Petersburg, FL is one of the exciting new technologies to which European surgeons, unlike most American surgeons, have access to as part of their surgical refractive armamentarium. The lens' optic is 5.
The IOL's two haptics, each with two footplates, sit posteriorly in the peripheral capsular bag. The surgeon performs his standard capsulorhexis and phacoemulsification technique are performed. They should not implant the Tetraflex if an anterior capsular radial tear is created during surgery. The lens is used internationally for both cataract and refractive lensectomy surgery. The Mechanism of Action The mechanism of action of the Tetraflex is multifactorial.
On ultrasound biomicroscopy UBM the lens moves forward during accommodative effort Figures 2 and 3. I think this movement occurs due to the contraction of the ciliary muscle that loosens the zonules as well as increases vitreous pressure.
In addition, the anterior surface of the optic curves more than the posterior surface during anterior vaulting of the lens. This higher radius of curvature of the lens' anterior surface increases the net refractive power of the lens as well as induces coma.
The later is an important part of the normal accommodative process in the prepresbyopic phakic eye. The accommodative effect of the lens may be seen using three-dimensional ray tracing, which shows increased depth of focus and mean and maximum myopia in eyes implanted with the Tetraflex during the accommodative effort D. Sanders, MD, oral communication, December Figure 4. To date, more than lenses have been implanted in this country, with 53 of eyes having 6 months or more of follow-up data on file with Lenstec, Inc.
In terms of evaluating the near performance of any presbyopic lens, distance-corrected near vision is considered the gold standard. Fifty-five percent of eyes demonstrated a monocular distance-corrected near vision of J5 print size of stock quotes or better, and 90 have a distance-corrected near vision of J8 standard newspaper print or better.
European data of near visual function show that the near performance of Tetraflex is even better when the lens is implanted bilaterally versus monocularly data on file with Lenstec, Inc. In terms of accommodative amplitude in the FDA study, of eyes had at least 2.
Currently, none of the patients implanted with the Tetraflex, either domestically or internationally, have experienced any capsular issues. My experience as a principal investigator in the FDA trial of this lens has been excellent. So far, I have implanted 35 of these IOLs. The lens is simple to implant, has none of the visual side effects such as glare, halo, and loss of contrast sensitivity of multifocal lenses, and is consistently giving my patients functional near vision without correction.
Because there is a single point of focus through all distances, the quality of vision through the lens is excellent. I consider this lens equivalent in distance performance to any monofocal lens that I use with the fringe benefit of improved near vision. Like any accommodative lens, however, I do not promise that all patients will throw away their glasses.
Some patients achieve lesser accommodative effect and may require near spectacles part of the time, particularly with low lighting and low-contrast print. I have found that patients with shorter axial lengths tend to have better subjective near vision with the Tetraflex than patients with longer axial lengths. Although I have needed to perform a YAG posterior capsulotomy on only a few eyes after the IOL's implantation, the laser does not seem to negatively affect accommodation, and all lenses have remained in perfect position postoperatively.
Many different lenses are available to treat presbyopia in the US, including both monofocal and multifocal IOLs. European surgeons have access to many exciting ophthalmic technologies not currently available here. One of these, the Tetraflex IOL, shows significant promise in helping the surgeon to deal with the presbyopic patient.
He receives travel support from Lenstec, Inc. Dougherty may be reached at ; info doughertylaservision. Advertisement - Issue Continues Below.