Friday, December 14, 2007

My eyes... my eyes... my eye color fascination

I admit, I am totally fascinated by eye color. I think it is pretty neat that the differing colors ultimately depend on the amount of melanin (pigment of skin and hair too) in the iris of the eye. Recall that the iris is the round structure in the front of your eye that forms and adjusts the opening called the pupil. Since melanin pigment ranges from black to brown, you might predict that eye (actually iris) colors should simply be shades of brown or light brown or even yellow... basically variations of brown. Yet, look around and you see eyes of blue, grey, green, and all shades of brown. Students are often surprised that there is no blue pigment in the iris or green pigment... just varying amounts of brown melanin. So how do we get all the amazing shades and colors of the iris? I was curious too...

Iris collage: digital images taken in BIO 25, Fall 2006/2007

Using 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.

5 comments:

Jose said...

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.

Angelica said...

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!

Anastasia said...

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.

Jessica Forester said...

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.

Leo Voisey said...

David Summers, a 37 year old MS patient from Murfreesboro, Tennessee was a score of 8.0 on the Expanded Disability Status Scale (EDSS) when he had the Combination Liberation Therapy and Stem Cell Transplantation at CCSVI Clinic in March of 2012. Having been diagnosed in 1996 he had been in a wheelchair for the past decade without any sensation below the waist or use of his legs.
“It was late 2011 and I didn’t have much future to look forward to” says David. “My MS was getting more progressive and ravaging my body. I was diagnosed as an 8.0 on the EDSS scale; 1 being mild symptoms, 10 being death. There were many new lesions on my optic nerves, in my brain and on my spinal cord. My neurologist just told me: ‘be prepared to deteriorate’. I knew that he was telling me I didn’t have much time left, or at least not much with any quality.” David had previously sought out the liberation therapy in 2010 and had it done in a clinic in Duluth Georgia. “The Interventional Radiologist who did it told me that 50% of all MS patients who have the jugular vein-clearing therapy eventually restenose. I didn’t believe that would happen to me if I could get it done. But I have had MS for 16 years and apparently my veins were pretty twisted up”. Within 90 days, David’s veins had narrowed again, and worse, they were now blocked in even more places than before his procedure.
“I was so happy after my original procedure in 2010. I immediately lost all of the typical symptoms of MS. The cog fog disappeared, my speech came back, the vision in my right eye improved, I was able to regulate my body temperature again, and some of the sensation in my hands came back. But as much as I wanted to believe I felt something, there was nothing below the waist. I kind of knew that I wouldn’t get anything back in my legs. There was just way too much nerve damage now”. But any improvements felt by David lasted for just a few months.
After his relapse, David and his family were frustrated but undaunted. They had seen what opening the jugular veins could do to improve him. Because the veins had closed so quickly after his liberation procedure, they considered another clinic that advocated stent implants to keep the veins open, but upon doing their due diligence, they decided it was just too risky. They kept on searching the many CCSVI information sites that were cropping up on the Internet for something that offered more hope. Finding a suitable treatment, especially where there was no known cure for the disease was also a race against time. David was still suffering new attacks and was definitely deteriorating. Then David’s mother Janice began reading some patient blogs about a Clinic that was offering both the liberation therapy and adult autologous stem cell injections in a series of procedures during a hospital stay. “These patients were reporting a ‘full recovery’ of their neurodegenerative deficits” says Janice, “I hadn’t seen anything like that anywhere else”. She contacted CCSVI Clinic in late 2011 and after a succession of calls with the researchers and surgeons they decided in favor of the combination therapies.For more information please visit http://www.ccsviclinic.ca/?p=904