In a medical malpractice case, the plaintiff always has the burden of showing, more likely than not, that the doctor breached the applicable standard of care and that but for the breach of the standard of care, the damages would not have occurred, or would have been much less severe. In all but the plainest of cases (clamp left inside patient; doctor amputated wrong leg), expert testimony is necessary to establish the standard of care, the breach of the standard of care, and the causal connection between the breach and the damages.
In the circumstance you describe, an opthalmologist would need to offer testimony, to a reasonable degree of medical certainty, that the examination performed by the opthalmologist you saw was inadequate given your symptoms, and that had an adequate examination been done, the retinal detachment you suffered would have been prevented or would have had less severe consequences than what actually happened to you.
A doctor who negligently fails to diagnose a condition--a doctor who commits undisputed malpractice--is not liable if there is no causal connection between the failure to diagnose and the damages suffered. I have no idea if a retinal detachment can be prevented, or significantly ameliorated, if it's diagnosed right at the very beginning of the sufferer's symptoms. But an opthalmologist will definitely know the answer to that question. You might consider posting such a question over on the medical section of Avvo.
Not legal advice as I don't practice law in Georgia. It's just my two cents on the facts you describe in light of general principles of law. If you need legal advice, please consult a lawyer who holds Georgia licensure. That's not me.
If you were not happy with the quality of care you received from the first doctor, I assume you went to a different doctor for the ultimate diagnosis of "detached retina." if that is so, did the second doctor tell you this is a problem the first doctor should have diagnosed? If you have not seen a different doctor for an answer to that question, you need to see one who will be honest with you about that answer.
I'm not a Georgia attorney so you will need local counsel to fully assess this. However, I know the medicine pretty well. Once a retina begins to detach, the patient has 24 to 48 hours to get it surgically corrected before the de-vascularized retinal flap begins to die. This means that a retinal reattachment procedure must happen fast to avoid significant vision loss. A plaintiff must prove not only that a doctor did something wrong but also that the injury could have been avoided.
In your case, you would need to have gotten to your ophthalmologist within 24 hours or so of the first onset of your floaters...or you would not likely have been able to get into a surgery fast enough to have fixed it. Your statement of facts does not clarify this timeline. You might want to get a good timeline together and then visit a local medical malpractice attorney. Good luck.