There are a variety of causes for optic neuritis, some of which are primarily neurological - such as MS, optic nerve compression by a tumor etc. But these are unlikely to cause episcleritis as well, unless there was some superimposed infection to the sclera.
Other causes include toxins such as methanol, alcohol, tobacco, certain drugs such as chloroquine (for malaria), amiodarone etc
Also, ischemic causes such as anterior ichemic optic neuropathy, usually related to severe anemia or hypotension. Glaucome is another cause - I do not knwo if your ocular pressure was elevated - if it was, and maybe seconarily to an infectious or autoimmune scleritis, then this can cause optic atrophy.
Infectious causes (think of any exposure in the Carribbean to animals, infected water etc) include syphilis, ameobiasis, toxoplasmosis, toxocara, bartonella and other parasitic infections. Autoimmune causes such as ankylosing spondylitis, inflammatory bowel disease and lupus could be tested for.
Its hard for me to be more specific without knowing more details - your doctors need to evaluate the likeliehood of these possibiliteis and test appropraitely. Many cases of optic neuritis remain undiagnosed. Later, if due to demyelinating disease (such as MS) they become apparant when other episodes of demyelination occur.
IV Steroids for autoimmune/demyelinating optic neuritis are benefical if given within 2-4 weeks of onset. oral steroids alone were not effective in the largest trials of MS related optic neuritis. Local steroids for autoimmune causes may be benefical but are outside my area of expertise - without a clear diagnosis first, a benefit is questionable. Repeated steroids may not damage the optic nerve but could cause other problems such as cataracts. If an infectious process is still a possibility they may not be such as good idea. Most of the infections I listed above are apparent by examination. In a discrete episode of optic neuritis, it resolves or reaches maximum improvement at 4-8 weeks. If episcleritis reappears after successful treatment, the search for an autoimmune or infectious cause may need to be reevaluated.
Good luck