Top 10 Questions about LASIK & Corneal Thickness

Corneal thickness is one of the main factors that your surgeon takes into consideration when determining if you are a good LASIK candidate.

To understand why corneal thickness is important in LASIK eye surgery, let’s answer the most common questions about the relationship between LASIK and corneal thickness.

What is the Normal Corneal Thickness?

The thickness of the cornea normally varies between people with an average of about 550 microns (that’s about 1/2 millimeter) in Caucasians. It is less in Blacks (520 microns) and even less in Asians.

How Corneal Thickness is measured?

Corneal thickness is measured with a device known as a pachymeter. The most common method of pachymetry is ultrasound, but certain corneal imaging systems such as Orbscan and Pentacam can also be used. The latter systems can provide a map representing the relative thickness of your cornea at various locations.

What is the Ideal Corneal Thickness for LASIK?

There is no ideal corneal thickness for LASIK. However, you should know that to improve your vision by LASIK surgery, you should have an adequate amount of corneal thickness. This amount depends on the degree of your refractive error.

Why Corneal Thickness is measured before LASIK Surgery?

It is important to determine your corneal thickness before your LASIK procedure because LASIK improves your vision by reshaping your cornea and it reshapes it by removing some tissue from your cornea. If the cornea is made too thin, vision may fluctuate and be of poor quality.

What is the Ablation Depth?

Ablation depth is the amount of tissue removed by the excimer laser from the middle layer of the cornea called the stroma. If you are shortsighted, the removal is in the center of your cornea. If you are farsighted, the removal is at the periphery of your cornea.

How Ablation Depth is calculated?

Ablation depth depends on the amount of treatment required, which in turn depends on the degree of your refractive error. Pupil size and parameters of the chosen excimer laser are other factors that affect the Ablation Depth.

In general, we can assume that with a pupil size of 6.0 mm, the excimer laser removes 12 microns of tissue for each diopter of LASIK treatment.

For example, if you have 4 diopters of shortsightedness, the ablation depth required to correct you vision would be 4 x 12 = 48 microns.

What is the Residual Stromal Bed?

Your LASIK surgeon will ensure that after creating the flap and applying the excimer laser, there is a minimum amount of corneal tissue remains untouched by the LASIK procedure. This critical amount is called the Residual Stromal bed and it is important to preserve the strength and integrity of your cornea after the LASIK procedure and avoid serious LASIK complications such as corneal ectasia.

How thick the Residual Stromal bed should be?

When the U.S. Food and Drug Administration (FDA) approved LASIK, it recommended that a minimum of 250 microns of residual stromal thickness should be left under the flap after LASIK surgery to avoid corneal ectasia.

Currently, most LASIK surgeons prefer to leave 275-300 microns of residual stromal bed for more safety and also to allow for LASIK enhancement (retreatment), should this be necessary.

How Residual Stromal Bed Thickness is calculated?

Residual Stromal thickness is calculated by taking the central corneal thickness before LASIK and subtracting the flap thickness and the calculated ablation depth for the particular refraction.

For example, if your central corneal thickness is 550 microns, the flap thickness is estimated to be 160 microns, and the ablation depth for your refraction is 60 microns, the residual stromal bed thickness would be 550 – (160 + 60) = 330 microns.

Can I Have LASIK if I have a high prescription and thin cornea?

If you have a thin cornea and a high degree of refractive error to be corrected, it may not be possible to leave the minimum 250 microns of residual stromal bed under the flap.

Sometimes, your surgeon can overcome this problem by creating a thinner flap, which allows more treatment to be performed while maintaining a corneal bed of at least 250 microns. Thinner LASIK flaps can be created either by the femtosecond laser flap maker during IntraLASIK or some types of microkeratomes during conventional LASIK.

If it is not possible to create a thinner flap, then other LASIK alternatives such as PRK, LASEK or Epi-LASIK might be a better option for you.

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What Are You Expecting LASIK Will Do For You?

If you are considering LASIK eye surgery to improve your vision, you will need a LASIK consultation.

In other words, you will need to consult an experienced LASIK surgeon to discuss your unique visual needs and find out if you are a good LASIK candidate.

