What Can You Expect at an Eye Exam?
An eye exam usually involves these steps:
- First, you will be asked about the reason for your visit, your medical history and any vision or eye related problems you might be experiencing.
- Next, your vision is measured. This helps determine your prescription for glasses.
- Other preliminary testing of your eyes may include eye pressure measurement, colour vision testing, and pupil assessment.
- Depending on the purpose of your visit or the condition to be assessed, you may receive drops that dilate your pupils.
- Your eye doctor will then assess your eyes, possibly using several lights to evaluate different parts of the eye.
- Finally, your eye doctor discusses what he or she found during the exam and answers questions you have about your eyes.
- Part of the examination, such as taking your medical history and the initial eye test, may be performed by a technician who assists your doctor.
- Several different tests may be performed during the eye exam. The tests are designed to check your vision and to examine the appearance and function of all parts of your eyes.
The first step in performing an eye exam is taking a thorough medical history. This will include asking questions relevant to your eye condition or the reason you were referred to the eye doctor. Common concerns that patients present to the eye doctor include vision loss or a red eye. Be prepared to answer questions surrounding these chief complaints. The eye doctor will also inquire about previous medical problems, ocular diseases or surgical procedures that you may have had. A list of current medications that you are taking will also be requested. A family history of glaucoma, retinal detachment, strabismus or a lazy eye may be relevant to the medical history.
A technician will assess your visual acuity before you see the doctor. It is important that you bring your distance and reading glasses to your appointment. Distance glasses are those that you wear to drive or watch TV. Testing your visual acuity involves covering one eye at a time with an occluder while you read letters or other symbols from an eye chart at a prespecified distance.
The pupil is the round, black hole in the centre of the iris, the coloured part of the eye. Pupils normally constrict when a light is shone on them. Pupils normally dilate when the light is removed. Examination of the pupils is an important part of the eye assessment, particularly in cases of vision loss. Abnormal pupils can be present in a multitude of medical diseases and will usually be assessed at the initial encounter. This is done prior to the instillation of dilating eye drops. After the vision is assessed, a bright light will be shone in each eye separately and the pupils will be observed for any abnormal responses.
The slit-lamp biomicroscope is a microscope that is specially designed to examine the front and back of the eye. It is the central aspect of the ocular examination. The slit-lamp examination is completed by the doctor while the patient is sitting in the examination chair. Your head will be positioned in the slit lamp for the exam while a slit light is used to inspect the eye by the examiner. The technician will also use a slit-lamp to assess the eyes prior to dilating them.
An eye has an inherent intraocular pressure (IOP) which can be measured much like your blood pressure can be measured. Measuring the IOP is important as it can be elevated is diseases such as glaucoma. There are various ways to measure the IOP but the most preferred is applanation tonometry. This will usually be completed by the technician but may also be repeated by the eye doctor. To complete this test, an anesthetic drop will be placed in your eye. The test is done at the slit-lamp biomicroscope which is used to examine your eye. An applanation tonometer probe is brought close to the eye and briefly touches the surface of the eye while the IOP is recorded.
The retina is a thin film of tissue which lines the back of the eye. It is necessary for vision as it processes the light that enters the eye and converts it to an electrical signal. It is important to examine the retina to rule out various conditions that could cause vision loss. In order for the retina to be assessed, your eyes will often require dilating drops. Examination of the retina requires the use of a special instrument called an ophthalmoscope which allows the doctor to see the retina with the use of a bright light.
Examination of the Eye
In order to examine the front and back of the eyes, your doctor will use several instruments that shine bright lights into the eye. The front of the eye will be examined with the slit-lamp biomicroscope as discussed above. The retina and optic nerve are located at the back of the eye. They will usually be examined after the instillation of dilating eye drops which can take up to 30 minutes to dilate the eyes, and may require up to 10 hours (or longer in less common cases) to dissipate. The eye doctor will use an ophthalmoscope to examine the back of the eye as discussed above.
After the Examination
After your examination your doctor may review some tests that were performed in office. Once your doctor has gathered all the information he/she will discuss the findings with you and your specific plan going forward. This may include whether you require treatment and/or further testing. We will also inform you of any follow up appointments that may be required. Afterwards, your doctor will be happy to answer any questions or concerns you may have.
The Role of Pre-Examination Technician
Prior to seeing the doctor, a technician will ask you some preliminary questions about your medical history and the reason you are seeing the eye doctor. The technician will also begin the examination by assessing your visual acuity and in some cases your IOP as discussed above. Your eyes may also be dilated in preparation for the doctor.
Common Testing That Might Be Performed at the Time of Your Consultation
Eye Muscle Testing is performed in cases where a patient complains of double vision or when an eye muscle imbalance is suspected, as in cases of strabismus. The patient is asked to follow a target and look in certain directions. Any abnormal deviation of the eyes may be measured with the use of prisms. Eye muscle testing may be completed by an orthoptist. An orthoptist is a health care worker who assesses patients with strabismus, amblyopia or eye movement disorders.
Refraction Assessment is done to assess the power of the glasses that the patient may require in order to see clearly. It is also completed in preparation for cataract surgery. The technician may perform part of this assessment with a machine that estimates the refractive error of the eye. The doctor may fine tune that assessment during the examination.
Visual Field Testing is a common test performed in the evaluation of glaucoma. It is performed by a machine. Each eye is tested separately and the patient is directed to click a button when they see a visual stimulus while fixating on a target straight ahead.
Optical Coherence Tomography (OCT) is completed by a machine which scans the back of the eye. OCT can be used to scan the macula, the centre of the retina. This is a common test used in the management of many retinal diseases including age-related macular degeneration (AMD) or diabetic retinopathy. The OCT is also used to scan the optic nerve in the management of glaucoma.
Heidelberg Retinal Tomography (HRT) is a test used in the management of glaucoma. A machine will scan the optic nerve and assess its structure. This is of value in monitoring for progression of disease. The HRT test is a non-insured service and is not covered by OHIP.
Colour Vision Testing is done on occasion in the assessment of certain diseases of the retina to assess for red-green colour deficits. The technician will use colour test plates to assess the patient’s ability to see colour in each eye separately. The patient will be asked to read coloured numbers off a background of a coloured pattern.
Screening for Glaucoma requires a few tests to be completed including measurement of the IOP and assessment of the optic nerve by the doctor. Certain tests, such as OCT and visual field testing, will be performed either prior to your examination with the doctor or on the same day. Your doctor may also recommend HRT testing.