FAQ

1. Will I have 20/20 vision without glasses after LASIK?
2. What is Monovision?
3. What are the possible risks/side effects of LASIK eye surgery?
4. How long does the surgery last?
5. What shall I expect after surgery?
6. References and additional reading
   

Will I have 20/20 vision without glasses after LASIK?

If the myopia is low to moderate (i.e. -7 D or less), then 96% patients achieve uncorrected visual acuities better than 20/40, however only 72% of patients achieve vision equal to or better than 20/20. As mentioned earlier, more people achieve 20/20 vision with wavefront-guided treatment. If the myopia is high (i.e. more than -7 D ), then 89% patients achieve uncorrected visual acuities better than 20/40, however only 48% of patients achieve vision equal to or better than 20/20. Note that the uncorrected vision results in high myopes is not as good as in low myopes (FDA data). LASIK and surface ablation have largely similar vision outcomes. Therefore, most - but not all - people will have 20/20 vision after LASIK without glasses. Some people will not be able to "get rid of glasses" to see 20/20. Taken together, this means that LASIK will almost certainly reduce your dependence on glasses and contact lenses, however, there is no certainty and there can be no guarantee that you will be able to achieve perfect vision without glasses. You have 90 to 95% chance of passing the vision test to get a drivers license without glasses (i.e 20/40 vision) and therefore 90 to 95% chance that you will be able to legally drive without glasses after LASIK. Our recommendation, however, is that you drive with the best vision that your eyes are capable of achieving.

What is Monovision?

For presbyopic individuals monovision is a very effective strategy to achieve good (not perfect) vision at distance as well as near without the need for any glasses. In monovision, one eye is corrected for distance vision and the other eye for near vision. The procedure entails using PRK or LASIK to fully correct one eye for distance and undercorrect the other eye (by 1 to 2 D) for near vision. Not every patient is a good candidate for monovision. The monovision option may be associated with compromises of binocular visual function, and some people may not be able or willing to accept the vision compromises. However, for those refractive surgery patients who are able to adapt, monovision represents a means of markedly decreasing dependence on spectacles for both near and distance work.

What are the possible risks/side effects of LASIK eye surgery?

Serious complications from refractive surgery are rare, as evidenced by the low rate of loss of best spectacle-corrected visual acuity. However, before undergoing any refractive procedure, you should carefully weigh the risks and benefits based on your own personal value system, and try to avoid being influenced by friends that have had the procedure or doctors encouraging you to do so. Remember that, even though rare, complications do occur.

• Some patients lose vision. Some patients lose lines of vision on the vision chart that cannot be corrected with glasses, contact lenses, or surgery as a result of treatment. Loss of best spectacle-corrected visual acuity of more than two lines is noted in just under 1·0% of patients (FDA data)

• Some patients develop debilitating visual symptoms. Some patients develop glare, halos, and/or double vision that can seriously affect nighttime vision. Even with good vision on the vision chart, some patients do not see as well in situations of low contrast, such as at night or in fog, after treatment as compared to before treatment. Even though it is unclear to what extent pupil size plays a role in the pathogenesis of glare and halos, patients with pupil diameter of more than 6.0 mm should be informed of the significant risk of night vision disturbances after LASIK. Generally, these symptoms abate over time. It is not clear if this is due to resolution of an underlying anatomic irregularity or to patient's adaptation. A small subset of patients report no significant improvement and can be substantially incapacitated under various lighting situations, such as night driving, despite good uncorrected visual acuity at high contrast levels (during daytime). There is growing evidence that higher order aberrations are the main reason for glare and halos after LASIK. Another reason relates to the pupil size. These symptoms are more pronounced after treatment of cylindrical errors (for high astigmatism) due to the oval shape of laser treatment with inherently smaller optical zone in the steep meridian. If pupils dilate to a diameter larger than the size of the optical treatment zone, rays of light refracted by the untreated peripheral cornea are not focused at the same position as the central rays and result in blur circles. Glare and halos may be significantly reduced through enlargement of the ablation zone by means of the currently developed wavefront- or topography-guided lasers. Leaving the car dome's light on when driving at night has also been reported to improve symptoms because the pupil becomes smaller.

