Nov 03, 2011
The Headline from yesterday's MailOnline article states that Dr. Gregg Homer from Stroma Medical in California, has developed a laser procedure to make brown eyes blue. It makes sense that a laser could be developed to target melanin containin cells in the iris and potentially help to break them up, but significant side might be a stumbling block to approval of the technology.
Melanin targeting lasers are already in use for other procedures. In fact, a laser I use frequently, the Lumenis Selecta II laser, is used to reduce intraocular pressure in patients with glaucoma. The procedure is called SLT or Selective Laser Trabeculoplasty. It uses a special wavelengh of 532 of nanometers, to selectively be absorbed by melanin containing cells in the trabecular meshwork of the eye, the outflow channels that control the eye's pressure. This laser is effective in improving fluid outflow through the meshwork but it does not lighten the pigmentation of the meshwork due to its lower power. If a laser could be made to affect those specific cells, it seems possible that a laser could also be made to affect the melanin containing cells of the iris.
Using currently available lasers in the eye, we generally use extremely low power levels and ultrashort pulses of energy (3 nanoseconds for the Selecta II laser.) We do this because, too much laser power can cause significant inflammation. It is the quick recovery, limited inflammation and superior safety that make the SLT procedure so popular. A surgeon might use 100 pulses with a laser spot size of 400 micron. The total area hit by a treatment would be less than 40 square millimeters with total duration of 300 nanonseconds.
Now, contrast using a new iris laser over the intire iris, and you might be looking at roughly a 92 square millimeter treatment area, double the area of a typical SLT treatment. The amount of power needed to break up the melanin granules, however, might have to be significantly higher. This in turn could create inflammation and possibly dangerous elevations in the eye pressure, as all the liberated pigment would tend to clog up the trabecular meshwork. Perhaps, multiple, low power sessions, could lessen inflammation. Also, the eye's crystalline lens is located directly behind the iris, so could there be concern that excess laser energy would affect the lens, leading to cataract formation? Finally, it should be remembered that the melanin pigment does have a purpose in absorbing visible light to improve visual performance and protect the retina from excess light. Could there be atrophy or thinning of the iris after a prolonged laser treatment, leading to potential loss of vision? These are the type of questions that will have to be answered.
In summary, while I am certainly no fan of anyone trying to change his or her eye color, it seems plausible that low power, targeted laser energy could, in theory, be used to at least lighten the color of brown eyes. Whether or not a desirable cosmetic result could be obtained, is at present, still unknown. The treatment would likely have to broken up into multipe sessions and the relative risk of side effects, including glaucoma, cataracts and decreased vision would have to be determined.