Dry Eyes after LASIK

Dry eyes after LASIK is normal during the immediate postoperative recovery.  Symptoms include burning and irritation.  While a nuisance, it generally is not a clinically serious condition.  Only very rarely can severe dryness lead to permanent vision loss by creating a permissive environment for corneal infection and scarring.  Dryness symptoms typically return to the preoperative level although it can take several months for this to happen.  However a small number of patients report dryness symptoms persisting even years after LASIK.  These patients often had significant dryness prior to undergoing LASIK.  There are several reasons for increased dryness symptoms after LASIK:

• Severed nerves.  While making the flap, the microkeratome severs sensory nerves involved in making tears.  These nerves take several months to regenerate before restoring normal tear secretion.
• Devitalized “goblet cells”.  Certain cells involved in maintaining good surface wetting are damaged when the microkeratome suction ring is seated onto the eye.  These “goblet cells”, as they are called, take time to regenerate.
• Deficient tear oil layer.  The tears on the eye include a thin layer of oil on top.  When deficient, the liquid layer underneath evaporates too quickly.  The oil is produced by oil glands in the upper and lower eyelids that empty their contents onto the eye at the eyelid margin.  Patients must not rub or touch their eyelids after refractive surgery.  But as a result, these glands are more likely to get plugged and cause a deficient oil layer.  This is called “meibomian gland dysfunction”.  Without a good oil layer, the liquid quickly evaporates and causes irritation.  Patients with meibomian gland dysfunction before the surgery are predisposed to dry eyes after the surgery.
• Altered cornea elevation.  Corneal refractive surgery alters the shape of the cornea, which can affect how tears bath the surface.  Certain parts of the cornea may become more or less moist depending on the new contours of the cornea.  In certain instances, this can cause dry spots and subsequent irritation.
• Incomplete lid closure or blink.  Many patients unknowingly do not close their eyes completely when sleeping or completely blink.  This can occur naturally but is common among patients that have had surgery to correct “droopy eyelids”.  The exposed eye is susceptible to drying and irritation.  Patients with incomplete lid close or partial blinking are more prone to dryness problems after LASIK.

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