Contact Lens Complications
 

Tight Lens Syndrome
Normally a contact lens should move slightly on the surface of the eye with blinking or eye movement. Soft lenses usually move a few millimeters with a blink, while rigid lenses (gas-permeable or hard lenses) move more. This movement allows tears to circulate across the surface of the eye, helping to provide oxygen to the cornea. Of course, some oxygen can diffuse directly through a contact lens also (more so in soft lenses and disposable extended wear lenses). For different reasons, a contact lens during the course of the day may begin to fit more tightly onto the surface of the eye. This may be because the lens was too tight fitting to begin with, or it may be related to increasing drying of the lens and eye as the day proceeds. If the lens reaches a point where it stops moving on the eye, several things may happen. The oxygen transmission to the cornea will begin to drop, and the cornea may begin to swell (corneal edema). This leads to further tightening of the lens on the eye, with a further worsening of swelling. Symptoms during this period may include redness, eye irritation or burning, and a dry sensation. The vision may begin to blur, and halos or rainbows may be seen around sources of light.

The use of rewetting drops may help prevent this cycle of lens tightening onto the eye, and may help to prevent complications. The fit of the lens may need to be checked as well, and sometimes a new lens is needed. Once the lens has tightened onto the eye enough to cause symptoms, the lens should be carefully removed. Lubricating drops should be placed several times to help loosen the lens before removal. Sometimes removal of a tight lens can lead to a painful corneal abrasion, which would require further treatment by an ophthalmologist. Another risk of the tight contact lens syndrome is of infection, or corneal ulcer.