Autoantibodies in melanoma-associated retinopathy target TRPM1 cation channels of retinal ON bipolar cells

Melanoma-associated retinopathy (MAR) is characterized by night blindness, photopsias, and a selective reduction of the electroretinogram b-wave. In certain cases, the serum contains autoantibodies that react with ON bipolar cells, but the target of these autoantibodies has not been identified. Here we show that the primary target of autoantibodies produced in MAR patients with reduced b-wave is the TRPM1 cation channel, the newly identified transduction channel in ON bipolar cells. Sera from two well characterized MAR patients, but not from a control subject, stained human embryonic kidney cells transfected with the TRPM1 gene, and Western blots probed with these MAR sera showed the expected band size (∼180 kDa). Staining of mouse and primate retina with MAR sera revealed immunoreactivity in all types of ON bipolar cells. Similar to staining for TRPM1, staining with the MAR sera was strong in dendritic tips and somas and was weak or absent in axon terminals. This staining colocalized with GFP in Grm6-GFP transgenic mice, where GFP is expressed in all and only ON bipolar cells, and also colocalized with Gα(o), a marker for all types of ON bipolar cells. The staining in ON bipolar cells was confirmed to be specific to TRPM1 because MAR serum did not stain these cells in a Trpm1(-/-) mouse. Evidence suggests that the recognized epitope is likely intracellular, and the sera can be internalized by retinal cells. We conclude that the vision of at least some patients with MAR is compromised due to autoantibody-mediated inactivation of the TRPM1 channel.

An electrophysiological study of retinal function in the diabetic female rat

PURPOSE

To examine retinal function in female Long-Evans rats with streptozotocin (STZ)-induced diabetes.

METHODS

Hyperglycemia was induced by IV injection of STZ, and ERG responses were recorded at 4-week intervals over 12 weeks. Oscillatory potentials (OPs) and responses to intermittent stimulation were analyzed with a custom computer program. The GABA-induced responses of individual rod bipolar cells were obtained from patch-clamp recordings, and immunohistochemistry was used to illustrate the retinal distribution of GABA (gamma-aminobutyric acid) and GABA(C) receptors.

RESULTS

Hyperglycemia developed in rats 2 to 3 days after injection of STZ. Compared with previous reports of the effects of diabetes in male rats, visual function abnormalities appeared to be milder in STZ-treated female rats. No significant differences were observed in the sensitivity or amplitude of the a- or b-wave components of the ERG between diabetic and control animals, and both animal groups exhibited a similar time course of neuronal dark adaptation. In contrast, diabetic animals showed significant differences in the pattern of OPs and in the amplitudes of their responses to flicker. The accumulation of GABA in the inner retina of diabetic rats, combined with the results of patch-clamp recordings from individual bipolar cells, revealed that the circuitry underlying the GABA signal of the proximal retina is affected by hyperglycemia.

CONCLUSIONS

The results suggest that changes in the GABA-signaling pathway may be the underlying cellular mechanism for altered ERG responses in STZ-induced diabetes in rats. Recognition of these early neurosensory defects would enable a better understanding of the pathophysiological basis of diabetic retinopathy.

Hypoxia and Dark Adaptation in Diabetic Retinopathy: Interactions, Consequences, and Therapy

In diabetes, retinal blood flow is compromised, and retinal hypoxia is likely to be further intensified during periods of darkness. During dark adaptation, rod photoreceptors in the outer retina are maximally depolarized and continuously release large amounts of the neurotransmitter glutamate-an energetically demanding process that requires the highest oxygen consumption per unit volume of any tissue of the body. In complete darkness, even more oxygen is consumed by the outer retina, producing a steep fall in the retinal oxygen tension curve which reaches a nadir at the depth of the mitochondrial-rich rod inner segments. In contrast to the normal retina, the diabetic retina cannot meet the added metabolic load imposed by the dark-adapted rod photoreceptors; this exacerbates retinal hypoxia and stimulates the overproduction of vascular endothelial growth factor (VEGF). The use of nocturnal illumination to prevent dark adaptation, specifically reducing the rod photoreceptor dark current, should ameliorate diabetic retinopathy.

Statin prescription rates and their facility-level variation in patients with peripheral artery disease and ischemic cerebrovascular disease: Insights from the Department of Veterans Affairs

