Correlation between ellipsoid zone thickness and the presence of subretinal drusenoid deposits in age-related macular degeneration

PURPOSE

Subretinal drusenoid deposits (SDDs) in age-related macular degeneration (AMD) are associated with systemic vascular diseases that compromise ocular perfusion. We demonstrate that SDDs are associated with decreased ellipsoid zone (EZ) thickness, further evidence of hypoxic damage.

METHODS

Post hoc analysis of a cross-sectional study. 165 AMD subjects (aged 51-100; 61% women). Spectral-domain optical coherence tomography was obtained in both eyes. Masked readers assigned subjects to three groups: drusen only, SDD+drusen (SDD+D) and SDD only. EZ thickness was measured subfoveally and 2000 µm nasally, temporally, superiorly and inferiorly from the fovea. Univariate testing was performed using two-tailed t-tests with Bonferroni correction.

RESULTS

The mean EZ thickness differences between the SDD+D and drusen-only groups were (in μm) 1.10, 0.67, 1.21, 1.10 and 0.50 at the foveal, nasal, temporal, superior and inferior locations, respectively (p=0.08 inferiorly, otherwise p≤0.01); between the SDD-only and drusen-only groups, the differences were 3.48, 2.48, 2.42, 2.08 and 1.42 (p≤0.0002). Differences in EZ thicknesses across all subjects and between groups were not significantly different based on gender, race or age.

CONCLUSION

Subjects with SDDs (±drusen) had thinner EZs than those with drusen only, and the inferior EZ was least affected. EZs were thinnest in SDD-only subjects. This thinning gradation is consistent with progressive destruction of highly oxygen-sensitive mitochondria in the EZ from hypoxia. These findings support the reduced ophthalmic perfusion hypothesis for the formation of SDDs secondary to high-risk systemic vasculopathy.

Internal Carotid Artery Stenosis and Ipsilateral Subretinal Drusenoid Deposits

Purpose

Subretinal drusenoid deposits (SDDs) in age-related macular degeneration (AMD) are strongly associated with vasculopathies such as myocardial infarction and ischemic stroke. This study evaluates ischemic stroke subjects for SDDs to determine whether ocular hypoperfusion from internal carotid artery (ICA) stenosis is associated with ipsilateral SDDs.

Methods

A cross-sectional study at Mount Sinai Hospital recruited 39 subjects with ischemic stroke (aged 52-90; 18 women, 21 men); 28 completed all study procedures. Computed tomography (CT) of the head and neck evaluated 54/56 ICAs for stenosis criteria: none (n = 33), mild (n = 12), moderate (n = 3), severe (n = 3), and complete (n = 3). Spectral-domain optical coherence tomography (SD-OCT) scans were read to consensus by two masked graders for soft drusen, SDDs and choroidal thickness (CTh; choroidal thinning = CTh < 250 µm). Univariate testing was done with Fisher's exact test. Multivariate logistic regression models tested age, gender, and ICA stenosis as covariates.

Results

Moderate or more ICA stenosis (≥50%-69%) was significantly associated with ipsilateral choroidal thinning (P = 0.021) and ipsilateral SDDs (P = 0.005); the latter were present distal to six of nine stenosed ICAs versus five of 33 normal ICAs. Mild ICA stenosis (≥1%-49%) was not significantly associated with ipsilateral SDDs. Multivariate regression found that older age (P = 0.015) and moderate or more ICA stenosis (P = 0.011) remained significant independent risks for ipsilateral SDDs.

Conclusions

At least moderate ICA stenosis (≥50%-69%) is strongly associated with ipsilateral SDDs and choroidal thinning, supporting downstream ophthalmic artery and choroidal hypoperfusion from ICA stenosis as the mechanism for SDD formation. SDDs may thus serve as sensitive biomarkers for ischemic stroke and other vascular diseases.

High Myopia Prevalence across Racial Groups in the United States: A Systematic Scoping Review

High myopia is a significant public health issue globally and in the United States (US), where it affects ~4% of the population or 13 million people. This is a potentially blinding condition, but complications can be prevented with early intervention in childhood. Several countries have developed robust data on high myopia, but the United States' data on high myopia remains lacking. Further, underrepresented populations are at particular risk of complications due to reduced access to optometric and ophthalmic care. We performed a systematic scoping review of population-based studies that investigated the prevalence of high myopia across racial and ethnic groups in the US to identify the impact of high myopia on underrepresented communities. Only four studies were identified that met inclusion criteria, which highlights the need to further investigate the topic in the United States. The prevalence of high myopia ranged from a low of 1.8% among Hispanic populations to a high of 11.8% among Chinese populations. Our study demonstrated a paucity of high myopia data in the United States and variable rates of high myopia depending on the time and location of each study. More complete prevalence data will help identify opportunities for community-based interventions to prevent debilitating and blinding complications of high myopia.

