Retinitis Flashcards
What is retinitis?
Inflammation of the retina
What are endogenous causes of retinitis?
1.Associated with systemic disease:
•E.g. HIV
2.Infections or infestations:
- Toxoplasmosis – parasite
- Cytomegalovirus retinitis - virus
- Candida endophthalmitis - fungus
3.Idiopathic
What are exogenous causes of retinitis?
- External injury
- Post surgical
What are the two main parasite based illnesses that cause retinitis?
- Toxoplasmosis from Toxoplasma Gondii
- Toxocariasis from Toxocara
What is the most common ocular parasite?
Toxoplasma Gondii
What is toxoplasmosis?
An illness caused due to infection by a parasite called Toxoplasma gondii.
What does Toxoplasma Gondii cause when it affects humans?
Toxoplasmosis
In what three forms does Toxoplasma Gondii exist?
- Oocysts – which are secreted in cat faeces
- Bradyzoite - which are encysted in tissue (inactive) (normally cat or pig)
- Tachyzoite – which is a proliferating active form
What is the prevalence of Toxoplasma Gondii like?
•Infects 10% adults in northern temperate countries (i.e. like the UK), 50% in Mediterranean and tropical countries
What are hosts of Toxoplasma Gondii?
Cats
Through what routes may a person become infected with Toxoplasma Gondii?
–Eating undercooked meat of animals harbouring bradyzoites tissue cysts e.g. cats or pigs
–Injestion of oocysts by consuming food or water contaminated with cat faeces
–Blood transfusion or organ transplantation
–Trans-placentally from mother to foetus
Which form of Toxoplasma Gondii leads to an inflammatory reaction?
The Tachyzoite proliferating form
Does a Bradyzoite cyst cause an inflammatory reaction?
No - this inactive stage can lie dormant (up to 20 years) within cysts in tissues such as the eye, brain
How does a bradyzoite progress to a tachyzoite form of Toxoplasma Gondii?
Bradyzoites cyst ruptures to release Tachyzoites
True or False- One can have congenital toxoplasmosis
True –approx one third of cases show themselves by 12 years old
The neurological problems associated can be severe!
In what px group does acquired childhood postnatal or adult toxoplasmosis occur?
Often immunocompromised patients who may either acquire or have reactivation of the existing disease.
How does active ocular toxoplasmosis occur and what is the most common cause?
- Often occurs when previously inactive cysts in retina rupture and release tachyzoites
- Recurrence of old healed congenital ocular toxoplasmosis is the most common cause (20-60% of all cases)
What is a granuloma?
A granuloma is an aggregation of macrophages that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances which it is unable to eliminate.
What are signs and symptoms of active ocular toxoplasmosis?
- Symptoms – unilateral acute onset of floaters and photophobia
- Posterior uveitis with spill over into anterior uveitis – may be granulomatous – can cause raised IOP, secondary glaucoma
- “Fluffy white” retinitis or chorio-retinitis (as seen on picture)
- Lesions tend to involve posterior pole
- Overlying vitritis
- Optic disc oedema
What condition does the following fundus image show?
Active ocular toxoplasmosis - except this time there are multiple lesions which are shown by mutliple fluffy white spots.
What can be seen in the following fundus image?
Old Toxoplasmosis Scar- you know this as there is a Demarcated atropic scar with hyper-pigmented borders - scars loose their ‘fluffy’ white appearance.
How do we treat toxoplasmosis?
- If old scar seen, no treatment required unless in high risk group e.g. immunosuppressed (e.g. organ transplant, HIV) or pregnant.
- Refer active infection
- Prednisolone - an anti-inflammatory drug
- Anti toxoplasmosis agents e.g. Pyrimethamine
- Topical steroids and mydriatic for anterior uveitis
What is Toxocariasis?
An infection caused by infestation with common roundworm of dogs (Toxocara) – particularly puppies
How may humans develop toxocariasis?
Whom is toxocariasis most likely to affect?
