![]() ![]() Approximately 50% of individuals with exudative AMD report experiencing repeated centrally located flashes that last for several seconds to a few minutes. Exudative (i.e., neovascular or wet) AMD, however, is another common cause of photopsias and the second most common cause in one reported case series. Patients will report decreased central vision and metamorphopsia but do not usually have photopsias associated with dry AMD. Non-exudative (i.e., dry) age-related macular degeneration (AMD) causes gradual bilateral central visual loss without related pain. A very uncommon form of migraine is an ophthalmoplegic migraine, which can cause a temporary paralysis of one of the three cranial nerves involved in ocular motion (CN III, CN IV, and CN VI) but is not associated with photopsias. Vision in a retinal migraine promptly returns to normal. In a retinal migraine, a patient experiences decrease in vision or complete blindness in one eye without a scintillating scotoma this is due to vasospasm of the retinal circulation or ophthalmic artery. Typically, auras begin prior to the headache as a central crescent-shaped scintillating scotoma that expands outwards and is surrounded by flashes or zigzags of light. ![]() Auras can manifest as small bright lights, blind spots, static/foggy vision, and/or complex visual disturbances. A migraine aura likely is a result of the initial wave of high neuronal activity related to the previously described spreading depression followed by an inhibition of activity. A leading theory is that migraines are caused by disturbances in cerebral blood flow and a wave of depressed neuronal activity moves slowly across the brain this process usually starts in the occipital lobe and spreads anteriorly. Migraine and auras are not fully understood, and there is much debate around their underlying mechanisms. Visual symptoms can occur with every migraine headache an individual has or may only happen once. Although the visual phenomenon typically occurs bilaterally, the photopsias may appear larger in one eye than the other. A "classic migraine" is described by having this prodrome (i.e., aura) lasting about 15 to 30 minutes and followed by a headache and related symptoms that can persist for hours. Migraine is a recurrent, frequently unilateral, headache syndrome often with a prodrome of bilateral positive visual phenomena. Thus, all patients should have a repeat dilated fundus examination within 4-6 weeks after initial presentation. In patients diagnosed with a PVD without a retinal tear, 3.4% had a retinal tear within six weeks of their initial presentation. If vitreous pigment ( i.e., Shafer's sign) is noted, then the risk of a retinal tear is as high as 88%. Conversely, if the patient reports a subjective decrease in visual acuity or a vitreous hemorrhage is seen, then the risk of a tear increases to 45% and 62%, respectively. found that 14% of patients presenting with floaters and/or flashes and a diagnosis of PVD also have a retinal tear however, if there is no subjective decline in visual acuity, this risk decreases to 8.9%. Differentiating between an acute PVD and retinal tears can be difficult based on history alone. Surgical intervention is required for RRDs, which are associated with persistent and progressive decrease in vision that patients typically described as a curtain or veil in their visual field. Retinal tears due to traction from trauma or PVD are typically horseshoe shaped, and, if large enough, the vitreous enters the subretinal space causing a rhegmatogenous retinal detachment (RRD). ![]() Retinal tears can also cause floaters and flashes of light in the periphery. Photopsias can occur unilaterally or bilaterally, but bilateral flashes typically occur at different times in each eye. The shape of the lightning streak is usually curvilinear due to the edge of the vitreoretinal traction. These flashes typically last less than one second and are described as a lightning streak or a camera flash in the periphery. The tension from the vitreous on the retina causes retinal cells to fire and leads to the perception of flashes of light. Photopsias occur as the vitreous pulls on the retina. On clinical examination, this vitreous separation from the circular optic nerve can be seen as a Weiss ring. Patients also often describe seeing a large opaque floater as the vitreous separates from around the optic nerve head. Floaters (Figure 1) are typically due to cells or debris floating in the vitreous that cast shadows onto the retina. Posterior Vitreous Detachment, Retinal Tears, and/or Retinal DetachmentĪ posterior vitreous detachment (PVD) is a common cause of floaters and photopsias in the general population, accounting for approximately 40% of patients presenting with these symptoms. ![]()
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