Optic atrophy 1
Overview
Optic atrophy type 1 (OPA1, or Kjer type optic atrophy) is characterized by bilateral and symmetric optic nerve pallor associated with insidious decrease in visual acuity usually between ages four and six years, visual field defects, and color vision defects. Visual impairment is usually moderate (6/10 to 2/10), but ranges from mild or even insignificant to severe (legal blindness with acuity
Symptoms
* Impaired vision * Pale optic disk * Impaired color vision
Causes
Optic atrophy usually results from central nervous system disorders (such as chiasmal tumors, syphilis, ischemic optic neuropathy, drugs, retinal vascular disease, or degenerative disease) or from end-stage glaucoma. Other causes include retinitis pigmentosa; chronic papilledema and papillitis; glaucoma; trauma; central retinal artery or vein occlusion that interrupts the blood supply to the optic nerve, causing degeneration of ganglion cells; ingestion of toxins, such as methanol and quinine; and deficiencies of vitamin B 12, amino acids, and zinc. There are several rare forms of hereditary optic atrophy that can affect children and young adults.
Diagnosis
The diagnosis of OPA1 is based on a combination of clinical findings, electrophysiologic studies, family history, and molecular genetic testing. Visual evoked potentials (VEPs) are typically absent or delayed; pattern electroretinogram (PERG) shows an abnormal N95:P50 ratio. OPA1 is the only gene known to be associated with OPA1. Sequence analysis of all exons of OPA1, available as a clinical test, detects mutations in 70%-90% of familial cases and about 50% of simplex cases. Deletion/duplication analysis is also available clinically.
Treatment
Treatment of manifestations: low-vision aids for decreased visual acuity. Surveillance: annual ophthalmologic and hearing evaluations. Agents/circumstances to avoid: smoking, excessive alcohol intake; avoidance of excessive UV exposure to the eyes is a good practice, though no evidence of its effectiveness exists.