Glaucoma–Congenital

Basics

DESCRIPTION

  • Elevation of intraocular pressure (IOP) and associated damage to the optic nerve
  • Subdivided into primary and secondary glaucomas
  • Primary congenital glaucomas (PCGs) can present at birth or before age 1 month (neonatal), before age 2 years (infantile), or later in life.
  • PCG can occur in isolation or in association with systemic disorders and other anterior segment anomalies.
  • >75% of childhood glaucoma presents in the 1st year of life.

EPIDEMIOLOGY

  • PCG accounts for ~1/2 of all cases of childhood glaucoma.
  • 1:10,000 births in the United States
  • Worldwide, ranges from 1:1,250 in Slovakian Romas to 1:18,500 in Great Britain
  • Consanguinity increases risk.
  • Male > female (3:2)
  • ~80% bilaterally affected

GENETICS

  • Most PCG is sporadic but 10–40% are familial.
  • Autosomal recessive with variable penetrance is most common.
  • PCG is associated with mutations in cytogenic locations 2p22.2 (GLC3A), 1p36.2-p36.1 (GLC3B), 14q24.3 (GLC3C), and 14q24.2-q24.3 (GLC3D).
  • Two identified genes for PCG include CYP1B1 (cytochrome P450 1B1) and LTBP2.
ALERT
PCG is a rare disease. Secondary glaucomas are far more common. All children who presents with glaucoma at birth or in infancy should be referred to a geneticist.

PATHOPHYSIOLOGY

  • PCG is caused by development anomaly of the anterior chamber angle (junction of iris and cornea) resulting in increased outflow resistance through the trabecular meshwork.
  • Secondary glaucoma is mostly due to damage or alteration of the trabecular meshwork.

ETIOLOGY

  • Aqueous humor is produced by the ciliary body at the posterior base of the iris, passes through the pupil and exits through the trabecular meshwork and Schlemm canal, which are located at the junction of the cornea and iris.
  • Outflow blockage of aqueous humor causes pressure to build in eye.
  • The blockage may be microscopic (open-angle glaucoma) or due to obstruction of the outflow by the iris (angle-closure glaucoma).
  • High IOP in young children leads to enlargement of eye and destruction of fibers of the optic nerve.

ASSOCIATED-CONDITIONS

  • Sturge-Weber syndrome
  • Neurofibromatosis type 1
  • Oculocerebrorenal (Lowe) syndrome
  • Marfan syndrome
  • Rubinstein-Taybi syndrome
  • Stickler syndrome
  • Walker-Warburg syndrome
  • Hepatocerebrorenal syndrome (Zellweger)
  • Pierre Robin syndrome
  • Homocystinuria
  • Rubella
  • Trisomy 13
  • Trisomy 21 (Down syndrome)
  • Axenfeld-Rieger syndrome
  • Ocular anomalies
    • Aniridia
    • Peters anomaly
    • Sclerocornea
    • Congenital iris ectropion syndrome
    • Congenital cataract
ALERT
Intraocular neoplasms such as retinoblastoma can cause glaucoma. Other causes of secondary glaucoma include ocular surgery (cataract extraction), trauma, chronic uveitis, steroid response, and retinopathy of prematurity.

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