Reviewed by Marc Michelson, M.D.
LASIK is by far the most popular Laser Eye Surgery for patients wishing to correct nearsightedness, farsightedness and astigmatism. In your decision to explore LASIK Eye Surgery as a method to correct your vision, you may be left with the impression that LASIK is a possibility for everyone who wants to have it. The information we have provided in www.seewithlasik.com is a broad overview of things to learn and consider before deciding to proceed with the LASIK consultation. The section regarding LASIK Risks and Complications is important for you to read carefully. In addition, we would like to provide the details of certain LASIK contraindications or reasons why you should not have LASIK.
You should know that there are really two types of contraindications. First there are absolute contraindications. If you have an absolute contraindication, it means that you have a clinical finding, condition or health reason to absolutely NOT have LASIK. Then there are relative contraindications. These are reasons, clinical findings or health conditions that mean that you would be considered to have a high likelihood of achieving the typically excellent safety, efficacy and predictability that the vast majority of LASIK patients enjoy. If you have a relative contraindication, it means that your LASIK surgeon will have to take special precautions in your treatment plan and actual surgery and even so, the results you achieve may not be quite as predictable.
Successful LASIK surgery requires a sufficient amount of corneal thickness so that after creating the flap and applying the laser, there is a threshold amount of corneal tissue remaining that has not been altered by the procedure. This threshold amount that needs to be left intact, is the amount necessary for the cornea to maintain is rigidity and its shape and is fairly agreed upon measurement by LASIK surgeons. Measurement of the corneal thickness of the cornea is performed with an instrument called a pachymeter. If you have a thin corneal measurement and you also have a significant degree of refractive error-nearsightedness, farsightedness or astigmatism-to be corrected, it may not be possible to leave the critical threshold of intact corneal tissue in place. Sometimes as part of your treatment plan, it is possible for the LASIK surgeon to create a thinner flap and overcome this anatomical problem that is unique to your cornea. This would be considered a relative contraindication for LASIK. If, it is not possible for the LASIK surgeon to create a thinner flap, then he or she might recommend that your treatment might be better performed with PRK, LASEK or Epi LASIK since there is no flap to create and thus no real concern about the remaining intact corneal tissue that must be left in place.
In some instances there is a true structural limitation of the cornea in patients who have a condition called Keratoconus. Keratoconus is a disease characterized by a pathological thinning of the cornea. It is also progressive in that it continually gets thinner and bulges into a "cone" shape causing major distortions to your vision. Keratoconus is an absolute contraindication for having LASIK and really any type of refractive Laser Eye Surgery.
The calculations for determining the amount of intact corneal tissue that must be left are quite straightforward. However, the amount of tissue that the laser will remove to correct your vision is a bit more difficult to calculate. The amount of tissue to be removed by the laser is called the ablation depth. Ablation depth depends not only on the prescription to be corrected, but also on your pupil size and whether or not you need a traditional or Custom LASIK procedure. In general, Custom LASIK is produces greater ablation depths and thus requires patients to have greater corneal thickness before their surgery. Custom LASIK corrects not only the nearsightedness, farsightedness or astigmatism-the so-called low order aberrations, but corrects even the most complex types of aberrations that plague some patients' night vision. In order to fully correct this, it requires greater ablation depth and thus greater corneal thickness.
So, large pupils and or Custom LASIK can potentially be a relative contraindication and may require a modification of your LASIK surgery plan in order to obtain the best results for your eyes if you do not have sufficient corneal thickness. Fortunately, all of these situations can be measured and planned for and compensated for during your consultation. If in fact you simply do not have sufficient corneal thickness, then the LASIK surgeon will recommend a different procedure or perhaps against have refractive Laser eye surgery at all.
General Health Conditions
Patients who suffer from certain systemic diseases may have relative or absolute contraindications to LASIK. For example, if you suffer from Lupus Erythematosus, Rheumatoid Arthritis, or Fibromyalgia it suggests that you have a compromised auto immune system. People with compromised autoimmune systems, sometime do not heal in a predictable fashion. For that reason, depending on the type and whether your autoimmune disease is well controlled, you may have a relative or absolute contraindication to LASIK and other refractive Laser eye surgery procedures.