• You may be under treated or over treated. Only a certain percent of patients achieve 20/20 vision without glasses or contacts. You may require additional treatment, but additional treatment may not be possible. You may still need glasses or contact lenses after surgery. This may be true even if you only required a very weak prescription before surgery. If you used reading glasses before surgery, you may still need reading glasses after surgery. Variations in corneal healing, atmospheric pressure, humidity, and ambient temperature are among the many factors that contribute to the relative unpredictability of refractive surgical procedures. Surgical procedures based on inaccurate refractions could result in significant residual or induced postoperative refractive errors. These include erroneous refraction, relying on non-cycloplegic refraction in an accommodating patient, and wrong information input into the laser secondary to human error. Failing to reexamine a contact lens wearer until a stable and reproducible refraction is obtained may result in unexpected refractive outcomes. Over- or under-correction may be corrected by lifting the flap (even months after the surgery) and applying additional laser ablation.

• Some patients may develop severe dry eye syndrome. The dry eye condition after LASIK may be due to decreased corneal sensation, resulting from severing of corneal nerves, with subsequent decreased blinking rate. As a result, your eye may not be able to produce enough tears to keep the eye moist and comfortable. Dry eye not only causes discomfort, but can reduce visual quality due to intermittent blurring and other visual symptoms. This condition may be permanent. Intensive drop therapy and use of plugs or other procedures may be required.

• Results are generally not as good in patients with very large refractive errors of any type. You should discuss your expectations with your doctor and realize that you may still require glasses or contacts after the surgery.

• For some farsighted patients, results may diminish with age. If you are farsighted, the level of improved vision you experience after surgery may decrease with age. This can occur if your manifest refraction (a vision exam with lenses before dilating drops) is very different from your cycloplegic refraction (a vision exam with lenses after dilating drops).

• Long-term data are not available. LASIK is a relatively new technology. The first laser was approved for LASIK eye surgery in 1998. Therefore, the long-term safety and effectiveness of LASIK surgery is not known. (US Food and Drug Administration: Department of Health and Human Services)

How long does the surgery last?

The surgery should take less than 30 minutes. You will lie on your back in a reclining chair in an exam room containing the laser system. The laser system includes a large machine with a microscope attached to it and a computer screen.

What shall I expect after surgery?

After PRK/LASEK/Epi-LASIK
Once the treatment is completed, anti-inflammatory and antibiotics drops are applied to the treated eye to promote healing and prevent pain and infection. A bandage soft contact lens is placed on the eye which acts as a patch to allow the surface cells to heal. The contact lens will stay in the eye for a period of 3-5 days (until the epithelium surface healing is complete). Patients may experience no discomfort, or have mild burning or pain, foreign body sensation, itchiness, light sensitivity, swelling of the lids, and/or blurring of varying degrees during the first week.

After LASIK/Intralase
Once the treatment is completed, anti-inflammatory and antibiotics drops are applied to the treated eye(s) to promote healing and prevent pain and infection. The eyes are examined to confirm flap placement and general appearance of the eye. The eyes are shielded to prevent accidental trauma for the 36-48 hours while the corneas are completing their initial healing phase. Eyedrops are continued and the eyes re-examined the following day, the following week, and then several weeks post-operatively. Vision initially will be blurred, but will normally begin clearing over the first few hours to days. Patients normally note a tolerable foreign body sensation present for the first 24-48 hours.

During the first few months after surgery, your vision may fluctuate.

• It may take up to three to six months for your vision to stabilize after surgery.

• Glare, haloes, difficulty driving at night, and other visual symptoms may also persist during this stabilization period. If further correction or enhancement is necessary, you should wait until your eye measurements are consistent for two consecutive visits at least 3 months apart before re-operation.

• It is important to realize that although distance vision may improve after re-operation, it is unlikely that other visual symptoms such as glare or haloes will improve.

• It is also important to note that no laser company has presented enough evidence for the FDA to make conclusions about the safety or effectiveness of enhancement surgery.

References and additional reading:

Sakimoto T, Rosenblatt MI, Azar DT. Laser eye surgery for refractive errors
Lancet 2006 Apr 29;367(9520):1432-47.

Melki SA, Azar DT. LASIK complications: etiology, management, and prevention.
Surv Ophthalmol. 2001 Sep-Oct;46(2):95-116.

Sippel KC, Jain S, Azar DT. Monovision achieved with excimer laser refractive surgery. Int Ophthalmol Clin. 2001 Spring;41(2):91-101.