Should I wait until the technology is better to have LASIK?



This question seems to pop up in the mind of everyone considering LASIK eye surgery. And I’m sure that you’ve thought about it.



Waiting for a better LASIK technology

If you want a simple and straight answer, I will tell you that you could wait!



Why?



Simply because LASIK eye surgery is an elective procedure and you can wait for a more advanced LASIK technology.



But before you stop reading, I want you to think about what you will miss out if you keep postponing your LASIK procedure (i.e. enjoying the freedom from eyeglasses and contact lenses as you wait). You should also keep in mind that the LASIK technology will continue to improve and you could continue to wait the rest of your life without ever having the procedure.



So the important question is whether the technological advances in LASIK eye surgery means an increase in quality of vision, chance of success or patient satisfaction after LASIK.



It is unlikely that for most patients there will be a noticeable difference if they choose to wait. In many cases, time spent waiting for the technological improvements also means less time to potentially benefit from the refractive surgery.



On the other hand, a few patients should wait for more advanced LASIK technologies and your doctor will tell you whether you fall into this group.



LASIK is safe and good enough to have the procedure now. So if you are an ideal LASIK candidate today, there is no need to wait. Future LASIK advances will allow those who are not good LASIK candidates today to undergo the LASIK procedure successfully.

All-laser Bladeless Z-LASIK

I was recently asked to explain how the Z-LASIK vision correction surgery is performed in more details.



First things first, what is Z-LASIK?



Z-LASIK is one of most advanced technology for bladeless all-Laser LASIK surgery available today. In the Z-LASIK procedure, your surgeon uses the LDV Femtosecond laser to create the LASIK flap and the Excimer laser to correct your vision by reshaping your cornea.



The LDV Femtosecond laser was developed by the Ziemer Group located in Port, Switzerland and has gained the Food and Drug Administration (FDA) approval for Bladeless LASIK in 2008.




How Z-LASIK Works?

Z-LASIK, as other all-laser LASIK procedures, creates the LASIK flap by applying small fast pulses of femtosecond laser light, not a microkeratome with a blade.



Now let’s watch this video which illustrates how the Ziemer FEMTO LDV Femtosecond Laser creates a corneal flap for a Z-LASIK procedure.



All-laser Bladeless Z-LASIK Vision Correction Surgery

This is question that is often asked. But, there is no simple answer.



The LASIK flap does heal over time, but the wound healing occurs mainly at the flap edge and minimally in the area under the flap.



LASIK Flap & Hinge

In a study conducted at Emory Eye Center, Emory University School of Medicine, the tensile strength of LASIK wounds was measured in 25 eye bank corneas from donors who had LASIK.(1)





The study found that the human cornea typically heals after LASIK in a limited and incomplete fashion, resulting in a weak scar under the flap that is on average 2.4% as strong as normal corneal stroma. On the other hand, the LASIK flap wound margin heals by producing a 10-fold stronger peripheral scar that is on average 28.1% as strong as normal corneal stroma.



This pattern of wound healing explains why LASIK surgeons can re-lift the LASIK flap with out complications, even years after it was originally created, to perform a LASIK re-treatment.



In conclusion we can say that the LASIK flap does heal over time, but it is never completely healed. However, you don’t need to worry, the flaps will not move with normal daily activities, and are only at risk with direct significant eye trauma. So if there is any risk that you might take a direct blow to the eye after LASIK, you should wear protective eyewear (e.g., protective goggles).




References

  1. Cohesive tensile strength of human LASIK wounds with histological, ultrastructural and clinical correlations. Journal of Refractive Surgery. Vol 21, No 5. Sep-Oct 2005.

You know that each LASIK procedure involves making a flap in the cornea.



But do you know...



What is LASIK flap, exactly? Why LASIK flap is required? How LASIK flap is created? What are the recent advances in LASIK flap creation? What are the characters of the ideal LASIK flap? How does the LASIK flap heal? And what are the LASIK flap complications?



Those are some of the most frequently asked questions about LASIK flap, and today I will answer them to give you a clear grasp on LASIK surgery.




What is LASIK flap?

LASIK Corneal Flap & Hinge

LASIK flap is a circular strip of the outer corneal tissue dissected away from the underlying corneal layers but left attached in one segment called the hinge. The most common location for the hinge is either the nasal (on the side) or the superior (upper) position.




Nasal hinge vs. upper hinge LASIK flaps: Which is better?

