Despite the widespread acceptance of LASIK and the vast amount of public information that is readily available, there are still certain areas of particular interest, as well as sources of potential confusion, to patients who are considering the procedure. In this report, the first of a series, we will examine and clarify some of the most common issues and choices patients face when considering Laser Vision Correction.

Bladeless All-Laser LASIK vs. Microkeratome Blade LASIK

In LASIK, a microscopic corneal flap is created under which an excimer laser applies the patient’s prescription. Healing of the corneal flap is quite rapid, allowing highly functional vision within 12 hours. The corneal flap can be made with a femtosecond laser (bladeless) or with an automated instrument called a microkeratome (using a microscopic blade).  Currently, about two-thirds of the procedures in the United States are done with a microkeratome. Both are excellent methods of performing LASIK, but most importantly, there are no statistical differences in visual outcomes between the two procedures. The prescription that is applied to the eye is the same with both methods and the success rate in achieving 20/20 vision is the same.  There are, however, important differences between the two methods. Microkeratome technology requires more training and experience, yet it is significantly less expensive, takes less time in surgery, and nearly always causes less discomfort than bladeless. Bladeless technology may be a better choice in patients with certain corneal parameters and is generally easier to learn and to use by surgeons who are less experienced in corneal surgery. It is important to choose a surgeon who offers both technologies, allowing the selection of the best procedure for you.

I Have Good Distance Vision but I Hate My Reading Glasses! Is Laser Vision Correction for Me?

Over the past decade, several procedures such as LTK, CK, and multifocal IOLs have been promoted as being able to eliminate reading glasses in patients over 40 while not reducing their distance vision. Despite the desirability of such a procedure, there is no technology that will create normal vision both at near and at distance simultaneously in an eye of a patient over the age of 40. As all patients who wear only reading glasses can attest to, the distance vision is blurred when looking through a reading prescription. Unfortunately, research testing of bifocal laser prescriptions has been uniformly unsuccessful… and, not surprisingly, the laser “time machine” which reverses the normal aging process has yet to be invented! 

Nonetheless, LASIK may eliminate distance and reading glasses simultaneously in patients over 40 given the correct scenario. If a patient can function well with one eye corrected for distance and one corrected eye for near, which is called monovision, and which many patients already achieve by wearing a distance contact in one eye and a reading contact in the other eye, then LASIK monovision is a highly successful option. LASIK monovision corrects one eye for distance and one eye for near, allowing a patient over age 40 to see both without glasses or contacts.

In patients who wear reading glasses only who are not regular contact lens wearers, a short trial of a reading contact lens in the non-dominant eye with their current Eye Doctor can usually determine if they can have LASIK monovision.

Related
• Recurrent Contact Lens Infections: Can I Still Have LASIK?
• Does LASIK Correct Astigmatism Better than Glasses and Contact Lenses?

Recurrent episodes of irritation and infection from contact lenses may range in severity from mild redness and discomfort during prolonged wear, to more severe and sight-threatening complications such as bacterial keratitis and corneal ulceration. Fortunately, most contact lens “infections” are not infections at all, but instead are chronic recurrent inflammatory or allergic conditions associated with contact lenses. Patients sometimes forget, that no matter how advanced contact lens technology may become, a contact lens is still an artificial plastic foreign body in the eye which nature never intended to be there.

Most contact lens irritations which cause redness, soreness, and a mild discharge can be attributed to simple problems such as poorly fitting or dirty contacts, contact lens overwear, or an underlying dry eye condition. In these cases, there is no real infection present, although patients may refer to the redness and irritation incorrectly as “conjunctivitis”.  Conjunctivitis, or pink eye in layman’s terms, more correctly refers to infection of the conjunctiva and may be viral or bacterial in etiology.

One special case of chronic contact lens irritation is Giant Papillary Conjunctivitis, or GPC, in which the patient develops an allergic response to proteins that bind to the contact lens. GPC results in redness, a foreign body sensation, itching, a mucous discharge, and a proliferation of papillae, or bumps, on the inner surface of the lids which cause discomfort. Unfortunately, medications do not treat this condition effectively, the only alternative being a drastic reduction of contact lens wearing time, or in many cases, a complete cessation of contacts.

Bacterial keratitis and corneal ulceration occur infrequently in patients who do not abuse contacts but are very serious sight-threatening conditions that cause severe pain, inflammation, light sensitivity, and if untreated, may cause scarring, corneal perforation, and permanent loss of vision. The risk of bacterial keratitis increases significantly in patients using extended wear lenses, especially if lenses are worn more than two weeks continuously.

Patients with chronic recurrent contact lens irritation and GPC may be excellent candidates for laser vision correction and LASIK. Very simply put, contact lenses cannot irritate the eye if they are not needed. In addition, patients who may not be able to wear contacts comfortably due to an underlying dry eye condition may still be excellent candidates for LASIK. Certain precautions and procedures must be undertaken in patients with dry eye syndrome undergoing LASIK; however, LASIK does not permanently worsen dry eyes.

