Chorioretinitis

Chorioretinitis is the inflammation of the posterior segment of the eye, including the choroid and the retina. The condition is usually caused by infections, the most common of which is toxoplasmosis. Some of these infections can affect the fetus in utero and present as congenital abnormalities. Systemic diseases such as sarcoidosis are also associated with this condition. Painless blurry vision, floaters, and scotomas are typical clinical features. With systemic and congenital disorders, extraocular manifestations are observed. Diagnosis is by funduscopy and slit-lamp examination, with use of laboratory tests and imaging dictated by the risk factors, medical history, and treatment monitoring. Treatment is directed toward eliminating the infection with antibiotics or antivirals and reducing inflammation with glucocorticoids or immunosuppressants.

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Overview

Definition

  • Also called retinochoroiditis
  • Inflammation of the choroid, a part of the posterior uvea, and the retina
  • A type of posterior uveitis

Anatomy

  • Choroid:
    • Vascular structure that provides support and nutrition to the retina
    • Continuous anteriorly with the ciliary body
  • Retina:
    • Innermost layer
    • Contains photoreceptors that convert light stimuli into nervous impulses
Eye anatomy

Anatomy of the human eye

Image by Lecturio.

Epidemiology and Etiology

Epidemiology

  • Among the types of uveitis, posterior uveitis is the least common form.
  • Chorioretinitis: often from infectious etiology
  • Toxoplasmosis: most common cause of chorioretinitis worldwide

Etiology

  • Infectious causes:
    • Toxoplasmosis (Toxoplasma gondii
    • Syphilis (Treponema pallidum)
    • Tuberculosis (TB) (Mycobacterium tuberculosis
    • Herpes simplex virus
    • Lymphocytic choriomeningitis virus
    • Rubella virus
    • Varicella virus
    • Cytomegalovirus (CMV) 
    • Histoplasmosis (Histoplasma capsulatum)
    • Candidiasis (Candida albicans)
    • Coccidioidomycosis (Coccidioides)
    • Toxocariasis (Toxocara canis, Toxocara cati)
  • Non-infectious causes:
    • Autoimmune diseases:
      • Sarcoidosis
      • Behcet’s disease
      • Systemic lupus erythematosus
      • Polyarteritis nodosa
      • Granulomatosis with polyangiitis 
    • No systemic association:
      • Birdshot choroidopathy
      • Multifocal choroiditis and panuveitis
      • Serpiginous choroidopathy
      • Multiple evanescent white dot syndrome (MEWDS)

Clinical Presentation

  • Usually painless, but pain occurs with panuveitis
  • Floaters 
  • Flashes of light (photopsia)
  • Vision impairment or loss
  • Scotomas (blind spots)
  • In neonates: usually asymptomatic at birth with manifestations observed later
  • Extraocular symptoms are dependent on the associated disease.

Infectious Chorioretinitis

Congenital toxoplasmosis

  • Only 10%30% of patients have manifestations at birth and in early infancy.
  • Fetuses infected in early pregnancy are more likely to show signs of infection.
  • In utero findings: intracranial calcifications/densities and hydrocephalus (most common findings)
  • Classic triad: 
    1. Intracranial calcifications
    2. Hydrocephalus
    3. Chorioretinitis: a common late manifestation of congenital toxoplasmosis
  • Symptoms: often painless blurred vision, scotoma, photophobia

Acquired toxoplasmosis

Active infection

  • High-risk patients: 
    • Can occur in all age groups
    • Patients from South and Central America (predominantly genotype I, which causes severe disease)
  • Symptoms: unilateral visual loss or floaters

Reactivated infection

  • High-risk patients: 
    • Those who acquired infection in utero or postnatally
    • Onset at > 40 years of age: increased risk of recurrence
  • Symptoms: bilateral visual loss or floaters with an inflammatory chorioretinal lesion

Congenital CMV retinitis

  • 90% asymptomatic at birth
  • High-risk patients: 
    • Newborns of mothers with known or suspected CMV infection
    • Immunocompromised newborns (severe combined immunodeficiency disorder)
  • In utero findings: growth restriction, periventricular calcifications, ventriculomegaly, microcephaly
  • Chorioretinitis: most common ocular finding
  • Symptoms: visual impairment, strabismus
  • Extraocular symptoms: petechiae, jaundice, hepatosplenomegaly, hearing loss, microcephaly, and ventricular calcifications

