Ophthalmology

Dry eyes after LASIK

Risk factors for worsened corneal sensitivity
Consequences of LASIK for the corneal nerves

LASIK

LASIK stands for "laser in situ keratomileusis" and is currently the most frequently used laser therapy for ametropia eyes worldwide.

The complication of dry eye is now a well-known consequence and often occurring side effect of the operation, which can also develop into chronic post-LASIK dry eye (i.e. a corneal disease caused by damaged nerves).

causes

Why can a chronic tear film disorder occur after laser surgery?

It is possible that the patient's eyes were slightly dry before the operation, which will then be exacerbated by the operation.
The particularly severely affected patients who suffer from dry eyes after a LASIK operation usually have an ocular surface disorder caused by the operation. This is caused by the severing of the corneal nerves during the procedure and thus a loss of sensitivity of the corneal surface, which in turn leads to the feedback from the surface of the eye to the lacrimal glands (Meibomian glands) does not work properly if there is not enough tear fluid on the eye.

This leads to inflammation of the permanently irritated cornea and the symptoms of classic dry eye, such as:

Burn (see also: Burning in the eye)
Foreign body sensation
Eye fatigue
Heaviness of the eyelids

Changes to the eye due to LASIK surgery

Changes to the Conjunctiva:

Directly after surgery occurs loss of the so-called Goblet cells on that which is for the eye indispensable tear fluid to produce. This creates one unstable tear film. This state usually lasts around the 6 months after the operation.

The so-called Break-up time (BUT), so the Tear break-up time, is after LASIK shortened and also the Schirmer test, which tests the tear secretion of the large lacrimal gland, a slightly diminished Show secretion.
There is also one increased osmolarity after LASIK and also after PRK (photorefractive keratectomy).

Surface changes on the eye due to LASIK

Through the LASIK procedure is a Contour change the surface of the Eye possible, whereby an even wetting of the Cornea With Tear fluid can be made more difficult.

Risk factors for worsened corneal sensitivity

Are particularly at risk severely myopic patientswhich require laser cutting deep into the cornea to correct the ametropia. It can be assumed that the associated Loss of sensitivity on deep nerve damage is due.

It could be shown that during the surgery with a knife (Microkeratome) a guided incision in the cornea of the eye stronger nerve-related failure on sensitivity the surface of the eye and one increased tear film disorder than is the case with an intervention with a laser (femtosecond laser).

Risk factors for tear film disorder after LASIK

Long-time contact lens wearers usually already have one permanent damage of the Corneal surface on, due to a mechanical disruption of the natural tear film.
Even patients who already had before the operation dry eye and one Schirmer test from less than 10mm per 5 minutes are particularly at risk after undergoing a lasting LASIK procedure Tear film disorder to suffer.

Further Risk factors seem that after many observations female gender (in particular after menopause), advanced age and Asian origin to be.

Consequences of LASIK for the corneal nerves

Through the severed nerve fibers (subbasal nerves) in the course of surgery, many patients develop one decreased corneal sensitivitywhich, however, changed over the course of 6-12 months again normalize should.
In a study it was found that the LASIK surgery on the eye changes the frequency of Blinking apparently permanent by 40% reducedwhich can also lead to dry eyes, as the tear fluid is normally evenly distributed over the surface of the eye by the regular blinking of the eye.

Diagnostics to be performed prior to LASIK surgery:

Before such a cosmetic surgery on the eye, it is important that quality of Tear film and the Surface of the eye to examine closely. It has to be additional Risk factors for a tear film disorder examined become, for example Eyelid inflammation and local drugs counting.

prevention

It can be helpful to see the eye already in front of the surgery regularly with moisturizing, preservative-free Tear substitutes to wet. In addition, the Tear production by balanced nutrition and also Food supplements be positively influenced with omega-3 and omega-6 fatty acids (unsaturated essential fatty acids).

As a procedure, a closure of the teardrop points with so-called punctum plugs is conceivable, which causes the tears formed by the body to drain less strongly. In addition, the surface of the eye can be treated with anti-inflammatory drugs in the form of eye drops (for example cyclosporine A 0.05%).

Comparison with alternative surgical methods

The operation using LASIK is the most risky under the refractory methodswhen it comes to surgery as a result Tear film disorder or even one chronic pain condition the cornea to develop.

Compared to LASIK, the PRK (Photorefractive keratectomy) less tear film disorders and Osmolarity increase to cause there to be a faster regeneration the damaged nerve comes.
According to a patient survey, the operated patients in both groups were very satisfied with the operation, although in both groups around 9% reported dry eyes.

There is also the so-called LASEK surgerywhere the uppermost corneal layer (Epithelium) lifted so that the laser can be applied on the exposed cornea underneath. According to initial findings, this method of intervention seems to be working less tear film disruption to lead as LASIK.