One of the difficult clinical situations is optic nerve disease collectively calledOptic Neuropathy
Many did not care to differentiate causes of optic neuropathies because there were very few treatment options for optic nerve disease
Nowadays many forms of optic neuropathy are treatable as we will point out which makes the differentiation of optic neuropathies more and more important.
We discussed previously how to spot optic nerve affection in subtle eye disease and in normal fundus with drop of vision,
so first lets summarize again:
1)drop of vision is the hallmark, there are mild neuropathies with 6/6 vision though.
2)color desaturation or loss.
3)RAPD in asymmetrical affection.
6)normal photostress test.
7)other less commonly used tests.
So clinically “a patient with a drop of vision, lost color vision and a RAPD has an optic neuropathy and if the disc looks normal, a retrobulbar neuropathy”
1)if the fundus is NORMAL this is retrobulbar neuropathy and is MS until proved otherwise
Your patient is usually in her (more) or his 20’s or 30’s.
An MRI is mandatory for early diagnosis and treatment of MS by immediate pulse steroids
If the fundus is normal but the loss is bilateral and profound remember to extend the MRI to the cervical region and to ask for anti aquaporin-4 Ab to diagnose NMO-related disease, immediate pulse steroids /immunosuppressors/plasmapharesis.
2)if the disc is SWOLLEN the chances of demyelination decrease and MRI is less urgent.
What should we think about:
-mitochondrial ON (Leber’s)
To arrive at the diagnosis of the cause, the history/clinical exam/patient’s demography are very important
1)Vitreous cells; this wonderful clinical sign immediately pinpoints inflammatory ON as in Behcet’s disease with marvelous response to steroids. ALWAYS look for vitreous cells.
2)History of Alcohol/Drug intake— remember methyl alcohol in males with pale swollen discs and acute loss of vision for immediate dialysis.
3)Systemic diseases that may cause ON infiltration as leukemias, lymphomas and sarcoidosis.
4)Pale swollen discs above 50 yrs are ischemic optic neuropathies; arteritic or non-arteritic.
5)Swollen discs in teen males with no drug history, systemic disease or vitreous cells are Leber’s ON.
6)Neuroretinitis; swollen disc with macular hard exudate–treat with azithromycin if cat scratch disease is suspected.