Does the pin-hole normally under estimate the post cataract surgery vision ?

[taurus1203]

I know that a pin hole or PAM test will normally be performed before a cataract surgery to project what will be the vision after the surgery.

What is the behind theory of a pin hole test to simulate the lens without a cataract ?

In general, will a patient (with pre-operation vision around 20/50) have a post-cataract-operation vision better than the pin hole test ? Or hard to say.


Thanks

[Ray T Oyakawa, MD]

A 20/50 cataract would not fall in this category.  Some patients see better than pam and some worse.  It really depends as mentioned on the skill of the examiner and the patient.  Some patients really try hard and others do not.  As with any subjective test results depend on the patient's responses.

Dr. O.

[taurus1203]

Thanks for your explanation.
Assuming there is no irregular astigmatism.
It seems the pinhole doesn't not necessary fully reflect the true potential as there may not much clear area in the cataract or the patient may not align the pin hole to the clearest point of the natural lens.
Base on your experience, does a patient normally have a better or worse than expected vision after the cataract surgery ?

Thanks