Eyelid Ptosis Repair and Long-term Contact Lens Usage

Any choice in therapy, treatment, or surgery carries risks.  The wearing of contacts can be affected with upper eyelid surgeries in roughly 3-5% of cases in my experience and should be considered as part of your pre-operative discussions.  The advice of an "expert" and presentation of "horror stories" are tactics used to make a point on emotional levels.  I wholeheartedly agree with Dr. Steinsapir's position on your question.  Do your homework, diligently seek other opinions of respected professionals, and then, make your best decision with this wisdom.  You are correct to ask, and this is a key educational benefit in using RealSelf.com.

I think this rate of complication is unrealistically high.  However, the reality is that as we age, our ability to tolerate contact lens decreases, surgery or not. Eventually there comes a time for many contact lens wears where they simply can't support the contact lens. Healing from eyelid surgery involves swelling and can exacerbate this decreasing capacity to tolerate the contact lens.  Did the surgery cause the breakdown in contact lens wear tolerance or was it the natural decline in the ability of the eye to support the contact lens?  Like many situations, it is a combination of both.  
Regarding your optometrists observations, remember as a national expert, he sees a disproportionate number of contact lens wearers who are in trouble.  This will naturally bias him regrading his recommendations.  On the other hand, perhaps you have had enough problems with contact lens wear that you sought out this person as an individual of last resort.  In which case, it is entirely reasonable for him to be concerned with how you will do with contact lens wear after such a surgery.  The more one presses the matter the more conservative the recommendations get.  If contact lens wear and the continued support by this optometrist is important to you, you should heed the advise.  He is basically telling you that he does not think that you will do well.

Having ptosis repair does not preclude you from wearing contact lenses in the future, but contact lenses are one of the causes of ptosis because the lens can rub under the eyelid.  , You should understand that it is not a totally risk-free proposal.  But, you can still usually wear contact lenses after ptosis surgery.  

There is a change in the shape of your cornea after a blepharoplasty procedure which makes putting in or removing contacts harder but not impossible. This is because of the scar across the cornea from the surgery. Is it very common and I tell all my patients that that will occur. The use of contacts has really decreased due to lasix though. Once the scars start to mature, this "difficulty" goes away. The percentage he is quoting is not realistic in my experience! 

While it is possible that you could have difficulty wearing contact lenses following surgery, the chance of that problem is very rare.  If you go to an experienced eyelid surgeon, the odds of that type of a problem would be less than 1%.
Hope this is helpful.