In the classic LASIK technique, the hinge position was typically nasal. Nowadays most LASIK surgeons create LASIK flaps with upper hinges. The flap can then be lifted up from the bottom, hence the name: down-up LASIK.



The down-up LASIK technique is more physiologic because the blinking helps keep the flap in position and contributes to its smoothing. Also the gravity tends to position the flap in the best way to promote healing.



On the other hand, LASIK surgeons who prefer the classic nasal hinge flap point out that creation of a nasal hinge flap reduce the risk of post-LASIK dry eye. In addition, it is easy to cut a nasal flap with many microkeratomes since there is no eyebrow to obstruct the path of the instrument.




Why LASIK flap is required?

LASIK is a type of laser vision correction surgery called “lamellar refractive surgery” because it is performed between the layers of the cornea. The LASIK flap is necessary in order to expose the deeper corneal layers to the excimer laser energy that reshapes your cornea to improve your vision.




How LASIK flap is created?

In conventional LASIK, your surgeon will use a hand-held device known as a microkeratome to create the LASIK flap. But if you are undergoing all-laser LASIK, your surgeon will make the LASIK flap using a type of high energy laser (femtosecond laser or IntraLase) instead of a blade.




Is IntraLase better than microkeratome for  flap creation?

LASIK safety and results are excellent using the microkeratome when performed by an experienced LASIK surgeon for well selected patients. However, the introduction of the IntraLase laser allowed for greater precision and predictability when creating the LASIK flap.




What are the characters of the ideal LASIK flap?

  • Smooth and uniform surfaces
  • Uniform cut depth
  • Regular and suitable diameter for the refractive ablation
  • A hinge that is sufficiently large as well as displaced from the laser ablation

What is the difference between IntraLase LASIK flap and conventional LASIK flap?

The microkeratome flap is variable in its dimensions, since its creation is influenced by many anatomical factors such as steepness and thickness of each individual cornea. Conversely, the IntraLase laser flap maker can create a LASIK flap with the precise dimensions specified by the surgeon.



Bladeless LASIK Flap vs. Conventional LAISK Flap

IntraLase Flap

Microkeratome Flap

IntraLase LASIK Flap

MicroKeratome Flap

Precise flap diameter

Irregular flap shape & diameter

Uniform thickness

Non-uniform thickness

Optimal hinge location

Varying hinge location

Beveled edge

Uneven edge

Precise centration

Decentered




What is the ideal LASIK flap thickness?

Traditional LASIK flaps were generally ranged in thickness from 140 to 180 microns. This is about one third of the total corneal thickness, given that the average normal cornea is about 540 microns in thickness.



Nowadays, with the newer types of microkeratomes and IntraLase lasers that can create thinner flaps, many LASIK surgeons prefer a flap thickness between 100 and 130 microns. The reason for this shift toward thinner LASIK flaps is

  • To maintain the corneal stability and avoid serious LASIK complications such as corneal ectasia by maximizing the amount of posterior corneal tissue that left untouched (This amount should be at least 250 microns and preferably 300 microns) after the LASIK procedure.
  • To allow correction of higher degrees of refractive errors since thinner LASIK flaps preserve a greater amount of corneal tissue under the flap for treatment.
  • To allow greater ability to perform enhancements, if required in the future.
  • To reduce the LASIK recovery period since thinner flaps heal faster.
  • To reduce the risk of post-LASIK dry eye syndrome since thinner flaps cause less damage to the corneal nerves.

What is the appropriate LASIK flap diameter?

Usually the diameter of the LASIK flap is more than 8.0 mm in nearsightedness and more than 8.75 mm in farsightedness. Larger LASIK flaps are better and required when the treatment zone is large; for example, in hyperopic LASIK, mixed astigmatism or custom wavefront LASIK. A larger flap is also useful if LASIK retreatment is expected.




How does the LASIK flap adhere to the underlying cornea?

After completion of the laser treatment, your surgeon will replace the flap into its original position and the LASIK procedure is complete. No stitches are required as the flap stays in place and adheres to the underlying corneal tissue by the following natural mechanisms:

  1. Surface tension
  2. Stickiness of molecules in the corneal stroma by  a gluey  substance secreted by the corneal cells (glycosaminoglycans)
  3. Suction pressure by corneal endothelial pump
  4. Mechanical approximation of tissues

How long does it take for the flap to heal after LASIK?

