lasik for astigmatism melbourne

LASIK for Astigmatism – How Does The Treatment Work?

Many patients believe that they are unable to access laser eye surgery due to their prescriptions involving astigmatism. While this may have been true in the past, with advancements in our ability to make precise calculations during laser eye surgery to accurately correct astigmatism, LASIK for astigmatism is now in fact just one of several refractive surgical techniques used to give an astigmatic patient clear vision without depending on glasses or contact lenses.

 

What is Astigmatism?

Before delving into how LASIK eye surgery, or any laser eye surgery, can be used to correct astigmatism, it helps to first understand what astigmatism is.

Astigmatism is a type of refractive error, an imperfection of the eye’s focusing system which leads to blurry or uncomfortable vision. It may occur alongside either long sightedness (hyperopia) or short sightedness (myopia). Most cases of astigmatism arise due to an uneven curvature of the cornea, which is the transparent dome at the front surface of the eye. This results in light entering at different positions through the cornea being bent, or refracted, by different degrees. The outcome of this is that different rays of light come to focus at two distinct points on the retina at the back of the eye, which we then perceive as blurry or distorted vision. A less common source of astigmatism is the crystalline lens inside the eye, in a case known as lenticular astigmatism.

Many eyecare practitioners will use the analogy of an AFL football versus a soccer ball – on an AFL football, following one line along the ball from tip to tip results in a flatter curvature than if you were to trace along the perpendicular meridian, around the girth of the ball. Conversely, a soccer ball is perfectly round and you will find the same degree of curvature no matter which line you follow around the ball. When it comes to the cornea or lens, light is refracted more sharply when passing through the steeper curve, which results in these rays coming to a focus point earlier within the eye than rays that passed through the flatter line of curvature, which will focus to a point further in the eye.

Patients with uncorrected astigmatism may find they experience:

  • Glare sensitivity, such as seeing oncoming car headlights or streetlights as a “starburst”
  • Ghosting, which refers to the perception a faint double image where there is only one object
  • Headaches, often after prolonged reading or other near vision activities

Originally, the only way to correct astigmatism was through the use of spectacle lenses. Since then, contact lens technology has developed to be able to correct higher degrees of astigmatism, and now soft contact lenses can often cover prescriptions of up to almost -6.00 dioptres of astigmatism; custom-made hard contact lenses can often correct astigmatism even higher than this.

Patients with astigmatism can be assured that now LASIK eye surgery, other forms of laser eye surgery such as PRK, and refractive techniques that don’t involve a laser, such as refractive lens exchange, are considered safe and accurate methods of surgically correcting astigmatism.

 

How Does LASIK for Astigmatism Work? 

LASIK for astigmatism works much the same way as general LASIK eye surgery. Laser eye surgery procedures work on the premise of reshaping the cornea through the process of photoablation, the removal of select areas of corneal tissue in order to redirect the passage of light through this surface.

After topical anaesthetic is applied, a flap of superficial corneal tissue is first created using either a manual bladed instrument or a femtosecond laser tool, and then moved aside while still remaining attached to the eye. An excimer laser is then applied to the underlying corneal layers for the reshaping process, and the corneal flap then repositioned when the work is done.

In order to accurately correct refractive error with LASIK eye surgery, whether the script involves astigmatism or not, precise mathematical wavefront measurements are taken of the eye and then fed into a complex computer algorithm, along with other biometric data of your eye. This then guides the excimer laser during surgery to ensure the correct areas of the cornea are subject to photoablation of just the right amount to correct your prescription. As astigmatic scripts can be a complex combination of both corneal and lenticular sources of astigmatism, it is important to be able to achieve precise biometric measurements prior to going into surgery, something that was not always available. With advancements in the ability to make accurate wavefront calculations, LASIK for astigmatism of up to around 5 dioptres has become possible.

As with any laser eye surgery, general eligibility criteria do apply for people interested in LASIK eye surgery. As LASIK involves removal of corneal tissue, it is important to establish a minimum corneal thickness to ensure that a sufficient amount of tissue remains to maintain the mechanical stability and integrity of the eyeball. As higher prescriptions typically require a greater amount of photoablation, a patient with a script within the treatable range may find they are in fact unsuitable for LASIK due to insufficient corneal tissue available to address their script. Such people may be guided towards another refractive procedure, such as PRK, intraocular contact lens, or refractive lens exchange.

 

 

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

lasik eye surgery Mornington

LASIK Eye Surgery – Are The Risks Worth The Cost?

