Buphthalmos is the medical term for the abnormal enlargement of an infant’s or young child’s eyeball, derived from a Greek term meaning “ox eye.” This condition can be present at birth or develop within the first few years of life. It is not a disease in itself, but the most visible sign of a serious underlying issue: primary congenital glaucoma. High pressure inside the eye from this condition causes the pliable eyeball to stretch and enlarge.
Underlying Causes
Buphthalmos is caused by elevated intraocular pressure (IOP) from congenital glaucoma. This high pressure occurs because the eye’s drainage system, the trabecular meshwork, is improperly developed and cannot drain the fluid inside the eye, called aqueous humor. The eye’s ciliary bodies produce this fluid, which normally circulates and drains out. When this outflow is blocked, the fluid accumulates and causes a sharp increase in pressure.
An infant’s eye is still developing, and the sclera—the white, outer layer of the eyeball—is softer and more elastic than an adult’s. This high internal pressure causes the pliable scleral and corneal tissues to stretch and expand. This developmental problem with the eye’s drainage angle is often due to genetic mutations, though in some cases, the cause is unknown.
Recognizable Signs and Symptoms
The most apparent sign of buphthalmos is one or both eyes appearing unusually large or prominent, which is often the first thing parents notice. Beyond the size of the eye, other symptoms are associated with the high intraocular pressure. These signs are direct results of the pressure affecting the eye’s delicate structures.
A cloudy or hazy appearance of the cornea, the clear front part of the eye, is a primary symptom. This cloudiness, called corneal edema, happens because high pressure forces fluid into the cornea. Another sign is excessive tearing (epiphora), where the baby’s eyes water even when not crying. This can occur with blepharospasm, which is an uncontrollable twitching of the eyelids.
Infants with this condition often exhibit sensitivity to light, a symptom called photophobia, causing them to squint or turn away from light. General irritability, fussiness, or poor feeding can also be associated signs. The discomfort from the high pressure in the eyes can make the infant distressed.
Diagnosis and Medical Evaluation
When a pediatrician suspects buphthalmos, they will refer the child to a pediatric ophthalmologist for a specialized evaluation. Because infants cannot cooperate with a standard eye exam, the evaluation is performed while the child is under anesthesia (EUA). This allows the specialist to conduct a thorough and accurate assessment without causing the child distress.
During the EUA, several measurements are performed. A primary step is measuring the intraocular pressure (IOP) using a tonometer. The ophthalmologist will also measure the corneal diameter; a diameter greater than 12 mm in a newborn is a strong indicator of congenital glaucoma.
The specialist will perform a gonioscopy, using a unique lens to examine the eye’s drainage angle for developmental abnormalities in the trabecular meshwork. Finally, the health of the optic nerve is assessed to check for damage, such as cupping. This damage occurs when high pressure harms the nerve fibers responsible for vision.
Treatment Approaches
The goal of treatment is to lower the high intraocular pressure to prevent optic nerve damage and vision loss. For congenital glaucoma causing buphthalmos, surgery is the required treatment. Eye drops may be used as a temporary measure to control pressure and clear the cornea before surgery, but this is not a standalone solution.
The objective of surgery is to create an improved drainage pathway for the aqueous humor, thereby reducing pressure. Two common procedures are goniotomy and trabeculotomy. In a goniotomy, the surgeon makes a small incision in the trabecular meshwork to open the natural drainage channels. A trabeculotomy achieves a similar outcome but is performed from the outside of the eye when a cloudy cornea prevents a clear view for goniotomy.
In more complex or persistent cases, implanting a glaucoma drainage device may be considered. These devices are small tubes that create an artificial channel to drain fluid from the eye. With successful treatment, the pressure is controlled, preventing further damage and offering the best possible visual outcome.