Refractive surgery - Laser surgery - all forms

Considerations

Young applicants who undergo any type of refractive surgery for myopia before the refractive error has stabilised are at risk of recurrence of myopia, albeit to a lesser degree.

There are different Laser procedures, all with their pros and cons. The results of refractive Laser surgery are generally excellent. However applicants should be reminded of occasional complications as it may affect their chances of employment in the aviation industry.

The Small Incision Lenticule Extraction laser procedure (SMILE) is a more recent surgical technique, made possible by the development of femtosecond lasers. This technique limits the surgical damage to peripheral corneal nerves. This can be expected to reduce the incidence of dry eye and other side effects. The localisation of the treatment to intrastromal corneal depths beneath the anterior elastic lamina can be expected to improve the strength of the treated cornea. However the loss of tissue volume inside the cornea rather than on the surface might result in complications not seen before. The Kamiya et al (2015) study has showed good stability of the correction with no change over 0.5 D over 12 months. Blum et al (2014) reported stability within +/- 1 D over five years. While the safety and outcomes of this technique are thought to be good, the full picture will only be available when longer term follow up studies are published. Meanwhile, CAA will impose stricter surveillance conditions following SMILE surgery than for other types of laser surgery. Please consult with CAA for any such cases.

Following Laser surgery, the cornea takes time to heal and the refraction takes time to stabilise to its new value. Flying is not permitted while the refraction may still change.

Evidence of stability generally requires:

• A waiting period since surgery of at least six weeks for refractive correction of 3 dioptres or less and three months for correction of more than 3 dioptres;
• A visual acuity remaining within standards for the Class sought when tested at different times, whether corrected or uncorrected;
• Absence of problem with haze, glare or contrast sensitivity.

Information to be provided

An applicant who first present with a history of refractive laser surgery should provide:

• All reports by the surgeon who undertook the procedure, if recent;
• Documentation indicating the pre-laser surgery refractive error or, if not obtainable, the pre-operative uncorrected and corrected visual acuity; and
• A special eye report completed not earlier than six weeks post-surgery (twelve weeks for correction of over 3 dioptres). This must include information about haze, glare, contrast sensitivity and all visual acuity and refractive error determinations done since the procedure (the latter unless the surgery occurred more than six months prior).

Disposition following refractive Laser surgery

Note: In case of SMILE laser surgery taking place within the past 12 months, please contact CAA for advice.

An applicant who has undergone refractive Laser surgery may be assessed as having a condition that is not of aeromedical significance if:

• The applicant meets the vision standards with or without corrections; and
• At least 6 weeks (three months for correction of over 3 dioptres) have lapsed since refractive surgery; and
• The visual acuity remains within standards for the Class sought when tested at different times, whether corrected or uncorrected; and
• There is no corneal haze; and
• There is normal contrast sensitivity; and
• The applicant does not suffer from glare.

Provided that the certificate is endorsed as follows:

• The appropriate endorsements requiring corrective lenses are applied if the standards can only be met while wearing corrective lenses;
• Surveillance is imposed requiring a special eye report at six months, one year and five years post-surgery for correction of less than 3 dioptres;
• Surveillance is imposed requiring a special eye report at six months, one year, two year and five years post-surgery for correction over 3 dioptres;
• Surveillance every five years thereafter should also be considered for Class 1 certificate holders.

Note: If the eyes are treated at different time, anisometropia may be an issue. Please refer to Anisometropia.