Cytomegalovirus retinitis, also known as CMV retinitis, is an inflammation of the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

of the eye that can lead to

blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

. Caused by

human cytomegalovirus ''Human betaherpesvirus 5'', also called human cytomegalovirus (HCMV), is species of virus in the genus '' Cytomegalovirus'', which in turn is a member of the viral family known as ''Herpesviridae'' or herpesviruses. It is also commonly calle ...

, it occurs predominantly in people whose

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splint ...

has been compromised, 15-40% of those with AIDS.

Signs and symptoms

The symptoms of cytomegalovirus retinitis have it usually starting in one eye (and also have the possibility of retinal detachment), presenting as: * Blurred vision * Blind spots * Specks in your vision

Cause

Cytomegalovirus (a type of

herpes Herpes simplex is a viral infection caused by the herpes simplex virus. Infections are categorized based on the part of the body infected. Oral herpes involves the face or mouth. It may result in small blisters in groups often called cold ...

virus) is what causes cytomegalovirus retinitis. Other types of herpes viruses include

herpes simplex Herpes simplex is a viral infection caused by the herpes simplex virus. Infections are categorized based on the part of the body infected. Oral herpes involves the face or mouth. It may result in small blisters in groups often called col ...

viruses and Epstein-Barr virus. Once an individual is infected with these viruses they stay in the body for life. What triggers the virus to reactivate are the following (though CMV can also be congenital). *

Leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ...

* AIDS * Immunosuppressive chemotherapy

Mechanism

Human cytomegalovirus ''Human betaherpesvirus 5'', also called human cytomegalovirus (HCMV), is species of virus in the genus '' Cytomegalovirus'', which in turn is a member of the viral family known as ''Herpesviridae'' or herpesviruses. It is also commonly calle ...

(HCMV or CMV) is a

DNA virus A DNA virus is a virus that has a genome made of deoxyribonucleic acid (DNA) that is replicated by a DNA polymerase. They can be divided between those that have two strands of DNA in their genome, called double-stranded DNA (dsDNA) viruses, and ...

in the family ''

Herpesviridae ''Herpesviridae'' is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word ''ἕρπει� ...

'' known for producing large cells with nuclear and cytoplasmic inclusions, CMV infects around 40% of the population worldwide. Those areas infected by cytomegalovirus have cells evolve to necrosis, though inflammation within the retina is not great. Rhegmatogenous retinal detachments can occur following the development of holes in areas of healed retinitis (retina may be

atrophic Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply t ...

Proliferative vitreoretinopathy Proliferative vitreoretinopathy (PVR) is a disease that develops as a complication of rhegmatogenous retinal detachment. PVR occurs in about 8–10% of patients undergoing primary retinal detachment surgery and prevents the successful surgical re ...

has been observed in cases of retinal detachment.

Diagnosis

The diagnosis of CMV retinitis can be done via the following: * Ophthalmic screening frequency is based on

CD4 count In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic ce ...

,(CD4 < 50 cells/mL, 0- 35% possibility of CMV retinitis) * BUN *

CD8+ A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected by intracellular pa ...

T-lymphocyte count * CMV DNA capture ( polymerase chain reaction (PCR) test) * DNA PCR ( ocular fluids) *

Viral load Viral load, also known as viral burden, is a numerical expression of the quantity of virus in a given volume of fluid, including biological and environmental specimens. It is not to be confused with viral titre or viral titer, which depends on the ...

* Complete blood count

Treatment

In terms of the treatment of cytomegalovirus retinitis, oral valganciclovir, intravenous

ganciclovir Ganciclovir, sold under the brand name Cytovene among others, is an antiviral medication used to treat cytomegalovirus (CMV) infections. Ganciclovir was patented in 1980 and approved for medical use in 1988. Medical use Ganciclovir is indicated ...

, IV

foscarnet Foscarnet (phosphonomethanoic acid), known by its brand name Foscavir, is an antiviral medication which is primarily used to treat viral infections involving the Herpesviridae family. It is classified as a pyrophosphate analog DNA polymerase inhi ...

, and IV

cidofovir Cidofovir, brand name Vistide, is a topical or injectable antiviral medication primarily used as a treatment for cytomegalovirus (CMV) retinitis (an infection of the retina of the eye) in people with AIDS. Cidofovir was approved for medical u ...

are all efficient in the treatment of this condition. Also intravitreal injections, an injection of medicine into the vitreous near the retina, of

in concomitance with oral valganciclovir can be used for treatment as well. Often individuals with CMV retinitis will need surgery for either retinal detachment or intravitreal instillation of ganciclovir. Retinal detachment occurs in up to 29% of affected eyes, repair being most effective with endolaser and silicone oil endotamponade. Intravitreal ganciclovir implant has the benefit of less systemic toxicity. An adverse effect of this is retinal detachment (and vitreous hemorrhage), also there is no systemic beneficial effect for cytomegalovirus organ disease.

References

External links

* {{Eye pathology HIV/AIDS Cytomegalovirus-associated diseases Disorders of choroid and retina