The 2013 American College of Cardiology/American Heart Association cholesterol guideline recommends moderate to high-intensity statin therapy in patients with peripheral artery disease (PAD) and ischemic cerebrovascular disease (ICVD). We examined frequency and facility-level variation in any statin prescription and in guideline-concordant statin prescriptions in patients with PAD and ICVD receiving primary care in 130 facilities across the Veterans Affairs (VA) health care system between October 2013 and September 2014. Guideline-concordant statin intensity was defined as the prescription of high-intensity statins in patients with PAD or ICVD ≤75 years and at least moderate-intensity statins in those >75 years. We calculated median rate ratios (MRR) after adjusting for patient demographic factors to assess the magnitude of facility-level variation in statin prescribing patterns independent of patient characteristics. Among 194,151 PAD patients, 153,438 patients (79.0%) were prescribed any statin and 79,435 (40.9%) were prescribed a guideline-concordant intensity of statin. PAD patients without ischemic heart disease were prescribed any statin and a guideline-concordant intensity of statin therapy less frequently (69.1% and 28.9%, respectively). Among 339,771 ICVD patients, 265,491 (78.1%) were prescribed any statin and 136,430 (40.2%) were prescribed a guideline-concordant intensity of statin. ICVD patients without ischemic heart disease were prescribed any statin and a guideline-concordant intensity of statin less frequently (70.9% and 30.5%, respectively). MRRs for both PAD and ICVD patients demonstrated a 20% and 28% variation among two facilities in treating two identical patients with statin therapy and guideline-concordant intensity of statin therapy, respectively. The prescription of statins, especially guideline-recommended intensity of statin therapy, is suboptimal in PAD and ICVD patients, with significant facility-level variation not explained by patient-level factors.

Streptozotocin-induced diabetes modulates GABA receptor activity of rat retinal neurons

Neural deficits suggestive of involvement of the GABA signaling pathway can often be detected early in the course of diabetic retinopathy, a leading cause of blindness in the United States. To examine in greater detail the nature of the neuronal changes associated with hyperglycemia, we investigated GABA receptor activity on retinal bipolar cells in streptozotocin-induced diabetic rats; cells from age-matched normal rats served as controls. Patch-clamp recordings from isolated rod-bipolar cells revealed that diabetes enhanced the whole cell currents elicited by GABA. Responses of the GABA(C) receptor, the predominant GABA receptor on rat rod bipolar cells, exhibited a greater sensitivity to GABA, larger maximum current responses, slower response kinetics, and a smaller single channel conductance among diabetic cells relative to those recorded from normal controls. Compared with the properties of homomeric rho1 and heteromeric rho1rho2 receptors formed in a heterologous expression system, these results suggested that there was a greater contribution from the rho1 subunit in the GABA(C) receptor-mediated response of diabetic cells. The levels of mRNA, measured with real-time RT-PCR, were consistent with this finding. There was a significant enhancement in the ratio of rho1/rho2 subunit expression in the retina of diabetic animals, although the levels of GABA rho1 subunit expression were comparable in diabetic and normal retinas. Taken together, the results suggest that diabetes modifies the subunit composition of the GABA(C) receptor on retinal neurons, most likely through its effect on the efficacy of gene transcription.

Automated image alignment and segmentation to follow progression of geographic atrophy in age-related macular degeneration

PURPOSE

To develop a computer-based image segmentation method for standardizing the quantification of geographic atrophy (GA).

METHODS

The authors present an automated image segmentation method based on the fuzzy c-means clustering algorithm for the detection of GA lesions. The method is evaluated by comparing computerized segmentation against outlines of GA drawn by an expert grader for a longitudinal series of fundus autofluorescence images with paired 30° color fundus photographs for 10 patients.

RESULTS

The automated segmentation method showed excellent agreement with an expert grader for fundus autofluorescence images, achieving a performance level of 94 ± 5% sensitivity and 98 ± 2% specificity on a per-pixel basis for the detection of GA area, but performed less well on color fundus photographs with a sensitivity of 47 ± 26% and specificity of 98 ± 2%. The segmentation algorithm identified 75 ± 16% of the GA border correctly in fundus autofluorescence images compared with just 42 ± 25% for color fundus photographs.

CONCLUSION

The results of this study demonstrate a promising computerized segmentation method that may enhance the reproducibility of GA measurement and provide an objective strategy to assist an expert in the grading of images.

Coffee and Caffeine Are Associated With Decreased Risk of Advanced Hepatic Fibrosis Among Patients With Hepatitis C

BACKGROUND & AIMS

Coffee or caffeine has been proposed to protect against hepatic fibrosis, but few data are available on their effects in patients with chronic hepatitis C virus (HCV) infection.

METHODS

We conducted a cross-sectional study of veterans with chronic HCV infection to evaluate the association between daily intake of caffeinated and decaffeinated coffee, tea, and soda, and level of hepatic fibrosis, based on the FibroSURE test (BioPredictive, Paris, France) (F0-F3, mild [controls] vs. F3/F4-F4, advanced). Models were adjusted for multiple potential confounders including age, alcohol abuse, and obesity.

RESULTS

Among 910 patients with chronic HCV infection, 98% were male and 38% had advanced hepatic fibrosis. Daily intake of caffeinated coffee was higher among controls than patients with advanced fibrosis (1.37 vs. 1.05 cups/d; P = .038). In contrast, daily intake of caffeinated tea (0.61 vs. 0.56 cups/d; P = .651) or soda (1.14 vs. 0.95 cans/d; P = .106) did not differ between the groups. A higher percentage of controls (66.0%) than patients with advanced fibrosis (57.9%) consumed 100 mg or more of caffeine daily from all sources (P = .014); controls also received a larger proportion of their caffeine from coffee (50.2% vs. 43.0%; P = .035). Hepatoprotective effects of an average daily intake of 100 mg or more of caffeine (adjusted odds ratio, 0.71; 95% confidence interval, 0.53-0.95; P = .020) and 1 cup or more of caffeinated tea by non-coffee drinkers (adjusted odds ratio, 0.56; 95% confidence interval, 0.34-0.94; P = .028) persisted after adjustment for confounders, including insulin resistance.

