Perimetry Topographic

Perimetric topography

*Perimetric *topography (PTP)* is a statistical technique that is used to estimate the boundaries of an object in an image. It was developed in the early 1960s, when there were many promising imaging techniques for detecting eye diseases. Today, PTP is still used by eye doctors to diagnose various diseases such as cataracts, glaucoma and retinal vascular diseases.

What is PTP?

PTP is a computer-assisted image analysis method. It includes algorithms that evaluate image characteristics such as edges, angles, and the curvature of the boundary of an object in an image. The results of this test can be used to predict a disease such as glaucoma or cataracts of the eye. Currently, PTP analysis and software are used in many laboratories around the world. *Why is this useful?* When a patient comes to the doctor, they can use software to create 3D models of the patient's eye, which helps determine whether they have the disease or not. This can be especially helpful if the patient has difficulty seeing and is unable to perform routine vision tests. This method can also help doctors understand changes in their patients' health.

Who needs PTP analysis?

Eye doctors now require this type of test for all patients who have a degree of presbyopia (inability to focus on objects). *How is it done?* When you undergo PTP, special glasses with convex lenses are placed over your eyes. You typically look at a point on the wall or table in front of you, which the operator uses to track your gaze. You then look into a camera mounted on a computer desk, which records an image of your eye as your eyes move. Through these glasses you get a view of your eye on a different scale than without them. This allows the computer to measure the angles of your eyes inside your head to determine the location and boundaries of your retinas (the light-sensitive inner lining of the eye that connects the optic nerve to the optic nerve that sends the signal), and to measure changes inside the cornea. The computer also produces the depth and shape of the dots, which allows the boundary of the lens to be determined at the height where it intersects the cornea.