Earlier today I responded to a query about eye colour and vision from Harry Avis off the top of my head. I've now followed up with the poor man's version of a literature review: I searched PubMed for abstracts. What I found suggests I won some, I lost some. Here are the results.
I suggested that blue-eyed people were more sensitive to light. As someone pointed out to me off-list, if true, this would mean that additional light would be entering through the iris, degrading vision. So blue-eyed people would have poorer visual acuity in bright light. False. Short (1975) found that "the density of iris pigmentation had no significant effect on visual acuity under conditions of bright light". I said that I thought that blue-eyed people were more prone to cataracts. False. Younan et al (2002) found an association between cataract and dark brown iris colour, just the opposite of my claim. I said that I thought that blue-eyed people were more prone to macular degeneration. True. Frank et al (2000) found that macular degeneration was more frequent in white people with blue or hazel eyes. Of course, this doesn't mean the decreased pigment is the cause--it could be a marker for a genetic susceptibility. And I will throw in the additional finding that those with blue or gray eyes are at increased risk of dying of metastatic intraocular melanoma (Regan et al, 1999). Goody. To end on a positive note after that downer, recall that I said that boosting lutein intake through eating spinach, corn, and orange veggies seemed a promising way to reduce macular degeneration. The latest edition of the British Medical Journal is out tonight, and coincidentally, it has a review of macular degeneration. Chopdar et al (2003) say: " By far the most biologically plausible micronutrients to have a potential protective role in age related macular degeneration are the carotenoids lutein and zeaxanthin, which are potent antioxidants found in high concentrations in the macular retina. The case for further trials aimed at testing the role of lutein and zeaxanthin in the prevention of age related macular degeneration is now compelling." But while we wait for that trial, munching those veggies can't hurt. Stephen Chopdar, A. (2003). Age related macular degeneration. British Medical Journal, 326, 185-- Regan, S. et al (1999). Iris color as a prognostic factor in acular melanoma. Archives of Ophthalmology, 117, 811-4 Frank, R. et al (2000). Race, iris color, and age-related macular degeneration. Transactions of the American Ophtalmology Society, 98, 109-15 Short, G. (1975). Iris pigmentation and photopic visual acuity: a preliminary study. American Journal of Physical Anthropology, 43, 425-33. Younan, C. et al (2002). Iris color and incident cataract and cataract surgery. American Journal of Ophtalmology, 134, 273-4 _______________________________________________________ Stephen L. Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy Check out TIPS listserv for teachers of psychology at: http://www.frostburg.edu/dept/psyc/southerly/tips ________________________________________________________ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
