Dry eye syndrome refers to a substandard tear film due to limited volume of tears or excessive tear evaporation. It is manifested by a number of symptoms such as burning, itching, foreign body sensation, heightened sensitivity to light, graininess, and other eye problems.
The tear film comprises of an outer layer of fatty substances secreted by the meibomian glands, a middle layer of watery tears produced by the lachrymal glands, and an inner layer of mucous created by the goblet cells in the conjunctiva, the inner lining of the eyelids.
Symptoms of dry eye may be experienced because of limited watery tears production, increased evaporative loss (because of limited lipid secretions), or mechanical factors such as poor blink distribution. With the rising popularity of laser-based surgery to correct refractive problems in the eye, particularly LASIK, there has also been an increase in reports of dry eye symptoms.
LASIK (laser in situ keratomileusis)
LASIK is the most preferred among four common techniques of refractive surgery using laser technology LASIK. to realign the cornea. A misshapen cornea causes errors in the refraction of light toward the retina, leading to vision problems. Once the cornea is properly formed, light is refracted directly onto the retina, improving vision and removing the need for contact lenses or spectacles.
You may choose to have LASIK surgery because you want spectacles and contact lenses. You may have grown tired of using and maintaining the contacts, and purchasing replacements and cleansers. Besides, long-term use of contact lenses may have caused dry eye symptoms. Unfortunately, there is no guarantee that dry eye symptoms will disappear after the surgery.
LASIK surgery has high impact, inflicting damage on the nerve network serving the cornea. It is necessary to cut out a flap in the centre of the cornea, slicing through the outer layer (epithelium) of the cornea to reach the inner layers (stroma). The surgeon burns a tiny patch of inner tissue with the laser, in order to reshape the cornea. It is a very quick procedure, with little or no pain or discomfort during surgery.
Dry eye symptoms will very likely keep disturbing you in the first month after LASIK. But as the eye heals, the dry eye symptoms lessen, and lapse completely after about six months. This, of course, is the objective. For many, however, the dry eye remains; for some, it can get worse.
A number of factors can cause dry eye problems to arise after LASIK. Some corneal nerves are cut during surgery, causing the cornea to lose sensation (this is called LASIK-induced neurotrophic epitheliopathy, or simply LINE). The loss of sensitivity means the triggers for the lachrymal glands and deactivates their capability to secrete tears, so aqueous tear production abates. The same thing happens to the nerve impulses that induce stimulate lipid secretion in the meibomian glands. The normal blink can also be disturbed, along with the ability of the goblet cells to secrete mucin for maintaining the mucous layer. The overall effect is an unstable tear film and a cornea with less pronounced curvature and impaired ability to maintain a fully protective tear film.
Management of Dry Eye after LASIK
Even before actual LASIK surgery, dry eye management should already be carried out. During pre-surgery preparations, the surgeon should check for signs or symptoms of dry eye disease, including blepharitis, contact lens intolerance, etc. Any eye health conditions existing before surgery can increase the post-operative effects of LINE. Ideally, these symptoms should be completely eliminated before surgery takes place.
The doctor may also prescribe artificial tears to provide added lubrication to the eye. However, the mainstay of treatment is topical castor oil mixed with cyclosporine. This is usually spread both before and in the months after the operation. Taking omega-3 fatty acid supplements may also help, especially where the patient is not responding well to the medication or the the cyclosporine prescription is not available.
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