piblake wrote:1) The site mentions that Verisyse and Visian have distinct advantages and disadvantages, but I wasn't able to find what they are. I read that Versisyse disrupts the endothelials cells on the back of the cornea--a distinct disadvantage, but that is all I was able to gather. Can you elaborate on the other advantages and disadvantages of both?
The relative advantage or disadvantage depends greatly on the physiology of the individual's eye.
Because the Verisyse is in front of the iris, it is easier to place. Because the area between the front of the iris and the back of the cornea is limited, there may not be enough room for the thickness of the optics. A smaller optic will reduce thickness, but a smaller optic may cause problems if the pupil is large. Vigorous rubbing of the eyes can cause trauma with the Verisyse. The Verisyse is visible to others, but they need to look pretty close. Because the Verisyse is attached to the iris, a specific angle is possible. A toric Verisyse (available outside the US as the Artisan) can correct astigmatism as well as myopia. Because the Verisyse is in front of the iris, it is relatively less difficult to remove.
Because the Visian is behind the iris it is very close to the natural lens. If the natural lens vaults forward and touches the Visian during accommodation (focusing), the trauma can cause a cataract. Placing a lens in this small space takes a lot of surgical skill. If the natural lens receives too much trauma during surgery, a cataract can form. The optic of the Visian has the same limitation as the Verisyse. Higher power is thicker. Smaller optic is thinner. Pupil size becomes involved. Because the Visian is behind the iris, it is relatively more difficult to remove.
With both, if the pupil becomes larger than the optics, glare, halos, starbursts, and poor vision can result.
piblake wrote:2) In your reply you are clear that the loss of endothelials cells is not good at all. If someone had P-IOL surgery with Verisyse, is it possible to determine when the lens should be removed based on the amount of endothelial loss. At what point should it be removed?.
This issue is a part of the FDA labeling and a concern we raised to the FDA. A formula was created to determine current cell count, probable loss at surgery, probable loss over time, and the minimum cell count necessary for eventual cataract surgery. Ongoing cell count can determine when the P-IOL must be removed. Unfortunately doctors can simply ignore this fact. Ask your Verisyse doctor if s/he will do an endothelial cell count every year to verify the health of your cornea and if that service is included in the price of the P-IOL.
piblake wrote:3) For either type of P-IOL surgery, you mention that the depth of the anterior chamber is important. Can you tell me what the minimum depth should be, please?.
The number is a variable depending upon the thickness of the lens to correct the refractive error. For the Verisyse, the distance from iris to back of cornea needs to be accurately measured. For the Visian the distance from the natural lens to the iris needs to be measured. Good technology exists to perform these measurements, but not every surgeon has this technology.
piblake wrote:4) Are the doctors approved by your organization and listed on this site, also approved for Verisyse or Visian?
We do not evaluate a specific procedure. We evaluate all refractive surgery procedures provided within a specific group of consecutive patients. If P-IOLs are in that group they are counted against the national norm, but P-IOLs may not be included. Our evaluation is refractive surgery as a class, not specific procedures.
piblake wrote:The product is so new that I'm not sure how to best evaluate the doctors I do know are doing it in my area (metropolitan Washington DC). Should I rely on how many cataracts surgery they've done since none of the three have completed a lot of P-IOLs?.
A history of successful cataract surgery shows skills within the eye. That is a good indication of ability, but cataract surgery is not the same as implanting a P-IOL. Wait until the doctor has completed enough of the P-IOL you are considering with patients that have your chamber depth, pupil size, and refractive error. In other words, the doctor needs to have enough practical knowledge of exactly what you would be receiving. Similar surgeries are valuable, but are not the same.
piblake wrote:5) Am I more likely to need reading glasses sooner if I, as a 42-year-old, high myopic at -8.00, choose to have one of the laser-type surgeries instead of P-IOL surgery? In other words, do the laser surgeries somehow cause you to lean closer to requiring glasses sooner while the P-IOL does not because the crystalline lens remains undisturbed?.
Refractive correction is almost always the same no matter what the method used. If you are corrected with Lasik. Epi-Lasik, P-IOL, or contact lenses your presbyopia will be essentially the same. The exception would be Refractive Lens Exchange (RLE), which would remove the natural lens and eliminate all natural accommodation, and spectacles, which provide a small mechanical advantage for near vision AND you can take them off to see things near.
piblake wrote:6) All else remaining the same, can I still be a candidate for laser-surgery if I chose to to P-IOL and then for some reason need to have the lenses removed?.
Assuming that the health of the cornea is not changed (which is probable), cornea based surgery would be the same after having P-IOLs implanted and then explanted.
piblake wrote:Thank you again for all your assistance. I've found your site most helpful.
I am glad to be of assistance, but you are the one who has to make the hard decisions.