Other entities associated with CNV include pathologic myopia, traumatic choroidal rupture, and presumed ocular histoplasmosis syndrome (POHS). These entities require specific findings and can usually be diagnosed with clinical examination and history. CNV related to myopia is associated with axial myopia, or a longer axial globe. A healthy eye with no refractive error is considered emmetropic, and has an axial length of about 24 mm. Eyes with degenerative myopia that are prone to myopic CNV have a refractive error of more than –6 diopters and an axial length of more than 26 mm. CNV in degenerative myopia originates from cracks in the Bruch membrane, called lacquer cracks, which tend to be small and well-circumscribed.
Choroidal ruptures can also be complicated by CNV. The ruptures are caused by a traumatic break in the Bruch membrane and are crescent-shaped and concentric to the optic disc. In these cases, CNV can occur years after a trauma. POHS can also cause CNV. Although seen around the world, it is endemic in the United States and is found in states that encompass the Ohio and Mississippi river valleys. It is believed to be secondary to a previous infection with the yeast form of Histoplasma capsulatum. The triad of POHS involves the macular lesion with CNV, atrophic chorioretinal scars, and peripapillary atrophy. Eyes with POHS typically have an absence of vitritis, and patients do not become symptomatic until CNV complicates a previously punched out macular scar.,/p>
Angioid streaks are breaks in an abnormally thickened and calcified Bruch membrane. They appear as reddish-brown to gray narrow lines that spread radially from the optic nerve head. They are associated with various systemic disorders, including pseudoxanthoma elasticum, beta thalassemia, sickle cell disease, Ehlers-Danlos syndrome, and Paget disease.
On physical examination, the patient in this case was noted to have enlargement of her skull, which was the reason for her headaches and her inability to wear fitted hats. It also explains her arthritis and hearing loss, which were related to bone growth and pagetic lesions in her legs and skull. After a complete workup and radiologic findings of both lytic and dense bone formation with elevated bone-specific alkaline phosphatase, the diagnosis of Paget disease was confirmed.
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Cite this: Ronald C Gentile, Brooke Nesmith. A 66-Year-Old Woman With Central Vision Loss - Medscape - Nov 02, 2016.