Fluorangiography

Generality

Fluorangiography is an eye examination, which allows the analysis of blood flow within the blood vessels of the retina and choroid. In fact, thanks to a fluorangiography, doctors are able to assess what the blood supply is to the main structures of the parts of the eye known as the medium tunic and internal frock.

Fluorangiography is used in the diagnosis of ocular diseases, such as: macular degeneration, diabetic retinopathy, retinal detachment, retinitis pigmentosa, etc.

The practice of a fluorangiography involves the use of a particular camera - in front of which the patient must put himself - and a fluorescent contrast medium.

Fluorangiography is a painless procedure, but not completely risk-free.

The results are immediate and reliable.

Short review of the anatomy of the eye

In the eye (or eyeball ), located in the orbital cavity, three concentric portions can be identified, which, from the outside towards the inside, are:

The external habit (or fibrous frock ). Area in which they reside cornea (anteriorly) and sclera (posteriorly), acts as an attack for the so-called extrinsic muscles of the eyeball.
It has a fibrous nature.
The medium tunic (or uvea ). It is a membrane of connective tissue, rich in blood vessels and pigment.
Interposed between sclera and retina, it deals with providing nourishment to the retina, or rather to the layers of retina with which it comes into contact.
Includes iris, ciliary body and choroid .
The internal habit . It consists of the retina ; the latter is a transparent film, formed by ten layers of nerve cells (or neurons) and with the task of converting light into an electrical signal decipherable by the brain.
The main nerve cells of the retina, which deal with visual function, are the cones and rods . Cones and rods are generally called photoreceptors.

Figure : anatomy of the eyeball.

What is fluorangiography?

Fluorangiography is an ocular medical examination, which allows the evaluation of blood flow through the blood vessels of the retina and choroid. It is a test that has a certain invasiveness, since, for its realization, it is necessary to resort to intravenous injection of a specific contrast medium.

uses

Fluorangiography is used to understand whether the flow of blood through the blood vessels of the retina, the choroid and all the other sections of the back of the eye is adequate for the needs. In other words, it allows to establish if the blood that reaches the retina, the choroid and the other neighboring structures is appropriate or insufficient (ex: there could be an obstacle, which prevents a normal blood flow).

Fluorangiography is mainly used in the diagnosis of ocular diseases, such as macular degeneration, diabetic retinopathy, retinal detachment, retinitis pigmentosa, etc. Moreover, it can be a useful test to clarify the possible causes of an unexplained loss of vision or other eye disorders, for which no other previous diagnostic examination has identified the actual origin.

MACULAR DEGENERATION

In medicine, the term macular degeneration refers to a group of ocular pathologies characterized by damage to the macula - which is the central area of the retina - and a progressive loss of vision.

The most known and widespread form of macular degeneration is the so-called age-related macular degeneration (or macular degeneration linked to old age or AMD ). This morbid condition is typical of elderly people and can be attributed to the natural aging process to which every human being is subjected.

DIABETIC RETINOPATHY

Diabetic retinopathy is a late complication of diabetes, characterized by permanent damage to the blood vessels supplying the retina and other posterior anatomical structures of the eye.

Diabetic retinopathy derives from an alteration of the retinal microvascular system (ie the system of small blood vessels in the retina), an alteration that, according to the most reliable theories, would be due to the high levels of glycaemia induced by diabetes.

Diabetes patients suffering from diabetic retinopathy are victims of vision loss and, in the terminal phase, of true blindness in the first phase of retinal disease.

In general, diabetic retinopathy affects both eyes.

DETACHMENT OF THE RETINA

Retinal detachment is a very serious ocular condition, characterized by the separation of the retina from its supporting tissues.

The main causes of retinal detachment include: vitreous detachment with retinal rupture, severe myopia, very severe eye trauma and eye surgery (in this case, retinal detachment is a surgical complication).

Considered a medical emergency, the detachment of the retina is responsible for several symptoms, including: myopia, the vision of light flashes, visual changes (eg blurred or distorted vision).

EMPLOYMENT OF FLUORANGIOGRAPHY IN THERAPUTIC AREA

Fluorangiography is also useful in the therapeutic field, for at least two reasons:

The diagnostic information it provides makes it possible to plan a treatment appropriate to the circumstances;
It allows to monitor the progress of an ocular medical condition subjected to therapy. In other words, it allows us to understand whether a treatment is having an effect or not.

Preparation

In preparation for fluorangiography, the future patient must:

Ask a relative or close friend for availability to accompany them home at the end of the procedure. During the execution of fluorangiography, the doctor injects eye drops for pupil dilation into the patient's eyes; the unnatural dilation of the pupils alters the sight and this can be extremely dangerous when driving or performing other delicate activities for one's own safety and that of others. The eye drops for pupil dilation can have a total duration of up to 12 hours;
Report to the doctor who will carry out the examination the possible pharmacological treatments to which it is subjected, including herbal supplements;
Report any allergies to drugs or substances that could be used as contrast agents, sedatives, painkillers, etc. to the doctor who will carry out the examination;
Tell the doctor who will carry out the examination if you suffer from eye diseases, such as glaucoma. In these situations, the fluorangiography is not contraindicated, but the indication to suspend the treatment for the present ocular pathology is valid, on the day in which the procedure will take place;
Do not wear contact lenses on the day of the procedure. This preparatory indication clearly applies to those patients who use contact lenses to remedy a visual defect.

