Four Ophthalmic Instruments Used in an Eye Exam

Eye exams are an important component of maintaining your health. An eye exam is relatively painless, although the medical equipment (ophthalmic instruments) used can look scary. This is especially true for children.

The American Optometric Association (AOA) makes several recommendations regarding eye exams:

* Young children should have their eyes checked at six months old and again at three years of age. They should have another test just before entering kindergarten. Children who don’t have problems (those who don’t need corrective lenses) should get their sight tested every other year.

* Adults (aged 18-60) should be tested every two years.

* Seniors (adults over the age of 60) should get an annual eye exam.

Are you or a child of yours is nervous about getting an eye exam? A basic understanding of some of the ophthalmic instruments used and what to expect may help allay fears:

1) Slit lamp: One of the first ophthalmic instruments you’ll encounter is the slit lamp. The doctor will first perform visual/manual inspection of your eyes. After this, he or she will examine the anterior structures of your eyes (eyelids, conjunctiva, sclera, iris, cornea and lens).

The test is performed by having the patient place his/her chin on a rest that can be adjusted for height. The patient focuses on a lens while a slit of light is shone into the eye. The doctor uses a biomicroscope to see a magnified view of the anterior portion of each eye.

2) Snellen chart: This is probably the world’s most well-known ophthalmic instrument. It’s that familiar chart with letters of the alphabet. This test is used to gauge a person’s visual acuity (ability to detect fine details).

The chart begins with a large letter ‘E’ at the top. Rows of other letters descend down the chart, with each row having progressively more letters and smaller print.

Other charts may be used for special situations, such as patients who cannot read. The child’s version uses familiar pictures and shapes instead of letters.

3) Tonometer: This is one of the most invasive ophthalmic instruments. It is used to measure the fluid pressure inside the eye. It’s ‘invasive’ because it actually comes into contact with the cornea (eyeball). For this reason, patients are given eye drops before this procedure. The drops numb the eyes so the device can’t be felt when it touches the eye.

4) Ophthalmoscope: This ophthalmic instrument is a small, hand-held tool. The doctor uses it to examine the fundus, or interior surface of the eye. It helps the doctor to check the health of the retina as well as the vitreous humor (the liquid gel-like substance that fills the eye).

The eye doctor may also use a small, hand-held flashlight. This test is performed to determine pupil function.

The light from the ophthalmic instrument is shone into the patient’s eye. A healthy eye/pupil will constrict when confronted with direct light. The pupil will dilate after the light is removed. This is how the pupil should react in normal situations, such as walking outside into sunlight, or entering a darkened room. Pupils that react abnormally may indicate neurological damage or disorders of the eye.

Some of the ophthalmic instruments used in a standard eye exam may appear intimidating. However, none of them cause pain. Discomfort may be felt at different times throughout an eye exam, especially when direct light is shone on the eye. An eye exam is generally less uncomfortable than a dental exam.

All ophthalmic instruments used during an eye exam are cleaned before use and between patients. Patients need not worry about transfer of bacteria or irritants through shared medical equipment.