Definition
It defines itself retinitis any inflammation of the retina, whether due to infections, hereditary degenerative diseases or to inflammatory processes of the nearby ocular tissues.
Although there are numerous subcategories, retinitis can be broadly divided into two macrogroups; according to the cause of origin, the following are distinguished:
- Infectious retinitis, induced by bacteria, viruses (in particular, by Cytomegalovirus) or fungi
- Retinitis pigmentosa, a hereditary-degenerative disease that almost always leads to blindness
Infectious retinitis
As the word itself suggests, infectious retinitis is due to an "infection triggered by bacteria, viruses or fungi. Infectious retinitis takes on the adjective" purulent "when it is induced by the transport of pathogens into the retina by blood (blood) .
The most common infectious retinitis are undoubtedly those sustained by bacteria and fungi. However, there are other less known variants, where the infectious insult is caused by protozoa (eg. Toxoplasma gondii).
- Retina: innermost membrane of the eye from which a complex neurological process that allows vision originates. Numerous light receptors are located in the retina, capable of transforming light stimuli into nerve impulses. Crossing the optic nerve, these impulses are transmitted to the central nervous system.
- Choroid: part of the vascular media of the eye which, together with the ciliary body and the lens, forms the uvea. The choroid is essential to ensure nourishment to the retina.
BACTERIAL RETINITES
Normally, bacterial retinitis is supported by Koch's bacillus (Mycobacterium tuberculosis) or from Treponema pallidum, the two main bacteria responsible for tuberculosis and syphilis, respectively. In general, this inflammation is not limited only to the retina *: most of the time, in fact, the inflammatory-infectious process also involves the choroid *. For this, we speak more often of chorioretinitis.
When the infection reaches the posterior pole of the retina (ie the choroid), the victim may experience a reduction in vision, a consequence of the development of microabscesses along the retinal tissue. In severe cases, retinitis causes the literal destruction of the retina. and subsequent replacement with a fibrous scar tissue.As a result, adhesions form between the retina and the choroid that could cause retinal detachment.
In these cases, it is necessary to intervene with massive doses of antibiotics (to be taken generally); when treatment is started too late, there is a real risk of permanent vision damage.
RETINITIS BY CYTOMEGALOVIRUS
Cytomegalovirus-borne retinitis is a fearsome infection of the retina that can lead to blindness. Let us briefly recall that Cytomegaloviruses are viruses belonging to the Herpesviridae family, the same pathogenic microorganisms involved in very common infections such as chicken pox, cold sores, St. Anthony's fire and many others. This type of retinitis tends to occur in particular in severely immunocompromised subjects - first of all AIDS patients - and in patients who have undergone a transplant.
The infection manifests itself with the appearance of white retinal foci surrounded by evident haemorrhages, such as to compromise the vision. In addition, the clinical picture of patients suffering from Cytomegalovirus retinitis is completed by the typical symptoms of ocular infections, ie severe pain at eye level, photophobia (intolerance to light) and hyperemia (eye redness).
The drugs most indicated for the treatment of the infection are ganciclovir, foscarnet or cidofovir (eg Vistide), which can be taken orally, intravenously, injected directly into the eye or administered via an intravitreal implant. The assumption of specific drugs for the treatment of the infection generally allows to stem the progression of the disease.
MYCOTIC RETINITIS
This type of retinal infection, devastating to say the least, is caused by an insult sustained by fungi, in particular by Candida albicans or Aspergillus.
- Similarly to the infection of the retina caused by Cytomegalovirus, Candida retinitis is also typical - albeit not exclusive - of immunocompromised patients. Furthermore, fungal retinitis can manifest itself with its terrible symptoms also following trauma or bad eye surgery. Certain cases of candida retinitis have been observed in drug addicts and in some catheterized patients. On physical examination, Candida retinitis manifests with whitish retinal lesions with a diameter of at least 1 mm; the vitreous body - the gelatinous and transparent mass between the retina and the lens, which covers 4/5 of the ocular globe - appears instead nebulous. Patients with mycotic retinitis complain of ocular pain and severe visual difficulty, which first results in a blurred vision, then (in case of missed / delayed therapy) in the most absolute blindness.
- Some forms of fungal retinitis are caused by an "Aspergillus infection. This kind of" eye infection has been observed in drug addicts, transplant patients, and lung cancer patients. Aspergillus retinitis manifests itself with yellowish infiltrates located below the retina, responsible for rapid loss of vision, very evident inflammation and, in some cases, hemorrhages.
In both variants of fungal retinitis, treatment with antifungal drugs must be timely to reverse the infection and ward off the pathogen. Generally, to completely eliminate the infectious focus, vitrectomy is used, that is the surgical ablation of the vitreous body.
All the various forms of infectious retinitis can spread to surrounding eye areas, causing damage such as uveitis and chorio-retinitis.
Retinitis pigmentosa
Subtle and unstoppable, retinitis pigmentosa is an exclusively hereditary degenerative disease of the retina which, in most cases, progresses to the point of causing blindness.
The phenomenon seems to find the most obvious explanation in a malformation of the photoreceptors (the receptors that pick up light impulses) or, sometimes, in an "anomaly of the retina itself.
Characteristic of retinitis pigmentosa is the so-called telescope vision or tunnel: in other words, the victim experiences a loss of the peripheral visual field.
Another symptom of the onset of the disease is the difficulty of adapting to the dark: the patient suffering from retinitis pigmentosa accuses a progressive reduction of vision at night which, from moderate, gradually becomes more and more marked up to complete night blindness.
Retinitis pigmentosa is not always recognized at birth: in fact, symptoms can also begin during childhood or adolescence. Typically, the later symptoms appear, the quicker the loss of vision.
Outside of vision, retinitis pigmentosa does not involve any physical malformation: the patients of this terrible disease, in fact, appear to be normal and healthy people.
Although experts continue research on possible treatments, currently, no drugs have yet been identified that can completely cure retinitis pigmentosa. However, it seems that the administration of vitamin A palmitate, taken daily, can delay the onset of blindness, thus slowing (but not blocking) the progression of retinitis pigmentosa.
See also: Medicines for the Treatment of Retinitis »
