Definition
Retinitis is defined as any inflammation affecting the retina, whether due to infections, hereditary degenerative diseases or inflammatory (inflammatory) processes of the neighboring ocular tissues.
Although numerous sub-categories exist, retinitis can be subdivided substantially into two macro-groups; according to the cause of origin, they are distinguished:
- Infective retinitis, induced by bacteria, viruses (in particular, by cytomegalovirus) or mycetes
- Retinitis pigmentosa, hereditary-degenerative disease that almost always leads to blindness
Infective retinitis
As the word itself predicts, infectious retinitis is due to an infection triggered by bacteria, viruses or fungi. Infective retinitis is dressed with the adjective "purulent" when it is induced by a pathogen transport in the retina via the blood (blood).
The most common infectious retinitis are undoubtedly those sustained by bacteria and fungi. However, there are other lesser known variants, where the infective insult is caused by protozoa (eg Toxoplasma gondii ).
Let's get some clarity ...- Retina: the innermost membrane of the eye from which originates a complex neurological process that allows vision. Numerous receptors for light are located in the retina, capable of transforming light stimuli into nerve impulses. As they pass through the optic nerve, these impulses are transmitted to the central nervous system.
- Choroid: part of the average vascular habit of the eye which, together with the ciliary body and crystalline, forms the uvea. The choroid is essential for securing the retina.
BACTERIAL RETINITES
Normally, bacterial retinitis are supported by the Koch bacillus ( Mycobacterium tuberculosis ) or by Treponema pallidum, the two main bacteria responsible for tuberculosis and syphilis, respectively. Generally, this inflammation is not limited only to the retina *: in most cases, in fact, the inflammatory-infective process also involves the choroid *. This is why we often speak of chorioretinitis .
When the infection reaches the posterior pole of the retina (or the choroid), the victim may experience a reduction in vision, a consequence of the development of micro-scesses along the retinal tissue. In more severe cases, retinitis causes the literal destruction of the retina, and the subsequent replacement with a fibrous scar tissue. Consequently, 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 the treatment is started too late, the risk of permanent vision damage is real.
CITOMEGALOVIRUS RETINITIS
Retinitis supported by cytomegalovirus is a fearsome retinal infection 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 chickenpox, cold sores, shingles and many others. This type of retinitis tends to present itself particularly in severely immunocompromised individuals - first among all AIDS patients - and in patients who have undergone a transplant.
The infection manifests itself with the appearance of white retinal foci surrounded by obvious hemorrhages, such as to compromise vision. In addition, the clinical picture of patients with cytomegalovirus retinitis is completed by the typical symptoms of ocular infections, namely severe pain in the eye, photophobia (light intolerance) and hyperemia (eye redness).
The most indicated drugs for treating 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 intake of specific drugs for treating the infection generally allows to stem the progression of the disease.
MICOTIC RETINITIS
This type of retinal infection, to say the least devastating, is caused by an insult sustained by mycetes, in particular by Candida albicans or Aspergillus.
- Similar to the cytomegalovirus-supported retinal infection, Candida retinitis is also typical - albeit not exclusive - of immunocompromised patients. Furthermore, fungal retinitis can manifest itself with its terrible symptoms even after injured trauma or eye surgery. Certain cases of candida retinitis have been observed in drug addicts and in some catheterized patients. On physical examination, Candida retinitis occurs 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 crystalline lens, which covers the 4/5 of the eyeball - appears instead nebulous. Patients with fungal retinitis complain of eye pain and severe visual impairment, which translates first into a blurred vision, then (in the case of failed / delayed therapy) in absolute blindness.
- Some forms of fungal retinitis are caused by an infection of Aspergillus. This kind of eye infection has been observed in drug addicts, transplant patients, and lung cancer patients. Aspergillus retinitis is manifested by yellowish infiltrates located below the retina, responsible for rapid vision loss, very obvious inflammation and, in some cases, bleeding.
In both variants of fungal retinitis, treatment with antifungal drugs must be timely to reverse the infection and remove the pathogen. Generally, to completely eliminate the infectious outbreak, vitrectomy is used, which is the surgical ablation of the vitreous body.
All the various forms of infectious retinitis can spread to neighboring eye areas, causing damage such as uveitis and chorio-retinitis.
Retinitis pigmentosa
Subtle and unstoppable, retinitis pigmentosa is a degenerative retinal disease of an exclusively hereditary nature that, in most cases, progresses to cause blindness.
The phenomenon seems to find the most obvious explanation in a malformation of the photoreceptors (the receptors that capture the light impulses) or, sometimes, in an anomaly of the same retina.
A characteristic of retinitis pigmentosa is the so-called telescope or tunnel vision : in other words, the victim has a loss of 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 has a progressive reduction in vision at night which, from moderate, gradually becomes more and more marked until complete night blindness.
Retinitis pigmentosa is not always recognized at birth: in fact, symptoms can begin even during childhood or adolescence. In general, the onset of symptoms is later, the loss of vision is more rapid.
Outside of vision, retinitis pigmentosa does not involve any physical malformation: in fact, patients with this terrible disease appear to be normal and healthy people.
Although experts continue the research on possible treatments, at present, no drugs have yet been identified that can completely cure retinitis pigmentosa. However, it seems that the administration of vitamin A palmitate, taken daily, may delay the onset of blindness, thus slowing (but not blocking) the progression of retinitis pigmentosa.
See also: Drugs for the treatment of retinitis "
