Of the new technologies presented at the joint meeting of the American Society of Cataract and Refractive Surgery (ASCRS) / University of California, Los Angeles (UCLA) Jules Stein Institute in Century City, the Tetraflex was probably the least likely to be remembered.
Lenstec Tetraflex IOL
This IOL platform, presented by Paul Dougherty, M.D., seemed to have only one benefit over multifocal IOLs: minimal post-operative glare. However, that benefit already exists with the Crystalens IOL.
This talk actually began with a discussion of the near acuity patients really need to read magazines, newspapers, etc. After a not very convincing explanation about why we really don't need to see the equivalent of 20/20 up close, Dr. Dougherty presented results that were objectively worse than what any of the presently available IOLs were capable of delivering.
One caveat: the patients in his study preferred the Tetraflex over the Crystalens even though the vision from the Crystalens eye could see smaller letters on the near eye chart. Now, I'll be the first to admit that our visual requirements in the real world do not directly correlate with what we can see on an eye chart. So, it is possible that the vision patients experience with the Tetraflex is somehow superior to what is measured with the eye chart.
It will be awhile before this IOL is approved for use in the US. Unless studies are able to show a clear benefit of this IOL over the currently available Crystalens, however, I seriously doubt this lens will become a major player in the IOLs offered by most surgeons.
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Dear Dr. Richardson:
ReplyDeletePerhaps you should have paid better attention to my talk at the recent Jules Stein/ASCRS meeting; Tetraflex is poised to become the dominant presbyopic lens, assuming FDA approval.
Unlike the multi-focals, Tetraflex gives high quality vision at all ranges without loss of contrast, night glare, an intermediate blur area or "waxy" vision. LIke many surgeons, I have stopped implanting these lenses for most patients because of the unpredictable subjective outcomes.
The benefits over crystalens are multiple - easier to implant, no need for atropine or a suture, no Z-syndrome, better material (hydrophylic acrylic versus silicone), smaller incision (I need a 3.2 for crystalens, I implant tetraflex through a 2.8, and have seen it implanted through a 2.2 mm incision with the new 1.6 mm cartridge.), larger optic to minimize edge glare (5.75 mm vs. 5.0). Plus, tetraflex works better for near work, both objectively and subjectively, as I discussed in my talk.
As I presented in the talk, my average tetraflex patient achieves 2 diopters of subjective accommodation post-op with monocular implantation, almost twice that which I see with crystalens, even the new HD. While the FDA study data for crystalens HD might have slightly better Best-corrected near vision while attempting to read a static near chart, this does not represent the real world. As we have shown, there is a statistically significant faster reading speed after binocual implantation with the tetraflex than the crystalens at multiple clinically relevant print sizes. The proof is in the pudding - Tetraflex patients have better near vision than crystalens patients both objectively as well as subjectively in my practice.
Paul Dougherty, MD
Dr. Dougherty,
ReplyDeleteWith all due respect, I was paying attention during your talk (the first half of which was spent trying to convince the audience that J5 was an acceptable near vision goal). Although I agree that all current IOLs are a compromise at best, it is difficult for me (as well as others in the audience who discussed your talk at the break) to accept that patients would be happy with J5 when most of us have experienced J3 "unhappy" patients with both the ReZoom and Crystalens IOLs. It is a real stretch for us to see how an IOL that provides only J5 near vision would result in a happy patient.
I readily accept that Snellen distance and near card testing has its limitations and look forward to an IOL platform that is an improvement over our present compromises. That being said, you must admit that the results you presented were less than convincing if one looked only at the best distance corrected near card results.
How then, can you say that the "Tetraflex patients have better near vision than the crystalens patients both objectively and subjectively." The near card (objective)testing did not beat the Crystalens though you did state that your patient "preferred" the Tetraflex over the Crystalens even when the near card testing favored the Crystalens. I agree that this needs to be researched further. However, the better near vision in the Tetraflex was subjective, not objective.
If I have read your slides incorrectly, then perhaps it is you that needs to redo your talk as I am not the only attendee who came away from your talk with this impression.
Sincerely,
David Richardson, MD