VISX CustomVue Optical Zone Inadequate for Most Patients
Considering LASIK? How large are YOUR pupils? Consumers should be aware that VISX wavefront treatments are not approved for an optical zone larger than 6.0 mm - which is SMALLER than the mean pupil size of refractive surgery candidates! See the FDA approval order for this laser on the FDA website:
http://www.fda.gov/cdrh/pdf/P930016s016b.pdf
The optical zone is the 'fully treated zone' that should be as large or ideally LARGER than the pupil as the resulting optical zone (fully treated area) typically ends up being smaller than intended.
'Blend zones' represent undertreated area if they fall within the area of the entrance pupil and may allow unfocused rays of light to enter the eye, resulting in a degraded retinal image. For this reason, patients with a pupil size as large or larger than the optical zone (fully treated area excluding blend) are at risk for a poor LASIK outcome.
Dark-adapted pupil sizes of candidates for refractive surgery are found to range from 4.3 to 8.9 mm with a mean diameter of 6.5 mm.
Source:
Netto MV, Ambrosio R Jr, Wilson SE. Pupil size in refractive surgery candidates. J of Refract Surg. 2004 Jul-Aug;20(4):337-42.
If half of refractive surgery candidates have pupil sizes as large or larger than 6.5mm, then the 6.0 mm optical zone approved for VISX CustomVue treatment is inadequate for more the majority of patients.
This from the FDA wesbsite
http://www.fda.gov/cdrh/pdf/P930016s016b.pdf:
Quote:
SUMMARY OF SAFETY AND EFFECTIVENESS DATA FOR A SUPPLEMENTAL PREMARKET APPROVAL APPLICATION
CustomVueTM ablations are approved for an optical zone of 6.0 mm, and a blend zone of 1.0 mm for a total ablation zone of 8 mm. No treatments with optical zones greater than 6.0 mm were attempted in the U.S. Clinical Trial.
The mean pupil diameter of patients is 6.5mm and the FDA approved upper limit for optical zone diameter wavefront treatment on the VISX laser is only 6.0mm? VISX, THIS IS A SERIOUS PROBLEM AND PATIENTS ARE LOSING VISION AS A RESULT.
Don't allow your surgeon to persuade you to undergo an 'off label' (non-FDA approved) treatment at a larger zone size! Zone size was limited by the FDA for a reason - because wavefront treatments consume more tisssue than standard treatments and thinner corneas may result in ectasia (progressive corneal bulging).