CONCLUSIONS

A modest daily caffeine intake (as little as 100 mg) may protect against advanced hepatic fibrosis in men with chronic HCV infection. Additional research is needed to confirm these findings in women and in people with other chronic liver diseases.

Evaluation of Aspirin and Statin Therapy Use and Adherence in Patients With Premature Atherosclerotic Cardiovascular Disease

IMPORTANCE

Studies on the use of and adherence to secondary prevention therapies in patients with premature and extremely premature atherosclerotic cardiovascular disease (ASCVD) are lacking.

OBJECTIVE

To evaluate and compare aspirin use, any statin use, high-intensity statin use, and statin adherence among patients with premature or extremely premature ASCVD compared with patients with nonpremature ASCVD.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cross-sectional study used the clinical and administrative data sets of the US Department of Veterans Affairs (VA) to identify adult patients with at least 1 primary care visit in the VA health care system between October 1, 2014, and September 30, 2015. The study cohort comprised patients with ASCVD (ischemic heart disease, peripheral arterial disease, or ischemic cerebrovascular disease) who were enrolled in the Veterans With Premature Atherosclerosis (VITAL) registry. Patients with missing data for date of birth or sex and those with limited life expectancy were excluded. Data were analyzed from November 1, 2019, to January 1, 2020.

EXPOSURES

Premature (the first ASCVD event occurred at age <55 years for men and age <65 years for women) vs nonpremature (the first ASCVD event occurred at age ≥55 years for men or age ≥65 years for women) ASCVD and extremely premature (the first ASCVD event occurred at age <40 years) vs nonpremature ASCVD.

MAIN OUTCOMES AND MEASURES

The primary outcomes were aspirin use, any statin use, high-intensity statin use, and statin adherence (measured by proportion of days covered [PDC] ≥0.8).

RESULTS

Of the 1 248 158 patients identified, 135 703 (10.9%) had premature ASCVD (mean [SD] age, 49.6 [5.8] years; 116 739 men [86.0%]), 1 112 455 (89.1%) had nonpremature ASCVD (mean [SD] age, 69.6 [8.9] years; 1 104 318 men [99.3%]), and 7716 (0.6%) had extremely premature ASCVD (mean [SD] age, 34.2 [4.3] years; 6576 men [85.2%]). Patients with premature ASCVD vs those with nonpremature ASCVD had lower rates of aspirin use (96 468 [71.1%] vs 860 726 [77.4%]; P < .001) and any statin use (98 908 [72.9%] vs 894 931 [80.5%]; P < .001); had a statin PDC of 0.8 or higher (57 306 [57.9%] vs 644 357 [72.0%]; P < .001); and a higher rate of high-intensity statin use (49 354 [36.4%] vs 332 820 [29.9%]; P < .001). Similarly, patients with extremely premature ASCVD were less likely to use aspirin (odds ratio [OR], 0.27; 95% CI, 0.26-0.29), any statin (OR, 0.25; 95% CI, 0.24-0.27), or high-intensity statin (OR, 0.78; 95% CI, 0.74-0.82) and to be statin adherent (OR, 0.44; 95% CI, 0.41-0.47).

CONCLUSIONS AND RELEVANCE

In this study, patients with premature or extremely premature ASCVD appeared to be less likely to use aspirin or statins and to adhere to statin therapy. This finding warrants further investigation into premature ASCVD and initiatives, including clinician and patient education, to better understand and mitigate the disparities in medication use and adherence.

Optic neuropathy after COVID-19 vaccination: a report of two cases

PURPOSE

We report two cases of optic nerve pathology after the administration of the Pfizer-BioNTech and AstraZeneca-Oxford COVID-19 vaccines, respectively, and describe the implications for management of post-vaccination central nervous system (CNS) inflammation.

CASE REPORTS

A 69-year-old woman presented with bilateral optic nerve head oedema, 16 days after the second dose of the Pfizer-BioNTech vaccine. She was diagnosed with post-vaccination CNS inflammatory syndrome and was treated for five days with intravenous methylprednisolone at a dose of 1 gram per day. Her optic disc swelling improved, and her vision stabilised. A 32-year-old woman presented six days after her first dose of the AstraZeneca-Oxford vaccine with two days of sudden onset of progressive blurring of vision in her left eye. Posterior segment examination revealed left optic disc swelling, and an MRI of the brain, orbit, and cervical spine was significant for left optic nerve enhancement. The patient was diagnosed with a unilateral post-vaccination optic neuritis. She was treated with a three-day course of intravenous methylprednisolone followed by oral prednisone. Her optic disc swelling and visual field improved, and she recovered 6/6 vision.

