Coats Disease: Exudative Retinopathy of Childhood

A Treatable Cause of Childhood Leukocoria

Coats disease (exudative retinitis) is a non-hereditary, idiopathic retinal telangiectasia with massive subretinal exudation → retinal detachment. Almost exclusively males (85–90%), onset 6–8 yrs (range infancy–adolescence). Unilateral (>95%).

Pathophysiology

Primary endothelial dysfunction → telangiectatic, incompetent vessels.
Plasma extravasation → lipid-laden macrophages → yellow subretinal exudates.
Progressive exudation → exudative retinal detachment → neovascular glaucoma (end-stage).

Staging (Modified Shields)

Stage	Findings	Management
1: Telangiectasia only	Retinal telangiectasia, no exudate	Laser photocoagulation to telangiectasia
2A: Exudation extrafoveal	Subretinal exudates away from fovea	Laser ± anti-VEGF
2B: Exudation foveal	Exudates involve fovea	Laser (fovea-sparing) + anti-VEGF
3A: Subtotal RD extrafoveal	RD not involving fovea	Laser + cryotherapy ± anti-VEGF
3B: Subtotal RD foveal	RD involving fovea	Cryotherapy ± scleral buckle ± vitrectomy
4: Total RD	Total retinal detachment	Vitrectomy + silicone oil ± buckle
5: End-stage	Neovascular glaucoma, phthisis	Pain control; enucleation if blind/painful

Diagnosis

Clinical: leukocoria, strabismus, vision loss.
OCT: subretinal fluid, exudates, outer retinal disruption.
FA: "light bulb" telangiectasia, late leakage, no early fluorescence (vs. retinoblastoma).
Ultrasound: high-reflective subretinal exudates (vs. tumor vascularity).
Genetic testing (NDP, CRB1) if atypical.

Treatment Details

Laser photocoagulation (argon/diode): Ablate telangiectasia, induce regression. Multiple sessions. Fovea-sparing patterns (grid, micropulse).
Anti-VEGF (bevacizumab 0.625 mg): Reduces permeability, exudation. Adjunct to laser. Recurrence common.
Cryotherapy: For anterior/peripheral telangiectasia, RD with tears.
Scleral buckle: For tractional components, large tears.
Vitrectomy: Stage 4–5; remove exudate, relieve traction, silicone oil tamponade.

Prognosis

Early stage (1–2): 70–80% maintain 20/40 or better.
Late stage (3–4): Vision often limited by macular exudation/detachment.
Fellow eye: 5–10% develop Coats-like changes — monitor annually.

Key Differentiator: Retinoblastoma

Retinoblastoma: calcifications on B-scan, FA shows feeder vessels, younger (<3 yrs), hereditary risk. Coats: no calcification, lipid exudates, older, male. **When in doubt, treat as retinoblastoma until proven otherwise.**

Bottom Line

Coats disease is a treatable cause of childhood leukocoria and vision loss. Early laser ± anti-VEGF preserves vision. Lifelong monitoring for late complications and fellow eye.