Symptoms and Signs of Ocular Ischemic Syndrome
Symptoms of OIS typically include gradual vision loss that develops over a period of weeks to months, aching pain localized to the orbital area of the affected eye, and prolonged vision recovery after exposure to bright light. Anterior segment signs include iris neovascularization in two-thirds of eyes and an anterior chamber cellular response in about one-fifth of eyes. Although iris and angle neovascularization are common, only one-half of eyes with this condition show an increase in IOP; the low or normal IOP in the other half is most likely caused by impaired aqueous production.
Ocular ischemic syndrome can cause a retinopathy similar in appearance to a partial occlusion of the central retinal vein; therefore, it was originally called venous stasis retinopathy. Typical retinal findings include narrowed arteries, dilated but not very tortuous veins, hemorrhages, microaneurysms, and neovascularization of the optic nerve head, retina, or both (Fig 6-14). The retinal hemorrhages in carotid occlusive disease are usually deep and round and are more often located in the midperipheral retina. A helpful method for differentiating between the 2 entities is to measure the retinal artery pressure, either by using an ophthalmodynamometer, or by gently pushing on the eye during the examination and observing the central retinal artery. An eye with CRVO will have normal artery pressure, whereas one with carotid occlusive disease will have low artery pressure, and the artery will therefore collapse easily.
Fluorescein angiography reveals delayed choroidal filling in 60% of eyes, prolonged arteriovenous transit time in 95% of eyes, and prominent vascular staining (particularly of the arteries) in 85% of eyes. Electroretinography demonstrates global amplitude reduction in disorders that affect the blood supply to the photoreceptors as well as the inner retina. An electronegative electroretinogram occurs if the blood supply to the inner retina is compromised as in CRVO or central retinal artery occlusion (CRAO), while supply to the photoreceptors is preserved.
Figure 6-14 Ocular ischemic syndrome (OIS). A, Clinical photograph of an eye with OIS displays features of conjunctival injection, cataract, and rubeosis iridis. B, Gonioscopic appearance of neovascularization of the iridocorneal angle due to OIS. C, Fundus photograph of an eye with OIS shows features of venous dilation, midperipheral intraretinal hemorrhages, and attenuated arterioles. D, Fluorescein angiography image taken at 19 seconds (arterial phase) demonstrates a prolonged arm-to-retina circulation time and a patchy choroidal filling pattern.
(Courtesy of Neal H. Atebara, MD.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.