Vision and Hydrocephalus
Some children and adults with hydrocephalus develop vision (eye) problems. In one small study, 80% of infants with hydrocephalus had problems with their vision (Persson et al., 2017). These problems can range from minor decreases in visual acuity to severe vision loss. Remember – it is critical to report any changes in vision to your doctor as a change may indicate treatment failure. There are other signs that a person could have hydrocephalus, such as headache or hearing a noise in the ears (whooshing). It would be important to mention these to the doctor if they are taking place.
Some vision problems may be “silent” at first, identifiable only through an ophthalmologic (eye) screening examination. It is therefore important for all individuals with hydrocephalus to undergo a baseline ophthalmologic exam.
During an exam, the need for glasses will be determined after the eyes have been dilated, using an objective test called “retinoscopy.” Glasses, if needed, can be prescribed even for very young children
An ophthalmologist typically looks for the following when examining a patient with hydrocephalus:
- Swelling of the optic nerve (papilledema)
- Misalignment of the eyes (strabismus)
- Reduced color vision
- Reduced side vision (visual field loss)
- Abnormal pupil reaction to light
- Less than 20/20 vision (with glasses if needed)
If possible, children should see a pediatric ophthalmologist, a doctor who gives special vision tests to children using videos and automated toys. These games help the child maximize his or her performance during testing.
Visual Symptoms of Hydrocephalus
There are some common visual symptoms that hydrocephalus patients may experience, but these symptoms are not unique to hydrocephalus.
- Grayouts or fuzzouts are when light or color appear to dim. Sometimes there is loss of peripheral (side) vision at the same time. This often occurs prior to fainting or when a person experiences low blood pressure.
- Double vision (diplopia) is the perception of two images of one object. These images can be overlapping, separate, or rotated. The double vision disappears when either eye is covered.
- Reduced vision is the partial loss of vision which can be temporary or permanent
- Misaligned eyes (strabismus) is when the eyes point in different directions
- Unstable, shaking eyes (nystagmus) is when the eyes make repetitive, uncontrolled movements
- Sunsetting eyes is when the eyes are driven down, with whites showing above, and occurs primarily in infants. This is often used as a sign of hydrocephalus (see below: Sunsetting Sign).
Why does Hydrocephalus Affect Vision?
Hydrocephalus can affect vision in two different ways: 1) Damage to Optic Nerve, 2) Damage to Nerves that Control the Eye Muscles.
Damage to Optic Nerve
Visual information is transmitted to the brain by the optic nerve, a bundle of fibers that run from the eye to the brain. If the optic nerve is damaged, the information from the eye cannot reach the brain or may be incomplete. This causes changes in how a person sees.
Hydrocephalus can damage the optic nerve when intracranial pressure (ICP) increases. This is because the meninges, thin tissue layers that surround the brain and spinal cord, also surround the optic nerve. As ICP increases, the brain and meninges feel this pressure as the brain is pressed outward toward the skull. The pressure from the meninges also increases the pressure felt by the optic nerve.
The increase in pressure can directly compress (flatten) the optic nerve. In addition, the pressure on the meninges can decrease the amount of blood flowing to the optic nerve. As the optic nerve is compressed and blood flow decreases, the amount of nutrients (food) and oxygen to the optic nerve decreases. This impairs the normal function of the nerve and causes the optic nerve to swell.
The swelling of the optic nerve is called “papilledema.” Damage to the optic nerve from papilledema can result in reduced vision, reduced color vision, and visual field loss.
Damage to Nerves that Control Eye Muscles
In addition, some nerves travel from the brain to control the eye muscles. Three in particular (the third, fourth, and sixth cranial nerves) control eye position and movement. With hydrocephalus, these nerves can be weakened, producing eye misalignment (strabismus). Adults may experience double vision (diplopia) as a result. Sometimes a head turn develops to avoid the resulting double vision.
In children, strabismus can force the child to assume an uncomfortable head posture, with a tilt or turn, causing pain. A child learning to walk can be hindered by a chin-down posture or large head turn. A lazy eye with poor vision (amblyopia) may occur in children under age eight when one eye is favored because of strabismus. Patching can treat poor vision from amblyopia.
Strabismus in children with hydrocephalus should be carefully tracked by a pediatric ophthalmologist. Sometimes eye muscle surgery can improve eye alignment if the eyes do not straighten after management of the child’s hydrocephalus.
The Sunsetting Sign
The “sunsetting sign,” sometimes observed in infants, is an eye misalignment that should be particularly emphasized. In this kind of misalignment, the eyes turn downward, the white showing above. This pattern occurs in infants before effective hydrocephalus treatment has been started, but a sudden reappearance of sunsetting may indicate that an implanted shunt is not working properly.
The sudden development of a turn to the eye or a new head position, or the appearance or reappearance of sunsetting eyes, should immediately be reported to a child’s physician. These conditions may be signs of a shunt malfunction.
Every individual with hydrocephalus, whether a child or a newly diagnosed adult, should have a baseline ophthalmologic examination. A child’s examination should be performed by a pediatric ophthalmologist, while adults should find a qualified neuro-ophthalmologist. Your physician can help you determine how often follow-up examinations should be performed in your particular case.
Remember: Many eye problems, for both children and adults with hydrocephalus, represent the effects of pressure, both past, and present. The eyes sometimes give us early warning signs of trouble. Changes in vision of any kind are critical to report as they may well be related to shunt failure, also known as shunt malfunction. If you’re in any doubt about visual symptoms you’re experiencing, discuss your concerns with your physician.
This article is designed to provide helpful information on the subjects discussed. It is not intended as a substitute for treatment advice from a medical professional. For diagnosis or treatment of any medical condition, consult your doctor.