Will not wearing glasses worsen an astigmatism?

I have a slight astigmatism in my right eye. I have glasses that I don't usually use... will not wearing glasses worsen it?

No, it won't make it worse.
Astigmatism is just another defect like being nearsighted. Glasses won't make it any better or worse whether you wear them or not.
If your eyes are going to change, then they will, regardless of the glasses.

Astigmatism can be corrected thru the use of corrective lenses, involving either glasses or contact lenses. Astigmatism can also be corrected with refractive eye surgery.
Corrective lenses are a conservative method of dealing with astigmatism. Glasses and contact lenses are able to counter the effects of the irregularly shaped cornea and provide vision considerable improvement.
Ortho-K is an alternative method that uses special contact lenses that actually reshape the cornea. These special lenses are worn only at night and they gradually reshape the cornea by applying pressure in the right way.
Not wearing contacts or glasses will worsen your case. Before you commit on anything, make sure that you consider all the advantages and disadvantages of having the procedure. Ask the doctor lots of questions so that you can make an informed decision about the right choice for you.

It can yes. But my sister had an astigmatism in one of her eyes but she was like 13 when she was daignosed with it and hardly ever wore her glasses.. and her eyes fixed themselves. So its hard to tell. If your young your eyes can get better.. or worse. You never know