The reason why insurance does not cover the cost of retinal imaging is because retinal imaging is not seen as a medically necessary diagnostic test.
Instead because retinal imaging is not medically necessary it's seen as a preventative and optional service so that's why that the cost of retinal imaging is paid for out of pocket and not by insurance.
Vision insurance plans often cover routine exams and dilated exams which are diagnostic and not considered optional but retinal imaging is optional.
Any tests and procedures that are optional and not medically necessary are not covered by insurance and are paid for out of pocket.
Any tests that are required and medically necessary to diagnose a medical condition which are considered medically necessary by a doctor are covered by insurance.
Lack of CPT code is also another reason why insurance does not cover retinal imaging.
Retinal imaging is not universally considered a covered procedure, and so a specific CPT current procedural terminology code has not been established for retinal imaging, which also makes it difficult to bill insurance companies for the procedure even if it were to be covered.
Also dilation of the eyes is a more established method of examining your retina and is often covered by vision insurance as part of comprehensive eye exam.
Dilation of the eye involves the use of eye drops to widen your pupils.