The LASIK flap Healing process starts immediately once the flap is replaced by the LASIK surgeon after the laser treatment. However, the healing process time will vary from person to person due to individual healing differences.



Generally, the flap will be secure within 2 weeks and after one month you can return to all activities, including sports. However, if there is any risk that you might take a direct blow to the eye, you should wear protective eyewear (e.g., protective goggles).




What are the LASIK flap complications?

Many complications unique to LASIK are related to the creation of the corneal flap. Those complications include free flaps, thin flaps, incomplete flaps, flap buttonholes, flap decentration and epithelial defects.



However, with the improvement in microkeratome technology and the introduction of IntraLase laser, the incidence of LASIK complications has dropped markedly.

In a previous article titled: How All-laser Bladeless LASIK is performed, you have learned that the IntraLASIK technique creates the LASIK flap by applying tiny rapid pulses of femtosecond laser light, not a microkeratome with a metal blade.



This makes IntraLASIK a 100% blade-free LASIK procedure and reduce the risk of LASIK flap complications.




Today, let’s watch a video of IntraLASIK vision correction surgery to understand how All-laser Bladeless LASIK works.




All-laser Bladeless IntraLASIK Surgery

After LASIK, your doctor will give you antibiotic/steroid eye drops to prevent infection and/or inflammation and artificial tears to lubricate the eye.



While these eye drops are important to help your LASIK recovery process, they are only useful if they are used regularly and instilled properly.



Let’s now learn how to instill eye drops properly after LASIK to achieve the best LASIK results and reduce the risk of LAISK complications such as displaced flap and infection.




General Instructions for Instilling Medications in the Eye:

  • Understand clearly from your doctor what the eye drops are for and what side effects you may notice. If you have allergy to certain medications, discuss your allergies with your doctor before using your eye drops. Don’t instill eye drops when wearing contact lenses unless your doctor says it is OK.
  • Read instructions carefully before using your eye medications.
  • Wash your hands well with soap and water before instilling the eye drops.
  • Make sure that the right drops are being used for the right number of times.
  • Shake the eye drop bottle well before using the eye drops.
  • Open the cap of the eye drop bottle carefully without touching the tip of the nozzle to avoid contamination.
  • Always instill eye drops before eye ointments.
  • Replace the cap of the bottle immediately after use.
  • Wait 5 minutes between each type of medications. This allows the first drop to enter the eye before being washed away by the second drops.
  • Close your eye for 5 minutes after applying the eye drops.
  • Only use your prescribed eye drops for the condition that it was prescribed.
  • Store your eye drops at room temperature and away from heat, moisture and direct light. Keep the drops out of reach of children.
  • Don’t use the drops if they change color, turn cloudy or have small fragments floating in them.
  • Don’t use or keep expired drops or medicine that you no longer need. Unused eye medication, once opened is discarded and never used for other persons.

How to Instill Eye Drops after LASIK

How to Instill Eye Drops after LASIK

  • Tilt your head back while you are sitting, standing, or lying down.
  • Look up toward your eyebrows.
  • Pull down your lower eyelid with your index finger placed just below the lower eyelid to form a pocket.
  • Squeeze the eye drop bottle to place the drop in the pocket between the eyeball and the lower eyelid. Don’t allow the tip of the bottle touch your eye.
  • Gently wipe away any excess eye drops with a clean tissue. Don’t rub your eyes.

  • Close your eyes  for 5 minutes after instilling the eye drop.
  • Repeat process for other eye.

Because what occurs after your LASIK surgery can affect your vision just as much as the procedure itself, it is very important to know what you should expect after LASIK. What you should do after LASIK? And what you should avoid after LASIK?



After your LASIK procedure, your surgeon will give you oral and written instructions about the early post-LASIK period. To have a better outcome after your LASIK surgery, you should follow your doctor’s instructions.



Let’s now highlight the general instructions you should follow after your LASIK surgery and explain their importance.




1. Rest or Sleep for Few Hours after LASIK

The best thing to do immediately after LASIK is to go home and rest as much as possible for the remainder of the day. Try to sleep the first few hours because keeping your eyes closed speed your recovery and help reduce discomfort. If you can’t sleep, rest with your eyes closed as much as possible for the first few hours.




