Refractive Surgery

This week’s blog on refractive surgery has been contributed by Dr Hamed Mofeez Anwar, Consultant Corneal and Refractive Surgeon.

If you’re nearsighted, farsighted, have astigmatism or are presbyopic (loss of reading ability due to age), refractive surgery is a term referring to procedures which can be used to improve your vision.

What are the benefits of refractive surgery?

For most patients, the vision after refractive surgery is similar to that with contact lenses prior to surgery, without the potential discomfort and limitations of performing activities.

Over 95% of patients are satisfied with the outcome of the surgery, with many describing it as a “life-changing”. Although refractive surgery is often considered to be a cosmetic surgery procedure, the benefits are primarily functional. It’s designed to make you less dependent on glasses and contact lenses, letting you lead an active lifestyle more easily.

Am I a good candidate for refractive surgery?

Refractive surgery may be a good option for you if you:

• Want to decrease your dependence on glasses or contact lenses.
• Are free of eye disease.
• Accept the inherent risks and potential side effects of the procedure.
• Understand that you might still need glasses or contacts after the procedure to achieve your best vision.
• Have an appropriate refractive error

What types of refractive surgery are there?

It’s important to remember that there is no universally-accepted, best method for correcting refractive errors.

The best option for you should be decided after a thorough examination and discussion with your ophthalmologist, especially taking into account your lifestyle and vision needs.

The focusing ability of your eyes can be adjusted by procedures which include:

• Laser vision correction – these procedures adjust the focusing power of the eye by reshaping the cornea (the clear window at the front of the eye).
• Implanting a lens inside the eye.

Laser refractive surgery:

Laser vision correction procedures use an excimer laser to reshape the cornea (the clear window at the front of the eye), therefore correcting refractive errors. Generally speaking, the cornea is flattened to treat near-sightedness or steepened to correct far-sightedness.

Laser refractive surgery procedures include:

• LASIK
• Surface laser treatment (PRK/Trans-PRK/LASEK)

The risks and benefits are similar amongst the two procedures and they generally provide good results in the appropriate patients.

The main difference among the two procedures is the speed of recovery. LASIK patients are usually able to return to work within a day or so after surgery while patients who have PRK done may need up to a week to attain driving standard vision.

It’s important to keep in mind that the visual results at 3 months are equivalent for all types of surgery.

LASIK

In LASIK, a very thin flap is created on the surface of the cornea using a femtosecond laser. This flap is then lifted up and an excimer laser is then applied to the corneal surface. At the end of the procedure, the flap is then placed back into its original position. After surgery, a minimal amount of discomfort may be experienced. Visual recovery after surgery is rapid, with many patients seeing well enough to work and drive within a day or so. However, it’s important to remember that patients who engage in contact sports must wait a month before resuming activities.

This video http://fyi.rendia.com/XZN8k shows how LASIK eye surgery is performed.

Surface laser treatment (PRK/TransPRK/LASEK)

In PRK laser treatment, a laser is applied directly to the corneal surface. This removes a lens shaped piece of tissue immediately below the clear skin of the cornea. The skin regrows over the course of a week, and then smooths out over the next 3 months. While the skin is growing again, the eye surface is normally very sore. This is the main difference between surface laser treatments and LASIK, both of which aim to keep the corneal skin layer intact.

This procedure requires minimal surgical manipulation and is especially suited to patients that aren’t suitable for LASIK because of a thin cornea or a very active lifestyle that puts them at risk of dislodging a corneal flap. The downsides of this procedure are postoperative pain that lasts a day or so after surgery and a more prolonged visual recovery that would extend to a week to attain driving standard vision. Patients who engage in contact sports can resume activity much sooner than with LASIK.

Laser vision correction for decreased reading vision (presbyopia)

Age related loss of reading vision (presbyopia) can be treated with laser vision correction surgery. To do this, one eye is treated so it sees well for distance, while the other eye is treated to see well for closer objects. This type of treatment is called monovision. When both eyes are open, our brain combines the two images to partially restore near vision with little compromise optically. This is the default strategy for improving the near range in older patients undergoing laser vision correction.

Lens implantation surgery:

Laser vision correction is not suitable for all patients.

Some people have high degrees of refractive errors which can’t be safely corrected with laser-based refractive surgery. Other people (generally above the age of 50) may have early cataractous changes in the lens of their eyes.

Younger patients:

In younger patients, a lens is surgically implanted inside the eye in front of the natural lens. This lens is placed either in front of or behind the iris of the eye. Once the lens is properly positioned inside the eye, it provides the necessary correction to focus light rays onto the retina. It’s important to note that the natural lens of the eye is not removed during this procedure.

Older patients

Early stages of cataract are often seen in older patients, and lens replacement surgery may be more appropriate in this group. In this surgery, the natural lens is replaced with a lens implant. A variety of different implants are used, which include multifocal lenses designed to reduce reliance on spectacles for near, intermediate and distance vision.

Is refractive surgery permanent?

In most cases, yes. Short sight and astigmatism normally stabilise in the late teens or early 20s, however natural changes in your eye power can happen at any stage in life. As a result, laser vision correction sometimes needs to be repeated.