Sounds simple, and it is. There’s just one problem.

Too often, you get caught up in how LASIK is performed. How common are the LASIK complications? How to choose a LASIK surgeon? How does Bladeless LASIK differ from standard LASIK? How much does LASIK cost? How to Finance LASIK Surgery?

And then you get surprised when your doctor tells you that you are not a good LASIK candidate.

During your LASIK consultation, your surgeon will evaluate your expectations and determine if they are realistic.

If you demand perfection and have too high expectations of LASIK eye surgery, your surgeon may consider you poor LASIK candidate even if you meet the medical and ophthalmic criteria for the LASIK procedure.

Over the last weeks the poll I’ve been running here on LASIK Guider has asked our valued readers about their LASIK expectations. The question was: What are you hoping LASIK eye surgery will do for you? The provided answers were:

• To get rid of my glasses and contact lenses.
• To become less dependent on glasses and contact lenses.
• To be more attractive.
• I don't know, I just want the surgery.

Let’s now see the results and comment on each response to learn how to adjust your LASIK expectations to avoid being rejected to undergo LASIK.

Get rid of My Eyeglasses and Contacts (76%)

This is the most common response because one of the major reasons for undergoing LASIK surgery is the annoyance of caring for and wearing eyeglasses or contact lenses.

So if you consider your eyeglasses or contacts really a pain, keep in mind that the main goal of LASIK eye surgery is to improve your vision and reduce your reliance on eyeglasses and contacts.

But eyeglasses may be needed for reading when you reach the middle 40s.

Glasses may also be needed for some distance activities, such as driving at night or in the rain. But it is rare for patients to request distance glasses after LASIK.

To Become Less Dependent on Glasses & Contacts (12%)

After reading the previous response, you know now that this is the ideal answer.

I Want To Be More Attractive (8%)

Eyeglasses are cosmetically unappealing for some. Many patients undergo LASIK because they feel that they will be more attractive without glasses in social and professional situations. If this is your case, why not give contact lenses a try before undergoing LASIK?

I don't Know, I just want The Surgery (4%)

No one would undergo a surgery with a potential risks and complications without having a good reason.

Think again because responses like this one are not appropriate and should raise a red flag about your candidacy for the LASIK procedure.

Conclusion

It is important to be aware of the LASIK procedure’s benefits, limitations, risks, complications and alternatives.

But you should understand that having expectations that are realistic for your particular case is most important to your final satisfaction with the results of the LASIK procedure.

Now, what are hoping LASIK surgery will do for you? Let me know in the comments.

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How All-laser Bladeless LASIK is performed?

All-laser LASIK is 100% blade-free LASIK procedure. In All-laser LASIK, your surgeon will use a femtosecond laser technology to create the corneal flap, the critical first step in the LASIK procedure.

But How Does a Femtosecond Laser Create a LASIK Flap?

Let’s find out by discussing how All-laser bladeless LASIK is performed step by step.

All-laser Bladeless LASIK is an outpatient refractive surgery procedure. It is done under local anesthesia in a surgeon's office or a same-day surgery center.

It is performed while you are awake, but sometimes you may be given a mild sedative such as Valium to make you relax. Usually both eyes are operated on at the same time, but if you prefer, it can be done one eye at a time.

Eye Preparation for the LASIK Procedure

• A few minutes before the LASIK procedure, a number of eye drops will be placed in your eye. These eye drops will numb your eye and prevent infection.
• A special solution, betadine, is used to clean around your eyes.
• A sterile adhesive drape is used to isolate the eye surface from the eyelids and surrounding face, as well as retract the lid margins.
• A small holding device is placed between your eyelids to keep your eyelids wide open and prevent you from blinking during the procedure.

LASIK Flap Creation with Femtosecond Laser

Unlike the conventional LASIK procedure, the IntraLASIK technique creates the corneal flap by applying tiny fast pulses of infrared laser light, not a microkeratome with a metal blade.

Each pulse of light passes throughout the top layers of the cornea and forms a microscopic bubble at precise depth and position within your cornea that is determined by your surgeon.

