with human MSCs exhibiting the highest level of myocilin expression. Expression of myocilin rose during the course of human MSC differentiation into osteoblasts but not into adipocytes, and treatment with exogenous myocilin further enhanced osteogenesis. MSCs derived from Myoc-null mice had a reduced ability to differentiate into the osteoblastic lineage, which was partially rescued by exogenous extracellular myocilin treatment. Myocilin also stimulated osteogenic differentiation of wild-type MSCs, which was associated with activation of the p38, Erk1/2, and JNK MAP kinase signaling pathways as well as up-regulated expression of the osteogenic transcription factors Runx2 and Dlx5. Finally, cortical bone thickness and trabecular volume, as well as the expression level of osteopontin, a known factor of bone remodeling and osteoblast differentiation, were reduced dramatically in the femurs of Myoc-null mice compared with wild-type mice. These data suggest that myocilin should be considered as a target for improving the bone regenerative potential of MSCs and may identify a new role for myocilin in bone formation and/or maintenance in vivo.

Cell transplantation approaches to retinal ganglion cell neuroprotection in glaucoma

Glaucoma is a complex neurodegenerative disease that involves interactions among multiple signaling pathways, ultimately leading to progressive retinal ganglion cell (RGC) death. The development of neuroprotective approaches to glaucoma therapy could preserve vision by modulating these pathologic pathways or by acting directly on RGCs to attenuate cell death and maintain function. Intraocular cell transplantation is being evaluated as one approach to achieve sustained RGC neuroprotection. Unlike traditional pharmacological approaches, transplanted cells might be capable of simultaneously targeting multiple pro-survival pathways via local delivery of secreted factors and/or via modulation of the intraocular microenvironment. Elucidating the mechanisms by which different cell types attenuate RGC death in models of glaucoma may uncover additional novel mechanisms of neuroprotection. In this review, we will discuss the rationale for transplantation-based approaches to neuroprotection for glaucoma and explore the various mechanisms of action proposed to account for RGC neuroprotection achieved by two distinct cell classes that have been studied most extensively for this purpose: glial cells and mesenchymal stem cells.

Abstract 102: FOCUS: Appropriate Use of Cardiac Imaging

Introduction The American College of Cardiology has created a new initiative (FOCUS) to help reduce inappropriate use of clinical imaging in cardiology. In accord with the effort, the Sanger Heart and Vascular Institute (SHVI) has designed a program to enhance appropriate use of cardiac imaging.

Hypothesis: By implementing a quality improvement program to evaluate the appropriateness of cardiac imaging, there will be a 10% improvement in the percentage of studies ordered for appropriate indications and a corresponding decrease in the number of studies ordered for inappropriate indications.

Methods: The initiative utilized an integrated multifaceted approach to quality improvement: 1) Staff / physician education with video teleconferences: Presentations were given at SHVI’s Grand Round, focusing on the appropriate use criteria as outlined in the ACCF/ASE/ASNC documents. An important component was interactive case studies highlighting the principles of appropriate use criteria. 2) Peer review and audits: Each practitioner and site received individual performance feedback. This was a complete analysis which included testing appropriateness as an indication. 3) System support tools: A comprehensive order sheet with check boxes for all appropriate indications was designed. All ordering physicians were asked to use this form for ordering all cardiac imaging studies. For those studies in which the form was not utilized, the imaging technologist attempted to obtain the appropriate information. All information from the forms was entered into a database designed specifically for this study. A baseline survey of 30 consecutive studies was selected for analysis from each echocardiography and cardiac nuclear imaging site within SHVI for a total of 360 studies. The ongoing post intervention survey conducts a monthly review of 25% of all studies per site.

Results: At baseline, 77% of transthoracic echocardiographic studies were ordered for appropriate indications. Post intervention there was significant improvement: 91% (p<0.0013) of studies were categorized as appropriate and 1% of studies categorized as inappropriate (14% improvement in each). Of the remaining studies, 9% could not be categorized. With regards to stress cardiac imaging, 71% of studies were ordered for appropriate indications at baseline. Post intervention, there was significant improvement: 94% (p<0.0008) of studies categorized as appropriate (23% improvement), 16% categorized as inappropriate, and 6% could not be categorized.

Conclusion: Although there is limited data on a national basis, published literature would suggest 70-80% appropriate use of cardiac imaging as a baseline benchmark. The results of this initiative demonstrated a statistically significant benefit in the appropriate use of cardiac imaging for SHVI from this baseline. The data gathering and database capabilities established during this initiative will allow quarterly reviews to providers, which will help ensure continued compliance with the guidelines.