CONCLUSIONS

Clinicians and patients should be aware of the potential for post-vaccination CNS inflammatory syndromes associated with COVID-19 vaccine administration. Neuroimaging and cerebrospinal fluid analysis may aid in the diagnosis of the cause of vision loss. Further studies are needed to evaluate the spectrum and frequency of optic nerve involvement associated with COVID-19 vaccination.

Complications of subspecialty ophthalmic care: endophthalmitis after intravitreal injections of anti-vascular endothelial growth factor medications

The use of medications directed against vascular endothelial growth factor (VEGF) signaling has revolutionized the treatment of age-related macular degeneration (AMD) and many other retinal diseases in the last decade. However, the rapidly increasing use of these agents has led to a rise in treatment-associated complications. One of the most feared by patients and ophthalmologists is post-injection endophthalmitis, which can result in severe vision loss and, in rare cases, loss of the eye. The aim of this article is to review the incidence, clinical findings, risk factors, management, and visual outcomes in cases of endophthalmitis following intravitreal injections of anti-VEGF medications.

Directional asymmetries in the optokinetic response of larval zebrafish (Danio rerio)

Photographic images of the optokinetic response (OKR) of larval zebrafish permitted the calculation of the amplitude and velocity of the response to gratings of various spatial frequencies rotating at different speeds. At low spatial frequencies, the amplitude of the OKR did not vary significantly for drum speeds ranging from 24 to 108 degrees/sec. Plotting the velocity of the OKR as a function of drum speed gave rise to a bell-shaped curve, with a maximum at about 48 degrees/sec. Interestingly, both eyes exhibited an asymmetric response to the rotating drum, that is, they were more responsive to temporal-to-nasal rotation than to nasal-to-temporal motion. Although this asymmetry persisted over the entire range of drum speeds tested, the situation was reversed when tested with gratings of higher spatial frequency (i.e., the eyes became more responsive to rotation in the nasal-to-temporal direction). The amplitude of the OKR for both eyes exhibited an inverse relation to increasing spatial frequency of the stimulus, whereas the velocity of the OKR showed a steep decline within the range of 0.08 to 0.14 cycles/degree. The data indicate that zebrafish are more responsive to objects with low spatial frequencies moving from behind the animal's head toward the frontal plane, and to high spatial frequencies of objects moving across the frontal plane (perpendicular to the anterior-posterior axis of the eye).

Effects of metformin on retinoblastoma growth in vitro and in vivo

Recent studies suggest that the anti-diabetic drug metformin may reduce the risk of cancer and have anti-proliferative effects for some but not all cancers. In this study, we examined the effects of metformin on human retinoblastoma cell proliferation in vitro and in vivo. Two different human retinoblastoma cell lines (Y79, WERI) were treated with metformin in vitro and xenografts of Y79 cells were established in nu/nu immune-deficient mice and used to assess the effects of pharmacological levels of metformin in vivo. Metformin inhibited proliferation of the retinoblastoma cells in vitro. Similar to other studies, high concentrations of metformin (mM) blocked the cell cycle in G0‑G1, indicated by a strong decrease of G1 cyclins, especially cyclin D, cyclin-dependent kinases (4 and 6), and flow cytometry assessment of the cell cycle. This was associated with activation of AMPK, inhibition of the mTOR pathways and autophagy marker LC3B. However, metformin failed to suppress growth of xenografted tumors of Y79 human retinoblastoma cells in nu/nu mice, even when treated with a maximally tolerated dose level achieved in human patients. In conclusion, suprapharmacological levels (mM) of metformin, well above those tolerated in vivo, inhibited the proliferation of retinoblastoma cells in vitro. However, physiological levels of metformin, such as seen in the clinical setting, did not affect the growth of retinoblastoma cells in vitro or in vivo. This suggests that the potential beneficial effects of metformin seen in epidemiological studies may be limited to specific tumor types or be related to indirect effects/mechanisms not observed under acute laboratory conditions.

Optical Coherence Tomography Angiography Biomarkers Predict Anatomical Response to Bevacizumab in Diabetic Macular Edema

PURPOSE

To identify biomarkers that may predict an early anatomical response to the treatment of diabetic macular edema (DME) with intravitreal bevacizumab (IVB) by means of optical coherence tomography angiography (OCTA).

METHODS

This study is a retrospective study of treatment-naïve patients with DME who underwent 6 × 6 mm OCTA imaging of the macula at baseline and after three monthly IVB injections. Thirty-six eyes of 23 patients were included. Eyes that demonstrated evidence of an early anatomical response, consisting of a >10% decrease in central macular thickness (CMT) (n = 18), were compared with those eyes that failed to show such an improvement (n = 18).

