Tech Connection
Super Spectacles
Imagine the possibilities — eyeglasses
that correct higher-order aberrations.
By Louis J. Catania, O.D., F.A.A.O.
IN MY LAST COLUMN,
I discussed the concept of using synthetic materials to overcome some of the limitations
of correcting higher-order aberrations (HOAs) with certain corneal and intraocular
surgical procedures. Perhaps even more exciting is the concept of nonsurgical HOA
correction with synthetic materials like good old spectacles and contact lenses.
The sky's the limit for optometry if such an approach can work.
Physical Limitations
Just as with corneal- and lens-based surgery,
point-to-point Zernike pupil correction is the key. But with spectacles and contact
lenses, the limitations aren't surgical or biological. They are inherent in the
devices themselves.
Spectacle frames are a perfect example
of these physical limitations. HOA- correcting, programmed optics like lens-let
arrays and diffraction gratings can be built into the center of spectacle lenses
very effectively with electromagnetic films, photosynthetic processes and even nanoconstruction.
These methods have been used for years with great results in high-powered telescopic
systems. And when applied to ophthalmic lenses, they are not outrageously expensive.
A spectacle lens system with HOA-correcting
optics in the center offers the potential for a unique combination of corrected
vision: High-resolution vision when looking directly at a target through the center
(the "sweet spot"), and normal lower-order correction with scanning gaze.
This type of correction could be very
useful for certain vocational and avocational needs, as well as for driving, especially
if the "sweet spot" reduces a lot of the annoying effects of fourth-order spherical
aberrations. This would address one of the biggest problems people face with aging:
Reduced mesopic and scotopic contrast sensitivity.
Look Good While Seeing Good
One important aspect of HOA-correcting spectacle
lenses, indeed, their potential for success, is the ability to mount these programmed
optics in stable and, of course, fashionable frames. To paraphrase Billy Crystal,
"It's better to look good than to see good, my darling!"
Clinical trials comparing HOA-correcting
spectacle lenses to standard lenses have shown great success. More than 90% of cohorts
preferred the HOA-correcting lenses. But these trials were conducted in controlled
conditions through phoropter-like instruments or trial frames. The real test and
value of these HOA-correcting spectacles must come from real-world, cosmetically
acceptable frames.
That real-world test is underway with
the first commercially available HOA-correcting spectacle lens (iZon by Ophthonix,
San Diego). After a refraction through a special wavefront aberrometer, the patient
selects from a limited number of frames suitable for mounting the programmed lenses.
The practitioner forwards the prescription to a designated lab for fabrication and
mounting.
It will be interesting to learn how
enthusiastically patients embrace this option, no doubt at premium prices, and even
more interesting to learn their satisfaction with HOA correction. If acceptance
is high, wavefront aberrometry will change the face of spectacle correction.
Next Up, Contact Lenses
And what about that other nonsurgical, synthetic
correction: contact lenses? That has even more interesting potential than spectacles.
Dr.
Catania is with Nicolitz Eye Consultants in Jacksonville, Fla. He does clinical
research; consults for ophthalmic companies and professional journals; and writes
and lectures worldwide. You can reach him at
lcatania@bellsouth.net.
Optometric Management, Issue: March 2006