What are the different types of Refractive surgery?
There are a number of ways of correcting short or long-sightedness (myopia and hyperopia respectively):
- LASIK: here 2 lasers are used - one is a femtosecond laser to cut a corneal flap, and then an excimer laser is used to reshape the corneal curvature to correct the refractive error. Advantages: fast visual recovery with minimal or no postoperative discomfort. Disadvantages: flap related complications including loss of corneal biomechanical strength, higher chance of dry eye symptoms due to laser cutting of corneal nerves.
- LASEK or PRK: here the first layer of the cornea is removed (usually by hand) and then an excimer laser is used to reshape the cornea to correct refractive error. Advantages: higher corneal biomechanical strength, no flap related complications (there is no flap!). Disadvantages: slow visual recovery with probability of mild to moderate discomfort over the first 2-5 days.
- Keyhole LASIK (ReLEx SMILE procedure, iSMILE, Z-SMILE): This is a newer procedure using only a femtosecond laser to cut a custom lens shape within the cornea, the tissue of which is then removed through one of two 2.0mm wide tiny ports. Advantages: higher corneal biomechanical strength, minimal or no postoperative discomfort, hugely reduced cutting of corneal nerves so less dry eyes symptoms. Disadvantages: visual recovery not as fast as LASIK but much faster than LASEK or PRK, only available since 2012 in Europe and 2015 in the US, so fewer surgeons offer this procedure and there is long-term data published compared to LASIK, LASEK or PRK.
- Refractive lens exchange (RLE)/ clear lens extraction, inc. refractive cataract surgery: This is where the lens inside the eye (the same lens that with age becomes cloudy to form a cataract), is removed by ultrasound and replaced with an artificial lens implant (intraocular lens, IOL). The power of the implanted lens can be chosen to correct any amount of short or long-sightedness. Additional incisions made at the time of the operation can be made to help correct any astigmatism. The operation is technically the same as a cataract operation (phacoemulsification and IOL implantation) except the indication is refractive correction, rather than to treat cataract. Femtosecond laser lens exchange/ cataract surgery is now available and may offer advantages over manual phacoemulsification (ultrasound) surgery.