And Infantile Glaucoma

Daniel T. Weaver
Alex V. Levin


BASICS


DESCRIPTION


• Trabeculodysgenesis with aqueous outflow obstruction resulting in increased intraocular pressure detected at birth or by age 3–4 years


• Differentiated from secondary forms of childhood glaucoma that may be associated with: Persistent fetal vasculature, Peters anomaly, Axenfeld-Rieger spectrum, aniridia, retinopathy of prematurity, Marfan syndrome, and microspherophakia.


• Differentiated from acquired forms of pediatric glaucoma, such as aphakic or pseudophakic glaucoma, infectious, uveitic, or trauma-related glaucoma.


• Unilateral (25%) or bilateral (75%)


EPIDEMIOLOGY


Incidence


• Variable depending on country


• In some Middle Eastern countries: 1 per 4 to 10,000


• In the US, 0.38 per 100,000 (1)[C]


Prevalence


• In the US, 1.46 per 100,000 (1)[C]


RISK FACTORS


• 3:2 Males:Females


• Family history


Genetics


• 10% are autosomal recessive with variable penetrance and expressivity; autosomal dominant forms are less common.


• Four loci have been identified (2)[C]:


– GLC3A (2p21), due to mutations in the cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1) gene


– GLC3B (1p36), gene not yet identified


– GLC3C (14q24.3), gene not yet identified


– GLC3D, due to mutations in the latent transforming growth factor binding protein 2 (LTBP2) gene


– Digenic with mutations in CYP1B1 and FKHL7/FOXC1/forkhead transcription factor


• Mutations in the myocillin (MYOC) gene have been identified in some cases of infantile glaucoma (autosomal dominant)


• Other loci are thought to exist but have not yet been characterized (2)[C]


GENERAL PREVENTION


• No known modes of prevention, other than genetic counseling. Prenatal testing only available if mutation known.


PATHOPHYSIOLOGY


• There are several theories of pathogenesis:


– Barkan’s membrane covering the trabecular meshwork (may not be true)


– Anterior insertion of the ciliary body (due to arrest in the normal migration of the uvea) may contribute to narrowing or collapse of Schlemm’s canal


– Absent Schlemm’s canal


– Anomalous trabecular meshwork development (neural crestopathy)


ETIOLOGY


• May result from genetic or teratogenic interference with neural crest cell formation, migration, and final differentiation during fetal development.


COMMONLY ASSOCIATED CONDITIONS


• Congenital glaucoma may be associated with many systemic syndromes including Sturge-Weber syndrome, Lowe syndrome, congenital rubella, Kniest skeletal dysplasia, Robinow syndrome, and others as well as with chromosomal abnormalities.


DIAGNOSIS


HISTORY


• Classic triad:


– Epiphora


– Photophobia


– Blepharospasm


• Large or asymmetric eyes


• Iris heterochromia may be present


• Cloudy cornea(s)


• Rapid myopic shift


PHYSICAL EXAM


• Exam under anesthesia or sedation may be needed to detect the following signs:


– Long axial length by A-scan


– Large corneal diameter (>12 mm for full term infants)


– Hand held slit-lamp examination may reveal cloudy corneas or Haab’s striae (breaks in Descemet’s membrane, usually horizontal)


– Cycloplegic streak retinoscopy may be useful in detecting progressive myopia or rapid loss of hyperopia


– Tonometry should be obtained at anesthesia induction with the Tonopen or Perkins tonometer. Normal infant IOP is 10–15 mm Hg; IOP in congenital glaucoma typically 25–35 mm Hg


– Gonioscopy may reveal an anterior iris insertion and indistinct trabecular meshwork.


– Ophthalmoscopy will reveal optic nerve cupping, which is usually concentric with healthy surrounding disc tissue until late stages (sloping, notching, and hemorrhage are uncommon). May be reversible.


• In the office, assess the following:


– Visual acuity


– Pupils (assess for afferent pupillary defect)



ALERT


Beware of falsely high (hypercarbia, speculum, pressure from anesthetic mask, 2–5 minutes after intubation, ketamine) or falsely low (corneal epithelial edema, halothane, hypocarbia) IOP

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on And Infantile Glaucoma

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