Importance of Fundoscopy

A. GENERAL IMPORTANCE IN NEUROLOGICAL DISORDERS

The retina is embryologically an extension of the diencephalon; thus, the fundus is the only location where the Central Nervous System (CNS) and its vasculature can be visualized directly and non-invasively.

1. Assessment of Intracranial Pressure (ICP)

• Papilledema: Blurring of disc margins, hyperemia, and venous engorgement indicate raised ICP.
  • Causes: Hydrocephalus, Brain tumors, Meningitis, Idiopathic Intracranial Hypertension (Pseudotumor Cerebri).
  • Significance: Contraindicates lumbar puncture (risk of herniation).
• Optic Atrophy: Pale, white disc indicating chronic compression or long-standing raised ICP (Post-papilledemic atrophy).

2. Demyelinating and Inflammatory Conditions

• Optic Neuritis (Papillitis): Hyperemic, swollen disc with reduced visual acuity. Seen in Acute Disseminated Encephalomyelitis (ADEM), Multiple Sclerosis (MS), and Neuromyelitis Optica (NMO).

3. Neurocutaneous Syndromes (Phakomatoses)

Fundus findings are often diagnostic:

• Tuberous Sclerosis: Retinal astrocytic hamartomas (Mulberry tumors).
• Neurofibromatosis (NF1): Optic pathway gliomas.
• Von Hippel-Lindau: Retinal hemangioblastomas (angiomas).
• Sturge-Weber Syndrome: Choroidal hemangiomas ("Tomato catsup" fundus).

4. Neuro-Metabolic and Degenerative Disorders

• Cherry Red Spot: Gangliosidoses (Tay-Sachs, GM1), Niemann-Pick disease, Sialidosis.
• Retinitis Pigmentosa: Bone-spicule pigmentation. Seen in Mitochondrial disorders (NARP, Kearns-Sayre), Refsum disease, and Abetalipoproteinemia.
• Optic Atrophy: Metachromatic Leukodystrophy (MLD), Krabbe disease.

5. Infections (Intrauterine and Acquired)

• Chorioretinitis: "Salt and pepper" retinopathy (Rubella), Perivascular scarring (Congenital CMV), Macular scar (Toxoplasmosis).
• Choroidal Tubercles: Pathognomonic for Disseminated (Miliary) Tuberculosis or TB Meningitis.

6. Vascular Pathologies

• Hemorrhages: Subhyaloid hemorrhages (Subarachnoid hemorrhage - Terson Syndrome), Retinal hemorrhages (Non-Accidental Injury/Shaken Baby Syndrome).

B. IMPORTANCE IN SEIZURES

In a child presenting with convulsions, fundoscopy helps identify the Etiology (Structural vs. Metabolic vs. Infectious).

1. To Rule Out Space Occupying Lesions (SOL)

• Presence of Papilledema suggests a tumor (e.g., Medulloblastoma), abscess, or hydrocephalus driving the seizure.
• Action: Urgent Neuro-imaging is mandated; LP is contra-indicated.

2. To Diagnose Phakomatoses (Neurocutaneous Disorders)

• Seizures (especially Infantile Spasms) are the presenting feature of Tuberous Sclerosis. Finding retinal phakomas confirms the diagnosis without needing MRI initially.
• Sturge-Weber syndrome presents with focal seizures; fundus may show choroidal hemangioma.

3. To Identify Metabolic Causes

• In an infant with refractory myoclonic seizures and regression:
  • Cherry Red Spot: Tay-Sachs, Sandhoff disease.
  • Optic Atrophy: Biotinidase deficiency, Menkes disease.

4. To Identify Non-Accidental Injury (NAI)

• In an infant with seizures and encephalopathy without a clear history, bilateral retinal hemorrhages are highly specific for Shaken Baby Syndrome (Abusive Head Trauma).

5. To Identify Infections

• Chorioretinitis indicates TORCH infections (CMV, Toxo) causing calcifications and seizures.
• Choroidal Tubercles indicates TB Meningitis causing vasculitic infarcts/seizures.

C. IMPORTANCE IN PARAPARESIS

In a child with weakness of lower limbs, fundoscopy helps distinguish between pure spinal cord pathology and widespread CNS involvement.

1. To Identify Neurometabolic/Degenerative Disorders

• Optic Atrophy: Seen in Metachromatic Leukodystrophy (MLD) and Krabbe’s disease. Presence suggests the paraparesis is part of a central white matter degeneration.
• Cherry Red Spot: Seen in GM1 Gangliosidosis or Niemann-Pick disease (associated with hypotonic weakness/regression).
• Retinitis Pigmentosa: Associated with Refsum disease (polyneuropathy) or Mitochondrial disorders (NARP).

2. To Identify Demyelinating Disorders

• Optic Neuritis (Papillitis): If a child has paraparesis (Transverse Myelitis) and optic neuritis, the diagnosis is Neuromyelitis Optica (Devic’s Disease) or Multiple Sclerosis (ADEM).

3. To Identify Raised Intracranial Pressure (Papilledema)

• Spinal Cord Tumors: High cervical or thoracic tumors can occasionally cause elevated CSF protein and obstruction, leading to communicating hydrocephalus and papilledema (Froin’s Syndrome variant).
• Disseminated Malignancy: CNS Leukemia or Medulloblastoma with "drop metastasis" to the spine (causing paraparesis) and brain (causing papilledema).

4. To Identify Phakomatoses (Neurocutaneous Syndromes)

• Lisch Nodules / Optic Glioma: Suggests Neurofibromatosis Type 1 (NF1). Paraparesis may be due to a spinal neurofibroma or dystrophic scoliosis.
• Retinal Angioma: Suggests Von Hippel-Lindau (VHL) disease. Paraparesis results from the associated Spinal Hemangioblastoma.

5. To Identify Infections

• Chorioretinitis: Indicates intrauterine infections (CMV, Toxoplasmosis) which cause Cerebral Palsy (Spastic Diplegia).