Friday, January 18, 2008

7.9 Wild crazy eyes

Every Halloween (celebrated on the night of Oct 31 wherever you are), someone will feel obliged to decorate their eyes for theatrical effects (in addition to wearing outlandish costumes) and show up at your door for "trick-or-treat"ing. This is done by using contact lenses with interesting patterns. A few examples are shown below:
( "Wild Eyes" by Ciba Vision)
Notice the most popular Cat's Eye (top left) usually rotate with each blink. For the onlookers, the appearance of asymmetrical vertical pupils is often quite disconcerting.

Often these lenses are used in the entertainment world. Master Po, in the Kung Fu TV series (1972-5), and Mr Richard B Riddick of the Chronicles of Riddick (2004) fame both wore white contacts with clear pupils (the latter further enhanced digitally). The Devil in Rosemary's Baby (1968), of course, was in Devil's Eye lenses. Judge Dredd in the movie of the same title (1995), on the other hand, appeared to have used cheap color contacts (more below).

These lenses are an outgrowth of artificial pupils, i.e., custom-lenses that can mask the traumatized eyes with torn irises hence distorted pupils, or from extensive scarring of the cornea known as band keratopathy. An example of the latter is shown below (the opaque cornea in the right eye, top; and with an artificial pupil, bottom):

These lenses are created by using an opaque lens upon which the iris pattern matching that of the fellow normal eye is superimposed - often a painstaking job for the artists. The pupillary area can be either clear of black (black in the above example). Each lens can cost hundreds of US dollars, however. And soft contacts do have limited useful lifespans. In some cases, corneal tattooing is an option and which is performed by an eye doctor who knows what he or she is doing. Interestingly, there appears a new fad now, or at least the beginning of it, i.e., tattooing of healthy corneas for whatever reason the recipient convinces him-/her-self of. This is a potentially blinding practice that probably should be banned outright.

Inexpensive off-the-shelf color contacts also can be used for damaged eyes; however, because of the transparency, the result is not as satisfactory. These lenses are usually manufactured with the combination of different patterns:
(A Freshlook lens made by Ciba Vision; the clear center allow vision)
The above, for example, is a cosmetic color contact lens based on three patterns (top), suitable for patients with light-colored irises. For dark irises, only deep blue or light hazel, sometimes gray, is appreciable. Color preference is naturally a very personal choice. These color lenses, although not designed on purpose, do reflect lights that makes the eyes "shine" - certainly an added attraction.

Most people, however, do not realize that these cosmetic lenses, even the ones with no refractive power, are still medical devices subject to FDA regulation. And they are by prescription only, not to be shared, and are to be worn under doctor's care.

There is a good reason to be careful: Usually these cosmetic contacts are "tight" lenses - to avoid excessive movement and off-center positioning from blinking - or the patient's vision is blurred from seeing the "pupillary" rims of the lenses. This is especially disturbing at night when the patient's pupils dilate to larger than the diameter of the clear zone of the lens. And a tight low-oxygen-transmitting lens often causes corneal hypoxia and its painful sequelae, inflammation and infection.

A trip to the emergency room in the middle of the night can certainly put a quick end to the fun.

1 comment:

corneal scarring said...

Corneal scars can be caused by improper use of contact lenses, deep scratches, lacerations, burns, and some diseases like shingles and syphilis.