Can someone please tell me which aberrometers can measure out to the full diameter of a patient with 8mm pupils?

I'll figure it out myself, then.

http://www.eyeworld.org/sep03/0903p30.html

Nidek OPD-Scan

Limited to a 6-mm sample size

While pupil sizes average 6 mm, about 5% of the population's eyes measure more than 7 mm or 8 mm. But for that 5%, a device that only can measure up to a 6-mm pupil will not pick up aberrations beyond that.



WaveFront Sciences' COAS

Has the ability to obtain wavefront measurements for up to a 9-mm pupil.

[This message was edited by Broken Eyes on September 27, 2003 at 09:56 AM.]

http://www.crstoday.com/02_current/crst0103_13.html

"A Shack-Hartmann aberrometer features a circle of lenslets that must align concentrically with the pupil in order to optimally measure aberrations. Pharmacologic dilation enlarges the pupil beyond the circumference of the array of lenslets, which are 6 or 7 mm in diameter."

http://www.opto.com.br/english/medicaldiv/products/WaveScan.htm


The VISX WaveScan


Hartmann-Shack sensor

Measurement Outgoing wavefront aberrometry

Pupil entry locations analyzed 180 (6 mm pupil)


Terms 1st through 6th order polynomials

Measurement range; Sphere: +6.0 D to -8.0 D (increments of 0.1 D); Cylinder: 0 D to 5.0 D (increments of 0.1 D); Axis: 0º to 180º (increments of 1º)

Measurement data; Lower order terms: Sphere, cylinder, axis; High order aberrations: Spherical aberration, coma, trefoil, etc.

http://www.eyeworld.org/aug01/0801p24.html

Comparing the wavefront aberrometers


by Brad Fundingsland Managing Editor

On April 30, the Refractive Surgery Clinical Committee of the American Society of Cataract and Refractive Surgery hosted a Wavefront Technology symposium. One person’s eyes were measured by several wavefront aberrometers in a comparative analysis of technologies. Video outputs from all these technologies were displayed in real time, so participants could view the process.

Moderator R. Doyle Stulting, MD, professor, Emory University, Atlanta, revealed the refractive information on the 20-year-old candidate, as detailed in Table 1. A manifest refraction was performed on both eyes before the symposium, to be used as a standard for comparison against the various wavefront refractions. Several participants said the right eye was keratoconic, based on the wavefront information, and had a best-corrected visual acuity of 20/30. The left eye had a BCVA of 20/16.


Marguerite B. McDonald, MD, clinical professor of ophthalmology, Tulane University, director of the Southern Vision Institute, New Orleans, chief medical editor for EyeWorld, and George Pettit, MD, PhD, chief scientist at Alcon Summit Autonomous, presented background information on the Alcon Summit Autonomous LADARWave device. The LADARWave uses automatic analysis of multiple measurements to create the wavefront map, which is exported to the CustomCornea system to make the laser ablations.


Pettit said that, due to the large amount of higher-order aberrations present in the right eye, the wavefront refraction numbers might not be that meaningful, as these numbers are pupil-size dependent.


Scott M. MacRae, MD, associate professor, Oregon Health Sciences University, Portland, next described the Bausch & Lomb Zyoptix wavefront system, which uses a Zywave aberrometer for optical customization and the Orbscan IIz for anatomical customization. These data are calculated by Zylink software and an ablation is performed with the Technolas 217.


Arturo S. Chayet, MD, in private practice in Chula Vista, Calif., and Tijuana, Mexico, presented on the Nidek OPD-Scan, ARK-1000 system with dynamic skiascopy. The method involves taking multiple information maps of the eye and making ablation data calculations with Final Fit software.


John F. Doane, MD, on the clinical faculty at the University of Kansas-Kansas City, presented information with the Visx WaveScan, WavePrint, PreVue lens, and variable spot scanning technology with the Visx ActiveTrak laser. The wavefront image is selected for a unique WavePrint image with the WaveScan device. The proprietary algorithm used the data to create a treatment table; the data are then placed into the laser to create the ablation.


Doane said he did not expect the patient’s wavefront refraction to match the subjective manifest refraction. “There are many other features to look at, because we have to compensate the sphere and the cylinder, just to correct the higher-order aberrations. This is one of many tools needed to perform an appropriate exam of refractive disorders. It is important to remember that only 1% of the total ablation is for wavefront correction.”


Doane added that, based on the wavefront data of the left eye, 80% of the visual problem is due to higher-order aberration, while only 20% is due to residual regular sphere and cylinder. In contrast, in the keratoconic right eye, 24% of the visual problem is due to higher-order aberrations, and 76% is due regular sphere and cylinder.


Matthias J. Maus, MD, in private practice in Cologne, Germany, presented information on the WaveLight Allegretto excimer laser and aberrometer.


Detailed visuals of the wavefront images produced from each system are included in Table 2.


Both the Bausch & Lomb and WaveLight systems failed to produce a wavefront image on the keratoconic right eye after multiple data-acquisition attempts. Committee member Richard L. Lindstrom, MD, clinical professor of ophthalmology, University of Minnesota, Minneapolis, said, “One of the things that we hope someday we’ll be able to do with this type of customized ablation is to rescue very irregular corneas. [The right eye] is an irregular cornea with irregular astigmatism, so if we can’t get a reading, we can’t rescue the cornea.”


Overall, the time for acquiring the data on the eye and processing the wavefront image ranged from 15 seconds to more than a minute and a half, as detailed in Table 3.