Intra-Arterial Tissue Plasminogen Activator for Central Retinal Artery Occlusion

Purpose

To investigate the benefit of early intra-arterial tissue plasminogen activator (IAT) for treatment of central retinal artery occlusion (CRAO).

Patients and Methods

Fifteen eyes of 15 patients presenting with acute CRAO were included in this retrospective consecutive interventional case series. Patients were excluded if treatment with IAT was not initiated within 12 hours. The diagnosis was confirmed by an ophthalmologist. IAT was performed via a transfemoral arterial approach. Tissue plasminogen activator (tPA) was infused into the ophthalmic artery in aliquots up to 3mg to a maximum of 22mg. Paracentesis was done at the ophthalmologist's discretion. The primary outcome measure was visual acuity after three weeks. Adverse events were recorded during treatment and follow-up visits.

Results

After treatment with IAT, there was a statistically significant improvement in visual acuity, with a mean change of -0.76 (SD 0.91; range -2.4 to 0.85) logMAR (p=0.006). Vision improved by 3 or more lines in 53%, and of these, the mean Snellen visual acuity improvement was >6 lines. Notably, 4 patients (27%) improved from CF or worse to 20/80 or better. The mean dose of tPA used was 17mg and the mean time to treatment was 8.83 hours (range: 5.5 to 12 hours). There were no statistically significant differences based on time to treatment, dose of tPA, or use of a paracentesis. No major adverse events were recorded.

Conclusion

IAT was safe and showed significant visual improvement in this small uncontrolled study. Larger studies and efforts to decrease time to treatment should be initiated to optimize outcomes.

Esophageal metastasis to the iris effectively palliated using stereotactic body radiation therapy and adjuvant intravitreal chemotherapy: case report and literature review

We report a case of isolated iris metastasis from esophageal adenocarcinoma that was successfully managed with local application of stereotactic body radiation therapy (SBRT) and adjunctive intravitreal therapy. A 53-year-old man with locally advanced esophageal adenocarcinoma achieved a complete clinical and radiographic response after surgery and chemotherapy. Four months later, he developed headache and decreased vision and was diagnosed with metastasis to the iris by slit-lamp examination. The decrease in vision was secondary to cystoid macular edema. The metastatic tumor and the patient's symptoms resolved after treatment with SBRT and intravitreal injections of bevacizumab and triamcinolone. We conclude that SBRT combined with intravitreal chemotherapy is an effective and well-tolerated palliative treatment for metastasis of esophageal adenocarcinoma to the iris.

Modes and models of GABA(A) receptor gating

Upon activation by agonist, the type A gamma-aminobutyric acid receptor (GABAR) 'gates', allowing chloride ions to permeate membranes and produce fast inhibition of neurons. There is no consensus kinetic model for the GABAR gating mechanism. We expressed human alpha(1)beta(1)gamma(2S) GABARs in HEK 293 cells and recorded single channel currents in the cell-attached configuration using various GABA concentrations (50-5000 microm). Closed and open events occurred individually and in clusters that had at least three different modes that were distinguishable by open probability (P(O)): High (P(O)= 0.73), Mid (P(O)= 0.50), and Low (P(O)= 0.21). We used a critical time to isolate shorter bursts of openings and to thus eliminate long-lived, desensitized events. Bursts from all three modes contained three closed and three open components. We employed maximum likelihood fitting, autocorrelation analysis and macroscopic current simulation to distinguish kinetic schemes. The 'core' gating scheme for most models contained two closed states that preceded an open state (C(1) C(2) O(1)). The two best-fitting models had a third closed state connected to C(1) and a second open state (O(2)) connected to C(2). The third open state, whose occupancy varied greatly between modes, could be connected either to O(2) or C(2). We estimated rate constants for two identical, independent GABA binding steps by globally fitting data across GABA concentrations ranging from 50 to 1000 microm. For the most highly ranked model the binding rate constants were: k(+)= 3 microm(-1) s(-1) and k(-)= 272 s(-1) (K(D)= 91 microm).