Acquired CMV retinitis

  • High-risk patients: 
    • Severely immunocompromised patients: AIDS with CD4 count < 50 cells/microL
  • Symptoms: 
    • Typically unilateral
    • Blurry or loss of central vision 
    • Scotoma 
    • Floaters, photopsia: symptomatic predictors of CMV retinitis in patients with AIDS
  • Associated with necrotizing retinitis, retinal vasculitis, and optic neuropathy

Tuberculosis

  • High-risk patients: 
    • Those living in endemic countries
    • Immunocompromised state
  • Results from hematogenous spread
  • Frequently presents as posterior uveitis with disseminated choroiditis
  • Symptoms: 
    • Diminished visual acuity when the macula is affected 
    • Unilateral or bilateral

Toxocariasis

  • High-risk patients: young patients with pets
  • Symptoms: Unilateral reduced vision, photophobia, floaters
  • Signs: leukocoria, ocular injection

Syphilis

  • High-risk patients: history of sexually transmitted diseases
  • Commonly manifests as iritis or iridocyclitis but also causes chorioretinitis
  • In HIV, placoid lesions develop: placoid chorioretinitis
  • Symptoms: blurry vision, floaters, light sensitivity

Ocular histoplasmosis syndrome

  • High-risk patients: in regions endemic for Histoplasma 
  • Often asymptomatic until choroidal neovascularization (CNV) occurs
  • Symptoms: central vision loss, metamorphopsia (distorted straight lines), scotomas

Non-infectious Chorioretinitis

Sarcoidosis

  • High-risk patients: African American women
  • Pulmonary and extrapulmonary symptoms
  • Affects posterior uvea in ⅓ of cases
  • Symptoms: blurry vision, floaters, photophobia; pain if with anterior uveitis

Behcet’s disease

  • Characterized by recurrent oral and genital ulcers, polyarthritis
  • Symptoms: 
    • Often bilateral, episodic
    • Can present as panuveitis (redness, tearing, pain, photophobia, blurry vision)
    • Severe visual loss from retinal vasculitis and optic neuritis

Birdshot retinochoroidopathy

  • High-risk patients: associated with HLA-A29
  • Symptoms: blurry vision, floaters, and glare

MEWDS

  • Rare but affects healthy young women
  • Symptoms: 
    • Acute unilateral painless loss of vision
    • Self-limited and resolves by 9 weeks

Diagnosis

Prenatal diagnosis

  • Screening includes syphilis
  • Sonogram can detect fetal changes that are suggestive of CMV and toxoplasmosis

Laboratory tests and imaging

Guided by:

  • High level of suspicion in patients with known or suspected perinatal infections
  • Presenting manifestations at birth and subsequent symptoms
  • Medical history
  • Predisposing high-risk factors (e.g., sexual behavior, pet ownership, residence in or travel to endemic areas)

Dilated fundus examination and slit-lamp biomicroscopy

  • Choroiditis: yellow patches, regular borders
  • Retinitis: whitish patch with ill-defined borders
  • Vitreous inflammation (leukocytes in the vitreous humor)
  • Vitreous opacities

Ophthalmologic findings in infectious chorioretinitis

InfectionOphthalmologic findings
Toxoplasmosis
  • Inactive stage: atrophic chorioretinal scars
  • Active stage:
    • Focal necrotizing retinitis
    • White focal retinitis with vitreous inflammation (“headlight in the fog”)
Congenital toxoplasmosisPunched-out or excavated macular lesion
CMV retinitis
  • Yellow-white, fluffy granular retinal lesions, hemorrhages’ “pizza pie” appearance
  • Congenital: optic atrophy, retinal scars, chorioretinitis
Tuberculosis
  • Disseminated choroiditis
  • Single or multiple, discrete yellow lesions (choroidal tubercles) seen in the posterior pole
ToxocariasisWhitish granuloma in periphery or posterior pole (from larval localization)
SyphilisGreat imitator: presents as chorioretinitis, papilledema, optic neuritis, placoid lesions
Ocular histoplasmosis syndromeDiscrete chorioretinal oval-round lesions (“punched-out” histo spots)

Ophthalmologic findings in non-infectious chorioretinitis

Disease/conditionOphthalmologic findings
Sarcoidosis
  • Chorioretinal granulomas, periretinal exudates (“candle wax drippings”)
  • Placoid lesions
Behcet’s disease
  • Vitreous haze
  • Necrotizing retinitis
  • Retinal vasculitis
Birdshot retinochoroidopathyBirdshot lesions: cream-colored choroidal lesions radiating from optic disc
White dot syndrome
  • White lesions in outer retina
  • Foveal granularity

Management

Goals

  • Preserve visual function.
  • Suppress host inflammatory response.
  • Eliminate infection (for infectious causes).

