Optic atrophy
 

The optic disc is pale. Note: if the patient is pseudophakic in one eye and has cataract in the other, the disc in the pseudophakic eye may appear paler in the absence of optic atrophy. The following features may help in the diagnosis.  Excavated appearance with the blood vessels dipping the edge (glaucoma) Indistinct edge with glial tissue (chronic papilloedema) Well-defined edge without excavation (opitc nerve disease) Look for: in young patient, mention you like to examine the eyes for internuclear ophthalmoplegia and cerebellar sign for multiple sclerosis in old patient, look for evidence of vascular diseases such as prominent temporal artery (or old scar indicating temporal artery biopsy) and carotid bruit  (or endarterectomy scar)

Questions:

1. What is Leber's optic optic neuropathy?

Answer
It is a mitochondrial disorder and is therefore a maternally inherited disease. It is characterised by acute or subacute bilateral central visual loss in otherwise healthy male (occasionally female) between the 20s and 40s of age. During the acute phase, there is swelling of the disc with telangiectatic vessels, as the disease progresses the disc becomes pale. The visual acuity is usually in the region of 6/60. There is no effective treatment.
The abnormal gene is in the mitochondrial DNA (mDNA). The point mutation have been located at nucleotide positions 11718, 3460 and 14484. Diagnosis can be made by genetic analysis of leukocyte mDNA.

2. Which types of optic nerve problems are characterized by centrocecal scotoma?

Answer
Toxic optic neuropathy and tobacco-alcohol amblyopia.
Toxic optic neuropathy can be caused by heavy metals such as lead or medications such as ethambutol, isoniazid, chloramphenicol and digitalis.
Tobacco-alcohol amblyopia occurs in patients who smoke and drink excessively. It is thought to be caused by a deficiency of vitamin B especially B12.

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