Laser Refractive Surgery methods
Customized,(wavefront-guided laser refractive surgery)
Optimized
Conventional
Why we need wavefront- guided refractive surgery?
Measurement of the wave front error of the eye provides an accurate method to:
Assess the optical properties of the eye beyond sphere and cylinder
Evaluate the optical properties of the eye
Provide the necessary information to design optical prescriptions for the eye to minimized all refractive errors
Conventional Laser Refractive Surgery:
May reduce contrast acuity.
Increase higher order aberrarions.
Increasing with the magnitude of refractive correction.
High refractive corrections, both myopic (>6.00 D) and hyperopic (>5.00 D), can lead to very high levels of corneal higher order aberrations.
Decrease night-driving visual performance.
Higher order aberrations can cause
Night vision disturbances such as starbursts, halos, glare.
Low contrast acuity.
Wavefront-guided Laser Refractive Surgery provides
Better contrast sensitivity.
Induces fewer higher order aberrations.
More effective than Plano scan in the correction of total, high order and 3rd order aberrations.
The most important advantage of the wavefront-guided technology is it saves tissue ablation depth in the range of 20% or 25%.
Clinically the most useful methods of evaluating the success of wavefront-guided repairs.
Subjective improvement
Contrast sensitivity
The pre operative evaluation consisted of
- Measurement of uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA).
- Manifest,Subjective and Cycloplegic refractions.
- Slit lamp biomicroscopy,
- Tonometry.
- Indirect ophthalmoscopy ,
- Corneal topography ,
- Ultrasound pachymetry ,
- Orbscan II 0r Pentacam
- Aberrometry (Zyoptix evaluation).
- Pupillometry
Exclusion criteria are history of
Previous refractive procedures.
Keratoconus
Cataract surgery
Diabetes
Glaucoma
Connective tissue disorders
Retinal disease
Pregnant or nursing period
Conductive Keratoplasty uses a tiny probe and low heat radio waves to apply “spots” around the periphery of the eye’s clear front surface. This relatively non-invasive method steepens the cornea, to provide near vision correction for people who are farsighted. CK also can be used to correct presbyopia or enhance near vision for people who have had LASIK or cataract surgery. CK received initial FDA approval in 2002.
Implantable lenses are another option for vision correction surgery.
Verisyse phakic IOL from Advanced Medical Optics.
Implantable Lenses (Visian ICL and Verisyse), similar to contact lenses, first received FDA approval in 2004. These surgically implanted lenses primarily are considered appropriate for higher levels of nearsightedness. When implantable lenses are used, your eye’s natural lens is left in place. Both of these lenses have a long track record of use, including more than 13 years in Europe.
Visian ICL Implantable Collamer Lens from Staar Surgical.)
Refractive Lens Exchange is another non-laser, internal eye procedure. RLE is much like cataract surgery. But instead of removing the eye’s natural lens that has grown cloudy due to cataract formation, RLE involves removing a clear natural lens and replacing it with an artificial lens of a different shape, usually to reduce or eliminate high degrees of farsightedness. RLE also might be considered as an option for correcting other types of vision problems, such as nearsightedness. But RLE has a higher risk of complications, compared with other vision correction procedures. For these reasons, RLE typically is used only in cases of severe vision correction needs.
Cataract surgery also can now be considered a vision correction procedure. New lens implants developed for cataract surgery can partially restore a person’s near vision in addition to correcting nearsightedness and farsightedness. These lenses, called multifocal IOLs or accommodating IOLs, currently are being used by many cataract surgeons, with promising results.