Does Flap Thickness Matter?

Laser Eye Surgery to correct impaired vision has always involved reshaping the cornea, but the thickness of the corneal flap treated in the surgery has reduced significantly over the years, so much so that today, there is even a flapless form of laser surgery.

This says a lot for how much flap thickness is related with safety during, and recovery following surgery.

The Reduction Of Flap Thickness

Thinner flaps preserve a thicker, more structurally integral cornea, meaning less discomfort, faster recovery times, minimal risk of haze, and a reduced risk of any dry eye post-operatively.

In addition, it has become widely accepted among surgeons that flaps created with advanced lasers, used in more modern techniques, promote more of these postoperative advantages than flaps created by microkeratomes used in conventional PRK/LASEK.

To get more of an idea of how the advancement of technology and laser surgery techniques have developed in the direction of reduced flap thickness and less intrusive forms of surgery, here’s a review of our most common procedures: PRK/LASEK, LASIK, and the new flapless, procedure previously mentioned, ReLEx SMILE.


PRK and LASEK, the first Laser Refractive Surgeries approved by the FDA in 1995, are both classed as surface procedures. Here, rather than creating a flap, the surgeon completely removes the cornea’s outer skin (epithelium), before permanently reshaping the exposed area of the cornea; The epithelium then regrows over the following days after surgery.


In LASIK, approved for use by the FDA in 1999, a computer-controlled instrument or a laser cuts a thin, hinged flap into the cornea. The flap is then folded back, allowing the laser to remove a set amount of tissue from the corneal bed. As only a small flap is cut, the healing process is far quicker, usually within a few hours.


ReLEx SMILE is a new, less intrusive form of surgery, developed by Carl Zeiss with help from London Vision Clinic. During this form of laser vision correction, the Carl Zeiss VisuMax laser is used to create an ultra-thin flap, placing a series of pulses in the centre of the cornea and forming bubbles less than 1/100th the width of a human hair. These microscopic bubbles pinpoint the tissue that needs to be removed, ready for the surgeon to draw out through a tiny connecting tunnel.

As no flap is created, the procedure takes only a few minutes, post-operative risks are decreased, and the healing time is even faster than conventional LASIK.

“Not only is the patient experience greatly enhanced, as there is less surgical manipulation of the eye – making it less invasive than traditional Laser Eye Surgery – but it also makes vision correction available to people who would have previously been told that they were unsuitable candidates. It’s a major development.” — Professor Dan Reinstein

If you would like to book a consultation at London Vision Clinic, or find out more about the benefits of ReLEx SMILE surgery, leave us a comment or give us a call us on 020 7224 1005.