A comprehensive eye exam reveals important information about eye health, as well as the patient’s general health, and is therefore required regularly. This eye examination consists of several tests to check vision and a screening for eye diseases. The ophthalmologist uses a variety of instruments, shines bright light sources and uses eye drops. A comprehensive eye exam is relatively simple and comfortable and normally takes no more than 45 to 90 minutes.
- For the eye exam
- Types of examinations at the ophthalmologist
- Medical history
- Visual acuity
- Pupils
- Peripheral vision: Visual field examination
- Eye movements: Eye muscle test
- Eye pressure
- The anterior part of the eye: Slit lamp examination
- The back part of the eye: Retina and optic nerve
- After the eye exams
For the eye exam
It is best for the patient to bring all contact lenses and/or glasses with him to the appointment. Sometimes it is necessary to take off glasses or contact lenses during an examination to see whether someone sees better or worse without lenses or glasses. The ophthalmologist applies fluorescein, a certain dye, to the eyes during an examination. This discolors the contact lenses permanently; That is why contact lenses should not always be left in. The ophthalmologist will then provide a suitable glasses prescription through a thorough eye examination.
Types of examinations at the ophthalmologist
The examination checks the following: medical history, visual acuity, pupils, visual field, eye muscles and the front and back parts of the eye.
Medical history
The ophthalmologist usually starts by asking the patient questions. He would like to learn more about the patient’s general health in the present, but also the past. Information about possible premature birth, (eye) surgery, previous ophthalmologist visits, etc. helps the ophthalmologist to get a first impression of the patient. It is also important to report the use of certain medications . Certain conditions and chronic diseases may increase the risk of developing eye disorders, such as diabetes mellitus, high blood pressure and cardiovascular disease. In that case, the patient should be checked more often. The patient’s family medical history is also of great importance. For example, if lazy eye runs in a patient’s family, it increases the risk of vision problems. In addition, the patient should also provide information about his current vision and whether he wears corrective lenses or one or more glasses and is satisfied with them. Other relevant health information should also be included, such as allergies (allergic reaction due to contact with a triggering substance) to medicines, food or other substances.
Visual acuity
Reading letters
Patients are probably most familiar with this part of an eye exam. During the examination, the ophthalmologist temporarily covers one eye or holds a hand over one eye. The test is done with one eye at a time. The patient may keep his lens in or glasses on. The ophthalmologist asks the patient to remotely read a standardized letter chart, also known as a Snellen chart, on a (wall) plate or screen. Normally the distance is a few meters. The alphabet letters on the card always decrease with the next line. The smallest row a patient can read is the vision in that eye. The short-distance vision test is performed using a letter chart at reading distance that is comparable to the Snellen chart at distance. Through this examination, the ophthalmologist determines how good the vision is at different distances, which is useful for the glasses prescription.
Visual acuity display
The visual acuity display is in fraction form. Normal visual acuity is 20/20. That term is derived from a standardized format in which a person with normal vision can see objects at a specified distance. For example, if a patient can see an object at a distance of 20 feet that is normally visible at 20 feet, then he has 20/20 vision. The larger the denominator, the worse the sharpness. If the patient has 20/200 vision, he will only see objects at a distance of 20 feet that a person with normal vision sees at 200 feet. In Europe and Australia the terms 6/6 are also common. This represents the distance in meters. If the patient is unable to read one of the lines, the ophthalmologist works with counting fingers and perceiving light (light perception).
Glasses prescription
During the refractive examination, the ophthalmologist determines the glasses prescription. The doctor often uses a phoropter (foropter) , a device that contains a number of lenses of different strengths. While the patient looks at the Snellen chart, the doctor offers the patient different lenses and asks if the letters become clearer. The doctor repeats this step until he finds the ideal combination for the best possible visual acuity.
