I posed a questioni to Mr. Google and here is what he came back with.
Definition:
Depth perception, also known as stereopsis, is the ability to perceive the distance between objects and their relative positions in space.
Causes:

Eye alignment problems:
Strabismus (crossed eyes) or amblyopia (lazy eye) can disrupt the alignment of the eyes, affecting depth perception.

Refractive errors:
Nearsightedness, farsightedness, or astigmatism can cause blurred vision, which can interfere with depth perception.
Brain injuries or neurological disorders:
Conditions such as multiple sclerosis, stroke, or traumatic brain injury can damage the brain's visual processing centers, leading to depth perception problems. (It's interesting that while MS was mentioned, PD wasn't. This response was generated by AI - Aritifical Intelligence --so Mr. Smarty-Pants AI isn't as "all that" as folks had hoped he would be.)
Aging:
As we age, our eyes may become less efficient at processing visual information, which can affect depth perception.
Certain medications:
Some medications, such as corticosteroids or antihistamines, can cause side effects that impair depth perception.

Symptoms:

Difficulty judging distances
Clumsiness or frequent tripping
Problems with hand-eye coordination
Difficulty driving or navigating stairs
Blurred or double vision
Eye strain or fatigue

Diagnosis:

Eye exam:
An eye doctor will perform a comprehensive eye exam to assess eye alignment, refractive errors, and overall eye health.

Depth perception tests:
Specific tests, such as the Wirt stereopsis test or the Random Dot Stereogram, can assess depth perception abilities.

Treatment:
Treatment depends on the underlying cause of depth perception problems. Options may include:

Eyeglasses or contact lenses:
To correct refractive errors and improve eye alignment.

Vision therapy:
Exercises and activities designed to improve eye coordination and depth perception.
Medications:
In some cases, medications may be prescribed to treat underlying conditions affecting depth perception.
Surgery:
In rare cases, surgery may be an option to correct eye alignment problems or remove tumors that are causing depth perception issues.

Prognosis:
The prognosis for depth perception problems depends on the underlying cause and the effectiveness of treatment. In many cases, with proper diagnosis and treatment, depth perception can be significantly improved or restored.