Illumination is on another structure than the structure of interest
Illuminates entire area (nonspecific)
Illuminates structure behind structure of interest
Illuminates area across the surface of a structure
When taking a fundus photo the eye must be dilated and the lens clean. The fundus photo of the retina allow the
practitioner to identify pathology on the retina such as drusen, neovascularization, and cotton wool spots. The funds
camera can also be used to create external photos of the eye.
External photography is a photograph of the external eye. The area of interest
must be lighted just right. A picture with a shadow on the area of interest will
not be useful. Also, a reflection of the camera flash on the area of interest
will not be useful.
A-scans use ultrasounds to make a image of the structures of the eye. Ophthal-
mologists use information gathered from A-Scans before cataract surgery.
There are five peaks that make up an A-Scan image. The first peak represents
the cornea. The second peak represents the front of the lens. The third peak
represents the back of the lens. The fourth peak represents the retina. The fifth
peak represents the sclera.
Corneal topography is a topographical map of the cornea.
Corneal topography helps the ophthalmologist know the best location to make
an incision. You will notice that this image also has color. The cooler the color
the the flatter the surface.
Scanning Laser Tests for Glaucoma/Retina
Scanning laser tests, such as the OCT, are used to monitor glaucoma and retina
problems. OCTs can return images of macular thickness. They can also return
images of the optic nerve which can indicate thinning of the optic disk and the
disk to cup ratios which are important in monitoring glaucoma.