Dr. William F. Hoyt's Amazing Images
Dr. William F. Hoyt has collected more than 800 images that show visible abnormalities of the optic disc. Below are some selections from Dr. William F. Hoyt's image collection of optical disks. Click here to read more about Dr. Hoyt in Visions Summer 2008 Newsletter.
Here is a normal optic disc, magnified, to use
This image shows an arteriovenous malformation of the retina and optic disc:
Here we see a myloblastic leukemic tumor on the disc:
Chronic optic disc swelling indicates intracranial pressure - possibly a brain tumor:
These red splotches are retinal hemorrhages caused by elevated intracranial pressure (from brain tumor):
This is called empty disc, or papillorenal syndrome. This congenital anomaly is linked to severe kidney disease:
To view Dr. Hoyt's entire collection, visit http://library.med.utah.edu/NOVEL/Hoyt/ or
search for "Hoyt collection."
Julie Schnapf, PhD, studies the nature of color vision at the Department of Ophthalmology. The two optical illusions below demonstrate how color signals of our red, green, and blue cone photoreceptors sometimes “trick” us into seeing colors that aren’t there.
The scientific explanation: The nervous system detects color from the relative strength of signals of the three cone types in response to different wavelengths of light. Staring at a colored image for a while produces an afterimage of complementary colors. This is because staring at the image causes signals from the three cone types to differentially weaken in different parts of the image; the resulting alteration in the strength of cone signals alters our perception of color.
Read more about Dr. Schnapf’s research in the Spring
2008 issue of Visions.
You are invited to subscribe, free, to this informative newsletter, which reports on advances in ophthalmology research, education and clinical care at UCSF. For a FREE subscription to Visions Newsletter, contact:
That Man May See, Inc.
(the official support foundation for the Department of Ophthalmology)
Telephone: (415) 476-4016
Fax: (415) 476-5412
University of California, San Francisco, Department of Ophthalmology