Brief Answer:
Refractive error, cataract are the common causes.

Detailed Answer:
Hello,
Welcome to Health Care Magic

Iam Dr. Dadapeer K, an Ophthalmologist and I answer health problems related to eye.

It seems from the history that you are having blurring of vision.

Blurring of vision is a common condition and many causes are known to cause it.
The common problems are
Refractive error
Cataract
Diabetic retinopathy

The causes depend on whether there is associated pain or not. As you have not mentioned association with pain the above mentioned problems are the most likely ones.

Coming to the second problem of seeing things on top of another is probably because of spreading of things common in refractive error.

Kindly do consult a optometrist or ophthalmologist for further evaluation and treatment accordingly.

Hope I have answered your query.

Thank you

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