As femtosecond laser moves back and forth across your eye, a uniform layer of these bubbles is created just below the corneal surface.

Your surgeon creates your LASIK flap by gently separating the tissue where the bubbles where formed.

The corneal flap is then folded back so the surgeon can perform the second step of your vision corrective treatment.

Laser Corrective Treatment (Excimer Laser Ablation)

The creation of the corneal flap prepares your eye for the second step of the LASIK procedure, where another laser known as excimer laser is used on the inner cornea to correct your vision.

In a series of short pulses, the excimer laser will reshape your cornea by removing some tissue from the middle layer of the cornea. A computer controls the amount of laser energy delivered to your eye according to your refractive error.

After completion of the laser ablation process, your surgeon will replace the flap back into its original position. The flap acts as a natural bandage over the treated area, promoting rapid recovery.

After The LASIK Procedure

• You should follow your doctor’s instructions after LASIK eye surgery.
• You may be able resume your usual activities the next day, but I recommend a couple of days of rest instead.
• You should expect some very common symptoms after LASIK such as burning and tearing, slight foreign body sensation, light sensitivity, and discomfort. These symptoms should improve with few days after the LASIK procedure.
• You should contact your doctor immediately, if your symptoms get worse or if you suspect a problem.

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Not a LASIK Candidate? IntraLASIK May Be for You

LASIK eye surgery is a popular method of correcting vision defects, but many people are not LASIK candidates.

If you were not a LASIK candidate a few years ago, it does not mean that you are not a LASIK candidate today.

Why?

Because LASIK technology is constantly being improved, enabling people who were once turned away from LASIK to be qualified.

All-laser IntraLASIK is one of the latest advances in LASIK laser surgery that corrects your vision defect by using two different lasers:

• A femtosecond laser for creating the corneal flap
• An excimer laser to reshape the underlying corneal tissue

One of the advantages of the IntraLASIK is it can allow many people who were disqualified for traditional LASIK to undergo the LASIK procedure.

Is IntraLASIK All-laser LASIK for Everyone?

Laser vision correction, in general, is not for everyone and some individuals will never be LASIK candidates.

If you wish to undergo IntraLASIK all laser eye surgery, you must first qualify for the procedure by meeting the basic requirements for laser vision correction:

• You are at least 18 years old
• You have had a stable vision prescription for at least one year
• You are in good general health
• You have no existing eye disease

Qualified candidates run a lower risk of complications during and after the LASIK procedure.

The best way to find out if you are an IntraLASIK candidate is by having a LASIK consultation.

IntraLASIK (Bladeless LASIK) Candidates

If you are qualified for traditional LASIK surgery, you can opt to undergo the All-laser IntraLASIK procedure. Usually your doctor will give you the choice of having your LASIK flaps cut with a blade or created with the new bladeless laser technology.

But if you are not a LASIK candidate, you may be an IntraLASIK candidate:

If you have a high prescription, very thin corneas or very flat corneas

Since the Femtosecond laser flap maker has the ability to create a very thin flap, a greater amount of corneal tissue remains available under the flap for treatment. Because of this, IntraLASIK is able to correct higher levels of refractive error than traditional LASIK. This also maintains the stability of the cornea and reduces the risk of severe LASIK complications such as ectasia.

If you have deep set eyes or tight eyelids

With IntraLASIK, tight eyelids or deep-set eyes are no longer a concern because the LASIK surgeon does not need a lid speculum to keep the eye open. Bladeless LASIK uses a small holding device that fits on most eyes. 

If you have poor vision after a previous corneal surgery

Many refractive surgeons now use All-laser LASIK to improve the vision of people who had undergone previous corneal surgeries such as Radial Keratotomy (RK). Bladeless LASIK can also used to improve the vision after cataract surgery or corneal transplantation.

If you have glaucoma or conditions in which reducing blood flow to the eye could be risky
The laser flap maker applies less pressure to the eye than the blade microkeratome. Thus, many LASIK surgeons consider Bladeless LASIK safer than traditional LASIK in glaucoma patients.

