Primary Congenital Glaucoma: Clinical Presentation and Pathophysiology
Primary congenital glaucoma presents with a classic triad of photophobia, blepharospasm, and epiphora (tearing), caused by corneal edema and enlargement secondary to elevated intraocular pressure in infants and young children. 1, 2
Core Clinical Symptoms and Their Pathophysiologic Basis
Ocular Surface Symptoms (The Classic Triad)
Photophobia (light sensitivity) develops because elevated IOP causes corneal edema, which disrupts the normal corneal architecture and creates light scatter that irritates the eye 1, 2
Blepharospasm (eyelid spasm) occurs as a reflex response to the corneal irritation and photophobia, representing the infant's attempt to protect the painful, light-sensitive eye 3, 2
Epiphora (excessive tearing) results from reflex lacrimation triggered by corneal epithelial edema and the associated ocular surface irritation 1, 2
Corneal Changes
Corneal enlargement (buphthalmos) develops because the infant eye is more distensible than the adult eye; elevated IOP stretches the immature corneal and scleral tissues, leading to progressive enlargement of the corneal diameter beyond normal values 3, 2
Corneal edema and clouding occur when elevated IOP exceeds the endothelial pump capacity, causing stromal and epithelial edema that manifests as a hazy, cloudy cornea 1, 2
Haab's striae (horizontal breaks in Descemet's membrane) form when the elevated IOP causes mechanical rupture of Descemet's membrane, appearing as horizontal or curvilinear lines in the posterior cornea 1, 2
Refractive and Structural Changes
Progressive myopia develops as the eye enlarges axially in response to elevated IOP, with the increased axial length causing a myopic shift in refraction 3, 2
Astigmatism results from irregular corneal stretching and the presence of Haab's striae, which distort the normal corneal curvature 3
Anisometropia occurs when the disease is asymmetric or unilateral, creating significant refractive differences between the two eyes that can lead to amblyopia 3
Optic Nerve Damage
Optic disc cupping and enlargement develop from mechanical compression and ischemic injury to the optic nerve head caused by elevated IOP, with progressive loss of retinal ganglion cells and their axons 3, 4
Progressive visual field loss occurs as retinal ganglion cell death advances, though this is difficult to quantitate in neonates and young children 3
Behavioral Manifestations
- Eye rubbing and irritability represent the infant's behavioral response to ocular discomfort, pain, and visual disturbance caused by the elevated IOP and corneal changes 2
Underlying Pathophysiology
The fundamental defect in primary congenital glaucoma is arrested development of neural crest-derived tissues in the anterior chamber angle during the third trimester, resulting in trabeculodysgenesis—an abnormal trabecular meshwork that obstructs aqueous humor outflow. 3, 2
The severity of clinical presentation correlates with the developmental stage at which arrest occurred; earlier arrest produces more severe obstruction and earlier symptom onset 2
This developmental anomaly is associated with CYP1B1 gene mutations in many populations, particularly those with higher rates of consanguinity, showing variable expressivity 2
The obstructed aqueous outflow leads to elevated IOP, which then drives all the secondary clinical manifestations described above 3, 4
Critical Diagnostic Pitfalls
Not all cases present with the classic triad—some children may have isolated findings such as unilateral corneal enlargement without tearing or photophobia, making diagnosis challenging and potentially delayed. 1
Initial examination under anesthesia may show normal IOP despite true disease, requiring serial examinations to detect progressive corneal enlargement, Haab's striae development, or IOP elevation 1
Corneal diameter measurement and IOP under anesthesia are more reliable monitoring parameters than visual acuity assessment in neonates, though neither should be used in isolation 3
Onset typically occurs between 2 months and 2-3 years of age, with earlier presentation generally indicating worse prognosis 3, 2