RESULTS

At baseline, early-response eyes had worse starting best-corrected visual acuity (BCVA, LogMAR 0.84 ± 0.41 versus LogMAR 0.51 ± 0.15, p = 0.004) and a larger CMT (490 ± 135 µm versus 356 ± 33 µm, p = 0.001), but smaller foveal avascular zones (FAZ) (0.309 ± 0.098mm versus 0.413 ± 0.095 mm, p = 0.003) compared with eyes that proved refractory to three monthly injections of IVB. The vascular density (VD) in both the foveal superficial and deep capillary plexuses was significantly greater in eyes that showed an early-treatment response compared with eyes that were non-responders (24.86 ± 6.90% versus 19.98 ± 7.13%, p = 0.045 and 32.30 ± 4.88% versus 26.95 ± 7.25%, p = 0.028, respectively). Early-treatment response to IVB was predicted by starting CMT (r 2= 0.266, p = 0.001), FAZ size (r 2= 0.234, p = 0.003), and VD in the superficial parafovea (r 2= 0.217, p = 0.004) and deep fovea (r 2= 0.157, p = 0.037).

CONCLUSION

Projection-resolved OCTA may be useful in predicting an early anatomical response of DME to treatment with IVB.

An Initiative to Improve Follow-up of Patients with Glaucoma

PURPOSE

This study describes the implementation of an electronic medical record (EMR)-based initiative aimed at reducing the number of patients with glaucoma-related diagnoses lost to follow-up (LTF) and reviews its short-term outcomes.

DESIGN

Retrospective, comparative case series.

PARTICIPANTS

Patients with glaucoma-related diagnoses seen 1 year prior at the Lahey Medical Center and who had not returned within the 6-month period between January 1, 2020, and June 30, 2020, which spanned the outbreak of the Coronavirus Disease 2019 (COVID-19) pandemic in the United States.

METHODS

An EMR-based tool was designed to identify patients suspected of being LTF with glaucoma-related diagnoses. Providers were enlisted to review the EMR for each of these patients and re-engage them, as appropriate. One month later, the initiative was evaluated by means of a retrospective chart review. Binary logistic regression analysis was used to identify demographic, clinical, and sociomedical factors associated with being LTF.

MAIN OUTCOME MEASURES

Patients who completed a telemedicine or in-person appointment, or had a future scheduled or ordered return appointment, were considered re-engaged.

RESULTS

Of the 3551 patients seen during the study period, 384 patients were identified as LTF (11%), with 60 identifying COVID-19 as the reason for canceling their visit (16%). Patients who lived farther from the eye clinic (P < 0.001) or who had a history of canceling or missing an appointment (P < 0.001) were more likely to be LTF. Patients with open-angle glaucoma (P = 0.042) or who had completed a visual field (P < 0.001) or ophthalmic imaging (P < 0.001) within the past year were less likely to be LTF. One month after the re-engagement initiative, 124 LTF patients (32%) had been re-engaged (40% through telemedicine), 238 patients (62%) had future scheduling orders in place, and 22 patients (6%) had no active plan for future follow-up.

CONCLUSIONS

An EMR-based tool is an effective method for identifying patients at risk of being LTF and provides an opportunity for providers to recall and re-engage patients. Use of telemedicine to recontact LTF patients shows promise of improving the management of glaucoma, enhancing clinical productivity, and documenting treatment plans, thereby potentially reducing medicolegal liability.

Modeling the impact of COVID-19 on Retina Clinic Performance

BACKGROUND

COVID-19, a highly contagious respiratory virus, presents unique challenges to ophthalmology practice as a high-volume, office-based specialty. In response to the COVID-19 pandemic, many operational changes were adopted in our ophthalmology clinic to enhance patient and provider safety while maintaining necessary clinical operations. The aim of this study was to evaluate how measures adopted during the pandemic period affected retina clinic performance and patient satisfaction, and to model future clinic flow to predict operational performance under conditions of increasing patient and provider volumes.

METHODS

Clinic event timestamps and demographics were extracted from the electronic medical records of in-person retina encounters from March 15 to May 15, 2020 and compared with the same period in 2019 to assess patient flow through the clinical encounter. Patient satisfaction was evaluated by Press Ganey patient experience surveys obtained from randomly selected outpatient encounters. A discrete-events simulation was designed to model the clinic with COVID-era restrictions to assess operational performance under conditions of increasing patient and provider volumes.

RESULTS

Retina clinic volume declined by 62 % during the COVID-19 health emergency. Average check-in-to-technician time declined 79 %, total visit length declined by 46 %, and time in the provider phase of care declined 53 %. Patient satisfaction regarding access nearly doubled during the COVID-period compared with the prior year (p < 0.0001), while satisfaction with overall care and safety remained high during both periods. A model incorporating COVID-related changes demonstrated that wait time before rooming reached levels similar to the pre-COVID era by 30 patients-per-provider in a 1-provider model and 25 patients-per-provider in a 2-provider model (p < 0.001). Capacity to maintain distancing between patients was exceeded only in the two 2-provider model above 25 patients-per-provider.

