Dr Peter Beckingsale
Optimising outcomes in ophthalmic surgery...

Laser Vision Correction

Refractive error is when the light from an object you are looking at does not focus accurately on the retina. There are 4 types of refractive error and you can have more than 1 type at the same time.

  1. Short sightedness (myopia) is when the light rays focus too close, which means near objects are seen clearly but distance are not.
  2. Far sightedness (hyperopia) means the light rays focus too far back, meaning distance vision is better than close, and with age distance vision becomes difficult as well.
  3. Astigmatism means the eye has 2 focal points because the cornea is shaped liked a rugby ball instead of a soccer ball. This means vision is not clear at any distance.
  4. Presbyopia is progressive hardening of the eye’s internal focusing lens which usually occurs in our mid to late 40s. It will affect everyone sooner or later, and results in the need for reading glasses in people who have normal distance vision.

While many people may be happy to wear glasses or contact lenses there are also plenty who are not. Modern refractive surgery is able to correct most refractive errors to allow high quality vision without glasses, but the best sort of procedure depends on numerous factors, including the refractive error, the anatomy of your eye, your age and the presence of any other medical conditions.

LASIK

Laser Assisted In Situ Keratomileusis (LASIK) is the most popular refractive procedure in Australia. A paper thin flap is created on the front of the cornea (the glassy window at the front of your eye) and then an excimer laser is used to precisely and safely change the shape of your cornea in a matter of seconds. For myopic corrections the cornea is flattened and for hyperopic corrections it is steepened. The flap is then repositioned allowing minimal pain and extremely rapid visual recovery. Most people can begin to see within minutes of the procedure.

Originally the flap was created with a microkeratome, a precise oscillating blade, which passed across the cornea. For the last 10 years the preferred technique has been to create the flap with a femtosecond laser as this is significantly safer and results in better visual outcomes.

LASIK is able to treat a very wide range of refractive error, from +6 to -12 and 6 diopters of astigmatism.

LASIK treatments are usually painless and take less than 15 minutes to complete. Around 98% of people will achieve high quality vision following the treatment. The most common downside is dry eyes, which is usually temporary and the occasional need for re-treatments, or enhancement which is needed in 3% of cases. Vigorous exercise should be avoided for 4-5 days and no contact sports should be played for 4 weeks, but by 4 weeks the flap is rock solid strong and there are oolong term restrictions in activities.

PRK

Photorefractive Keratectomy (PRK) is when the same excimer laser used in LASIK is directed to the front surface of the cornea once the transparent skin (epithelium) has been removed. Epi-LASIK and LASEK are variations of PRK which are not widely used any more.

The advantage of PRK over LASIK is excellent strength of the cornea straight away. This is particularly useful for highly active people and those involved in contact sports or jobs with high risk of trauma (military, police etc). PRK is usually cheaper than LASIK as only 1 laser is required instead of 2.

The downside to PRK is slower visual recovery. Most people won’t be able to drive for 4-5 days, and while vision is quite good after 1 week it may be as long as 2-3 months until final sharpness is achieved. PRK is also best for relatively low scripts, up to about -3.0 myopia with low astigmatism. It is generally not recommended for hyperopic corrections.

SMILE

The latest laser vision correction technique is Small Incision Lenticule Extraction (SMILE). This uses the same femtosecond laser used to create modern LASIK flaps to complete the whole treatment internally with only a 2mm keyhole incision, instead of the near circumferential incision of a LASIK flap. This allows virtually instant near normal strength, so there is no restrictions in activities following a SMILE treatment. Because the corneal surface is less disrupted there is also likely to be a lower incidence of long term dry eyes than LASIK or PRK, but it can still occur.

The downside to SMILE is that the laser interface is more complicated, so it is a more expensive treatment. It may also be more difficult to perform an enhancement if required, tough it is still possible and vision may be slightly slower to return to normal than with LASIK, but much faster than PRK. More corneal thickness is needed for a SMILE treatment than LASIK or PRK, and it does not work as well for very low or high shortsightedness and it is unable to correct hyperopia.

The final visual outcomes for all these laser treatments is essentially the same, and the safety profiles are similar and excellent for all of them as well.

Alternatives

Not everyone is suitable for laser correction, usually due to degree of refractive error, age or individual corneal variations. There are excellent alternative treatments available for many people who are unable to have laser vision correction.

Phakic Lens Implant



Lens Exchange