I just had a eye biopsy done in my eye docs office. He and his staff attempted to numb me with several drops prior to the Novocaine being injected. Unfortunately he wasn't able to get back to me quickly enough and the numbing had mostly worn off. The injection stung pretty bad, but wasn't anything horrible. I did feel at least part of the biopsy its self, and a long strip of my membrane was cut or excised for lab work. Again, not horrible nor unbearable at all. If you are going to the hospital, rest assured they will do everything possible to make you comfortable and likely far more then myself. Only 2 days and my eye is nearly back to normal, with occasional discomfort and sharp stinging up till now. The swelling is almost gone, but there is still a touch of periodic discomfort. Far better then an injection and recovery from a pulled tooth. The worst part isn't the procedure, it's the unknown reason it needs to be done. That is the torture. Waiting on the results now.... Best wishes to anyone having a eye biopsy done.
There are numerous possible causes of yellow subretinal fluid, including unusual parasitic infections and tumor. If the amber circle developed "overnight" this would tend to speak against tumor. However often something has been present for awhile and is suddenly 'noticed' by the patient.
The method, pain, and recovery are totally dependent on how the doctor is going to do the biopsy. Ask him.