CONCLUSIONS

Clinic throughput was optimized in response to the COVID-19 health emergency. Modeling these clinic changes can help plan for eventual volume increases in the setting of limits imposed in the COVID-era.

Automated Image Alignment for Comparing Microvascular Changes Detected by Fluorescein Angiography and Optical Coherence Tomography Angiography in Diabetic Retinopathy

PURPOSE

To quantitatively compare microvascular features in the macula of patients with diabetic retinopathy (DR) using fluorescein angiography (FA) and optical coherence tomography angiography (OCTA).

METHODS

Patients with DR were recruited from the Cairo University Hospital. FA was performed using a Topcon TRC-50DX or Heidelberg Spectralis HRA+OCT. OCTA was performed using an Optovue RTVue-XR Avanti. FA images were cropped and aligned to the corresponding OCTA images using i2k Align Retina software. The foveal avascular zone (FAZ), area of ischemia, and microaneurysms (MAs) were manually quantified using ImageJ. The fractal dimension (FD) was calculated from each skeletonized image using the FracLac plugin of ImageJ after retinal vascular segmentation.

RESULTS

Twenty-four eyes of 17 patients were evaluated, but only 18 eyes were successfully aligned. There was no difference in FAZ area measured for FA and OCTA images. Compared with OCTA images, FD was significantly less for FA images (1.66 ± 0.048 versus 1.72 ± 0.023, p < .001). Significantly more MAs were identified on FA images (102 ± 27.5) compared with OCTA (47.5 ± 11.7, p < .0001). The number of MAs on FA correlated with decreasing best corrected visual acuity (r2 = 0.315, p = .015) and increasing central macular thickness (r2 = 0.492, p = .001). No such associations were found with MAs detected on OCTA. Nevertheless, the area of ischemia in the FA images (8.5 ± 4.1%) was significantly smaller compared with the area measured in both the superficial (30.7 ± 9.5%) and deep capillary plexus (21.6 ± 10.9%) of the OCTA (p < .001). Interestingly, number of MAs in the FA images correlated with increasing area of ischemia in the FA (r2 = 0.568, p < .001) but only the superficial segment of the depth-resolved OCTA scans (r2 = 0.539, p < .001).

CONCLUSIONS

OCTA is a non-invasive tool capable of resolving the retinal vasculature in greater detail when compared with FA but detects significantly fewer MAs. Automatic alignment facilitates quantitative comparison of the microvascular features in DR.

Presbyopia: a pilot investigation of the barriers and benefits of near visual acuity correction among a rural Filipino population

BACKGROUND

Presbyopia is the age-related decline in accommodation that diminishes the ability of the eye to focus on near objects. Presbyopia is common and easy to correct; however, many communities lack access to basic eye care. The purpose of this project was to assess the burden of uncorrected presbyopia in a rural Filipino population and to pilot an intervention aimed at increasing access to reading glasses in the community.

METHODS

Individuals above the age of 40 who presented to a health outreach in the Philippines were invited to undergo a near vision exam to detect the presence of functional presbyopia and be fitted with ready-made, single-vision glasses. The change in stereoacuity was used as a surrogate measure of functional improvement after near vision correction. A questionnaire was administered to assess this population's perceived barriers and benefits to correcting near vision.

RESULTS

The average age of the participants was 57 ± 11 years, with 87.6% of participants having an uncorrected near visual acuity of <20/50. Reading glasses improved near vision to 20/40 or better in 77.7% of participants having near-vision impairment (uncorrected near visual acuity of <20/40). Over 75% of participants also showed improvement in stereoacuity. Cost, rather than availability, was perceived to be the greater barrier to the procurement of glasses, and 84% of participants reported that the glasses dispensed would greatly improve their ability to earn a living.

CONCLUSIONS

Dispensing ready-made, single-vision glasses is a simple and cost-effective intervention to improve near vision and enhance depth perception. A greater understanding of the barriers and benefits to correcting near vision will inform the design and execution of a sustainable program to correct presbyopia in developing countries.

Genetic advances in ophthalmology: the role of melanopsin-expressing, intrinsically photosensitive retinal ganglion cells in the circadian organization of the visual system

Daily changes in the light-dark cycle are the principal environmental signal that enables organisms to synchronize their internal biology with the 24-hour day-night cycle. In humans, the visual system is integral to photoentrainment and is primarily driven by a specialized class of intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin (OPN4) in the inner retina. These cells project through the retinohypothalamic tract (RHT) to the suprachiasmatic nuclei (SCN) of the hypothalamus, which serves as the body's master biological clock. At the same time, the retina itself possesses intrinsic circadian oscillations, exemplified by diurnal fluctuations in visual sensitivity, neurotransmitter levels, and outer segment turnover rates. Recently, it has been noted that both central and peripheral oscillators share a molecular clock consisting of an endogenous, circadian-driven, transcription-translation feedback loop that cycles with a periodicity of approximately 24 hours. This review will cover the role that melanopsin and ipRGCs play in the circadian organization of the visual system.

