With 20 years of laser eye surgery development behind us, many questions about patient risks and outcomes remain. A review of how far the procedure has come and what considerations are needed before opting into refractive surgery are outlined here.
Millions of people in North America, Europe, and Asia have had successful laser eye surgery, making it the most practiced procedure to correct vision problems caused by refractive errors. Laser surgery corrects nearsightedness, farsightedness, and astigmatism.
How it works
In Canada, commonly performed procedures are photo-refractive keratectomy (PRK), first introduced in the early 90s, and LASIK, introduced in the mid-90s. In PRK, just enough tissue is removed to reshape the cornea in a way that corrects vision. The initial healing process takes a week. In LASIK, a flap in the cornea is cut away to remove tissue from the inside layers of the cornea to correct vision. The recent advancement of Wavefront technology creates a detailed map of the eye, allowing for even more precise vision correction.
Progress has been made in each type of surgery. A move from broad beam lasers (6 to 8 mm diameter) to flying spot lasers (0.95 mm diameter) have improved accuracy. Femtosecond lasers have replaced manual ones used for flap cutting, reducing intra-ocular complications related to flap cutting.
The range of prescriptions suitable for refractive surgery has increased. Nearsightedness up to -12.50D,farsightedness up to +6.75D, astigmatism up to -6.00, and presbyopia (the inability to focus on nearby objects caused by normal ageing) can now be corrected.
A procedure called refractive lenticule extraction-small incision lenticule extraction (ReLEx-SMILE), a flapless laser eye or keyhole surgery, is accurate enough to avoid flap-related complications. It also has less biomechanical impact on the cornea because it preserves the strongest part of the cornea.
Laser blended vision is a corneal laser eye surgery that takes about 10 minutes to perform in both eyes, heals in a few hours, and can correct 97 per cent of all people with bifocals or reading glasses by increasing the depth of field of each eye. Laser blended vision enables surgeons to avoid the outdated technique of replacing a clear permanent lens inside the eye.
Patients not suited for surgery are those at the very extremes of prescriptions—outside of the +6.75D farsightedness and -12.50D nearsightedness range. These people still require lenses to be inserted into the eye to correct their high prescriptions.
Benefits and risks
Each type of surgery causes different symptoms, but in general all include pain ranging from moderate to severe for the first few days after the procedure, hazy vision during the healing process for up to one week after surgery, and regression. In some cases, patients’ vision may return to the original prescription within six months. If this happens, a second operation is required. Dry eyes, poor night vision, and corneal ectasia, which is the weakening and bulging of the cornea, can take place. Severe cases may need to be treated with a corneal transplant or implant. Also, corneal infection may result in loss of vision.
To be considered, your eyes must be healthy and create sufficient tears, with no complications present within the past year. Your cornea must have sufficient thickness for the procedure to be successful without impairing your vision. If your pupils are overly large you could be at increased risk of side effects such as halos, glares, and starbursts in low light, especially when driving at night. Your prescription must not be too high due to nearsightedness, farsightedness, or astigmatism. You must also have stable vision for at least one year, with no prescription change.
Minimize your risk
When all of the benefits and risks have been weighed and you’ve made the decision to undergo treatment, take the time to give careful consideration in choosing an eye surgeon. Use a referral from a trusted eye care professional, such as your FYidoctors optometrist. Discuss the risks, benefits, and your expectations with the surgeon. After surgery, follow your post-operative care guidelines.