DAHUNSI AYOMIKUN NIFEMI (OD)
Images courtesy of Dr Xiaoxuan Liu and Dr Aditya Kale, University Hospitals Birmingham NHS Foundation Trust.
We’ve witnessed an advancement in leaps and bounds over the last years In Optometry practice. There have constantly been technological advancements to our toolkit to help us diagnose and improve our clinical investigations as a clinician.
A tonometer is a vital instrument that measures the pressure inside of your eye. Knowing the intraocular pressure and how it changes with time, helps us monitor your eye health in special conditions like glaucoma, Fuchs’ dystrophy, post-LASIK, corneal edema, refractive surgery, keratoconus, and irregular or thin corneas.
Pachymetry has become a standard ancillary test in the complete eye examination for patients at risk of having glaucoma. The first widespread use of this test was as a late addition to the Ocular Hypertension Treatment Study (OHTS) after it had been observed that patients with thicker corneas were less likely to develop glaucoma than people with thinner corneas. There is a tendency though to misinterpret the findings of pachymetry as being a correction factor when measuring intraocular pressure. Pachymetry is an independent risk factor for progression of glaucoma, not a correction factor for IOP. Patients with thinner corneas are at greater risk to have their glaucoma get worse at lower eye pressure readings and those with particularly thick corneas can be viewed as having a level of protection against developing glaucoma damage.
The slit lamp gives us a magnified, three dimensional view of your eye. We can use the slit lamp to look at the front parts of the eye (cornea and sclera), the lens, the colored part (iris), and the front section of the gel-like fluid that fills the large space in the middle of the eye. Special lenses can be placed between the slit lamp and the cornea to view the deeper structures of your eyes, such as the optic nerve, retina, and the area where fluid drains out of the eye. The slit lamp helps us detect many disorders throughout the eye, identify foreign objects in the eye and detect eye problems that may be caused by other diseases or contact lenses.
A visual field test checks the extent and intensity of what you are able to see including your entire peripheral (side) vision. By measuring the extent and the intensity of one’s visual field, many visual and general health conditions can be detected. During the test, you will watch a red light. The computer will randomly flash small lights in your side vision. When this occurs, you push a button to tell the instrument that you were able to see the light. It can tell when you are not looking straight ahead and will retest all the points that you missed. Some of the things we look for are glaucoma, retinal detachments, retinal degeneration, optic neuritis, brain tumors, toxic effects of ingested items, the cause of visual flashes and floaters, and the visual field effects of traumatic and vascular cerebral and ocular accidents.
Optical coherence tomography (OCT) is a non-invasive imaging test. OCT uses light waves to take cross-section pictures of your retina. With OCT, you can see each of the retina’s distinctive layers. This allows us to map and measure their thickness. These measurements help with diagnosis. They also provide treatment guidance for glaucoma and diseases of the retina. These retinal diseases include age-related macular degeneration (AMD) and diabetic eye disease. OCT is often used to evaluate disorders of the optic nerve as well. The OCT exam helps you see changes to the fibers of the optic nerve. For example, it can detect changes caused by glaucoma. OCT relies on light waves. It cannot be used with conditions that interfere with light passing through the eye. These conditions include dense cataracts or significant bleeding in the vitreous.
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