If it is a routine eye exam, it takes about 20 to 30 minutes. In a routine eye test, the person undergoing eye exam usually does not have any complaints.
Basic tests include:
- Visual acuity
- Eye pressure test
- Assessment of refractive status of the eye
- Slit-lamp examination of the anterior segment of the eyes
- Quick examination of central retina
If the person has any eye complaints, the time taken for the whole eye exam will depend on what specific complaint the patient has. Depending on the complaints, the patient may undergo further tests to investigate in that direction.
For example, if glaucoma is suspected, more tests are performed to assess the severity of the disease and amount of damage to the eyes. This may involve an examination of the optic nerve, measurement of eye pressure with an applanation tonometer, visual field assessment and retinal nerve fiber analysis. This may need an extra hour for the complete eye examination.
Similarly, if there is a need to dilate the pupil by putting dilator eye drops for further assessment of posterior segment (which includes retina and optic nerve mainly), that itself may take up to 30-40 minutes.
To get an idea of your eye health and vision health correctly, your doctor needs to know your medical history and family history. Some eye conditions (e.g. glaucoma) are hereditary and some systemic health conditions affect your eye health.
Depending on expected and unexpected findings during your comprehensive eye exam, more tests may be performed to diagnose eye diseases and conditions and decide the treatment.
It should be kept in mind that the estimated durations mentioned here do not include the time spent in waiting for your turn for consultation and tests.
1. Visual Acuity
What Is Visual Acuity?
This is the ability of the eye to see details clearly. Your eyes are two of the most important parts of your body. In fact, the eyes are the most important part of your brain. And your eyes are constantly trying to get information from your environment. Therefore, it’s so important to have clear vision.
How is Visual Acuity Tested?
There are several ways to measure visual acuity. A good test requires only a few simple steps.
First, the patient will be asked to look at a chart and report which letter they can read. It is measured in a test called Snellen eye chart. Snellen chart is printed on a card. The person’s eyes are then covered alternately with a piece of cardboard and the person is asked to identify each letter or symbol with his or her open eye.
The chart has letters in various sizes and is placed at 20 feet (6 meters) away from the eye. The patient must be able to see the letter or number that he or she is told to read.
If the patient cannot do this, the doctor will place different lenses in front of the eye to correct the vision. Next, the doctor will repeat the test with the new lenses. Finally, the doctor will test and compare the patient’s vision with both the new and old glasses/lenses.
Visual Acuity with Glasses
A person with glasses will have better visual acuity than one without glasses. However, old and scratched glasses can cause problems like blurry vision, headaches and eyestrain. They can also make reading difficult because they limit your field of view.
If you wear glasses, you probably know the basics: your prescription, the strength of your lenses, and whether you need bifocals or progressive lenses.
2.Eye Pressure Test
What Is Intraocular Pressure (IOP)?
It is the force of fluid that keeps the eyeball from collapsing. The force of fluid in the eye is called intraocular pressure. It is measured in millimeters of mercury (mm Hg) with a special instrument called a tonometer.
Normal intraocular pressure is between 10 and 20 mm Hg. An eye with a normal intraocular pressure is said to have normal tension. When intraocular pressure goes up above 21 mm Hg, it’s considered to be high eye pressure.
If your eye pressure is greater than 21 mm Hg, you may have glaucoma. Glaucoma is a group of diseases that cause damage to the optic nerve and can lead to blindness. This condition is treated by reducing eye pressure.
What Are Tonometers?
The instrument to measure intraocular pressure is called a tonometer. It uses the principle of applanation to measure the pressure in the eye. An applanation tonometer has a prism that touches the cornea to flatten it. When the pressure of the eye is measured, the prism flattens the cornea and the force pushing it back into the eye can be calculated. There are different types of tonometers. The most common tonometer is the Goldmann applanation tonometer. Other types, including non-applanation ones, are Perkins, Schiotz, and Tonopen.
They are used to measure the amount of intraocular pressure in the eye. This helps a doctor determine if the patient has glaucoma. Glaucoma is a condition in which the optic nerve is damaged. This can cause a person to lose their vision.
Glaucoma is a condition that affects millions of people worldwide. It is a leading cause of blindness. It can be caused by several factors, including increased pressure of the fluid inside the eye (aqueous humor), high blood pressure, or other diseases.
The most common treatment is to have the pressure in the eye lowered. This can be done surgically or medically. Another treatment is to prevent the eye from producing too much fluid. This can be done through medication or laser surgery.
3. Assessment of Refractive Status of the Eye
Refractive status of the eye is assessed by performing various tests. These tests help to estimate how well we can see objects and to determine the best glasses for the patient.
How Is Astigmatism Diagnosed?
