Perimetry
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Octopus Visual Field Perimeter
A visual field test or perimeter is a part of a modern optometry practice and is an ocular examination that can detect dysfunction in the central and peripheral vision which may be caused by various medical conditions such as glaucoma, stroke, brain tumors or other neurological deficits.
The retina, the light-sensitive tissue at the back of the eye, is composed of photoreceptors, that change light energy into electrical energy. The central area of the retina is the most sensitive to light and provides the best acuity. The more peripheral areas of the retina are less sensitive to light, but they allow us to see, though less clearly, objects off to the side or above or below straight-ahead vision and detect motion. Just how much we can see of the world around us is known as our visual field. Each part of the retina "sees" a particular area of the visual field. Each photoreceptor's signal is then picked up by a nerve cell called a ganglion cell. The ganglion cells then transmit the signal via the optic nerve to the brain, producing vision. Any disruption in the function of the ganglion cells will block the signal's transmission to the brain and render that portion of the retina and the accompanying visual field less sensitive to light.
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Glaucoma is a process by which the optic nerve cells can become damaged and die, at least partially due to the pressure within the eye. There are millions of these cells, nevertheless an individual can lose perhaps as many as 40% of them before being aware of any visual loss. In fact a small number of cells die every year as we mature. A visual field test is only one part of a glaucoma evaluation. But the visual field is a critical component of a comprehensive ocular examination. The test results are interpreted by Dr. Vincent Troia in order to diagnose and categorize glaucoma, to help create treatment plans, and to establish a baseline for future comparison. If Dr. Troia suspects a person may have glaucoma (if, for example, intraocular pressure is not within the normal range and/or the optic nerve looks unusual), a visual field test may help confirm or rule out glaucoma as the cause. Especially in the later stages of glaucoma the visual field provides essential information about whether the glaucoma is stable or is progressing.
Troia Eye & Laser PC utilizes the state of the art Octopus 311 Perimeter which is the leader in reliability and accuracy. The Octopus 311 Perimeter utilizes Automated Eye Tracking and the exclusive Octopus TOP test strategy to finish a threshold test in 2:30 minutes, providing excellent repeatability for the usage in follow up and progression analysis. TOP is the preferred test strategy chosen by patients and can even be reliably performed in children age 7 and up.
Foresee PHP - Preferential Hyperacuity Perimeter
The Foresee Preferential Hyperacuity Perimeter (PHP) is a visual field analyzer designed specifically for monitoring disease progression in patients with Age-related Macular Degeneration (AMD). Since the introduction of the Amsler Grid in 1947, the management of AMD has evolved substantially. New treatments for Wet AMD are now available that can preserve, and in some cases, return lost vision to patients. However, early detection remains the vital precursor to saving vision and maximizing treatment outcomes. New treatments deserve new effective methods of detection. The Reichert Foresee PHP provides an unsurpassed level of sensitivity and specificity in detecting recent onset Wet AMD. Troia Eye & Laser PC is at the forefront in the management of AMD patients to ensure that treatment is begun as early as possible.
The Foresee Preferential Hyperacuity Perimeter provides an unsurpassed level of sensitivity and specificity in detecting recent onset of wet state AMD or Choroidal Neovascularization (CNV) and differentiating it from the intermediate or dry state of AMD.
The visual field analyzer monitors macular function by measuring relative photoreceptor field location and utilizing the phenomenon of hyperacuity. Hyperacuity, also known as Vernier acuity, is the ability to detect misalignment of an object's location relative to other objects in space. This ability to detect misalignments is in the magnitude of 3-6 seconds of arc, which is 10 times better than the resolution ability in the fovea (around 30-60 seconds of arc). Hyperacuity is unaffected by a patient's age and is highly resistant to retinal image degradation, and is thus suitable for assessing retinal function in patients with cataracts as well.
The Foresee PHP Technology can identify CNV lesions when they are small and when visual symptoms are still unnoticed. Early detection remains the vital precursor to preserving vision and maximizing treatment outcomes. The earlier the detection, the earlier the treatment, and better the visual outcome.