If you are uncomfortable with the idea of your eyes being touched by a blade

IntraLASIK is the procedure of choice for blade-cautious patients. If you are one of those, be relaxed, no blade will touch your eyes. Bladeless LASIK corrects your vision using lasers from beginning to end.

Do you feel you need All-laser LASIK? Let me know in the comments.

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What is All-laser LASIK? Do You Need it?

If you are interested in laser vision correction procedures to improve your eyesight, you probably heard about LASIK eye surgery before. It is all over the place.

But what is All-laser LASIK?

And more importantly, do you need it?

First things first, what is All-laser LASIK?

All-Laser LASIK refers to a new type of LASIK eye surgery known as IntraLASIK or Bladeless LASIK. The IntraLASIK procedure employs two different types of lasers (Femtosecond laser and Excimer laser) to correct your vision.

The term All-laser LASIK may have a certain marketing appeal, since you may feel that if one laser is good, two lasers must be even better.

However, you should know that all LASIK procedures, including Bladeless LASIK, accomplish the same thing:

• Improving your vision.
• Decreasing your reliance on eyeglasses and contact lenses.
• Correcting nearsightedness, farsightedness and/or astigmatism.

The Difference between All-laser LASIK and Conventional LASIK?

When we discussed how LASIK is performed, you have learned that the creation of the hinged corneal flap is the most critical step in LASIK eye surgery.

The difference between All-laser LASIK and conventional LASIK is in how the LASIK surgeon creates the corneal flap. 

In conventional LASIK, your surgeon will use a hand-held device known as a microkeratome to create the flap by cutting across your cornea. The cutting action of the microkeratome is derived from a metal blade that is powered by an electromechanical system.

In All-laser LASIK, your surgeon will utilize a femtosecond laser microkeratome, rather than a blade microkeratome, to create the corneal flap during the LASIK procedure.

After creation of the flap in both types of LASIK, the flap is then folded out of the way; allowing the excimer laser to reshapes your cornea under the flap. Finally, the flap is replaced into its original position, covering the area where the corneal tissue was removed.

Bladeless LASIK Flap versus Conventional LASIK Flap

The microkeratome flap is meniscus-shaped (i.e., thicker in the center, and thinner in the periphery). It is more variable in its dimensions, since its creation is influenced by many factors such as steepness and thickness of each individual cornea.

The IntraLase laser microkeratome is more accurate than the blade microkeratome. It can create a LASIK flap with the precise thickness, depth and diameter specified by the surgeon. So the IntraLase flap has the same thickness in the center and the periphery.

Types of All-laser LASIK (Bladeless LASIK):

The IntraLASIK name comes from a combination of the name of a femtosecond laser manufacturer (IntraLase, Inc. of Irvine, California) and LASIK.

The IntraLase laser was the first commercially available femtosecond laser, which gained the Food and Drug Administration (FDA) approval for Bladeless LASIK in 2001.

Since then, many laser manufacturers have introduced other femtosecond laser systems under different marketing terms. These terms have no special meaning other than being limited to the use of a particular lasers made by a particular laser manufacturer.

Types of All-laser LASIK (Bladeless LASIK)
Marketing Term	Manufacturer	FDA-Approval
FEMTEC	20/10 Perfect Vision, Germany	2004
VisuMax	Carl Zeiss Meditec, Inc.	2007
iLASIK	Abbott Medical Optics	2007
zLASIK	Ziemer Ophthalmic Systems	2008

Many of these femtosecond laser systems can be combined with any approved excimer laser system to create a flap for bladeless LASIK.

Do You Need All-laser LASIK?

In general, both conventional LASIK and bladeless LASIK have comparable outcomes with few complications, as reported in the FDA clinical trials.

If you are an ideal candidate for conventional LASIK, All-Laser Lasik is an option for you. Most patients choose All-laser LASIK over conventional LASIK with a microkeratome when given the choice.

If you have a high refractive error, thin corneas, or other condition that disqualifies you for conventional LASIK, All-laser LASIK may be a requirement that give you a second chance to undergo the LASIK procedure. Find out if you are a good candidate for bladeless laser eye surgery.

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LASIK Price & LASIK Pricing Related Problems

Surfing around the web this morning I came across an interesting article about LASIK eye surgery titled

LASIK Advertising Initiatives for 2008: Has LASIK Become a Commodity?

