Fundus examination: what is it and how is it performed?

The fundus exam is a painless, quick, and simple test that is very helpful in detecting eye problems. Ideally, a person should have it once a year, especially after age 50.

Last update: September 28, 2021

Ideally, the fundus exam should be part of your regular medical check-ups. of anyone, but it is not always the case. It is a simple test that can detect common eye problems, even before they cause symptoms.

The fundus examination is a technique that makes it possible to observe the inside of the eyeball. This makes it possible to detect the presence of any abnormalities in vision. It also serves to follow the evolution of some pathologies such as hypertension and diabetes.

This is considered the most routine test in ophthalmology. It is painless and does not cause discomfort beyond the dilation of the pupil, which causes blurred vision for a few hours. The fundus examination allows us to observe the state of the optic nerve, the blood vessels and the retina.

What is a fundus exam?

The fundus is a diagnostic test that allows you to see the inside of the eyeball.

The fundus examination it is a screening test performed by the ophthalmologist to look at the back and inside of the eye. It is also known as "ophthalmoscopy" or "funduscopy."

This technique allows the deepest part of the eye to be seen through the pupil. With this test it is possible to visualize areas such as the macula, the retina, the optic disc and the transparent media that are: the cornea, the crystalline lens, the vitreous humor and the aqueous humor.

With this technique you can also monitor eye problems such as glaucoma, macular degeneration, eye cancer, optic nerve problems, and eye injuries.

Types of fundus exam

The fundus examination is carried out with a device called an ophthalmoscope.. It is composed of a series of crystals and mirrors that illuminate the retina, without the light being reflected. This allows you to see everything clearly, without flashing.

Depending on the type of ophthalmoscope used, there are three types of fundus examination:

  • Direct ophthalmoscopy. It is the simplest technique. It allows to obtain the image of a single eye, which is one-dimensional; that is, flat.
  • Indirect ophthalmoscopy. It is a more complex technique that makes it possible to obtain the image of both eyes.
  • Indirect Slit Lamp Ophthalmoscopy. It is the most complex of all and allows a three-dimensional image of both eyes to be obtained.

At present, other more advanced techniques are also applied such as digital fundus photographs that make it possible to detect the evolution of the retina in certain pathologies. Also fluorescein angiography, which makes it possible to see blood vessels in detail.

What is a fundus exam for?

The main utility of the fundus examination is that allows to identify serious eye diseases in their early stages. The test also makes it possible to track any abnormalities that have been identified.

This test can diagnose, among others, the following disorders:

  • Retinal detachment. It is a separation of the retina, more common in myopic people.
  • Retinal thrombosis. Obstruction of any of the veins that carry blood to the retina.
  • Macular degeneration. Causes sharp, central vision to be lost.
  • Glaucoma. It is a loss of peripheral vision due to damage to the optic nerve. If it is not treated in time, it can cause blindness.
  • Ocular melanoma. It is a type of cancer.
  • Diabetic retinopathy. It is damage to the blood vessels of the retina, caused by diabetes.

The most interesting thing is that with the fundus examination non-ocular diseases such as hypertension and diabetes are also detected. It is believed that in the future it will even make it possible to diagnose neurodegenerative diseases.

How is a fundus examination performed?

To perform an eye fundus it is necessary to dilate the pupil.

Upon arrival at the fundus examination consultation the first thing to do is apply a few drops to the eye. These can sting a bit and their function is to dilate the pupil little by little. The process can take from a few minutes to an hour.

When the dilation is estimated to be at the ideal point, the patient is asked to come into the office and the lights are turned off. If the direct or indirect technique is used, the person will have to sit in a reclined chair or lie down on a table.

The doctor will ask the person to fixate on a specific point and hold it that way for a moment.. In the direct technique, you will look at each eye separately. In the direct, you will examine both eyes at the same time; in the latter case, the ophthalmologist will use a device similar to a miner's helmet.

If the fundus exam is done with a slit lamp, the patient will have to sit in a chair and support the chin on a metal device. You will also have to fix your eyes on a point to make the exam possible. In all cases, the exam takes only a few minutes.

Contraindications to this test

The fundus examination rarely causes complications. Only in very rare cases may there be an allergy to drops that are applied to the eyes. This causes more itchiness than normal and redness of the eyes.

There are no absolute contraindications, but ophthalmologists are especially cautious in the cases of people with glaucoma, as the drops can cause an increase in intraocular pressure and lead to an acute attack.

Special care should also be taken when a person has cataracts, since the lens may be thickened. Either way, the doctor will assess the situation and take the appropriate measures to avoid generating risks to the patient.

An examination that requires accompaniment by the patient

After the fundus examination there may be some discomfort. The pupil will have been dilated and will not return to normal until after a few hours. Therefore, there will be blurred vision and you will feel discomfort in the light of the sun.

For the next few hours, It will not be possible to perform actions such as reading or any activity that requires sharp vision. For this reason, it is recommended that the person be accompanied to this examination, so that they do not have difficulties to return home.