Who Should Not Have Laser Eye Surgery? All You Need To Know

Laser eye surgery is an alternative to wearing glasses and contact lenses to correct imperfect sight due to refractive errors such as short- or long-sightedness. All types of surgery come with advantages but also risks, such as infection or other complications. Though many people are eligible to undergo laser eye surgery, it’s always important to balance the benefits with the potential risk. People who have certain factors or characteristics that may increase their risk of a complication are those who should not have laser eye surgery or who may need to have their expectations more delicately managed. 

How Does Laser Eye Surgery Work?

Laser eye surgery encompasses a group of procedures that correct an eye’s prescription by surgically altering the cornea at its front surface. The cornea is the clear tissue covering the coloured iris and is one of the components of the eyeball responsible for focusing light. The other anatomical component involved in this process, known as refraction, is the crystalline lens. If the light is not focused at a sharp point onto the retina, you will perceive your sight as blurry or unclear. This is the basis of refractive error, which can include:

• Myopia or short-sightedness. This occurs when light is bent too acutely and comes to a focus in front of the retina.
• Hyperopia or long-sightedness. This happens when light isn’t focused enough through the cornea or lens and only comes to a focal point once it’s passed the retina.
• Astigmatism. Astigmatism is slightly different in that it usually occurs because the cornea (or lens) is unevenly curved. This results in light coming to two separate focal points. 

By modifying the curvature of the cornea, laser eye surgery is able to adjust the way that light is refracted through this tissue with the aim of bringing the focus to a sharp point right on the retina.  There are three techniques of laser eye surgery commonly used today. In addition to these, there are also other methods with slight variations. The three main techniques are:

• LASIK (laser-assisted in situ keratomileusis)
• PRK (photorefractive keratectomy)
• SMILE (small incision lenticule extraction) 

LASIK and PRK both involve the process of photoablation, which is the application of an excimer laser tool to selectively vaporise areas of the cornea in order to adjust its curvature. As the excimer laser needs to be able to work on the deeper cells, the upper layers of corneal tissue must first be removed. In LASIK, this is achieved by creating a hinged flap of the upper layers, which is opened to the side to perform photoablation and then later repositioned. In PRK, only the topmost layer of cells, the epithelium, is removed and discarded. The epithelial layer later regenerates during the healing process.  SMILE laser eye surgery works a little differently in that it doesn’t require disruption of the outer cornea. Instead, the beam from a femtosecond laser can pass through these outer cells to create a disc of tissue from the deeper layers. This disc, also known as a lenticule, is shaped in such a way that when it’s removed through a keyhole incision, the resultant corneal curvature corrects the eye’s refractive error. 

Who Should Not Have Laser Eye Surgery?

As LASIK, PRK, and SMILE are all slightly different procedures, the finer details of who should not have laser eye surgery can be dependent on which technique you’re looking at. These are known as contraindications for laser eye surgery. Possible contraindications that apply to all forms of laser eye surgery include:

• Having a condition that impairs healing. Conditions that inhibit the body’s healing response, such as keloids or autoimmune disease, can be a contraindication to laser eye surgery as it may result in haziness of the cornea and suboptimal sight post-operatively.
• Corneal infection. Applying a laser to a cornea with an active infection or ulcer may result in further, uncontrolled damage to the corneal tissues. Some surgeons may also be hesitant to perform laser eye surgery on people with a past history of herpes eye infection (keratitis), as the laser may reactivate the virus.
• Keratoconus. Keratoconus is a disease in which the cornea thins and bulges. As laser eye surgery involves removing tissue, it may weaken this structure further and significantly impair sight. 
• Taking isotretinoin. Also known as Accutane, this medication is often prescribed for skin acne. However, it’s also associated with significant post-operative dry eye in patients who undergo laser eye surgery.
• Taking amiodarone. Amiodarone is a medication prescribed for heart arrhythmia. Studies have shown that this drug may be associated with visual disturbances after having laser eye surgery, such as seeing flashing lights or coloured rings.
•  People under the age of 18. Your surgeon may have a higher minimum age, such as 21. The purpose of this contraindication is that the eyeball is still growing and changing under this age, which can result in your refractive error continuing to change after you’ve had laser eye surgery. 
• Dry eyes. One of the more common side effects after laser eye surgery is dry eyes. Those who have severe pre-existing dry eyes or another condition that makes them susceptible to dry eyes are among those who should not have laser eye surgery.

A comprehensive consultation with your surgeon will be able to identify whether you are among those who should not have laser eye surgery. Call us on (03) 9070 5788 today. Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner. 

References

LASIK: A Primer for Family Physicians. https://www.aafp.org/pubs/afp/issues/2010/0101/p42.html#:~:text=Contraindications%20include%20the%20use%20of,eye%20trauma%20should%20avoid%20LASIK.  Contraindications for Laser Vision Correction. https://eyesoneyecare.com/resources/contraindications-for-laser-vision-correction/ [/fusion_text][/fusion_builder_column][fusion_global id=”13433″][/fusion_builder_row][/fusion_builder_container]