If you go to an optometrist and happen to have a retinal tear or worse could the!

Generally speaking, Ophthalmologists dilate your eyes with drugs routinely.. that is why you need to organise someone to drive you home (as your vision is blurred and glary for at least 4 hours).
Optometrist do not routinely dilate your eyes (although I do know of a few practices who routinely dilate every 'new' patient).

To answer your question... Optometrists are trained to detect most if not all types of eye disease that are clinical (that is they have detectable signs when assess in a health clinic). They also know general treatment procedures but do not actually 'treat' using surgery or restricted drugs.

As for retinal tears, as they happen in the peripheral or extreme peripheral retina, most are not readily seen in an undilated eye no matter what qualifications you have. You as the patient have to direct your optometrist to look for retinal tears... by letting them know of the symptoms... like Flashes of lights, running water on glass vision, grey/white curtain coming down..etc.. then your optometrist will dilate your eyes and search for these tears.

Once detected, you will be referred to an Ophthalmologist who will LASER sew the tear so that it doesn't progress to a possible retinal detachment.

It is possible to see your retina without dilation. Without dilation, it is harder to see at the edges, and not as much detail can be seen anywhere.

Optometrists are not as good at detecting retinal problems as general ophthalmologists, and general ophthalmologists are not as good as retina specialists, but they are pretty close.

If you have reason to believe that you have a retinal tear, you should see an ophthalmologist.

If he is looking for it he might see it but you would see it first. It would be flashing lights or a curtain coming down. An ophthalmologist would definitely see it. An optometrist fits a person for glasses and does not prescribe or use medications.