Anterior optic neuropathy results in loss of vision due to damage to the optic nerve. The damage to the nerve is caused by impaired blood supply to the nerve. One eye is affected first, followed by loss of vision in the other eye. In most cases, only part of the visual field is affected.
Types of Anterior Ischemic Optic Neuropathy (AION)
There are two types of anterior ischemic optic neuropathy, namely arteritic AION and non-arteritic AION. Arteritic AION is caused by inflammation of big blood vessels while non-arteritic AION (NAION) is caused by crowded optic discs. The latter is comm on in younger age groups and is caused by cardiovascular problems. NAION is a stroke of the optic nerve and is associated with sudden loss of vision related to optic nerve damage.
Patients suffering from diabetes, hypertension and high cholesterol levels are predisposed to NAION. A sudden drop in blood pressure during sleep impairs the flow of blood to the optic nerve and causes the optic stroke. A sudden drop in blood sugar can also cause this neuropathy. In most cases, the loss of vision is not complete but partial.
Symptoms of Infantile Diabetes with Anterior Ischemic Optic Neuropathy :
- Sudden impairment in vision
- Tenderness in the scalp and pain in the temple and neck area
- Loss of appetite and weight
- Pain in the joints and jaw muscles
- Transient loss of vision
- Blurred vision with dark shadow in the visual field
Risks Associated with Anterior Ischemic Optic Neuropathy
Loss of vision or visual acuity is the main risk of this neuropathy. Depending on the amount of damage suffered by the optic nerve and the location of the damage, loss of vision may be profound or slight. In some patients, there is loss of perception of light while in others there may be loss of peripheral vision that can result in tunnel vision. Loss of sensitivity to contrast can result in an inability to judge the depth of objects. Patients find it difficult to walk down stairs and tend to bump into objects while walking. They also find it difficult to drive cars and work. Most develop neuropathy in the other eye within 3 years of damage to the first eye.
Studies have shown that therapy involving large doses of corticosteroids can improve visual acuity in the early stages of NAION. However, this improvement can be observed only within the first 6 months. Medication to lower intra-ocular pressure and to provide protection to the nerve should be administered. Medication to treat hypertension should be administered, but care should be taken to prevent any sudden lowering of blood pressure. A neuro-ophthalmologist should be consulted and treatment should be administered to minimize cardiovascular risk factors and prevent damage to the twin eye. Medications should be administered or discontinued only after prior consultation with the specialist.
Infantile diabetes with anterior ischemic neuropathy should be treated at the earliest, but care should be taken to ensure that the patient doesn't suffer from sudden loss of blood sugar or low blood pressure. Should an infant suffer from vision problems, a neuro-ophthalmologist should be consulted at the earliest to recover lost vision and to prevent damage to the second eye.
Manual of Neuro-Opthalmology, Amar Agarwal, Athiya Agarwal, 2009.