I absolutely believe that 5 vaxxed Texan legislators got infected. And I believe that an eye doc spending a half hour in a small room that has poor ventilation with an infected person is at risk even if they are vaccinated. Vaccination lowers your chance of infection but doesn’t eliminate it if you get exposed to a large enough* amount of the virus. His and his patient’s masks may be just enough additional protection to prevent him from getting a large enough dose of virus from the patient.
*large enough differs from one person to the next. If the eye doc is 70 years old, has high blood pressure and is obese large enough is probably a lot smaller than if he’s 35 and healthy/fit.