Coats' Disease and Retinal Macroaneurysm

• The following are study notes on Coats' Disease and Retinal Arterial Macroaneurysm (RAM).

Coats' Disease

• Characterized by retinal telangiectasia, which involves abnormal vessel growth in the retina.
• Peripheral dilated capillaries and small aneurysms lead to fluid accumulation and exudation in the peripheral retina.
• Exudation can progress to exudative retinal detachment.
• Typically idiopathic with no identified hereditary pattern or racial predilection.
• Unilateral in 95% of cases.
• More common in males (75%) during the first decade of life.
• Patients may experience decreased vision, leukocoria (white pupillary reflex), or strabismus (misaligned eyes).
• Affects primarily the periphery of the retina rather than the macula.

Coats' Disease Treatment

• Stage 1, involving only telangiectasia, is typically managed with observation.
• Stage 2, with telangiectasia and exudation, is treated with laser therapy.
• Stage 3, with retinal detachment, is treated with cryotherapy.
• Over-aggressive treatment may worsen the retinal detachment.
• Repeated treatments are performed at 3-month intervals for subretinal fluid reabsorption.
• Extensive retinal detachment may require a scleral buckle, vitrectomy, or both.

Coats’ Disease Classification Progression

• Stage 1: Telangiectasia only, visual acuity of 20/200 or worse is rare
• Stage 2: Telangiectasia and exudation, visual acuity of 20/200 or worse in 50% of cases
• Stage 3: Retinal detachment, visual acuity of 20/200 or worse in 75% of cases, even with treatment
• Stage 4: Total retinal detachment and secondary glaucoma with poor visual prognosis
• Stage 5: End-stage approaching phthisis bulbi (shrinking of the eye)

Posterior Segment Signs of Coats' Disease

• Telangiectasias are present at the equator and periphery, rarely involving the macula.
• Clusters of microaneurysms appear grape-like, with fusiform dilation of retinal arterioles.
• Vessels exhibit sheathing and venous beading.
• Massive exudates migrate toward the macula.
• Exudative retinal detachment occurs.

Retinal Arterial Macroaneurysm (RAM)

• An acquired focal aneurysmal dilation of a retinal arteriole is usually within the first three orders of the retinal arterial system.
• Uncommon, affecting approximately 1 in 4,500 people.
• Unilateral, with bilaterality in less than 10% of cases.
• Predilection for elderly, hypertensive women (64-74 years old).
• 75% of patients have hypertension.
• Occurs along temporal branches, often at bifurcations or arteriovenous crossings within the first three bifurcations of the central retinal artery.

RAM Etiology

• Thickening of the arteriolar vessel wall, similar to arteriosclerosis, leads to focal ischemia and remodeling of intimal collagen.
• A combination of arteriosclerosis and hypertension causes dilation of the vessel diameter.
• Breaks in the arteriolar wall lead to fusiform dilation and increased risk of exudation and rupture.

RAM Signs

• Blood is present in multiple layers, including subretinal, intraretinal, preretinal, and vitreal layers.
• Often, the macroaneurysm appears as a rounded dilation within an artery.
• Exudation may be present, usually in a circinate pattern around the aneurysm, but can also be in the macular region.

Different RAM Presentations

• Quiescent/Quiet: Hemorrhage or exudation exists, but the macula is spared, and visual acuity is unaffected.
• Exudative
• Hemorrhagic

RAM Symptoms

• Acute or insidious vision loss occurs when hemorrhage or edema involves the macula or when vitreous hemorrhage is present.

FA and ICG for RAM

• FA may show no leakage if "self-sealed" or late leakage.
• ICG is useful if blood obscures the view.

RAM and OCT findings

• The RAM elevates the internal limiting membrane and ganglion cell layers.
• Produces a shadowing effect of deeper retinal layers.
• Sub-ILM hemorrhage found between the ILM and posterior vitreous cortex.

Clinical Course of RAM

• RAMs usually resolve spontaneously without significant sequelae.
• The most common complication is vision loss from hemorrhagic complications or chronic macular edema.
• Eyes with vitreous and pre-retinal hemorrhage tend to recover better visual acuity compared to eyes with macular edema and deeper retinal hemorrhaging.
• Submacular hemorrhage yields the poorest visual outcome due to damage to the photoreceptors.

Clinical Course and Sequelae of RAM

• Macular holes
• CNVM (choroidal neovascularization)
• Serous or hemorrhagic retinal detachments
• Retinal vein occlusion

RAM Differentials

• Coats’ disease (young patients)
• Valsalva retinopathy
• Posterior vitreous detachment with secondary preretinal hemorrhage
• Proliferative diabetic retinopathy
• Exudative ARMD (age-related macular degeneration)
• Leber's miliary aneurysms (younger, milder form of Coats')
• Angiomatosis retinae (younger, peripherally located)

RAM Treatment

• Asymptomatic cases can be monitored for spontaneous involution at 1-month intervals initially, then at 3-month intervals.
• If pre-retinal, intra-retinal, and vitreous hemorrhage, spontaneous resolution can occur but should still be closely monitored within the first 3 months.
• Macular involvement treatment includes argon laser, anti-VEGF, or pars plana vitrectomy for significant vitreous hemorrhage.
• Anti-VEGF reduces vascular permeability via vasoconstriction, balancing coagulation and fibrinolysis to promote faster hemorrhage clearance and reduce surrounding edema.