Risks of Refractive Surgery
WHAT IS INVOLVED?
It is my hope to inform you concerning the side effects, limitations and complications of laser refractive surgery. It is a struggle to balance the benefits of laser surgery with the known and the unknown risks. Please understand this important message:
It is impossible to perform any form of surgery without risks. All patients need to be willing to accept a certain degree of responsibility for these risks.
My intention is not to frighten or dissuade someone from pursuing laser surgery, as most of my patients will never encounter any serious complications, and the vast majority are pleased with the improvement they achieve. It is my intention, however, to accurately outline the associated risks to all candidates so that they may either elect not to accept the risks associated or be better prepared to deal with any unexpected complication or side effects. The only way in which a patient can avoid all surgical risks is by not proceeding with surgery.
There is a risk of INFECTION with all laser refractive surgery. The risk of serious infection is far less in LASIK than in PRK. The risk is reduced five fold from approximately 1/100 with PRK to 1/5000 with LASIK.
Refractive problems that may be encountered include too much correction, too little correction, a prescription imbalance between eyes, aggravation of muscle imbalance problems or a loss of effect from regression. LASIK and PRK may result in over corrections and under corrections due to the variability in patient healing patterns and other surgical variables, leaving patients nearsighted, farsighted, or with astigmatism. This may or may not require patients to wear spectacles, contact lenses or undergo further surgery.
Incidence of significant over correction: 1 in 100
Incidence of significant under correction: varies with prescription
There is a risk of PAIN with all laser refractive surgery, the risk of pain is far less in LASIK than in PRK. This risk of pain is reduced fivefold from approximately 1/10 with PRK to 1/50 with LASIK. It is common to feel a mild foreign body sensation similar to an eyelash sensation. It is common for patients to have some; light sensitivity, tearing, mild redness and swelling following the surgery.
The risk of SCAR TISSUE or CORNEAL HAZE (see photo) from LASIK is less than 0.5%, this is 1/5 to 1/10 the rate as compared to PRK. The risk of scar tissue formation with PRK ranges from 1-5%, increasing in incidence with the degree of attempted correction, Scar tissue is composed of collagen proteins which develop on the surface of the eye with PRK and beneath the corneal flap with LASIK. It presents usually as a dirty windshield type of appearance to your vision.
Night Glare is common in nearsighted individuals even before any refractive procedure is performed but increases almost immediately in the healing process and is more common when only one eye has been treated. Typically, 6 months after both eyes have been treated, only 2% of patients still experience significant night glare which seriously interferes with their night driving. Severe night glare can reduce vision in all reduced lighting conditions producing blurriness, ghosting or haloes. Patients with large pupils and severe myopia are at greatest risk for night glare.
BLURRINESS OR LOSS OF BEST CORRECTED VISION:
Almost all patients describe BLURRINESS immediately following surgery. Blurriness to one degree or another is common. With the LASIK procedure there is considerable improvement in vision within the first 24-48 hours. Approximately 80% of the visual recovery occurs within the first several days, with the last 20% of vision improving over 3-6 months. Patients experience a large quantitative jump in vision within days, with the qualitative “fine tuning” or sharpness of vision taking much longer, in the order of several weeks. Many patients do experience a profound and dramatic visual improvement and become able to read half or more of the eye chart the next day, but most state it is still not clear and crisp, and has been described as “Vaseline Vision”.
Approximately, 1-2% of patients independent of the procedure performed will develop corneal irregularities reducing the sharpness, crispness, and clarity of their vision preventing them form reading the bottom 2 or more lines on an eye chart that glasses, contacts or another surgery cannot restore. That is, the initial blurriness resolves in 98-99% of patients over 6-12 months, however it may be permanent in 1-2% of treated patients. There is no way of predicting or predetermining who will be in this 1-2%. A patient that loses sharpness, will have vision that is permanently worse. All forms of eye surgeries alter human tissue and possess some risk.
Regression refers to the tendency of the eye to bounce back somewhat towards your original prescription following Laser Vision Correction. If your vision regresses, you may require an enhancement procedure or a thin pair of glasses. In most cases, the regression experienced is minimal and is accounted for when planning your procedure. In some cases, glasses for night driving may be all that is required by a patient who experiences regression.
It is essential that you understand as much as possible about the risks associated with the excimer laser procedure. The risk of having a serious vision-threatening complication is much less than 1%, however, the excimer laser procedure, like all surgical procedures, has limitations and risks.
