Page 44 - The Book Pi in eye

Rajesh Khanna, MD

Figure 5.7 A slit view of cornea and cataract lens

The actual slit-lamp, flashes slits of light on the eye showing the
doctor of any diseases. The size of the slit is adjustable, as well as the
power of the light being used.

Visual Field Measurement:
This measures how far you can see to the right and left, out of the
corner of your eye (peripheral vision). The easiest way to determine
how well your visual field is by testing your focus on a single point
and moving an object from side to side and signaling when you no
longer can see. The doctor can also use a device called the perimeter,
which emits flashes of white light that reveals any blind spots.

Contrast Sensitivity testing:
CST checks for the ability to detect between light and dark and is
as important as seeing 20/20. It helps vision at dusk, and in
conditions of fog and glare. Cataracts, glaucoma, diabetic retinopathy
can suppress it.

Ocular Coherence Tomography (OCT):
This system uses infrared light and interferometry to obtain
detailed scans of various parts of the eye including the cornea and
retina. The cross sectional eye scan will be displayed in color: similar
to viewing live tissue under the microscope. The optic nerve, the

38