Infectious chorioretinitis

  • Toxoplasmosis:
    • Inactive disease: no treatment if asymptomatic
    • Active disease: trimethoprim-sulfamethoxazole or pyrimethamine + sulfadiazine + leucovorin
    • < 14 weeks’ pregnant with active disease: spiramycin
    • > 14 weeks’ pregnant with active disease: pyrimethamine-sulfadiazine
    • Infants with confirmed diagnosis: pyrimethamine + sulfadiazine + leucovorin
  • CMV retinitis: severity determines medication and route
    • Ganciclovir
    • Valganciclovir
    • Foscarnet
    • Cidofovir
  • Tuberculosis: antitubercular therapy
    • Isoniazid
    • Rifampicin
    • Pyrazinamide
    • Ethambutol
  • Toxocariasis: prednisone and albendazole (for sight-threatening inflammation)
  • Syphilis: IV penicillin G 24 million units/day for 1014 days (similar to neurosyphilis)
  • Histoplasmosis: 
    • Observation and monitoring for CNV
    • Anti-vascular endothelial growth factor (VEGF) for CNV

Non-infectious chorioretinitis

Non-infectious chorioretinitis is treated with corticosteroids and immunosuppressants.

Non-resolving chorioretinitis

For non-resolving chorioretinitis, rule out malignancies (masquerade syndromes).

Differential Diagnosis

The differential diagnoses of chorioretinitis include the following conditions:

  • Vitreoretinal lymphoma: most common intraocular lymphoproliferative disorder. The disorder is one of the masquerade syndromes that presents a diagnostic dilemma. Patients have gradual visual impairment with floaters. Gold standard of diagnosis is cytopathologic examination of ocular fluid or chorioretinal biopsy.
  • Choroidal melanoma: a malignancy that presents with uveitis (masquerade syndrome). Patients can be asymptomatic or can present with floaters, visual field defects, and flashes. Diagnosis is by funduscopic examination showing pigmented dome-shaped tumor. Fine needle biopsy is performed for molecular prognostic testing.
  • Retinoblastoma: the most common intraocular malignancy in childhood, usually diagnosed before the age of 5. Retinoblastoma frequently presents as abnormal white reflection from the retina, called leukocoria. Other features include red-eye, strabismus, and nystagmus. Ophthalmoscopic examination reveals a retinal mass. Additional imaging studies, including ocular ultrasound, can be used for diagnosis.

References

  1. Duplechain, A., Conrady,C., Patel, B. (2020). Uveitis. www.ncbi.nlm.nih.gov/books/NBK540993
  2. Garweg, J., Petersen, E., Durand, M., Mitty, J. (2020) Toxoplasmosis: Ocular disease.UpToDate. Retrieved September 22, 2020, from https://www.uptodate.com/contents/toxoplasmosis-ocular-disease
  3. Geetha, R., Tripathy, K. (2020). Chorioretinitis. https://www.ncbi.nlm.nih.gov/books/NBK551705/
  4. Harbour, J., Shih, H., Atkins, M, Berman, R. (2018). Initial management of uveal and conjunctival melanomas. UpToDate. Retrieved September 22, 2020, from https://www.uptodate.com/contents/initial-management-of-uveal-and-conjunctival-melanomas
  5. Jacobson,M., Bartlett, J., Mitty, J. (2020) Pathogenesis, clinical manifestations and diagnosis of AIDS-related cytomegalovirus. UpToDate. Retrieved September 22, 2020, from https://www.uptodate.com/contents/pathogenesis-clinical-manifestations-and-diagnosis-of-aids-related-cytomegalovirus-retinitis
  6. Petersen, E.m Mandelbrot, L.,Simpson, L.,Weller, P., Barss, V., Mitty, J. (2020). Toxoplasmosis and pregnancy. UpToDate. Retrieved September 22, 2020, from https://www.uptodate.com/contents/toxoplasmosis-and-pregnancy
  7. Rathinam, S., Bernardo, J., Gardiner, M., Baron, E. (2019). Tuberculosis and the eye. UpToDate. Retrieved September 22, 2020, from https://www.uptodate.com/contents/tuberculosis-and-the-eye?search=tuberculosis
  8. Roque, M., Steele, R., Schleiss, M, Windle, M. (2016). Chorioretinitis. Medscape. Retrieved September 22, 2020, from  https://emedicine.medscape.com/article/962761-overview
  9. Sudharshan, S., Ganesh, S., Biswas, J. (2010) Current approach in the diagnosis and management of posterior uveitis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841371/

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