CORNEAL FLAP COMPLICATIONS:
The entire incision time is approximately 2 seconds, but during this brief interval a lot of things need to go right. The overwhelming majority of LASIK complications are related to the creation of the corneal flap. Primarily, there must be adequate internal suction pressure within the eye. Suction pressure and microkeratome assembly and function determine the thickness of the corneal flap of tissue. There is a 1% risk that the eye will experience a corneal flap complication. The primary result of inadequate suction pressure is a corneal flap that is too thin which may result in (1) postponing the procedure for three months; permanent blurred vision. Other potential flap complications include a corneal flap incision which is too long, resulting in a free flap, this may increase the potential for prolonged visual recovery, blurred vision and epithelial ingrowth (discussed below). Corneal flap incisions which are too short necessitate postponing surgery for three months. The most dangerous risk is if the incision goes too deep, this may result in perforation of the eye and immediate blindness. There is a plate in the microkeratome that prevents the incision from perforating the eye. The plate and microkeratome assembly is checked before each and every procedure and the unit tested for proper functioning.
PROLONGED SURFACE HEALING:
During the LASIK surgery, the corneal surface is essentially left intact on the flap. Sometimes the outer layer of cells is not sufficiently attached to the underlying tissue. When this is so, the process of using the microkeratome may remove a small portion of the outer cell layer. This will cause pain in the post-operative period for up to two days as the cornea heals. This condition responds well to either patching the eye or using a soft contact lens as a bandage, along with additional pain medication. Visual acuity will be reduced during the healing process.
During the first 24 hours the epithelial protective layer grows over the corneal flap. There is a 2% risk that epithelial cells may grow underneath the flap. This is more common in people with weak protective layers which bond poorly to the eye surface. Any intra-operative breakdown of the protective layer may increase the incidence of epithelial ingrowth. Treatment involves lifting the flap and clearing the cells. Untreated epithelial ingrowth may distort vision and may actually damage the flap if severe and progressive. Small ingrowths do not usually present any visual problems and need only be monitored.
1% of patients develop significant complications (note, this goes up significantly higher in surgeons who are in their learning curve). NO ONE ever believes they will be in the 1% of people who have complications. LASIK performed for severe myopia and astigmatism is associated with a higher risk of complications; approximately 2%. No one has ever gone blind from Excimer laser surgery BUT you could be the first.
There are no guarantees of perfect vision. There are no guarantees of zero glasses or contacts. There are no guarantees that you will not be in the 1% of people that have significant complications. LASIK carries a higher risk of perforation and blindness than PRK, but a lower risk of pain, infection, scarring with faster recovery and less need for eye drops. LASIK carries a higher risk of intra-operative complications and lower post-operative complications.
The goal of the procedure is to achieve the best visual result in the safest way. The goal is NOT to eliminate glasses and contacts completely but to dramatically reduce the dependence upon them. Night driving glasses and readers may always be needed even with a successful procedure.
The degree of correction required determines both the rate of recovery and the initial accuracy of the procedure. Severe prescriptions require at least two procedures. Patient differences in healing will also greatly affect visual recovery and final visual outcome and is impossible to predict.
As discussed, even 90% clarity of vision is 10% blurry. Enhancement surgeries can be performed when vision is stable UNLESS it is unwise or unsafe. Typically if -1.00 diopter or greater correction remains or vision is 20/40 or worse, an enhancement may be performed. Enhancement surgeries are generally performed no sooner than 3 months after the first surgery. Generally, at this point there is no need to make another cut with the microkeratome, the original flap can usually be lifted with specialized techniques. After 6 months of healing, a new LASIK incision is usually required, incurring a greater risk.
In order to perform an enhancement surgery, there must be adequate tissue remaining. If there is inadequate tissue, it may not be possible to perform an enhancement. An assessment and consultation will be held with the surgeon at which time the benefits and risks of an enhancement surgery will be discussed.
IMPROVEMENT OF VISUAL POTENTIAL:
Patients who do not see 20/20 or 100% before surgery even with the strongest prescription cannot expect to anticipate 100% after surgery. That is, after the best vision a patient can attain is the vision they experienced per-operatively with their correction. This surgery does not improve visual potential.
Everyone over the age of 40 will eventually experience presbyopia, resulting in the need for reading glasses or bifocals. In monovision the aim is to have the non-dominant eye a little under-corrected to help reading vision. This involves giving up a little distance sharpness. Night driving glasses are more common and readers may still be required for fine print or prolonged reading BUT overall dependence is still dramatically reduced. Monovision helps with simple near tasks such as opening mail reading price tags, or looking at one’s watch. Patients who desire the best distance vision unaided should avoid monovision.
An important note from Dr. Thompson:
See: Risks of Refractive Surgery. Remember surgery is surgery and all surgery has risks. This is not meant to discourage you but these are facts you should know if you plan to have surgery preformed. This office is extensively involved in refractive surgery and would be happy to meet with you and discuss your case. I have personally had refractive surgery. But, just because these risks were acceptable to me does not mean they will be acceptable to you. I strongly recommend you educate yourself prior to surgery and then consult a knowledgeable eye care provider to further guide you through the procedure and follow-up. Pre and post operative care is critical in maximizing your chance of a good outcome.
Our office policy is to educate our refractive surgery patients well enough that they have realistic expectations and know the risks before they commit to the surgery, we believe in informed consent. Once the decision is made, it is our goal to get that person to the best surgeon for the amount of money they want to spend.