The patient is automatically moved head first into the CT gantry, and the x-ray tomogram is acquired. Now the patient is automatically moved through the PET gantry, which is mounted in parallel with the CT gantry, and the PET slices are acquired. The patient may now leave the device, and the PET-CT software starts reconstructing and aligning the PET and CT images.
Diagnostic Procedures. Three common diagnostic procedures, tonometry, visual field tests, and ophthalmoscopy, enable ophthalmologists to screen patients for glaucoma. To make a definitive diagnosis, ophthalmologists often use all 3 procedures as part of an overall eye examination. The procedures are simple, relatively quick, and virtually painless.
Glaucoma is diagnosed using three pieces of information: the appearance of the optic nerve, the eye pressure, and the results of specialized testing. Optic nerve-the optic nerve is like a telephone cable that connects the eye and the brain. It has the appearance of a yellow-orange circle in the back of the eye.The circle actually looks more like a crater or donut in three dimensions.Glaucoma causes changes in the appearance of the optic nerve â the crater gets deeper with thinner walls, or the donut gets a much bigger hole and a thinner rim (see diagram to left).he circle actually looks more like a crater or donut in three dimensions. Glaucoma causes changes in the appearance of the optic nerve â the crater gets deeper with thinner walls, or the donut gets a much bigger hole and a thinner rim (see diagram to left).