Iris collage: digital images taken in BIO 25, Fall 2006/2007Using Google, I came across the following wikipedia-ish website with a very nice description of the structural determinants of eye color... you should check it out.
According to this website, the overall determinants of eye color are the combination in the amount of melanin in the iris and the scattering of light (light bouncing back from an object) from the iris' structural, connective tissue layer (i.e., the stromal layer) made with lots of collagen. An iris with high amounts of melanin absorbs more light and appears as brown and there is very little scattering/reflection from the collagen layers of the iris so it appears smooth or velvety (see image above). Now, what about blue and green... in these cases there is less melanin pigment to absorb light and thus the light hits the collagen layer and is scattered/reflected as blue or grey-ish. With green/hazel eyes, there are moderate amounts of melanin which abrorbs some light and this would appear yellow or light brown but there is also some blue color from the remaining light hitting the collagen layers... yellow + blue =? Green. The greater amount of scattered/reflected light from the stromal layer in green or blue eyes gives the iris the weblike or stringy appearance as compared to the smooth brown eyes. But besides the differences in melanin, structurally the brown eyes would seemingly have the same stringy, weblike structure but you don't see it since the light is absorbed and not scattered. Get it? Freckles on the iris seem to be clusters of melanocytes with melanin pigment... oh yeah, the pupil is black since it is a hole and like a doorway into an unlit room, it looks dark or black. Shine enough light into the pupil and you get a reflection back from the retina that appears? Red due to blood vessels.... red eye in your pictures.
4 comments:
I wonder how long it is going to be until the day people will pay to have eye color surgery to change their eye color to what they desire... I'll stick with my Super Dark Brown, although green would be nice.
Have you checked out the HUMAN BODY: PUSHING THE LIMITS on the Discovery Channel? They had a episode on THE EYE and it was SUPER INTERESTING!
What's it mean when you have freckles in your eyes that are black, like the pupil? My eyes are green with brown overlaying and there are tons of black, jagged freckles. My mom's are blue and one has a brown pigment spot. My freckles don't look like pigment spots.
After 6 months of offering stem cell therapy in combination with the venous angioplasty liberation procedure, patients of CCSVI Clinic have reported excellent health outcomes. Ms. Kasma Gianopoulos of Athens Greece, who was diagnosed with the Relapsing/Remitting form of MS in 1997 called the combination of treatments a “cure”. “I feel I am completely cured” says Ms. Gianopoulos, “my symptoms have disappeared and I have a recovery of many functions, notably my balance and my muscle strength is all coming (back). Even after six months, I feel like there are good changes happening almost every day. Before, my biggest fear was that the changes wouldn’t (hold). I don’t even worry about having a relapse anymore. I’m looking forward to a normal life with my family. I think I would call that a miracle.”
Other recent MS patients who have had Autologous Stem Cell Transplantation (ASCT), or stem cell therapy have posted videos and comments on YouTube. www.youtube.com/watch?v=jFQr2eqm3Cg.
Dr. Avneesh Gupte, the Neurosurgeon at Noble Hospital performing the procedure has been encouraged by results in Cerebral Palsy patients as well. “We are fortunate to be able to offer the treatment because not every hospital is able to perform these types of transplants. You must have the specialized medical equipment and specially trained doctors and nurses”. With regard to MS patients, “We are cautious, but nevertheless excited by what patients are telling us. Suffice to say that the few patients who have had the therapy through us are noticing recovery of neuro deficits beyond what the venous angioplasty only should account for”.
Dr. Unmesh of Noble continues: “These are early days and certainly all evidence that the combination of liberation and stem cell therapies working together at this point is anecdotal. However I am not aware of other medical facilities in the world that offer the synthesis of both to MS patients on an approved basis and it is indeed a rare opportunity for MS patients to take advantage of a treatment that is quite possibly unique in the world”.
Autologous stem cell transplantation is a procedure by which blood-forming stem cells are removed, and later injected back into the patient. All stem cells are taken from the patient themselves and cultured for later injection. In the case of a bone marrow transplant, the HSC are typically removed from the Pelvis through a large needle that can reach into the bone. The technique is referred to as a bone marrow harvest and is performed under a general anesthesia. The incidence of patients experiencing rejection is rare due to the donor and recipient being the same individual.This remains the only approved method of the SCT therapy.
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