The GABA rho1 subunit interacts with a cellular retinoic acid binding protein in mammalian retina

Interactions between the intracellular domain of ligand-gated membrane receptors and cytoplasmic proteins play important roles in their assembly, clustering, and function. In addition, protein-protein interactions may provide an alternative mechanism by which neurotransmitters activate intracellular pathways. In this study, we report a novel interaction between the GABA rho1 subunit and cellular retinoic acid binding protein in mammalian retina that could serve as a link between the GABA signaling pathway and the control of gene expression in neurons. The interaction between the intracellular loop of the human GABA rho subunit and cellular retinoic acid binding protein was identified using a CytoTrap XR yeast two-hybrid system, and was further confirmed by co-precipitation of the human GABA rho subunit and cellular retinoic acid binding protein from baboon retinal samples. The cellular retinoic acid binding protein binding domain on the human rho1 subunit was located to the C-terminal region of human GABA rho subunit, and the interaction of the human GABA rho subunit with cellular retinoic acid binding protein could be antagonized by a peptide derived from within the binding domain of the rho1 subunit. Since cellular retinoic acid binding protein is a carrier protein for retinoic acid, we investigated the effect of GABA on retinoic acid activity in neuroblastoma cells containing endogenously expressed cellular retinoic acid binding protein. In the absence of the rho1 receptor, these cells showed enhanced neurite outgrowth when exposed to retinoic acid and GABA had no effect on their response to retinoic acid. In contrast, cells stably transfected with the human rho1 subunit showed a significantly reduced sensitivity to retinoic acid when exposed to GABA. These results suggest that the GABA receptor subunit effectively altered gene expression through its interaction with the cellular retinoic acid binding protein pathway.

Remote Screening for Optic Nerve Cupping Using Smartphone-based Nonmydriatic Fundus Photography

PRECIS

Evaluation of nonmydriatic fundus photographs captured with a low-cost, smartphone-based camera facilitated remote screening of patients for enlarged optic nerve cup-to-disc ratio in the Independent Nation of Samoa, an underserved setting with one full-time ophthalmologist in the entire country.

PURPOSE

To investigate factors that impact inter-rater agreement of glaucoma suspect optic disc status using a low-cost, handheld nonmydriatic fundus camera.

METHODS

Color fundus photographs were obtained using the PanOptic iExaminer attached to an iPhone 6S by a lay examiner on 206 participants in the Independent Nation of Samoa. Images were remotely graded by an ophthalmologist and optometrist, and images from participants identified as at-risk for glaucoma were escalated to a glaucoma subspecialist for review. Fundus photo brightness, contrast, and focus were measured using the cup, rim, and temporal regions of the disc. Stereoscopic image pairs were subsequently generated from a subset of individual nonmydriatic photographs.

RESULTS

Features suggestive of glaucoma based on optic disc cupping were identified in 16.0% (33/206) of participants. There was moderately strong agreement between graders (90.3%) with κ=0.53 [95% confidence interval (CI)=0.33-0.73]. The intraclass correlation coefficients for the cup-to-disc ratio (CDR) and its difference were 0.84 (95% CI=0.81-0.87) and 0.68 (95% CI=0.59-0.75). Of the 33 participants identified, 94% had clinical risk criteria for potential glaucoma when reviewed by a subspecialist. Color fundus photograph cup brightness was significantly associated with cup-to-disc (CDR) grade, R2=0.36 (P<0.001), in which a brighter disc yielded a higher CDR.

CONCLUSIONS

Smartphone-based screening is a simple, low-cost method capable of measuring the CDR of the optic nerve. When combined with testing for other glaucoma risk factors such as intraocular pressure, this method of measuring CDR may help identify those patients who should be referred for further ophthalmologic assessment. We are currently conducting studies to assess the sensitivity and specificity of smart phone-based remote screening.

Utilization of Remote Diabetic Retinal Screening in a Suburban Healthcare System

PURPOSE

We conducted a cross-sectional study to assess the utilization of a tele-ophthalmology screening program in a low-risk, suburban population of patients with diabetes.

METHODS

A total of 214 diabetic patients without previously documented diabetic retinopathy (DR) underwent point-of-care non-mydriatic fundus photography through their primary care providers at five Beth Israel Lahey Health locations. The characteristics of the patients who received remote screening were compared with those patients who were eligible for screening but did not take part in the program. Time-driven activity-based costing (TDABC) was implemented to examine the cost of screening by tele-ophthalmology compared with in-person examinations.

RESULTS

Tele-ophthalmology screening was more likely to be provided for patients who were younger (OR 0.985; 95% CI 0.973-0.997, p=0.016), who were obese (OR 2.04; 95% CI: 1.47-2.84, p=0.008), who had an HbA1c above 8.0% (OR 1.60; 95% CI: 1.13-2.26, p=0.031), or who had an eye examination in the past year (OR 5.55; 95% CI: 3.89-7.92, p<0.001). Those patients newly diagnosed with DR because of the program were more likely to have diabetic nephropathy (OR 7.79; 95% CI: 1.73-35.05, p=0.007). TDABC identified a health system cost-savings of between $8 and $29 per patient screened by tele-ophthalmology compared with the cost of in-person eye examinations.

