Why do you ask your question AnthonyGA. Do you have knowledge or experience in this area?
I'm not a doctor, but I do know that there are at least a dozen different causes for what you experienced, which (as you note) is called amaurosis fugax ("fleeting darkness"). It surprises me that an ophthalmologist would be able to confidently pronounce that it must have been a TIA, since the cause of this symptom can be difficult to pin down.
The reason why I question it is that a wrong diagnosis could lead to incorrect assumptions about the prognosis or required treatment (if any). Not only that, but declaring that you had a TIA could affect the status of your aviation medical. If it turned out to just be something benign, that would be a shame. It's a bit like doctors who blithely diagnose ADHD, and prescribe medication, not realizing that this diagnosis (which is notoriously difficult to establish unambiguously) could prevent a person from getting a pilot's license, even if he doesn't really have ADHD.
I'd get a second and third opinion, from cardiologists or neurologists or others more likely to be very specialized in the diagnosis and treatment of TIAs. You wouldn't go to a cardiologist to treat glaucoma, so best not to rely solely on an ophthalmologist to diagnose TIA. Especially given the potential health implications and the potential impact on your license. Doctors are only human, and each specialist has his own area of expertise, and may be a bit fuzzy on other areas (nobody's an expert in everything).