Divakar Gupta

Orbital neoplasms in adults may be categorized on the basis of location and histologic type. Imaging features of these lesions often reflect their tissue composition. Cavernous malformations (also known as cavernous hemangiomas), although not true neoplasms, are the most common benign adult orbital tumor. They typically appear as a well-circumscribed, ovoid intraconal mass on cross-sectional images. Lymphoma, which may be primary or secondary to systemic disease, is the most prevalent orbital neoplasm in older adults (≥60 years of age). Choroidal melanoma is the most common primary adult ocular malignancy. Melanin has intrinsic T1 and T2 shortening effects, classically manifesting with hyperintense signal on T1-weighted magnetic resonance (MR) images and with hypointense signal on T2-weighted images. However, amelanotic or mildly pigmented lesions of melanoma do not demonstrate these characteristic MR imaging features. Breast cancer is the most common malignancy to metastasize to the orbit, followed by prostate cancer, melanoma, and lung cancer. In women with bilateral enophthalmos, metastatic scirrhous breast cancer should be considered in the differential diagnosis. Neoplasms that arise from the optic nerve or its sheath include glioma and meningioma. At imaging, gliomas often cause fusiform expansion of the optic nerve, in which the nerve itself cannot be delineated from the lesion. In contrast, meningiomas classically have a "tram-track" configuration, whereby the contrast-enhancing tumor is seen alongside the optic nerve. Neoplasms that derive from peripheral nerves include schwannoma and neurofibroma, the latter of which is associated with neurofibromatosis type 1. MR imaging is particularly valuable for evaluation of orbital neoplasms, as it provides critical anatomic information about ocular structures involved, perineural spread, and intracranial extension.

PURPOSE: To investigate optic disc perfusion differences in normal, primary open-angle glaucoma (POAG), and normal tension glaucoma (NTG) eyes using optical microangiography (OMAG) based optical coherence tomography (OCT) angiography technique. DESIGN: Cross-sectional, observational study. SUBJECTS: Twenty-eight normal, 30 POAG, and 31 NTG subjects. METHODS: One eye from each subject was scanned with a 68 kHz Cirrus HD-OCT 5,000-based OMAG prototype system centered at the optic nerve head (ONH) (Carl Zeiss Meditec Inc, Dublin, CA). Microvascular images were generated from the OMAG dataset by detecting the differences in OCT signal between consecutive B-scans. The pre-laminar layer (preLC) was isolated by a semi-automatic segmentation program. MAIN OUTCOME MEASURES: Optic disc perfusion, quantified as flux, vessel area density, and normalized flux (flux normalized by the vessel area) within the ONH. RESULTS: Glaucomatous eyes had significantly lower optic disc perfusion in preLC in all three perfusion metrics (p<0.0001) compared to normal eyes. The visual field (VF) mean deviation (MD) and pattern standard deviation (PSD) were similar between the POAG and NTG groups, and no differences in optic disc perfusion were observed between POAG and NTG. Univariate analysis revealed significant correlation between optic disc perfusion and VF MD, VF PSD, and rim area in both POAG and NTG groups (p≤0.0288). However, normalized optic disc perfusion was correlated with some structural measures (retinal nerve fiber layer thickness and ONH cup/disc ratio) only in POAG eyes. CONCLUSIONS: Optic disc perfusion detected with OMAG was significantly reduced in POAG and NTG groups compared to normal controls, but no difference was seen between POAG and NTG groups with similar levels of VF damage. Disc perfusion was significantly correlated with VF MD, VF PSD, and rim area in glaucomatous eyes. Vascular changes at the optic disc as measured using OMAG may provide useful information for diagnosis and monitoring of glaucoma.

Glaucoma is a set of irreversible, progressive optic neuropathies that can lead to severe visual field loss and blindness. The two most common forms of glaucoma, primary open-angle glaucoma and primary angle-closure glaucoma, affect more than 2 million Americans and are increasing in prevalence. Many patients with glaucoma are asymptomatic and do not know they have the disease. Risk factors for primary open-angle glaucoma include older age, black race, Hispanic origin, family history of glaucoma, and diabetes mellitus. Risk factors for primary angle-closure glaucoma include older age, Asian descent, and female sex. Advanced disease at initial presentation and treatment nonadherence put patients with glaucoma at risk of disease progression to blindness. The U.S. Preventive Services Task Force has concluded that the evidence is insufficient to assess the potential benefits and harms of screening for glaucoma in the primary care setting. Regular eye examinations for adults are recommended by the American Academy of Ophthalmology, with the interval depending on patient age and risk factors. Diagnosis of glaucoma requires careful optic nerve evaluation and functional studies assessing a patient's visual field. The goal of treatment with eye drops, laser therapy, or surgery is to slow visual field loss by lowering intraocular pressure. Family physicians can contribute to lowering morbidity from glaucoma through early identification of high-risk patients and by emphasizing treatment adherence in patients with glaucoma.

BACKGROUND: To investigate the differences of perfusion in the optic nerve head (ONH) between normal and glaucomatous eyes using optical microangiography (OMAG) based optical coherence tomography (OCT) angiography technique. METHODS: One eye from each subject was scanned with a 68 kHz Cirrus 5000 HD-OCT-based OMAG prototype system centered at the ONH (Carl Zeiss Meditec Inc, Dublin, CA, USA). Microvascular images were generated from the OMAG dataset by detecting the differences in OCT signal between consecutive B-scans. The pre-laminar layer (preLC) was isolated by a semi-automatic segmentation program. En face OMAG images for preLC were generated using signals with highest blood flow signal intensity. ONH perfusion was quantified as flux, vessel area density, and normalized flux within the ONH. Standard t-tests were performed to analyze the ONH perfusion differences between normal and glaucomatous eyes. Linear regression models were constructed to analyze the correlation between ONH perfusion and other clinical measurements. RESULTS: Twenty normal and 21 glaucoma subjects were enrolled. Glaucomatous eyes had significantly lower ONH perfusion in preLC in all three perfusion metrics compared to normal eyes (P≤0.0003). Significant correlations between ONH perfusion and disease severity as well as structural changes were detected in glaucomatous eyes (P≤0.012). CONCLUSIONS: ONH perfusion detected by OMAG showed significant differences between glaucoma and normal controls and was significantly correlated with disease severity and structural defects in glaucomatous eyes. ONH perfusion measurement using OMAG may provide useful information for detection and monitoring of glaucoma.