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Case: Streaks radiate from optic nerve head
A 75-year-old white male presented to the VA eye clinic for a periodic follow-up for bilateral dry age-related macular degeneration. He reported that his vision has remained stable since his last visit.
Other than AMD, his ocular history was significant for an epiretinal membrane in both eyes. His medical history was significant for type 2 diabetes mellitus with no complications and coronary artery disease, followed regularly by an endocrinologist and cardiologist, respectively.
Upon examination, his best-corrected visual acuity was 20/30- OD and 20/25- OS. Pupillary function was normal with no relative afferent defect, ocular motility was full in both eyes, and visual fields were full to finger counting in both eyes. Amsler grid testing was notable for central metamorphopsia in the right eye and metamorphopsia superior to fixation in the left eye. Biomicroscopic evaluation of the anterior segment was unremarkable in each eye.
Upon dilated examination in each eye, the vitreous was notable for a posterior vitreous detachment, the vasculature appeared normal, and the macula was significant for drusen and retinal pigment epithelium (RPE) mottling. Careful examination of the patient’s optic nerve heads revealed streaks resembling stretch marks radiating from each optic nerve head. The streaks appeared worse in the left eye with an intraretinal hemorrhage adjacent and temporal to the optic nerve head.
OCT through the optic nerve head in both eyes indicated associated focal disruption in the photoreceptor/RPE complex, with no obvious formation of a choroidal neovascular membrane.
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Our differential diagnosis included choroidal rupture secondary to trauma, choroidal sclerosis, peripapillary neovascularization, lacquer cracks and central serous retinopathy. After careful examination and specialty testing, we diagnosed the patient with angioid streaks of both eyes. We consulted with a staff retina specialist who confirmed our findings and ordered fluorescein angiography (FA). The FA results showed hyperfluorescent lesions radiating from the optic nerve head in the left eye greater than the right eye. There was no obvious choroidal neovascular membrane in either eye.
On funduscopy, angioid streaks appear as greyish-red lines radiating from the optic disc. There may be an associated mottled appearance to the fundus. The streaks are often confined to the peripapillary region but may be seen extending into the posterior pole or even further out into the retinal periphery. Retinal or subretinal hemorrhages may be seen alongside the streaks. Typically, the fovea is uninvolved, and patients remain asymptomatic. In cases where there is foveal involvement, patients may present with complaints of a metamorphopsia, scotoma and/or reduced visual acuity.
Histologically, angioid streaks result from a break in Bruch’s membrane. This membrane, which is the innermost layer of the choroid, is primarily composed of elastin and collagen. It is attached to the RPE and functions to transport nutrients and metabolites between the RPE and the choriocapillaris. Another main function of Bruch’s membrane is separating the choroidal circulation from the retinal circulation. It is believed that a lack of mineralization of the elastic-rich membrane leads to the radial breaks seen in angioid streaks. These breaks can disrupt the barrier between the choriocapillaris and retinal circulation, which may result in the development of choroidal neovascularization emanating through the defects.
Angioid streaks are often seen in patients with pseudoxanthoma elasticum, Ehlers-Danlos syndrome, Paget’s disease, Marfan syndrome, hypercalcemia and various sickle cell hemoglobinopathies. These diseases specifically impact the elastic layer of Bruch’s membrane. Less often, angioid streaks have also been seen in patients with acromegaly, neurofibromatosis, Sturge-Weber syndrome, coronary artery disease, diabetes mellitus, trauma and myopia. It has also been reported that in about half of the patients with angioid streaks, there has been no relation to any systemic disease (Abusamak).
Work-up
The ophthalmic work-up for angioid streaks includes a series of multimodal diagnostic imaging methods, including infrared imaging, autofluorescence, OCT, OCT angiography, FA and indocyanine green angiography (ICGA). Any or all of these tests may be useful for diagnosing, evaluating and managing the patient. Infrared imaging highlights the dark streaks once viewed against a lighter background. Angioid streaks appear hypo-autofluoresced on fundus autofluorescence imaging due to disruptions in or lack of RPE. OCT reveals the localized areas of disruption and loss at the level of Bruch’s membrane and RPE. OCTA, FA and ICGA play a valuable role in identifying and confirming the presence or lack of a choroidal neovascular membrane.
The systemic work-up includes a cocktail of tests depending on which disease is being ruled out. Genetic testing can be obtained in the case of pseudoxanthoma elasticum, Ehlers-Danlos and Paget’s disease, as a genetic pattern has been noted in these diseases. Evaluating levels of serum calcium, phosphorous and alkaline phosphatase is critical for diagnosis of Paget’s disease. Skin biopsies and gastrointestinal evaluation can be helpful in patients with pseudoxanthoma elasticum. Other tests that can be used to evaluate for systemic associations are CBC, blood smear, hemoglobin electrophoresis and many others.
Treatment
Angioid streaks are typically harmless to the eye and require observation only. In the event of choroidal neovascular (CNV) membrane formation, there are several treatment modalities that have been used. Previous therapies included laser photocoagulation, ICG-mediated photothrombosis, transpupillary thermotherapy and photodynamic therapy. These treatments are no longer in widespread use due to adverse side effects and discouraging results. Currently, anti-VEGF injections are the treatment of choice for CNV formation. Studies have shown that these anti-VEGF agents have long-term benefits by stabilizing visual acuity and de-activating the CNV (Georgalas et al.). Based on prior studies, there is no benefit to prophylactically treating angioid streaks that do not possess a neovascular membrane.
This patient’s management
In the case of our patient, the angioid streaks may be related to his type 2 diabetes mellitus and long history of coronary artery disease. Our patient tested negative for the most common systemic disease, including pseudoxanthoma elasticum and Paget’s disease. Although diabetes and coronary artery disease are in the group of systemic diseases less commonly seen in association with angioid streaks, it could not be concluded that our patient’s angioid streaks were idiopathic because of his medical history.
After further ophthalmic testing, the angioid streaks appeared to be confined to the peripapillary region with no evidence of a choroidal neovascular membrane through fundus exam and FA. Because there was no evidence of complications at this time, it was recommended that the patient be monitored closely with no treatment. Continued observation is recommended because 72% to 86% of all patients with angioid streaks go on to develop a neovascular membrane (Abusamak).
- References:
- Abusamak M. Angioid streaks. Medscape. Available at emedicine.medscape.com/article/1190444-overview. Posted October 4, 2017. Accessed May 16, 2019.
- Brayer G., et al. J Am Optom Assoc. 1993;64:250-253.
- Chatziralli I, et al. Retina. 2019;doi:10.1097/IAE.0000000000002327.
- Georgalas I, et al. Ther Clin Risk Manag. 2009;5(1):81-89.
- Wagar M, et al. Postgrad Med J. 2018;doi:10.1136/postgradmedj-2018-136088.
- For more information:
- Joyce Rached, OD, is a New England College of Optometry ocular disease resident at the VA Medical Center, Providence, R.I. She can be reached at: joyce.rached2@va.gov.
- John C. Sellechio, OD, is a staff optometrist at the VA Medical Center in Providence, R.I., in private practice in Warwick, R.I., and a clinical instructor of optometry with the New England College of Optometry. He can be reached at: john.sellechio@va.gov.
- Edited by Leo P. Semes, OD, FAAO, a Primary Care Optometry News Editorial Board Member and Professor Emeritus in the Department of Optometry and Vision Science at the University of Alabama at Birmingham. He can be reached at: leopsemes@gmail.com.
Disclosures: Rached, Sellechio and Semes report no relevant financial disclosures.