Do you ever wonder what all those gadgets are that an Optometrist uses to look in your eyes? Why are they used? What do they do? Here are some descriptions of the Optometry equipment that we use during your eye exam.
The Pupil Light is a light used to check the response of the pupils – both to direct and indirect illumination. Why do we care if the pupils are functioning properly? Pupil function is directly related to neurological function. An Optometrist can tell if there is optic nerve disease, a disorder of accommodation, Horner’s disease and even a third nerve disorder by just examining the pupils. Normal pupil function is when the eyes are both equal, round, and reactive to light.
Perkins Tonometer/Non-Contact Tonometer
These two units are used to measure eye pressure. The Perkins Tonometer measures eye pressure by using a technique called applanation tonometry, where it gently pushes on the eye ball.
The Non-Contact Tonometer “puff test” uses rapid air to applanate the cornea. High eye pressure can cause pressure to build up within the eye and result in damage to the optic nerve head which can cause glaucoma. Glaucoma is a slow progressing disease which has no symptoms – only signs (one sign is high eye pressure). Normal eye pressure usually ranges between 11-21 mmHg.
A Lensometer is used to measure the prescription in your old glasses. A Lensometer can measure both the distance and near prescription in your old lenses. There is no need to worry about bringing in a copy of your old prescription. We can easily read it right off of the glasses you are wearing. It is important to bring in your old prescription glasses so we can tell you how much your prescription has changed by comparing your old and new prescription.
The Autorefractor is a machine that goes in and out of focus and calculates the way light is changed as it enters your eye. It gives an Optometrist a starting point for your prescription. The readings are then taken into the exam room and “fine-tuned” before finalizing your new prescription.
The Phoropter is a machine which is used to “fine tune” your prescription. It houses a wide range of lenses which are placed in front of your eyes to check your distance, intermediate, and near prescriptions. The Phoropter corrects for nearsightedness, farsightedness, astigmatism, and prism.
A Retinoscope is sometimes used in young children when they are too small to be placed behind the Phoropter. An Optometrist uses a Retinoscope to objectively measure the prescription in both the right and left eyes. Light from the Retinoscope is reflected into the eye. This light streak is “neutralized” by a lens rack or Phoropter.
A Slit Lamp is essentially a big microscope. An Optometrist will check the health of both the front of the eye (lids/lashes/conjunctiva/cornea/iris) and the back of the eye (lens/vitreous/retina). An Optometrist checks for ocular conditions like: blepharitis, hordeolums, pterygiums, nevi, cataracts, diabetic and hypertensive retinopathy, glaucoma, and macular degeneration.
An Ophthalmoscope is usually used to check the health of children’s eyes when they are too small to be placed in the slit lamp. An Optometrist looks at the lenses, optic nerves (peripheral vision), macular (central vision), and retinal vasculature (arteries and veins) of both eyes.
Binocular Indirect Ophthalmoscope
A Binocular Indirect Ophthalmoscope (BIO) is used to look in the far periphery of the retina when a patient is dilated. An Optometrist uses the BIO with a 20 diopter lens to check for retinal holes, tears, detachments, hemorrhages, and nevi.
Hopefully this gave you an idea of the Optometry Equipment we use during an eye exam. If you have any questions about any of the equipment we use, please feel free to ask one of our Optometrists.