Refractive & Laser Eye Surgery Brisbane
What is refractive surgery?
Refractive surgery refers to laser eye surgery performed to correct focusing errors (refractive errors) of the eye. It is performed on those who wish to reduce their dependence on glasses or contact lenses.
What is a refractive error?
To achieve clear vision without glasses or contact lenses, the eye needs to focus the light travelling through it. In those with myopia (“short-sightedness”), hyperopia (“long sightedness”) and astigmatism, light is poorly focused by the eye resulting in blurred vision. Myopia, hyperopia and astigmatism can be treated with glasses or contact lenses and clear vision achieved.
Presbyopia is a condition in which the eye, with age, loses its ability to focus on near objects. Presbyopia occurs in the mid 40’s and affects everyone. Initially it is apparent as the need to hold near objects further away from the eye to obtain a clear image. Eventually, those with presbyopia lose their ability to read and require reading glasses or laser eye surgery.
What are the different types of refractive surgery?
There are 2 main categories of refractive surgery. The first type is laser eye surgery such as LASIK or Photorefractive Keratectomy (also known as “surface LASIK”). In laser eye surgery, or laser refractive surgery, a highly precise laser known as an excimer laser is applied to the cornea (the clear focusing window at the front of the eye) to improve the way light is focused by the eye, resulting in improved vision without glasses or contact lenses.
The second main type of refractive surgery is lens-based refractive surgery. In lens-based refractive surgery, the eyes’ natural lens can be removed and replaced with a new artificial lens which improves the focusing ability of the eye. Alternatively, the eye’s natural lens is left in place and a new artificial lens is planted on top of the natural lens to correct the eye’s refractive error.
Laser in-situ keratomileusis (LASIK)
LASIK is a type of laser eye surgery used to treat refractive errors such as myopia (short- sightedness), hyperopia (long-sightedness) and astigmatism.
LASIK acts in a similar way to glasses or contact lenses but is a permanent treatment. In LASIK a flap is created in the cornea, the flap is lifted, and the excimer laser is applied to the deeper layers of the cornea. The laser changes the shape of the cornea and alters the way it focuses light, resulting in much clearer vision.
Photorefractive keratectomy (PRK)
Photorefractive keratectomy (PRK), like LASIK, uses an excimer laser to change the shape of the cornea through laser eye surgery. In PRK, the laser is applied to the surface of the cornea and, unlike LASIK, no flap in the cornea is created.
What is better type of Laser Eye Surgery, PRK or LASIK?
A recent large review of international literature comparing PRK and LASIK as laser eye surgery treatments was performed by the Cochrane Library, considered to provide highest quality of scientific evidence. This study showed that there was no significant difference in the final vision and accuracy between LASIK and PRK.
The benefits of LASIK laser eye surgery include the fact that the procedure has less pain immediately after surgery and that the vision improves rapidly. The disadvantages of LASIK are that, because a flap of tissue is created in the cornea, the eye will always have some structural weakness. This means that the flap can dislodge if there is future trauma to the eye and there is a small chance the shape of the cornea can become irregular with time (post-LASIK ectasia), both of which can result in deterioration of vision.
The benefits of PRK laser eye surgery include the fact that structurally the cornea is stronger as there is no flap created. This means that there is no flap that can be dislodged if there is ever trauma to the eye and that there in essentially no risk of the cornea becoming irregular in the future. The disadvantages include the fact that there is some pain after the eye surgery (that can be controlled with pain-killers) and that the vision takes a few weeks to become as clear as possible.
Refractive lens exchange
In a refractive lens exchange, the natural lens of the eye is removed and replaced with an artificial lens that is permanently implanted into the eye to correct any focusing error. Refractive lens exchange is most commonly performed for presbyopia. There are 3 ways in which the need for glasses or contact lenses can be reduced in refractive lens exchange.
Option 1: Multifocal artificial lens implant in both eyes.
Multifocal intraocular lenses provide excellent vision for objects at all distances. They provide excellent distance vision (driving, watching TV), intermediate vision (eg working with computers) and near vision (eg reading tablets, phones, books). They are the lens type which are most likely to result in spectacle independence. In some people multifocal lenses can result in haloes around lights which are most commonly noticed when driving at night. Usually these are very mild. However, in around 1 in 200 cases, haloes can be very troubling to the point where these lenses need to be removed.
Option 2: Extended depth of focus (EDOF) lens implants.
EDOF lenses provide not only excellent distance vision without glasses (eg driving, watching TV), they also provide excellent intermediate distance vision (eg working with computers). EDOF lenses also provide some degree of near vision (eg reading tablets, phones, books), although glasses are still required to read small print, particularly under low light conditions. Although the near vision provided by EDOF lenses is not quite as good as that provided by multifocal lenses, it is very rare for haloes to be noticed by patients.
Option 3: “Blended vision” or “monovision.”
In blended vision, artificial lens implants are inserted which result in one eye being focused for distance and the other eye being focused for near. Blended vision significantly reduces the need to wear glasses after cataract surgery. It usually allows people to be glasses-free for most daily activities. Patients may still require glasses for reading very fine print and/or for driving at night. Because one eye is focused for distance and the other for near, it can take the brain a few months to fully adapt to blended vision.
Implantable collimer lens (ICL)
The ICL is an artificial lens implant that is inserted into the eye and placed in front of the natural lens, inside the eye. It is akin to a permanent contact lens. Each ICL is custom made for the individual eye.
ICLs have traditionally been used in eyes with varying degrees of refractive error where PRK and LASIK may be less likely to have an excellent outcome. With recent advances in the designs of these lenses and increased safety, the ICL is being increasingly used in eyes with lower refractive errors as an alternative to PRK and LASIK.
There are many benefits of the ICL compared to laser eye surgery. These include the fact the procedure is reversible (in the very unlikely event of an unsatisfactory outcome, the ICL is simple to remove), whereas PRK and LASIK are not. Also, an ICL doesn’t change the shape of the cornea like PRK and LASIK laser eye surgery do. In the future, most people will require cataract surgery, where the natural lens that has become clouded (ie a cataract) is removed. In eyes that have had prior PRK or LASIK, determining the correct strength of lens to implant into the eye at the time of cataract surgery can be very challenging. There is increased risk of the focus not being correct in the eye. In an eye with a prior ICL, this is not an issue and cataract surgery can be performed with confidence that the lens implant that will be inserted into the eye will be correct.
Other benefits include the fact that there are none of the possible complications that can occur in LASIK due to the presence of a corneal flap, such as dislocation from trauma, dry eye and changing corneal shape with time (post-LASIK ectasia).
Dr McLintock provides eye surgery consultations in Brisbane at Upper Mount Gravatt, Taringa, Spring Hill and Hervey Bay. Find your nearest Laser Eye Surgery Brisbane clinic here.