“Are eye exercises that effective?”

Eye exercises are generally not effective in improving poor eyesight. There are numerous causes for poor eyesight, most commonly due to refractive errors. Eyeglasses, contacts and sometimes laser vision corrections are all widely accepted and proven treatments nearsightedness, farsightedness and astigmatism. Presbyopia is due to changes in the flexibility of the lens of the eye and to some extent the strength of the muscles that control the lens. It occurs as we age with onset between 40-50 years of age. Some patients are able to "train" their eyes to focus close up for short periods of time, but this effect is short lived in greater than 90% of the population. This is why most people over the age of 50 require glasses to read.

The eye is not a muscle. There are no exercises for sensory organs. I will assume your doctor was an optometrist and not an ophthalmologist (as I am). I hope you have not signed up for an exercise routine

Eye exercises may help to relax the eye muscles to l reduce the stress of near vision in myopia. This is a factor in induction of myopia in children.
Convergence eye exercises are recommended in convergence insufficiency or mild divergent squinting.