Knapp Striae are also known as
Knapp striae are a rare disorder of the eye / visual system. They are a binocular condition, meaning that both eyes are usually affected.
Knapp striae appear as reddish to dark-brown irregular streaks extending radially outwards from the optic disc beneath the retinal vessels. These "streaks" are actually small irregular breaks in the Bruch's Membrane (an elastic tissue that can become calcified and crack).
Note that these would be seen on the retina, not as radial lines in the iris when observing the patient with the naked eye.
Problems that can result from Knapp Striae:
Recall from knowledge of the structure of the eye, that the choroid is the thin highly vascular (that is, containing many blood vessels) layer of the eyeball located between the retina and the sclera, and that the Bruch's Membrane is the transparent innermost layer of the choroid.
The small breaks in the Bruch's Membrane known as Knapp striae can sometimes form the sites of new blood vessels that develop from the choroid then leak, adversely affecting vision through the affected eye(s).
The apperance of Knapp striae is one of the symptoms associated with pseudoxanthoma elasticum, a hereditary disease affecting elastic tissues. Approx. 50% of people with Knapp striae have pseudoxanthoma elasticum. The combination of Knapp striae and pseudoxanthoma elasticum is known as Grönblad-Strandberg Syndrome, after Swedish Ophthalmologist, Ester E. Grönblad (1898-1942) and Swedish Dermatologist, James V. Strandberg (1883-1942) and also has several other names.
More about Ophthalmology:
This section includes short definitions
of many diseases, disorders, and conditions of the eyes and visual system.
For definitions of other terms in this category, choose from the list to the left (but note that this is not a complete/exhaustive list).
Other related pages include
- A diagram of the eye
- Definitions and descriptions of the parts of the eye
- A concise description of the human retina
- Definitions of parts of the retina
- Clinical and surgical procedures re. eyes and human visual system
For further information see also our pages of books about ophthalmology.