I doubt it is the medication. Medication side effects generally affect both eyes, although sometimes unevenly. This problem is only in one eye. I'm guessing you are in the UK or Canada. I would suggest paying out of pocket to see an ophthalmologist sooner.
Thank you, Dr. Brown. About 3 years before the blurred vision started and before I started taking BP meds.,I noticed that my left eye bulges slightly. At that time an ophthalmologist measured my eyes and said the left eye appears to be bulging, but the measurements are perfectly fine. I have already started to make arrangements to see an ophthalmologist sooner.