Procedure

At the beginning of the fluorangiography, the doctor injects some eye drops into the patient's eyes, which are used to dilate the pupils. Therefore, once the drops have taken effect, invite the person under examination to sit in front of a special instrument, equipped with a support for the chin and a support for the forehead. This special instrument - known as a retinograph - is, substantially, a camera, with various functions, including the ability to retract in detail the internal structures of the eye, in particular the retina and the surrounding areas.

Once the correct positioning of the patient has occurred, the doctor takes a first series of preliminary photographs, which have the purpose of verifying the correct functioning of the instrument.

Immediately at the end of this first series of photos, the one that can be considered the most important phase of fluorangiography begins. This phase includes:

The injection, in a vein of the patient's arm, of a contrast medium with fluorescent capabilities;
The waiting time necessary for the contrast medium to spread also in the blood vessels of the retina and neighboring structures. Generally, it takes just a few seconds;
The emission, by the retinograph, of a blue or infrared light, which, by striking the blood vessels of the eye in which the contrast medium circulates, stimulates the fluorescent capacities of the latter;
The retinograph captures the fluorescence emitted by the contrast medium, under the stimulus of blue or infrared light;
The construction, once again through the retinograph, of images that show the characteristics of the blood flow - fluorescent for the aforementioned reasons - inside the ocular blood vessels.

Retina during the effects of Fluorangiography. Image from en.wikipedia.org

The images are immediately available. This means that the doctor who is carrying out the examination can notice any abnormalities already during the execution of the fluorangiography.

CONTRAST MEDIUM

There are two contrast media that can be used for fluorangiography: fluorescein and indocyanine .

Fluorescein shows its fluorescent abilities under the stimulus of blue light and is ideal for highlighting the blood vessels of the retina, but not those of the choroid.

Indocyanine, on the other hand, shows its own fluorescent abilities under the stimulus of infrared light and is ideal for analyzing blood flow through the choroid vessels, but not blood flow through the retinal vessels.

DURATION OF THE PROCEDURE

Generally, after pupil dilation, fluorangiography lasts between 10 and 30 minutes . The duration of the examination depends on the type of contrast medium used (indocyanine requires more time for its highlighting) and on the number of photographs necessary for the construction of images of the retina and of the neighboring anatomical structures.

How long can they take the pupils to dilate?

The dilation of the pupils, under the stimulation of the eye drops, can take from 15 to 40 minutes.

Risks and complications

Fluorangiography is a painless exam, which, however, presents some risks, some of which are also very serious. Fortunately, the most serious complications are very rare.

Among the less serious adverse effects, the sense of nausea, vomiting, dry mouth (or, alternatively, increased salivation), increased heart rate and tendency deserve a mention due to the frequency of appearance. to sneeze repeatedly.

The most serious complication is the development of an allergic reaction to the contrast medium . The typical consequences of this reaction are: laryngeal swelling, hives, respiratory problems, fainting and cardiac arrest.

TYPICAL CONSEQUENCES OF THE CONTRACT MEANS

The contrast medium involves typical transitory consequences, which after a few minutes or a few hours from the intervention resolve spontaneously and without aftermath.

Among the transient effects of the contrast medium, used during the fluorangiography, they deserve a quotation:

Obscured or slightly colored vision. The duration of this adverse effect is in the order of minutes;
Yellowish coloration of the skin. Its duration is of the order of a few hours;
Dark orange or yellow urine. The duration of this adverse effect is in the order of 24 hours;
Sense of burning at the point of the arm where the doctor performed the injection. The burning is due to the spillage of the contrast medium from the vein and its adverse reaction on the skin. The duration of the burning is of the order of a few hours.

IN CASE OF PREGNANCY

According to experts, pregnancy would be a contraindication to fluorangiography, as the consequences of the contrast agent on the fetus are not clear.

Therefore, if a pregnant woman has to undergo fluorangiography, it is good to wait for the end of the gestation period.

For more information on this, it is advisable to consult your doctor.

Results

Given the immediacy with which the retinograph creates the desired images, the doctor who performed the fluorangiography can illustrate to the patient the results of the diagnostic procedure, already after the conclusion of the latter. The wait, therefore, is really minimal.

RESULTS IN THE STANDARD

The results of a fluorangiography can be considered normal when:

The blood vessels of the ocular districts analyzed have a normal size;
There are no newly formed abnormal blood vessels;
The blood vessels do not present obstacles in their interior or are intact (therefore they are not the protagonists of blood loss).

ANOMALOUS RESULTS

The results of the fluorangiography are to be considered anomalous if they bring to light a blood loss from the blood vessels, an obstruction inside the vessels or the presence of vessels of a tumoral nature.

List of the main medical conditions that a doctor could diagnose based on the abnormal results of a fluorangiography:

Diabetic retinopathy and other types of retinopathy;
Macular edema and inflammatory states of the macula;
Ocular hypertension;
Presence of microaneurysms at the level of retinal capillaries;
Swelling of the optic disk;
Macular degeneration;
Retinal detachment;
Retinitis pigmentosa;
Ocular tumors;
Presence of obstructions at the level of the arteries or veins of the retina and neighboring regions.