The author in this article talk about the problems related to LASIK prices and misleading LASIK advertising. He also wonders if LASIK surgery has become a commodity and whether this is a good or a bad thing for LASIK patients?

Here is a part of this article:

Over the past ten years LASIK has become a very common form of laser vision correction. Millions of people have had successful LASIK eye surgery. More than 1 million Americans will most likely undergo LASIK surgery this year, and the majority will get improved vision. This relatively safe procedure can be very effective when provided by an experienced LASIK surgeon. With the success of this procedure has also come attempts to create the southwest airlines business model for LASIK.

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10 Misleading Expressions in LASIK Advertisements

The majority of LASIK surgeons and LASIK centers advertise as a way to let people know about the services they offer. These LASIK advertisements may be in many forms such as newspaper advertisements, promotional television infomercials and/or radio spots.

Although all advertisements, including LASIK vision correction surgery advertisements, are supposed to be truthful, several LASIK advertisements contain misleading information or promise things they cannot deliver.

So let’s highlight the most common misleading words or statements that might be found in LASIK advertisements.

Low-priced LASIK Surgery “LASIK as low as $199.99″

Do not be fooled by the very low price advertised in big print. If you read the small print, only a small percentage of patients qualify for this pricing, based on their refractive error. Typically additional charges may apply for astigmatism, higher corrections, preoperative visits, follow-up care, and medications after surgery.

Perfect Vision Guaranteed

Expressions such as “Just crisp, clear vision” and “We guarantee 20/20 vision” are considered exaggerated. While the possibility of excellent visual outcomes after LASIK is very high, you should know that perfect vision after LASIK can’t be guaranteed for every patient. Successful LASIK outcome depends on the individual. Everyone's eyes and vision are unique. What works for you may not work for others.

Throw Away Your Glasses

As a fact LASIK will almost improve your vision and reduce your dependence on eyeglasses and contacts. However, you should know that glasses may be needed for certain tasks such as driving at night. In addition, Glasses may be needed for reading when you reach the middle 40s.

Risk free LASIK– Complication free LASIK

It is important to understand that the risk free surgery does not exist. Like all other surgical procedure, in addition to benefits, LASIK has risks and potential complications.

Exclusive LASIK technique

You should know that nearly all laser vision correction techniques are available to all refractive surgeons. While surgical techniques may differ from one doctor to another, most LASIK surgeons use a very similar LASIK technique.

100% patient Satisfaction

Your final satisfaction with your LASIK outcome depends mostly on having realistic expectations. Persons who demand perfection and have too high expectations of LASIK vision correction are poor LASIK candidates.

Optimal results by one LASIK surgery

In some patients, LASIK Retreatment may be required to obtain optimal outcomes. A typical retreatment rate is approximately 10%, meaning 90% of patients achieve their vision goals with one LASIK surgery. Retreatment rates will be higher for patients with more extreme refractive errors.

LASIK for Everyone

Although most people who wear glasses or contact lenses are potential candidates for LASIK vision correction, you should realize that LASIK surgery is not appropriate for everyone. Several conditions may disqualify you from having your vision defect corrected by LASIK.

No limits

If your existing vision defect fall within an acceptable LASIK correction range and have not changed considerably for at least a year, LASIK surgery may be an option for you to reduce or eliminate your dependence on glasses or contact lenses

LASIK at Home

LASIK eye surgery is an outpatient refractive surgery procedure. It is done under local anesthesia in a surgeon's office or a same-day surgery center.

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Radial Keratotomy Video

In our previous article titled LASIK Alternatives: Radial Keratotomy, We have discussed that in Radial keratotomy; a series of tiny radial incisions is created in the surface of the peripheral part of the cornea and thus flatten its central part, resulting in correction of shortsightedness.

As an alternative to LASIK, the use of Radial Keratotomy surgery is now limited to correction of low degrees of myopia in patients who are not good candidates for LASIK surgery.

Now it is video time, let us watch a video of Radial Keratotomy surgery to understand how Radial Keratotomy is performed.

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