Treatment of pediatric glaucoma

Traditional teaching dictated that childhood glaucoma was a surgical disease. Advances in the pharmacologic management of glaucoma have changed this dictum to some degree. However, surgery is still the primary form of treatment for many types of glaucoma that occur in children.

Angle surgery remains the first line of therapy in primary infantile glaucoma. Medical therapy is often tried first in cases of juvenile open-angle glaucoma, aphakic glaucoma, and in the treatment of secondary glaucoma. However, the implications of lifelong medical therapy (with attendant side-effects) including cost and compliance are significant and need to be considered carefully in choosing therapeutic options. Many promising drugs are now available and approved for use in children, but the long-term side-effects remain unknown. As the routine use of the miotic drugs (i.e. pilocarpine) has been largely supplanted in the treatment of glaucoma, there remain four classes of drug with which the primary care provider should be familiar in the care and treatment of pediatric patients. All four classes of these drugs are used on both a shortand long-term basis.

Drug treatment

CARBONIC ANHYDRASE INHIBITORS

The oral carbonic anhydrase inhibitor acetazolamide has been used safely and effectively for over 50 years in the treatment of pediatric glaucoma. It acts as a suppressant of aqueous humor production. The pressurelowering achieved can be upwards of 30–40% and can in many cases clear the cornea preoperatively to allow safe angle surgery. Sideeffects include decreased appetite, diarrhea, and metabolic acidosis. The latter can be problematic in infants under 12 months of age. Topical carbonic anhydrase inhibitors are now available. Brinzolamide and dorzolamide are widely used in both adult and pediatric patients. They are utilized mostly in an adjunctive role with other topical medication. All carbonic anhydrase inhibitors should be avoided in patients with sulfa allergy.

BETA BLOCKERS

The topical beta blockers have an important role in the treatment of pediatric glaucoma. The mode of action is suppression of aqueous humor production. As in adults, the side-effects include fatigue, lethargy, bradycardia, apnea, and asthma exacerbation. The initial dose may produce an adequate therapeutic effect in many cases and may obviate further topical or surgical therapy for the patient.

ADRENERGIC AGONISTS

Apraclonidine and brimonidine are both approved for the topical therapy of glaucoma in adult patients. The mechanism of action has a dual effect, producing both suppression of aqueous humor production and an increase in uveoscleral outflow. The use of apraclonidine in adults has been limited by the high incidence of topical allergy, which approached 15% in some studies. It is not used routinely to any degree in the treatment of pediatric glaucoma. Topical brimonidine has produced lethargy and somnolence in toddlers and apnea, bradycardia, and hypotension in infants. The use of brimonidine in the treatment of childhood glaucoma should therefore be restricted to older children. It should not be considered first-line therapy and the very real possibility of life-threatening side-effects should be discussed with the patient’s parents prior to the initiation of treatment in all cases.

PROSTAGLANDIN ANALOGS

The prostaglandin analogs include latanaprost, bimatoprost, and travoprost. This class of drugs works by enhancing uveoscleral outflow and can produce dramatic reductions in IOP, approaching 25–30% in many cases. They are dosed once-daily, thereby improving therapeutic compliance. Systemic side-effects are minimal, but excessive eyelash growth and darkening of the iris are frequently noted. The prostaglandin drugs should be used with caution where intraocular inflammation coexists with glaucoma, due to the risk of increasing the inflammatory response.

Surgical management

Goniotomy was introduced by Barkan in the 1940s and revolutionized the therapy for primary infantile glaucoma, with cure rates today approaching 80% in experienced hands (162–164). A special lens is placed on the cornea which allows visualization of the angle structures. A knife is passed across the anterior

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162 Goniotomy demonstrating incision of Barkan’s membrane in a counter-clockwise direction. Modern technique generally includes the use of a viscoelastic agent such as Healon.

chamber and an incision is made into the abnormal tissue blocking fluid passage out of the eye. A relatively clear cornea is needed to perform a goniotomy.

Trabeculotomy is an alternative form of angle surgery in which the canal of Schlemm is cannulated externally with the trabeculotome (or suture material). This is then utilized to tear

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163 Severely photophobic patient with bilateral corneal opacification.IOP was 35 mmHg right eye and 37 mmHg left eye.Angle surgery was required.