At Will Vision, dry eye following Lasik is very rare. The reason for this dramatic improvement in post Lasik dry eye is newer technology. So how does the most advanced laser technology mitigate dry eye? Inquiring minds just may want to know.
Less Cell Injury and Cell Death
Less injury to the cell structure in the cornea is a significant key to reducing post Lasik dry eye. The basis for this requires that we understand what causes dry eye symptoms in the first place and how Lasik impacts with those factors.
The cornea is extremely sensitive having ultrafine nerve fibers that actively monitor the corneal surface for irritation or dryness. Stimulation of those nerves causes the person to blink; it causes the eye to secrete more tears and; the neurotransmitters (chemical messengers) released by the nerve endings cause the cells residing on the surface of the cornea to reproduce and divide at a normal rate in order to keep the ocular surface healthy.
Whenever we create a flap on the corneal surface these fine nerve fibers are severed. Fortunately, the nerves grow back and do so quite quickly. However, there are certain factors that are inhibitory to nerve regeneration. One of the biggest inhibitors to nerve regeneration is the presence of either dead or dying (apoptotic) cells near the flap interface. These dead cells occur whenever a flap incision is made – either with a blade or an infrared femtosecond laser.
The key to improving nerve regeneration is to reduce the number of dead cells created in the tissue by the surgical event. This is accomplished by using the least amount of laser energy to create the flap as possible. This is a principle reason that Will Vision routinely invests in the most advanced femtosecond lasers available. The more advanced the laser the more focused the laser energy is within the tissue which in turn reduces collateral damage to the adjacent corneal tissue. In addition, the amount of energy used for each laser pulse is also markedly reduced in newer versus older laser models. The result, as shown using ultra-high microscope studies, is that fewer corneal cells are injured and die. As a consequence, the corneal nerves heal much more rapidly and the cornea returns to a level of innervation that is comparable to that found prior to Lasik. Older blade and older generation laser technology cannot deliver this endpoint.
Less Disorganization of the Collagen Structure
A second aspect to using the lowest laser pulse energy and the most precise laser focus is the improvements in the disruption of the orderly orientation of collagen fibers in the cornea found with newer lasers. In order for the cornea to be clear, the collagen fibers that create the corneal structure must be arranged in a highly ordered fashion. Excessive laser pulse energy and / or poor laser focus from pulse to pulse from an infrared femtosecond laser will create an area of locally disorganized collagen adjacent to the flap interface. This disorganized structure is inhibitory to nerve regeneration because the tiny proteins called “integrins” located on the neuronal growth cone of an actively growing nerve fiber are not able to properly connect to this disrupted matrix. As a result, the nerves cannot penetrate this disorganized area so they are not able to reconnect with the corneal surface.
Thankfully, this has all changed for the better. The latest generation Zeiss VisuMax® femtosecond laser used exclusively in the Pacific Northwest by Will Vision uses the least energy per pulse of any laser available in the world. In addition, our studies have shown that the Advanced Femtosecond Laser or iFS femtosecond laser from the Johnson and Johnson Vision® used at Will Vision creates the least amount of cell injury and death of any laser today. This all translates to a very low incidence of post Lasik dry eye compared to generic laser centers that cling to outdated technology.
When it comes to reducing incidence and severity of dry eye following Lasik, bladeless Lasik is the procedure of choice. Moreover, the least amount of laser energy per pulse and the least amount of injury to the corneal cells delivered by the modern advanced laser technology found exclusively at Will Vision is critical to attaining that goal.
Smoother Lasik Surfaces
As femtosecond laser have supplanted the use of antiquated bladed microkeratome systems the incidence and severity of dry eye post Lasik has plummeted. That observation certainly calls into question those generic Lasik centers that still offer such outdated methods for Lasik surgery – at a discount.
A significant factor contributing to the decline in dry eye is actually the smoothness of the surface of the residual corneal bed and undersurface of the Lasik flap. Roughness of either or both of those surfaces markedly contributes to post Lasik dry eye syndrome. High magnification scanning electron microscopy has shown that the smoothness of these surfaces has improved dramatically with the use of infrared femtosecond lasers over bladed microkeratomes. In addition, each new generation of femtosecond laser technology has resulted in dramatic reductions in post Lasik dry eye simply due to their ability to deliver less laser energy per laser pulse; their improved optics and laser focus and; smoother flap surfaces.
These reductions in dry eye are related to enhanced nerve regeneration found in Lasik with the smoothest flap surfaces compared to rough flap interfaces. That is because the neuronal growth cone is not able to cross any gap in tissue structure even if such a gap is only a few microns in width. The rougher the Lasik flap interface the more such gaps will exist in the Lasik interface. The larger and more extensive these gaps are, the more difficult it will be for growing nerves to reach the corneal surface.
Less Dry Eye
Post Lasik dry eye is not likely at Will Vision due to our use of only the most advanced laser technology available. These modern laser systems enhance corneal nerve regeneration in the post Lasik eye by reducing the amount of cell injury in the cornea which is inhibitory to nerve growth; they reduce disorganization of the corneal matrix by using more precisely focused laser energy allowing for nerves to grow back to the surface and; they deliver much smoother Lasik interface which eliminates physical barriers to nerve regeneration.
Less dry eye, better nerve regeneration and a smoother Lasik interface – it’s all better at Will Vision. Come visit us today and See the Difference.