Pediatric glaucoma is classified into primary and secondary pediatric glaucoma. Primary pediatric glaucoma is further categorized into primary congenital glaucoma and juvenile open-angle glaucoma. Secondary pediatric glaucoma includes postoperative secondary glaucoma (following cataract surgery), glaucoma associated with non-acquired systemic diseases or syndromes, glaucoma associated with non-acquired ocular anomalies, and glaucoma associated with acquired diseases.
Primary Congenital Glaucoma
Primary congenital glaucoma (PCG) presents in newborns or infants, with an incidence of approximately 1 in 30,000. About 80% of cases are diagnosed within the first year of life. Approximately 65% of patients are male, and bilateral involvement occurs in around 70% of cases.
Etiology
Primary congenital glaucoma results from isolated developmental abnormalities of the anterior chamber angle (with or without iris abnormalities), leading to obstruction of aqueous outflow and elevated intraocular pressure (IOP). The precise cause remains unclear. Histopathologically, there is anterior displacement of the iris root, excessive iris processes covering the trabecular meshwork, and dense uveal trabecular tissue with poor permeability, resembling an incomplete differentiation of the anterior chamber angle during late embryogenesis. In advanced cases, schlemn canal closure may also be observed, but it is likely a consequence of prolonged elevated IOP rather than the primary cause.
Clinical Features
Photophobia, Tearing, and Blepharospasm
These are the three hallmark symptoms. Newborns or infants presenting with these symptoms require further evaluation.
Corneal Changes
These may include corneal enlargement. In newborns, a corneal diameter greater than or equal to 11 mm, corneal diameters exceeding 12 mm in infants under 1 year, or corneal diameters over 13 mm at any age are suggestive. Elevated IOP can lead to corneal epithelial edema, causing a cloudy "ground-glass" appearance. In some cases, Descemet's membrane ruptures (known as Haab striae), manifesting as horizontal or concentric linear opacities. Persistent elevated IOP over time can lead to varying degrees of corneal opacification.
Elevated IOP, Angle Abnormalities, Glaucomatous Optic Disc Cupping, and Axial Length Elongation
These findings are crucial for diagnosis. For patients with unilateral glaucoma, notable asymmetry in eye size may be evident.
Deep anterior chambers are typically characteristic of primary congenital glaucoma. Gonioscopy may reveal anterior insertion of the iris, obliteration of the scleral spur, masking of the peripheral iris pigment epithelium over the angle structures, or thickened and dense uveal trabecular meshwork.
Optic disc cupping develops rapidly and progressively in infants and may expand vertically or concentrically. Reversal of optic disc cupping is possible once IOP is normalized.
For infants younger than 6 months, IOP measurement can be performed during breastfeeding or postfeeding sleep. Under general anesthesia, drug-induced IOP changes should be considered when interpreting results. Most general anesthetics and sedatives lower IOP, except for ketamine.
Ultrasound and Axial Length Measurements
Ultrasound imaging and axial length monitoring can provide additional evidence regarding glaucoma progression.
Differential Diagnosis
PCG should be differentiated from a variety of conditions, including:
- Nasolacrimal duct obstruction, entropion with trichiasis, keratitis, or congenital megalocornea, which may present with similar tearing or corneal changes.
- Corneal rupture of Descemet's membrane due to birth trauma, which is commonly associated with the use of forceps during delivery. In birth trauma, corneal striae are typically vertical or oblique, without corneal enlargement or optic nerve changes.
- Congenital corneal opacity caused by other factors, such as metabolic or congenital dystrophic disorders.
Treatment
Early surgical intervention is the standard following diagnosis. Long-term medical therapy has limited value due to potential drug toxicity but may be used temporarily for IOP reduction prior to surgery or as postoperative adjunctive treatment.
The preferred surgical options are goniotomy or trabeculotomy to control IOP. Initial surgery success rates are high, especially in patients aged 1–24 months, with better outcomes in the 1–12 month age group. Repeated surgeries are possible if necessary.
For patients with corneal opacities, an external 360° trabeculotomy can be performed, while those with clear corneas can undergo an internal 360° trabeculotomy.
If IOP remains uncontrolled following goniotomy or trabeculotomy, trabeculectomy or other filtration surgeries may be considered. However, postoperative complications, such as subconjunctival scarring due to the active wound healing response in children, remain a significant challenge. Surgical implant of drainage devices is another option for refractory cases.
Additional attention should be given to managing complications caused by the condition itself:
- Amblyopia prevention: Corneal opacities can result in amblyopia, necessitating corrective interventions.
- Myopia management: Axial elongation from enlarged eyeballs may lead to axial myopia, requiring proper optical correction.
- Astigmatism correction: Descemet’s membrane rupture may result in significant astigmatism, which needs to be addressed post-IOP normalization.
Juvenile Open-Angle Glaucoma
Juvenile open-angle glaucoma (JOAG) is associated with genetic factors, with causative genes in certain autosomal dominant cases mapped to chromosome 1q21-31. Elevated intraocular pressure (IOP) typically begins after the age of 3. By this age, the elasticity of ocular wall tissues has decreased, which means increased IOP generally does not produce symptoms or signs such as photophobia, tearing, or corneal enlargement. Clinically, aside from greater fluctuations in IOP, the features of JOAG are essentially the same as those of primary open-angle glaucoma (POAG). The diagnosis and management of JOAG also align closely with POAG. In cases where IOP cannot be controlled with medications, trabeculotomy or trabeculectomy may be performed.
Glaucoma Associated with Other Congenital Anomalies
This group of glaucomas is characterized by significant developmental abnormalities of the eye and/or other systemic organs and often presents in syndromic forms. Common examples include:
Axenfeld-Rieger Syndrom
Axenfeld-Rieger syndrome encompasses a group of developmental disorders with familial inheritance and autosomal dominant transmission, affecting both eyes and showing no gender predilection. Approximately 50% of affected individuals develop glaucoma, which is more commonly seen during childhood or adolescence.
Axenfeld Anomaly
Slit-lamp examination reveals white-line structures near the corneal limbus (posterior embryotoxon). Gonioscopy or ultrasound biomicroscopy (UBM) shows prominent thickening and anterior displacement of Schwalbe's line.
Rieger Anomaly
Iris abnormalities range from mild stromal thinning to significant atrophy with perforations, accompanied by corectopia (displaced pupil) and ectropion uveae (iris pigment epithelium exposed on the anterior surface of the iris).
Extraocular Abnormalities
These include dental and maxillofacial malformations, such as underdeveloped teeth or hypoplasia of the jaw, a long and pointed face, umbilical skin protrusions, hypospadias, hearing loss, hydrocephalus, congenital heart and kidney anomalies, and congenital hip dislocation.
Peters Anomaly
Peters anomaly is characterized by a congenital central corneal opacity, defects in the posterior stroma and Descemet’s membrane, and may or may not include adhesions between the iris and the peripheral edge of the opacity. Patients commonly have shallow anterior chambers, and 80% of cases involve both eyes. Systemic abnormalities may include craniofacial anomalies, central nervous system disorders, and features of "Peters plus" syndrome.
Treatment
The treatment of this group of glaucomas primarily relies on surgical intervention. However, IOP control is only one aspect of management, as concurrent ocular and systemic congenital abnormalities introduce many challenges and complicating factors. These additional difficulties often lead to poor prognoses.