A patient may have astigmatism if their eye has different curvatures in vertical and horizontal meridian. Astigmatism can be caused by errors in the shape of the cornea (the clear, dome-shaped front surface of the eyeball). Astigmatism is most often caused by the bending, flattening or thickening of the cornea.
What Are Some Common Causes of Astigmatism?
There are various factors that can lead to astigmatism, such as trauma, infection, congenital conditions, or injury to the eye.
How Is Presbyopia (Age Related) Diagnosed?
Presbyopia is also called “the natural aging process of the lens of the eye.” It occurs when the lens of the eye loses its elasticity and can no longer change its shape to focus on near objects. This means that older people need to wear reading glasses to see close up.
How Is Hypermetropia (Hyperopia) Diagnosed?
Hypermetropia is a refractive error in which the eyeball is too short and/or it doesn’t bend inward enough to focus on distant objects. The cornea and lens in the eye cause the light to be focused behind the retina.
What Is Diplopia?
Diplopia is also known as “double vision” or “twin vision.” It is caused by an imbalance of the muscles of one or both eyes. Also, when one of your eyes is not focusing on the image properly, you get double vision. If this happens, you will see two images of objects at different locations in the visual field.
How Is Myopia (Nearsightedness) Diagnosed?
If you have a long distance to focus, your eyes are more likely to lose their ability to focus clearly on distant objects. This is called myopia, or “nearsightedness.” Myopia can be corrected with glasses or contact lenses and sometimes even surgery.
How Do I Diagnose Myopia (Nearsightedness)?
The first step in diagnosing myopia (nearsightedness) is to evaluate your distance vision. How well can you see things far away? You should have 20/20 vision at a distance. If your vision is not corrected to 20/20, you can also test your distance vision by looking at a series of objects with increasing distances, such as reading the newspaper at a distance, then the street signs at a distance, then the clock at a distance, etc.
4. Slit-Lamp Examination of the Anterior Segment of the Eyes
Slit-lamp examination is a medical procedure used to examine the eyes with a magnified view. It is commonly performed by ophthalmologists and optometrists to examine all parts of the eyes and any abnormalities of the eyes, if present.
The doctor then places a lens (90 Diopter or 78 Diopter) in front of the eye, which allows the doctor to see behind the iris. The doctor may also place drops into the eye to dilate the pupil to allow more light to pass through. This helps them see details of lens, vitreous, optic nerve and retina which are behind the iris of the eye.
What Is a Slit-Lamp?
A slit-lamp is an instrument that is used to examine the eye. It has two major components: an illuminating light source and an optical system. A slit-lamp is a binocular microscope with or without an attached camera.
5. Examination of Central Retina (Fundus Examination)
Retina is the light-sensitive tissue at the back of the eye. It has rods and cones which are responsible for seeing color and details. The retina also contains blood vessels and nerve fibers, which help the brain see the images.
Central retina is usually affected by diabetic retinopathy. The changes in diabetic retinopathy are very well visualised with a 90 D lens or contact lens exam.
There are two main types of vision: central and peripheral. Central vision is when we see objects directly in front of us. Peripheral vision is what we see in our peripheral field. We have good vision in the center of our field, but poor vision outside that area.
In other words, we can see all the details in our central field, but we cannot see the details in our peripheral field.
So, how do we examine the retina? This is done with dilated eye exam by looking through a lens which is called a fundus lens. The lens is placed in front of your eye after pupil dilation and then the doctor examines the retina in detail.
But how can we examine the entire retina with one fundus lens? The solution to this is to ask the patient to look up, down, left and right sequentially to allow visualization of peripheral retina in all directions.
Examination of Retina with Direct Ophthalmoscope
A direct ophthalmoscope is an instrument that allows the doctor to examine the back of the eye. It’s a portable device that is used besides the standard eye exam equipment. The direct ophthalmoscope has a light source that is focused on the retina and a series of small lenses that magnify the image on the retina. This magnified image allows the doctor to examine the retina and identify any abnormalities.
Examination of Retina with Indirect Ophthalmoscope
The best way to examine the peripheral retina is with an indirect ophthalmoscope. This type of instrument allows you to see the back of the eye, which is otherwise hidden behind the iris.
Indirect ophthalmoscopes are used to check mainly for peripheral retinal diseases, including retinal degeneration, retinal tears, retinal detachment and inflammation, etc.
So the bottom line is that when you want to have an eye exam, you should be mentally prepared to spend more time than expected. It’s equally important to understand that long duration and multiple tests for eye exam do not necessarily mean that you will be handed over a scary diagnosis.
Tests may be negative for what is suspected. It is always better to do additional tests or investigations if some serious disease is suspected. Ruling out such conditions would make sure that they are not missed and mismanaged.
For some eye conditions, annual eye exams are desirable.