Refractive (LASIK, PRK, ICL)
What is refractive surgery?
Refractive procedures are optional procedures meant for those who have refractive errors (spectacle power) and need or want to get rid of their spectacles and/or contact lenses.
Who needs refractive surgery?
Patients may need or want to remove spectacles for various purposes including vocational (army, navy, marine, pilot, etc) and cosmetic issues.
Patients may not be able to wear contact lens because of contact lens intolerance or vocational issues (like sports).
Who is an ideal candidate for refractive surgery?
- More than 18 years old
- Stable refractive error (spectacle power) for at least one year
- Have no major eye diseases (eg.dry eye, keratoconus, corneal opacity)
- Have no major medical issues (diabetes, rheumatological diseases, certain drugs)
- No history of pregnancy / breast feeding for last six months.
What are the diagnostics before refractive surgery?
Prior to refractive surgery, after complete eye examination, a corneal examination is done to find out whether the patient is a suitable candidate for refractive surgery and to find out whether complete correction is possible for the patient (Orbscan/ZDW3 in Susrut). ZDW3 also measures, and provides an opportunity to treat, higher order aberrations in the optical system of the eye.
What is LASIK?
LASIK involves reshaping the cornea, to correct the refractive error, with an excimer laser (Teneo 317 inSusrut).
First a flap is lifted from the front surface of the cornea. This can be done either with a blade (Moria SBK in Susrut) or without a blade (by using another laser – femtosecond laser, LenSx in Susrut).
After the flap is lifted, the excimer laser is used to reshape the underlying cornea. It usually takes less than 10 seconds for the excimer laser to reshape the cornea. During the laser application, the positioning of the laser on the eye is maintained by an eye-tracker, which compensates for any movement of the eye during the procedure. After the cornea is reshaped, the flap is repositioned in place.
What are the various types of LASIK treatments available in Susrut?
The excimer reshaping can be patterned in three ways
- Wavefront Optimised (PROSCAN in Teneo 317)- Here the refractive error (as measured conventionally in the clinic) is entered in the excimer laser. Only spherical and cylindrical refractive errors can be corrected. Additional correction is made by the machine itself to reduce creation of spherical aberration (a type of higher order aberration).
- Wavefront Guided (ZYOPTIX HD in Teneo 317)- Here wavefront data from ZDW3 is automatically transferred to the excimer laser. This pattern provides an opportunity to correct higher order aberrations (in addition to correcting spherical and cylindrical errors). It has been shown to provide better vision to patients with pre-existing higher order aberrations.
- Near vision correction (SUPRACOR in Teneo 317) – For patients older than 45 years, who have both distance and near vision errors, this method provides intermediate/near vision (eg: mobile phone use) correction, in one or both eyes, in addition to distance vision correction in both eyes.
What is PRK?
PRK is an alternative refractive procedure. Here flap making is not required. The excimer laser reshapes the cornea, after the epithelium (outer lining) of the cornea is removed. Following PRK, the discomfort level is more and visual recovery takes longer, compared to LASIK. It is meant for patients with thinner corneas and certain corneal disorders (like EBMD).
What is phakic IOL / ICL / IPCL?
For patients with very high refractive error (spectacle power), which is not amenable to LASIK, the refractive error can be corrected by placing an intraocular lens (different from the intraocular lens implanted during cataract surgery) inside the eye.