Pupils
An examination of pupillary function first involves inspecting the pupils for equal size (1 mm or less difference is normal). The ophthalmologist also looks at a regular shape, the reaction to light and the pupillary reflex. The ophthalmologist also assesses the reaction of the pupils to light. To do this, he (partially) darkens the room and shines a bright beam of light through the pupils. With a normal pupillary response , the pupil contracts and becomes smaller. If the pupils respond by dilating (the medical term is “pupil dilation”), this often indicates an underlying problem such as a neurological disorder or optic nerve damage. When light is moved from one eye to the other, both eyes begin to dilate, but then constrict again when the light reaches the other eye.
Peripheral vision: Visual field examination
For example, one of the primary symptoms of glaucoma is the loss of peripheral vision. This is the view on the sides of your vision . Usually this vision disappears before the patient is aware of it. That is why a visual field examination (perimetry) is important. This research can be done in roughly three ways. The ophthalmologist sits nose to nose with the patient, then covers one eye and then moves his hand. The movements start just outside the field of view and move towards the patient. First they go from left to right and then from top to bottom. The patient should always look straight ahead and then say whether he sees the hand and, if necessary, he also has to count fingers. Then it is the turn of the next eye. During a manual visual field examination, a patient sits in front of a kind of ball with his chin on a chin rest. He must focus on a point in the center of this sphere. The examiner then makes an object move and the patient must notify him when he sees it; Here too, one eye is covered. A third visual field examination is done completely automatically via an automated computer program. The patient presses a button as soon as he sees a light on or an object moving with an eye also covered. Common visual field problems include scotomas (seeing blind spots in the visual field) and hemianopsia (loss of half the visual field).
Eye movements: Eye muscle test
The eye muscle test examines the so-called eye muscles that make eye movements. The doctor looks at how the eye responds to slow and fast movements when the patient follows an object such as a pen or light. The doctor examines whether both eyes work together properly and that there is no unnecessary pressure on the eye muscles. Good muscle balance is especially important if the patient reads a lot or uses the computer.
Eye pressure
Tonometry measures the pressure in the eye (intraocular eye pressure). Increased eye pressure is sometimes a sign of glaucoma, although increased eye pressure is not the only symptom of glaucoma. There are several ways to check eye pressure. A patient sits with his chin on a chin rest and focuses on an object and then quickly presses some air onto the eye. Another method is a manual examination with a tonometer. The ophthalmologist uses anesthetic eye drops to dilate the pupils for the examination. These sting a little, but this will go away after a few seconds, making the examination itself painless. The eye pressure examination is usually performed five to thirty minutes after administering the eye drops. Using the slit lamp, the ophthalmologist moves the tonometer so that it touches the cornea and then determines the eye pressure.
The anterior part of the eye: Slit lamp examination
A slit lamp (special microscope) illuminates the front part of the eye , such as the conjunctiva, eyelids, cornea, iris, lens and eyelashes. For this purpose, the ophthalmologist also uses the yellow dye fluorescein in some patients, which he applies painlessly to the patient’s eyes. Abnormal results from this examination may indicate the development of cataracts, scars or scratches on the cornea or a corneal disorder.
The back part of the eye: Retina and optic nerve
For this examination, the ophthalmologist dilates the patient’s eye by administering drops (mydriatics). This allows a thorough inspection of the retina and optic nerve, which are located at the back of the eye . The eyes are then sensitive to light for a few hours (photophobia) because they are dilated.
Sometimes further examinations are required using specialized imaging techniques such as an OCT scan, CT scan of the orbit and eyes, corneal topography or fundus photographs. These tests are often crucial in diagnosing disease in its early stages. The ophthalmologist finds abnormalities in the back of the eye, on the surface of the eye or in the eye.
After the eye exams
The eye drops make it no longer possible to drive home independently by car . Arranging transport is therefore desirable.
read more
- Visual acuity: Importance and measurement via a Snellen chart
- Orthoptist: Detecting and improving eye problems through training
- Have regular eye examinations by an ophthalmologist
- App HEyeWay: Photos of the eye with the iPhone
