Keratometry and Corneal Topography Instructions

Generally the keratometer & corneal topographer are combined into one instrument that does each reading. The instructions in this slideshow are written for the combined keratometer / corneal topographer instrument, however, they can be used for each instrument separately if necessary.

Both the keratometer and corneal topography do readings and measurements automatically. These tests are generally run on patients who wear or want to wear contact lens. Your doctor, however, may request a reading from them for various reasons.

1 1 Seat the patient at the instrument. Instructions Keratometry & Corneal Topography Hold and stabilize the chair as the patient sits down, especially if the chair has wheels.

2 2 Clean the instrument with alcohol wipes and/or make sure the paper on the chin rest is clean. Instructions Keratometry & Corneal Topography

3 3 Know whether the patient has contact lenses in or not, and whether you will be doing the test with or without the contact lenses in. Instructions Keratometry & Corneal Topography If the patient does not need to wear contact lenses for this test, ask them to remove them before going any further.

4 4 Explain the instrument to the patient: “This instrument measures the curvature of the front surface of your eye, called the cornea. Many people’s eyes are shaped like an egg or football, instead of being perfectly round; this is called astigmatism and is normal, although it usually distorts your vision. This instrument gives the doctor data so he can determine if you are a good candidate and it also checks the health of your cornea. This test must be done every year since the curvature of your eye can change due to growth, inflammation, disease, degeneration, or injury – plus a yearly contact lens check is required by the FDA. We will start with your right eye.” Instructions Keratometry & Corneal Topography

4 4 If the patient already wears contact lens, the technician can add: “This instrument helps measure your eyes for the best contact lens fit and, because you wear contact lens, it checks the health of your cornea and it helps the doctor determine if there is any swelling due to over wearing of the contacts.” Instructions Keratometry & Corneal Topography

4 4 If the topographer is a separate instrument, the technician should tell the patient why the doctor wants the test – i.e. whether it is for contact lenses, planning for refractive surgery, etc. The explanation does not need to be long, but rather it should be a simple message that gets the point across. Instructions Keratometry & Corneal Topography

4 4 For example, if the topographer is used for a contact lens patient, the tech can say the following: “This instrument is like getting your fingerprint. It maps out the front of your eye, called the cornea, and gives the doctor a lot of information concerning the health of your eye. It helps determine which contact lens best suits your eyes and also helps the doctor find out how much oxygen is getting to your eyes through the contacts. A yearly contact lens check is required by the FDA. We will start with the right eye.” Instructions Keratometry & Corneal Topography

5 5 Align the instrument to the patient’s eye. Each eye is measured separately. This can be accomplished in two parts: a)a coarse alignment b)a fine alignment Instructions Keratometry & Corneal Topography NOTE: this instrument is as accurate as the assistant operating it.

5a5a 5a5a a)C ourse Alignment A coarse alignment is made using the automatic table, the chin rest height adjust, and/or the vertical adjustment knob with the assistant looking from the side of the instrument. With the patient sitting back from the instrument adjust the table height so the head rest is even with the patient's brows when he or she is sitting in an upright position. If the table is automatic, it can be easily raised or lowered by moving the toggle switch (on the base of the table). Instructions Keratometry & Corneal Topography

a)Course Alignment Ask the patient to sit up close to the instrument and place his/her arms on the table, his chin forward against the chin rest, and his forehead lightly against the forehead rest. Adjust the chin rest so the corner of the patient's eye is level with the etched line on the headrest post. Gross adjustments might be needed with the vertical adjust knob. Instructions Keratometry & Corneal Topography 5a5a 5a5a

a)Course Alignment Walk the patient through the test, telling them what to expect and what is going on. “Looking inside the instrument, do you see a light (or a picture)? “Good. Keep looking at that [light / picture]. Blink a few times, relax, and look at that [light / picture].” Instructions Keratometry & Corneal Topography 5a5a 5a5a

b) Fine Alignment A fine alignment is made by moving the joystick right and left for horizontal movements or turning it for vertical movements to adjust the instrument to the patient’s eye to gain the necessary measurements. Instructions Keratometry & Corneal Topography 5b5b 5b5b

b) Fine Alignment Move to the operator's side and look into the small monitor screen to operate the instrument. Make sure all the correct settings are ready for running the instrument. Use the joystick (control lever) to gently bring the instrument in front of the patient’s eye to find it on the monitor. The keratometer / corneal topographer detects which eye is being measured. Instructions Keratometry & Corneal Topography 5b5b 5b5b

b) Fine Alignment Move the joystick horizontally or turn it for vertical alignment once the patient's eye appears on the screen. Set the “bulls-eye” inside the pupil. Ask the patient to look at the light (the target) and relax when it comes into view. Move the joystick forward and back to focus the patient's eye until it is clearly visible. The instrument should guide you through taking this measurement. Instructions Keratometry & Corneal Topography 5b5b 5b5b

Set the keratometer / corneal topographer’s settings according to the instrument model & doctor’s instructions. The technician should be aware of what settings the instrument is on before running a test. 6 6 Instructions Keratometry & Corneal Topography

At the end of the readings, the technician should praise or say things to the patient to let the patient know that the test is finished – words like:  “Good job, you can sit back now.”  “Perfect! We’re done with this reading.”  “We’re finished; you can relax.”  “We got the readings, so you’re welcome to sit back.” 7 7 Instructions Keratometry & Corneal Topography

Often times when a technician says nothing, the patient may wonder if the readings are finished, if they did a good job, or if they can sit back and relax. It is the technician’s job to help the patient understand what is going on and to make the patient feel as comfortable as possible. 7 7 Instructions Keratometry & Corneal Topography

Depending on your office, the readings from the keratometer / corneal topographer will either automatically transfer to the computer or should be printed out and recorded in the patient’s chart. The technician should know the office procedures and follow the necessary instructions to either transfer data to a computer and/or to print the data. 8 8 Instructions Keratometry & Corneal Topography

The instrument automatically knows which eye is being screened, so when it prints out the readings, all the readings for the right eye will be listed first and the left eye listed second. When printed, the technician should record the information correctly in the patient chart (whether it is paper or computer format). “O.D.”  right eye = “O.D.” “O.S.”  left eye = “O.S.” 8 8 Instructions Keratometry & Corneal Topography

The technician should not explain the results of the test to the patient – this is the doctor’s job. If the patient inquires about the results, the technician can simply tell the patient that the doctor will go over the results during their exam. 9 9 Instructions Keratometry & Corneal Topography