LASIK may be an outstanding alternative to contacts in patients who have previously had serious corneal infection and ulceration. Microscopic scarring of the cornea from infection or ulceration is not an absolute contraindication to laser vision correction and LASIK. In fact, the laser vision correction procedure can be specifically designed to remove the microscopic scar tissue as well as correct the patient’s prescription.

Next in our series:  “I’m over 40 and I hate these reading glasses!”  Is LASIK Monovision for me?

Patients who have normal distance vision will usually require reading glasses beginning in their early 40’s.  The aging of the proteins inside the human lens leads to a progressive loss of focusing power, eventually resulting in blurred vision at near.  Many patients over the age of 40 can use simple over-the-counter reading glasses for their near vision. It is not surprising that the newly found need for reading glasses is a significant annoyance to people who have previously enjoyed clear vision without glasses for their entire lives. As a consequence, one of the most frequently asked questions about LASIK is whether it will correct the need for reading glasses.

The simple answer is yes, the more complete answer is that it requires LASIK monovision.

As many patients are aware, reading glasses work only for near vision and make everything blurry at a distance. If a patient has both eyes corrected for reading with glasses (or contacts or LASIK), then distance vision is blurred. Only one eye can be corrected for reading if distance vision is to remain clear. The situation where one eye is corrected for distance and the other eye is corrected for reading is called monovision.  The resultant vision is a compromise, and a combination of distance and near vision, and although not absolutely perfect at distance or near, many patients adapt to monovision extremely well. There seems to be a direct correlation between the ability to adapt to monovision and how much an individual dislikes reading glasses.

Many patients use monovision in their contact lenses. If a person has normal distance vision, they can wear a single reading contact in one eye. If a person wears bifocal glasses, they can wear a reading contact in one eye and a distance contact in the other eye.

If a patient is an acceptable candidate for LASIK based upon a number of other factors, LASIK can create virtually any reading or distance prescription, and therefore, can create monovision as well. Prior to having LASIK monovision, a patient must undergo a monovision contact trial in order to test their ability to function and adapt to the vision. Virtually any eye care provider can provide a monovision contact lens trial without requiring the purchase of contacts. Patients typically know right away if they can adapt to monovision and if it would be successful in reducing or eliminating their dependence on glasses and contacts. Patients who are successful with Monovision LASIK are able to enjoy vision at distance and near… without searching for those annoying reading glasses!

Next in our series of articles:

“Seeing Without Glasses after Cataract Surgery: Your Lens Implant Options”

The second article in our series “Considering your Laser Vision Correction Options” addresses the frequently asked question,

Astigmatism is not a disease, but rather a refractive error of the eye which simply causes blurred vision. If the cornea (the front window of the eye) has a surface curvature which is spherical, such as the shape of a basketball, the eye has no astigmatism. If the cornea has a toric shape, like the surface of a football, it has two different curvatures on the surface, and has astigmatism. These two curvatures are usually at right angles to each other with one curvature steeper and one flatter. A greater difference in curvatures creates a larger amount, or magnitude, of astigmatism.

In addition, astigmatism also has an axis (direction) which is determined by the orientation of the steeper curvature of the cornea. Put another way, the football shape of the cornea can be pointed in any direction like the needle of a compass.  Thus, astigmatism has a magnitude and a direction which are equally important.

Glasses and contacts correct blurred vision from astigmatism by using the opposite shape of the correcting lens to “cancel out” the abnormal shape of the eye. For this reason, the frame of the glasses or the fit of the contacts must match exactly the correct magnitude and direction of the astigmatism of the eye. Any deviation in the compensating lens will cause blurred or fluctuating vision. This is why patients with astigmatism and glasses can tolerate very little twisting or maladjustment of the frame as it sits on their face. Similarly, patients with toric (astigmatism correcting) contact lenses frequently notice large fluctuations in vision as the contact lens spins on the eye. These problems arise because glasses and contacts simply compensate for the abnormal shape of the underlying cornea by adding the opposite shape in the correcting lens in front of the eye.

Laser vision correction and LASIK, on the other hand, actually correct the astigmatism by reshaping the cornea, eliminating the two different curvatures, thereby creating the correct spherical shape of the cornea. Laser vision correction actually corrects astigmatism, it does not compensate for the refractive error in a similar manner to glasses and contacts.  As a result, patients with astigmatism frequently notice better vision with LASIK than with contacts or glasses. In fact, with the newest laser software, LASIK can frequently correct larger magnitudes of astigmatism than can even be placed in glasses or is available in contacts. In addition, patients with small amounts of astigmatism who do not wear toric contacts notice better vision after LASIK than with spherical contacts.

Related

Recurrent Contact Lens Infections and the LASIK Alternative