CONCLUSION

Tele-ophthalmology presents an opportunity to reduce the costs of screening patients without prior evidence of DR, especially those who have completed a comprehensive eye examination within the prior year.

An initiative to improve follow-up of patients with diabetic retinopathy

BACKGROUND

This study describes the implementation of an electronic medical record (EMR)-based initiative aimed at identifying and reducing the number of patients with diabetic retinopathy (DR) lost to follow-up (LTF).

METHOD

Providers were enlisted to review the EMRs and re-engage patients with DR seen 1 year prior and who had not returned for care within the past 6 months. Binary logistic regression analysis was used to identify demographic, clinical and sociomedical factors associated with being LTF, as well as those predictive of re-engagement.

RESULTS

Out of 673 patients with DR, 78 (12%) were identified as LTF. Patients LTF were more likely to be younger (p = 0.001) and have poorly controlled haemoglobin A1c (HbA1c ≥ 8%, p = 0.04) and cholesterol (LDL ≥ 100 mg/dL, p < 0.001) levels. These patients were also more likely to have completed fewer ophthalmology appointments (p < 0.001), and less likely to have had retinal imaging within the last year (p < 0.001). Charts reviewed 1 month after the EMR-based initiative revealed that 22 patients (28%) had been successfully re-engaged by providers, while 56 patients (72%) remained LTF. History of prior treatment for DR was associated with re-engagement by providers (p = 0.04). One month following the provider-based intervention, the LTF rate dropped to 8.3%, and by 1 year only 3.6% of the patients remained LTF.

CONCLUSIONS

Electronic medical record-based tools can successfully identify DR patients as being LTF, offering an opportunity for providers to re-engage patients in a timely manner. Future studies are needed to determine the long-term impact of patient re-engagement on DR outcomes and efficiency of clinical practice.

Risk factors associated with sickle cell retinopathy: findings from the Cooperative Study of Sickle Cell Disease

BACKGROUND

Sickle cell retinopathy (SCR) is one of the most important ocular manifestations of sickle cell disease (SCD). This study aims to assess the prevalence of SCR in SCD, identify risk factors for its development and progression to proliferative sickle cell retinopathy (PSCR), and evaluate the potential implications of these results on clinical practice.

METHODS

This research is a secondary analysis of patients diagnosed with SCD from the epidemiological, multicenter Cooperative Study of Sickle Cell Disease (CSSCD). We included all patients who completed a full ophthalmic evaluation. We identified clinical and laboratory SCD characteristics associated with SCR using multivariate logistic regression models. Proliferative sickle cell retinopathy (PSCR) was diagnosed according to the Goldberg classification system.

RESULTS

Of the 1904 study participants with SCD who met the inclusion criteria, 953 (50.1%) had retinopathy; of which 642 (67.3%) had bilateral disease. SCR was associated with older age (p < 0.001), history of smoking (p = 0.001), hematuria (p = 0.050), and a lower hemoglobin F (HbF) level (p < 0.001). PSCR risk increased with smoking (p = 0.005), older age (p < 0.001) higher hemoglobin level (p < 0.001) and higher white blood cell count (p = 0.011). Previous blood transfusion (p = 0.050), higher reticulocyte count (p = 0.019) and higher HbF level (p < 0.001) were protective factors against the development of PSCR. Ocular symptoms were associated with progression to PSCR in patients with SCR (p = 0.021).

CONCLUSION

In this cohort of individuals with SCD, half of the participants had signs of SCR. Smoking and blood hemoglobin level were the two modifiable risk factors associated with increased retinopathy progression. Screening to identify the different stages of retinopathy, actively promoting smoking cessation, and optimizing the hematological profile of patients with SCD should guide treatment protocols designed to prevent the vision-threatening complications of the disease.

Complications of subspecialty ophthalmic care: systemic complications from the intravitreal administration of agents that target the vascular endothelial growth factor pathway

The treatment of neovascular age-related macular degeneration (AMD) and other pathologic ocular conditions that overexpress the vascular endothelial growth factor (VEGF) has been revolutionized in the last decade by the introduction of intravitreal agents that target the VEGF pathway. Since treatment trials are designed primarily to assess the prevention of vision loss caused by ocular conditions, they are inadequate for detecting rare, but potentially serious, systemic side effects. The aim of this article is to present what the ophthalmologist needs to know about systemic complications from anti-VEGF therapy and review the likelihood that these side effects occur in the context of small, but often-repeated, intravitreal doses of these potent biological medications. Preferred practice patterns need to be developed that weigh the ability of these medications to mitigate potentially blinding conditions, while at the same time minimizing the risk of adverse outcomes in specific patient populations that possess multiple and often interrelated medical comorbidities.