LASIK eye surgery for the correction of refractive error was first approved in the mid-90s. Ever since then, LASIK surgery has gained popularity around the world, performed millions of times for people looking to gain some independence from glasses and contact lenses. Though any sort of surgical procedure carries with it some risk of complication or adverse outcome, the success rates of LASIK eye surgery in Australia and the developed world are excellent, sitting close to 100%. If you’ve ever thought about taking steps to be able to leave those spectacles in the drawer all day, read on for what you need to know about LASIK surgery.

 

What is LASIK?

LASIK is short for laser assisted in situ keratomileusis. LASIK surgery is just one of the several techniques of refractive surgery readily available across Australia, which also include procedures such as PRK (photorefractive keratectomy), SMILE® (small incision lenticule extraction), and ICL (implantable contact lens). The ultimate goal of all these refractive surgical methods is to correct the way that light bends through the eye so that you can achieve clear vision without needing to put on glasses or insert contact lenses. For some, this results in sharp vision across all distances without the need for any optical aids; for others, this may provide perfect vision at either long distance or up close while the patient still prefers to wear glasses for certain activities.

lasik eye surgery in Mornington

Like all other refractive laser procedures, LASIK eye surgery works by reshaping the cornea, which sits at the front surface of the eye. The result of this is that light bends, or refracts, to focus at a sharp point on the retina at the back of the eye instead of falling behind this plane (as is the case in long-sightedness) or before the plane of the retina (as in short-sightedness).

LASIK surgery is a two-step procedure. The first step is to move aside the top layers of the cornea by forming a hinged flap of tissue, which is comprised of the epithelial layer of the cornea as well as a small part of the underlying stromal tissue. Some surgeons prefer to use a manual bladed instrument for this step while other specialists use a femtosecond laser tool. An excimer laser is then applied to the exposed stroma of the cornea in a process called photoablation, which involves the removal of selected areas of tissue that are calculated to correct the refraction of light through the corneal surface. After the excimer laser has completed its reshaping work, the flap of superficial corneal tissue is then repositioned and allowed to self-heal.

 

What is LASIK Used For? 

Long-sightedness (also known as hyperopia), short-sightedness (also called myopia), and astigmatism are all types of refractive error. Depending on the patient’s age and the magnitude of their refractive error, vision may be blurry only at certain distances, such as for objects far away for myopic patients, or can be blurry at all distances, such as for a hyperopic patient over the age of 50.

LASIK eye surgery can be used to address all these types of refractive errors up to certain limitations. These limitations are largely guided by the amount of corneal tissue available in each eye for the photoablation process as there must remain a minimum corneal thickness after the procedure to maintain the integrity of the eye’s surface. As a general rule, LASIK surgery can correct prescriptions of:

  • Myopia between -1.00 to -10.00 dioptres
  • Hyperopia up to +4.00 dioptres
  • Astigmatism up to -4.00 dioptres

lasik eye surgery at MorningtonPatients over the age of around 45 will typically start to experience another type of visual difficulty known as presbyopia, which is the natural age-related deterioration of near vision. Though not all presbyopic patients are appropriate candidates, LASIK eye surgery may be used to address both refractive error for distance vision as well as the presbyopia for reading vision.

This can be done with an arrangement known as monovision, which involves one eye being surgically corrected for distance vision and the other corrected for near vision; alternatively, a variation of LASIK surgery known as Presbyond can provided laser blended vision, where both eyes are surgically corrected with a degree of both long and short sight in each eye.

Some patients, due to various factors including corneal thickness, may fall outside the eligibility criteria for safe LASIK eye surgery. However, this does not necessarily mean they are unsuitable for refractive surgery altogether. LASIK surgery is just one of a number of refractive surgery techniques, all of which come with their own benefits and disadvantages. If you are considered unsuitable for LASIK eye surgery on the basis of thin corneas, your eye specialist may direct you to another technique more suitable for your eyes, such as PRK. Bear in mind that though LASIK surgery is not ideal for situations such as thin corneas or patients with hobbies or vocations that involve a risk of physical trauma, it does carry advantages in other aspects, such as a faster visual recovery time and less post-operative discomfort when compared to PRK.

 

What to Expect After LASIK Surgery

After LASIK eye surgery you will notice a significant improvement to your vision as soon as within 24 hours. There may be some dryness and irritation of the eye as it heals but your eye specialist and clinical team will provide you with post-operative care instructions, a protective eye shield, and a few eye drop medications to support recovery. Many patients feel well enough to return to work the day immediately after surgery, though this depends in part on the nature of their vocation.

 

If you have questions about LASIK eye surgery contact us on (03) 9070 3580 LASIK coordinator for more information and to determine if you’re a good candidate for eye surgery.

 

 

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.