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Measurement of corneal thickness (pachymetry).
Measurement of intraocular pressure to detect glaucoma or pre-glaucomatous conditions. Glaucoma is a visual loss caused by damage to the optic nerve from excessively high pressures in the eye. It is a common cause of pre-ventable vision loss.
A-scan : This instrument measures the length of the eye with ultrasound. This measurement, along with the corneal curvature (see above) are used to select the proper power of the intraocular lens to be implanted in the eye. Another instrument that measures the eye with a laser-like light may be used to gather this information.
Gonioscopy: used to examine the anterior chamber angle, the portion of the eye that directs aqueous humor (the fluid produced by the eye). Gonioscopy is a standard part of a glaucoma evaluation. A special mirrored contact lens is used during this evaluation.
Corneal topography: produces detailed information about the curvature of the cornea. Computer software is used to measure and analyze the surface of the cornea and generate a color map from the data. The data is helpful to evaluate and plan to correct astigmatism, monitor corneal disease and detect irregularities in the shape of the cornea. Accurate measurement of astigmatism is important for refractive surgery, contact lens fitting and calculating the power of intraocular lenses.
Fundus photography: may be ordered by your physician to document the status of the optic nerve, macula, retina, blood vessels and the vitreous. Specialized cameras are used to document the progression of diseases such as macular degeneration, glaucoma, and diabetic retinopathy.
Fluorescein angiogram: is useful for evaluating various disease effects on the retina. The test requires an injectable dye (fluorescein), specialized camera with filters, and timing. The dye is injected into the patient's arm; within seconds, the dye travels to the blood vessels inside the eye. Photographs are taken to document any fluid leakage as the dye circulates through the eye. A digital camera is often used which allows the physician to interpret the results immediately.
Keratometry: the measurement of the steepest and the flattest surfaces of the cornea. Accurate measurements are easily obtained from most eyes with a keratometer. Corneal topography is used to obtain more corneal details, or when reliable keratometry measurements cannot be obtained. Corneal measurements are an important component in formulas used to calculate and determine the power of intraocular lenses and in the fitting of contact lenses.
Slitlamp. This examination enables assessment of many conditions of the external parts of the eye as well as the cornea, pupil, and lens.
Ophthalmoscopy: is performed with an ophthalmoscope and allows the ophthalmologist to examine the retina and vitreous. Opthalmoscopy is usually performed with dilated pupils, to allow the best view inside the eye. Two types of ophthalmoscopes may be used: direct and indirect. The direct ophthalmoscope has a battery powered light source and is hand-held. Multiple lenses may be selected with a dial, which allows the doctor to focus on and view the optic nerve and the central retina. The periphery, or entire retina, may be viewed by using an indirect ophthalmoscope, which is worn on the doctor's head. A lens is placed in front of the patient's eye while the doctor looks through the magnifying glasses in the headgear. The combination of the instrument and the lens allows a good view of the entire retina.
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