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| LASIK and pupil size http://lasik-flap.com/forum/viewtopic.php?f=3&t=1057 |
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| Author: | Broken Eyes [ Fri Dec 08, 2006 8:21 pm ] |
| Post subject: | LASIK and pupil size |
What does the FDA, AAO, ASCRS, OMIC and FTC think about the importance of pupil size? From the FDA website, "When is LASIK not for me?" http://www.fda.gov/cdrh/LASIK/when.htm Large pupils. Make sure this evaluation is done in a dark room. Younger patients and patients on certain medications may be prone to having large pupils under dim lighting conditions. This can cause symptoms such as glare, halos, starbursts, and ghost images (double vision) after surgery. In some patients these symptoms may be debilitating. For example, a patient may no longer be able to drive a car at night or in certain weather conditions, such as fog. From the American Academy of Ophthalmology website: http://www.aao.org/education/library/re ... /lasik.cfm Summary Recommendations for LASIK Issued March 28, 2002 Patient Examination In determining suitability, a baseline eye evaluation should include: Manifest and cycloplegic refraction Measurement of intraocular pressure Slit-lamp biomicroscopy Tear film evaluation Corneal topography Evaluation of preoperative corneal thickness Dilated fundoscopic examination Measurement of scotopic pupil size From the ASCRS Eye Surgery Education Counsil website, LASIK Patient Screening Guidelines: http://www.lasikinstitute.org/LASIK_Pat ... lines.html • Measurement of pupil size in dim and room light. Pupil size is an important factor in counseling a candidate about night vision and planning the appropriate laser vision correction strategy. From the OMIC website (requires pre-op pupil measurement): http://www.omic.com/products/bus_produc ... %20app.rtf PATIENT SELECTION As part of the independent evaluation, the surgeon must personally examine the patient’s eyes and ocular adnexa, perform a slit lamp exam, and carefully review topographies, pupil size, pachymetry, refractive stability, eye health history, and prior records. From the Federal Trade Commission website: http://www.ftc.gov/bcp/conline/pubs/health/lasik.htm Take the following measurements: The curvature of your cornea and your pupils. You may be rejected if your pupils are too large. |
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| Author: | kaleyedoscope [ Wed Feb 14, 2007 1:57 pm ] |
| Post subject: | |
http://www.vectorvision.com/html/educat ... rgery.html "Pupil Size and the Quality of Vision after Refractive Surgery:Pupil size is very important when quantifying the quality of vision. The quality of vision is typically much worse for patients in darkened environments than in bright conditions. This is because the larger pupil allows more light into the eye from the edge of the corneal zone where the laser has ablated tissue (ablation zone). Studies by Boxer Wachler and others have shown that the size of the ablation zone is related to the quality of vision. If the pupil size is large and overlaps the ablation zone, the quality of vision suffers." "Glare and Contrast Sensitivity Evaluation for Refractive Surgery:Many patients complain of glare after refractive surgery and it is tempting to test these patients with a glare test in order to assess the quality of vision. However, glare testing, which shines a bright light in the patient's eye, reduces pupil size and typically causes vision to improve. The graph below shows the results of a patient tested for contrast sensitivity in darkness and then again with glare. Note that the glare condition dramatically improves the contrast sensitivity. It is not recommended that LASIK patients be tested with a high-luminance glare test to quantify the quality of vision." |
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| Author: | Broken Eyes [ Sat Feb 24, 2007 7:53 pm ] |
| Post subject: | |
The principle of Occam's razor states, "All things being equal, the simplest solution tends to be the best one." If the pupil is larger than the fully corrected cornea, night vision disturbances will be present. If a surgeon wants to conduct a study to find the truth about the importance of pupil size, he'll have to control the lighting, ensure the pupils are accurately measured, and only include patients whose refractive error and surgical parameters are identical with the only difference being their pupil size. Then he'll have to weed out patients with any complications or refractive error after surgery. And he must objectively measure the degree (severity) of the aberrations at the patients natural dark-adapted pupil size, not just ask about the frequency of the aberrations. |
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| Author: | Eye [ Mon Feb 26, 2007 5:43 pm ] |
| Post subject: | It would be easy to design a good pupil size study |
Unfortunately nobody wants to because it would prove that large pupils are a huge risk factor for a poor corneal refractive surgery outcome and that the FDA approved optical zone sizes are TOO SMALL FOR EVEN AN AVERAGE SIZE PUPIL. A lot of people are losing a lot of vision at the hands of so-called doctors. If you want to understand more about the relationship between pupil size and a poor LASIK outcome read The LASIK Report at http://www.thelasikreport.com . KNOWLEDGE IS POWER. |
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| Author: | Bill [ Tue Oct 16, 2007 12:50 pm ] |
| Post subject: | |
The FDA recently revised their statement on pupil size: http://www.fda.gov/cdrh/lasik/when.htm Quote: Large pupils. Make sure this evaluation is done in a dark room. Although anyone may have large pupils, younger patients and patients on certain medications may be particularly prone to having large pupils under dim lighting conditions. This can cause symptoms such as glare, halos, starbursts, and ghost images (double vision) after surgery. In some patients these symptoms may be debilitating. For example, a patient may no longer be able to drive a car at night or in certain weather conditions, such as fog.
Apparently they were hearing from a lot of older patients with large pupils who were visually impaired after LASIK. |
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