2. Use Your Prescribed Medications

After LASIK surgery, start using your eye drops as directed by your doctor. These eye drops usually include:

  • Combined antibiotics-steroids eye drops to prevent infection and control inflammation.
  • Preservative free artificial tears eye drops to lubricate the LASIK flap and reduce irritation. Frequent use of artificial tears eye drops is recommended for the first 3 months after LASIK, because the tears secretion after LASIK surgery.

To decrease the risk of LASIK complications such as infection and displaced flap, don’t forget to follow your doctor’s instructions on how to properly instill eye drops after LASIK.




3. Avoid touching or Rubbing Your Eyes for 2 Weeks after LASIK

Since the LASIK flap is not sutured, if you rub or touch your eyes, the LASIK flap may become dislodged, requiring repositioning and further treatment. In addition, touching your eyes can transmit contaminants to your eyes, increasing the risk of infection.




4. Wear a Protective Eye Shield while Sleeping

LASIK Eye Shield

To prevent accidentally rubbing or poking your eyes while sleeping, wear a protective shield over your eyes for the first three nights after your LASIK procedure.

These eye shields come in various designs and are usually given to you by your doctor.





5. Wear Dark Glasses When You Go out

To help your cornea heal and protect your eyes from exposure to bright light which may irritate your eyes, wear dark sunglasses during day after your LASIK surgery.




6. Take a Couple of Days Off Work after LASIK

You may be able to return to work the day following your LASIK procedure, but if possible, take a couple of days off work until the post-LASIK symptoms get better.




7. Resume Your Usual Daily Activities Gradually

When you can resume a certain activity after LASIK surgery will depend on the amount of activity required, how you feel, and your doctor's instructions.



One day after your LASIK surgery, you can read, watch TV and work on the computer in moderation. It is important to keep your eyes moisturized with artificial tears eye drops during these activities.



Two to three days after your LASIK procedure, you can resume Non-contact sports such as running, golf, etc., if you feel capable. Wear a headband to keep sweat out of your eyes.



Strenuous or contact sports such as boxing, football, karate, etc. should not be attempted for at least one month after your LASIK surgery. However in the first few weeks after your LASIK procedure, if there is any risk that you might take a direct blow to the eye (e.g., racquet sports), you should wear protective eyewear (e.g., protective goggles).




8. Avoid Driving for 2 Days after LASIK

Your surgeon will warn you not to drive for a certain period after your LASIK procedure. This period can vary depending on how your eyes are healing. Most LASIK patients are allowed to drive 2-3 days after the procedure, but only for short periods of time.




9. Avoid Eye Make-up for One Week after LASIK

You may wear face make-up after 3 days, but avoid wearing eye make-up and applying lotions or creams around the eye for at least one week after your LASIK procedure. This rule is important to:

  • Reduce the possibility that makeup particles might get under the LASIK flap
  • Reduce the possibility of accidentally injuring the flap with a make-up applicator
  • Reduce the possibility of infection from contaminated make-up

It is strongly recommend that you buy new eye make-up, particularly mascara, eye liner and eye shadow, to avoid possible infection after your LASIK treatment.




10. Avoid Swimming for 2 Weeks after LASIK

To reduce the risk of infection from contaminated water, you should stay out of swimming pools for at least 2 weeks following your LASIK procedure, and rivers, lakes, hot tubs, sea and oceans for one month after your LASIK treatment.




11. Take Baths instead of Showers for 2 Weeks after LASIK

You may take showers and baths after your LASIK procedure, but try to keep your eyes closed to prevent the water, soap or shampoo from getting in your eyes. Be careful not to allow the water to strike your face directly for at least one week after your LASIK surgery. When drying off, use a face cloth and avoid rubbing your eyes.




12. Keep up All Your Post-LASIK Appointments

Follow up after LASIK surgery is as important as the actual procedure. Your doctor should examine your eyes the day following your LASIK procedure. This is important to make sure that the flap has remained in proper position and no evidence of infection or inflammation is present.



In the absence of complications, your next appointments are usually 1 week, 1 month, 3 months, 6 months, and 1 year after LASIK surgery. Keeping your follow up appointments are critical to assess the healing of your eyes and the stability of your vision.




13. Contact Your Doctor Immediately if You Suspect a Problem

After your LASIK procedure, you should expect some common symptoms such as burning and tearing, foreign body sensation, sensitivity to light, and discomfort. These symptoms should get better within 2-3 days after LASIK surgery. If your symptoms get worse or if you suspect a problem, you should contact your surgeon immediately and not wait for your scheduled visit.

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.


LASIK & Corneal Thickness

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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