Q: Hi, How long does it take to achieve the final result after PRK surgery? and Is it normal after PRK surgery for the vision to become a little blurry after it was clear two weeks after surgery? A: It can take 3-6 months to achieve the final vision. During this time the vision will fluctuate. Andrew Caster, MD

Q:  I'm 44 yrs old and have been wearing glasses/corrective lenses since I was 18 months old due to ambliopia. I went through the viewmaster, patch therapy as a child, The eye that turned in when I took off my lenses no longer turns in due to aging? I lost some vision in this eye as a result of the amblopia (about 20/70 with contacts). Actually I have noticed this eye does more work now as my "good" eye tires. My prescription has been +3.50 for the last 10 years with the addition of +1 recently (bifocals) due to aging. I wonder if there is any possibility that I may be a candidate for vision surgery now or in the future? A:  Many doctors, including me, would be reluctant for safety reasons to operate on a patient in which one eye is correctable with glasses to only 20/70. For others, this is not an issue. +3.50 is correctable with laser vision correction, though in your case one eye is not correctable to better than 20/70. Andrew Caster, MD www.castervision.com

Q: I've spoken to several people who say they have improved their vision through "eye exercises". Why are these not practiced more mainstream, and do they work? A:  The best known of the eye exercise programs to improve visual acuity is known as the Bates Method. Unfortunately, when this method is subjected to scientific study, it has been shown to not be effective. It is sold through informercials on TV, but it would be irresponsible for a doctor to recommend such a treatment when it is not effective. Andrew Caster, MD www.castervision.com

Q: I have had the prescreening done to determine if I am a good candidate for LASIK. I have been advised that I am on the borderline because of the thickness of my cornea for wavefront LASIK. Also, my pupils are larger than normal & I may have some issues there as well. I am nearsighted approx -9 diopters I have been given the option of having regular LASIK & possibly having halos, or going ahead with the wavefront knowing that I have less tissue available for future enhancements. I would like you opinion if I should have the surgery & also your feedback on which laser manufacturers have a greater success rate for reducing problems with halos. A:  The issue of halos is not well understood. Everyone has some degree of halos, whether or not he or she has had any surgery. People with larger pupils seem to be more likely to have increased halos, as well as people with larger corrections. Wavefront seems to cause less halos, but not all of the time. So in your case the answer is not clear cut. -9 is rather high to have wavefront. Andrew Caster, MD www.castervision.com

Q: My question is, can Lasik surgery help macular degeneration? A: Unfortunately, it cannot. Andrew Caster, MD www.castervision.com

Q: Can LASIK or PRK correct or at least improve the starburst side effect of previous RK surgery (1995)? A: If the starburst effect is lessened by putting on the proper prescription glasses, then Lasik or PRK can achieve a similar effect. Andrew Caster, MD

Q: What eye perceptions occur with Stereopsis? The eye doctor said my grandson has Stereopsis, and I need to know what is the result...does it affect his reading, hand/eye coordination, etc.??important for a child with ADHD. to an ADHD child whose A: Stereopsis is normal, and is a good thing. Stereopsis means that you see in stereo. It is similar to hearing in stereo. Many people are not capable of seeing in stereo; it is not a big defect. Andrew Caster, MD www.castervision.com

Q:  I am 19 and a half, and have a prescription of -12, -13. I wanted to have LASIK surgery, but my prescription just changed in August by -1 in each eye. A doctor told me that I should wait till my eyesight stabilizes, and wear contacts, as they are better in stabilizing your power. Is that true? And can I have LASIK with perfect vision? A: The contacts probably do not stabilize the prescription. But you should wait until your prescription stabilizes. Andrew Caster, MD www.castervision.com

Q:  I had RK over 15 years ago and through the years my near and far sighted ness has demised. I can not get a prescription that works because my vision changes many times through out the day. I have been trying to find out if one of the bad effects for RK is dizziness because when I am in a large bright open area I get very dizzy. I can not get glasses to work because of the constant change of prescription during the day plus both eyes are changing at different times. So each day my prescription at the same time it was taken the day before is different. So I need help!! Can I do contacts lenses or any other kind of eye surgery that can fix my problem? A: I would try contact lenses to see if they work for you. I would not recommend further eye surgery. Andrew Caster, MD www.castervision.com

Q: I just had lasik 11 days ago. I have 2 questions. Will smoking marijuana damage my eyes, and will vomiting damage my eyes. (Like from the pressure or something). Thank you, Jennifer A: Smoking marijuana can lower the pressure in the eyes. In rare cases, this can result in a mild undercorrection, which might require a touch-up procedure. Vomiting should not damage the eyes. Andrew Caster, MD.