What is the management and treatment approach for Coats disease, including its clinical features and pathology?

Coats Disease: Clinical Features, Pathology, and Management

Clinical Features

Coats disease is a rare, idiopathic retinal vascular disorder characterized by retinal telangiectasia, aneurysmal dilatations, and intraretinal/subretinal exudation, predominantly affecting young males unilaterally in the first two decades of life. 1, 2

Demographics and Presentation

• Male predominance (80%) with unilateral involvement in nearly all cases 3
• Median age at diagnosis: 3.5 years, though adult-onset (≥35 years) occurs in 7% of cases 3, 4
• Younger patients present with more severe disease and poorer visual outcomes 2

Presenting Symptoms (Stage-Dependent)

• Early stages: Asymptomatic or incidentally discovered 1
• Common presentations:
  • Decreased vision (50-83% of cases) 3, 4
  • Leukocoria (23%) 3
  • Strabismus (27%) 3
• Advanced stages: Painful red eye, secondary glaucoma, or ocular atrophy 1

Clinical Examination Findings

• Retinal telangiectasia with aneurysmal dilatations surrounded by avascular areas 5
• Arterial system more severely affected than venous system on fluorescein angiography 5
• Intraretinal and subretinal exudation without vitreal traction 2
• Adult-onset disease shows localized involvement (<6 clock hours in 74%) versus diffuse involvement in children 4

Pathology

Pathophysiologic Mechanisms

• Vascular endothelial growth factor (VEGF) upregulation from ischemic retinal areas drives angiogenesis and blood-retinal barrier breakdown 1
• Multifactorial etiology involving inflammatory, vascular, and potentially genetic components 1
• Reduced capillary blood flow density demonstrated on OCT angiography 1

Histopathologic Features

• Retinal telangiectasia with macroaneurysm-like arterial dilatations 5
• Exudative retinal detachment in advanced cases 3
• Vascular closure and avascular zones in progressive disease 5

Management

Persistent and aggressive long-term treatment is mandatory, as untreated Coats disease has a poor prognosis with progression to enucleation. 5

Stage-Based Treatment Algorithm

Stage 1 (Retinal Telangiectasia Only)

• Laser photocoagulation to telangiectatic vessels 2
• Close observation with fluorescein angiography 5

Stage 2 (Telangiectasia with Extrafoveal Exudation)

• Primary treatment: Laser photocoagulation (27% of cases) targeting abnormal vessels 3
• Cryotherapy (54% of cases) for peripheral lesions 3
• Intravitreal anti-VEGF agents (23%) as adjuvant therapy 3
• Intravitreal steroids (23%) for exudation control 3
• Multiple treatment sessions required (1-9 sessions per patient) 5

Stage 3A (Subtotal Retinal Detachment)

• Combination therapy: Laser/cryotherapy plus anti-VEGF 2
• Aggressive treatment of all telangiectatic vessels 5

Stage 3B (Total Exudative Retinal Detachment)

• Subretinal fluid drainage with anterior chamber maintainer placement before drainage without vitrectomy achieves complete retinal reattachment 3
• Pars plana vitrectomy with transscleral drainage for complex cases 1, 2
• Adjuvant anti-VEGF and laser/cryotherapy post-drainage 3

Stage 4 (Total Detachment with Glaucoma)

• Surgical drainage with glaucoma management 3
• Enucleation reserved for painful blind eyes with uncontrolled glaucoma 5, 3

Stage 5 (Advanced End-Stage)

• Enucleation for painful blind eyes or phthisis 5, 3

Treatment Outcomes

• 73% of eyes show improvement or stabilization with individualized management 3
• 11 of 14 treated eyes maintained or improved vision with long-term follow-up (1-8 years) 5
• Adult-onset disease has more favorable outcomes due to localized involvement 4
• Enucleation rate: 15% in modern series with aggressive treatment 3

Critical Management Principles

• Fluorescein angiography mandatory for treatment planning and identifying all telangiectatic vessels 5
• OCT and OCT angiography for monitoring exudation and capillary perfusion 1
• Close long-term follow-up essential due to chronic relapsing nature 2
• Bilateral disease monitoring in adult-onset cases (though rare) 4

Common Pitfalls to Avoid

• Undertreatment of peripheral telangiectasia leads to progression and exudation 5
• Delayed intervention in young children results in irreversible vision loss 2
• Premature enucleation without attempting drainage procedures in stage 3B disease 3
• Inadequate follow-up missing disease progression or fellow eye involvement 4
• Single treatment session expectations when multiple sessions (up to 9) may be required 5