Patients who suffer from diabetes also may have relative or absolute contraindications to LASIK. LASIK requires good stability of your blood sugar measurement over a prolonged time in order to be certain that there is accuracy in the measurement of your prescription. Also, in certain instances diabetes can cause dIabetic retinopathy that may compromise vision due to changes in the retina. This too may be a contraindication to LASIK.
Recently, Spanish researchers reported on a retrospective case-controlled clinical study to determine the anatomic and functional outcomes of corneal laser eye surgery in patients with underlying systemic diseases considered to be relative or absolute contraindications.
These typical contraindications included autoimmune connective tissue disorders, intestinal inflammatory diseases, diabetes and keloid formation.
The results showed that any mild anatomic complications that were observed were found in equal percentages between the case and control groups with mo statistical differences. They did find that refractive outcome was significant worse in the collagen vascular diseases group compared with controls. No other statistical differences were detected in the other systemic disease groups.
According to the study’s authors, LASIK can be performed effectively and safely in selected patients with stable and controlled systemic diseases with favorable postoperative anatomic and visual outcomes. They believe that the absolute exclusion of certain systemic contraindications should be reconsidered.
Patients who are pregnant, anticipating becoming pregnant or who are currently nursing presents another relative contraindication to LASIK as well as other refractive Laser Eye Surgery procedures. During pregnancy and nursing, the hormonal changes that are a normal part of the process, may cause your prescription to become unstable making LASIK a relative contraindication until several months after you have completed nursing.
Eye Health Conditions
Patients, who have even the very beginnings of the formation of cataracts, or clouding of the crystalline lens, are considered to have an absolute contraindication for LASIK as cataracts are generally progressive and worsen over time necessitating their surgical removal and replacement of the crystalline lens with and intraocular lens. Fortunately, while these patients may not be good candidates for LASIK - they typically will be good candidates for Crystalens or ReSTOR ReSTOR & Crystalens Lens Replacement Surgery during which their nearsightedness or farsightedness can be corrected as the new lens is implanted.
Patients who are being treated for glaucoma and currently using eye drops are also considered to have contraindications to LASIK. In fact, if you have a history of serious past eye infection from Ocular Herpes this too may preclude you from having LASIK, but may only be a relative contraindication if the LASIK surgeon is able to use oral and topical medications before your treatment to prevent a recurrence of your infection. Patients, who have had a retinal detachment with surgery to restore their vision, also pose a relative contraindication to LASIK. For these patients, a confirmation by a Retinal Surgeon that their eye is healthy enough and the retina will not be harmed during the LASIK procedure is necessary.
LASIK requires that you have sufficient tear quantity and quality to heal properly. If you have been a long-term contact lens wearer, take certain medications, or have other health or age related conditions that cause you to have dry eyes, you may have a relative contraindication to LASIK. During your consultation, the surgeon and staff will carefully examine your tears. If you have a relative contraindication due to dry eyes, he or she will likely recommend a number of possible approaches to enable your tears to be adequate for LASIK surgery. These approaches can be as simple as the use of artificial tears and lubricating drops, dietary supplements, insertion of punctual plugs to help you retain tears, or even a prescription medication called Restasis, to help you produce more of your own tears naturally. If even after you have taken these significant therapeutic measures to overcome the relative contraindication of dry eyes, and not been able to achieve a good tear film quantity and quality, then you would not be considered a good candidate for LASIK.
Stability of Prescription
To obtain the best results from LASIK it is important that all measurements-especially that of your prescription is accurate and consistent. In general LASIK surgeons prefer to have patients where it can be demonstrated that they have had little or no change in their prescription for about 12 months prior to their LASIK surgery date. Refractive stability is a relative contraindication as for some patients who fully understand the risk of the lack of stability; the benefit of dramatically improved vision may outweigh the risk of less than optimum predictability. Usually in order to have good refractive stability, LASIK surgeons will not treat patients less than 18 years of age as their eyes may still be changing.
This discussion of LASIK contraindications is meant to provide you with a working knowledge of the common conditions that may mean that you either cannot have LASIK, should have another Laser Eye Surgery procedure or can have LASIK with certain careful considerations. It is not exhaustive and may not list everything that you might possibly experience. For a complete understanding of LASIK Eye Surgery contraindications, it is best to fully discuss your individual situation with a LASIK surgeon or their staff.