Dr. Terry E. Burris This is Me

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1. 1. Ophthalmology Times - Micro-thin inserts have few spherical aberrations

   www.ophthalmologytimes.com/oph - [Cached]

   Published on: 1/15/2002   Last Visited: 4/4/2002

   The wavefront patterns for the 0.45-mm micro-thin prescription inserts (left) and for LASIK treatment of -5 D (right) are shown. (Photo courtesy of Terry E. Burris, MD)
   
   Portland, OR-Myopic correction with micro-thin prescription inserts (Intacs, Addition Technology Inc., Fremont, CA) is associated with a more favorable effect on corneal asphericity and is less likely to cause adverse spherical aberrations than LASIK, according to interferometry and wavefront analysis studies conducted by Terry E. Burris, MD, clinical associate professor of ophthalmology, Oregon Health Sciences University, Portland.
   
   He suggested that this might be important in the quest for supranormal vision.
   
   Zernike surface maps plotted using a laser holographic interferometer (KeraMetrics Inc.) showed that eyes treated with the inserts were prolately aspheric, characterized by a steep center and flat periphery. In contrast, LASIK induced oblate asphericity with central flattening and steepening in the periphery.
   
   Calculated Zernike spherical aberration components in eyes treated with the inserts were similar to those found in comparator groups of both normal unoperated eyes and standardized prolate test objects. For the eyes with the inserts, the interferometric asphericity quotient ranged between the value expected for a normal eye, -0.25 Q, and the ideal value of -0.50 that has been suggested as optimal for eliminating spherical aberration in the eye. In the LASIK eyes, the values were opposite in sign to those determined for the prolate test objects and most normal eyes studied preoperatively, said Dr. Burris, who also has a private practice in Portland.
   
   Inserts eyes more natural >
   
   "These investigations show eyes treated with Intacs resemble the normal eye in terms of spherical aberration component, whereas LASIK-treated eyes show a deviation from normal.
   ...
   However, the abnormalities in the periphery indicate a risk for distortions with increasing pupil size," Dr. Burris noted.
   
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