Does a detaching retina cause pressure in the left ear and fullness in the head?

Not really. Detached retina causes vision change or lost with floaters and flashes. It does not cause earache or headache. The patient may get eye strain from vision change.
Typically not! Retinal detachment typically only causes visual symptoms such as floaters, flashes, and black curtains in the vision. If by chance the detachment has caused the pressure in the eye to elevate, it could cause pain and pressure (headache, nausea and vomiting)!