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Retinoschisis

ROUTINE — Retina

Symptoms

  • often asymptomatic: frequently an incidental finding during routine exams
  • peripheral field loss: noticed as a "blind spot" rather than a "curtain" (absolute scotoma)
  • decreased vision: occurs if the schisis involves the macula (juvenile form)
  • floaters: rare, unless associated with a vitreous hemorrhage or secondary RD

Clinical Findings

Degenerative (senile) form

  • smooth dome: transparent, immobile elevation usually in the inferotemporal periphery
  • snowflakes: white crystalline spots on the inner wall (Müller cell footplates)
  • sheathed vessels: retinal vessels within the inner wall often appear white or sclerosed
  • absolute scotoma: the area of elevation corresponds to a complete lack of light perception

Juvenile X-linked form

  • spoke-wheel maculopathy: cystic spaces radiating from the fovea in a stellate pattern
  • negative erg: preserved a-wave but markedly reduced b-wave
  • peripheral schisis: present in ~50% of affected males

Schisis vs. retinal detachment (RD)

  • schisis: smooth/tight surface, immobile, absolute scotoma, no "tobacco dust"
  • detachment: corrugated/wrinkled surface, undulates with eye movement, relative scotoma

Etiology

Degenerative

  • idiopathic splitting of the retinal layers (usually at the outer plexiform layer)
  • strongly associated with hyperopia and older age

Juvenile X-linked

  • mutation in the RS1 gene (retinoschisin protein) essential for cell-to-cell adhesion
  • X-linked recessive inheritance (affects males; females are carriers)

Red Flags

  • outer-layer breaks: high risk for progressing to a schisis-associated retinal detachment
  • vitreous hemorrhage: may occur from bridging vessels in the schisis cavity
  • progressive encroachment: if the schisis cavity moves toward the fovea
  • "tobacco dust" (Shafer sign): if present, indicates a full-thickness tear and RD

Investigations

Imaging

  • oct: the "gold standard" to visualize the layer of splitting and distinguish from RD
  • ivfa: shows NO leakage in juvenile foveal schisis (differentiates from true CME)
  • visual field: confirms an absolute scotoma in the area of elevation

Electrophysiology

  • erg: essential for juvenile cases; shows a "negative" waveform

Treatment

Conservative

  • observation: most degenerative cases are stable and never require surgery

Medical (juvenile)

  • topical dorzolamide: may reduce foveal cystic spaces and improve visual acuity

Surgical

  • vitrectomy or scleral buckle: reserved for schisis-associated retinal detachments
  • laser demarcation: occasionally used if schisis is progressively nearing the macula

Clinical Pearl

Retinoschisis has an absolute scotoma, retinal detachment has a relative one — if you cannot tell clinically, B-scan and OCT usually distinguish them, and schisis rarely needs surgery.

Differential Diagnosis

  • • rhegmatogenous retinal detachment (the most critical differentiator)
  • • cystoid macular edema (leakage on FA, unlike juvenile schisis)
  • • choroidal detachment (darker, more solid appearance)

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