- Human infection from accidental ingestion of soil or sand contaminated with ova shed from dogs’ faeces.
- Usually affects young children (more likely to ingest infected material)
How does toxocariasis affect humans?
- After a human ingests the eggs, the eggs hatch in the small intestine and release parasitic larvae.
- Larvae penetrate the intestinal wall, enter the circulation, and migrate to organs where they induce inflammatory reactions.
What is ocular toxocariasis characterised by?
–Chronic endophthalmitis – inflammation of inner membranes of the eye including vitreous
–Posterior pole granuloma
–Fibrous traction bands which can form leading to tractional retinal detachment
What can be seen in the following fundus?
Posterior pole granuloma with traction bands
What can be seen in the following fundus?
Inflammation of vitreous (vitreous veil)
How do granulomas present and what layers of the retina do they affect?
They present as a white/yellow spot/circle.
They can affect the outerlayers of the retina as seen by example A OCT.
They can affect inner retinal layers as seen by example B OCT.
They can affect all retinal layers as seen by example C OCT. (In this case can be accompanied by photoreceptor abnormalities in that area)
What are ocular symptoms of Toxocariasis?
•blurred/cloudy vision, usually affecting one eye
What is the treatment for toxocariasis?
- Toxocariasis often asymptomatic and doesn’t require treatment.
- If eyes actively affected, refer for corticosteroids (prednisolone) to reduce inflammation, and possible other treatment e.g. for retinal detachment.
What are the most common viral causes of Retinitis?
- Human Immunodeficiency Virus (HIV)
- Cytomegalovirus (CMV)
How does the transmission of HIV occur?
–Sexual intercourse
–Blood infusion, needles
–Passage from infected mother to child
What does HIV affect/cause to happen?
It Depletes CD4 T Cells (white blood cells) that are vital to the immune system
What is AIDS and how may it be the result of HIV?
AIDS (acquired immunodeficiency syndrome) is characterised by having a CD4 count of less than 200cells/mm.
Without HIV treatment 50% of patients develop AIDS in 10 years
How do we manage HIV?
Anti-retroviral therapy slows the progression of the disease
What is the prevalence of HIV?
- Approx 1 in 200 Londoners aged between 15-59.
- World Health Organization estimates that around 35 million people in the world are living with HIV. The virus is more common in many sub-Saharan African countries
What are examples of ocular manifestations of HIV?
- Eye lid and conjunctiva – Kaposi Sarcoma
- HIV related micro-angiopathy this includes having:
–Cotton Wool Spots
–Retinal Haemorrhages
–Microaneurysms
- Cytomegalovirus (CMV) retinopathy – you are more likely to have this if you are immunocompromised (e.g. have HIV)
- Toxoplasmosis you are more likely to have this if you are immunocompromised (e.g. have HIV)
- Fungal infections e.g. candida retinitis, presumed ocular histoplasmosis - you are more likely to have this if you are immunocompromised (e.g. have HIV)
- CMV, toxoplasmosis, fungal infections etc are opportunistic infections.
What are opportunistic infections?
Those that thrive/affect immunocompromised pxs.
What are the following fundus images showing and what clinical signs confirm this?
HIV Microangiopathy.
This is confirmed through the presence of:
Cotton Wool Spots in retinal nerve fibre layer.
Retinal Haemorrhages
Microaneurysms
Which viral agent causes CMV (Cytomegalovirus)?
Human herpes virus-5 (HHV-5)
[Same one that causes shingles]
True or False- CMV is benign in a high proportion of adults
True
Why is CMV (Cytomegalovirus) strongly associated with HIV?
As it is strongly associated with a low CD4 count thus most common ocular infection in px with HIV
Without treatment what can CMV retintis cause?
•Without treatment (antiviral) CMV causes severe visual loss
What are ocular signs of CMV retinitis?
–Areas of dense white retinal infiltration (“pizza pie” appearance)
–Begins as granular lesions near major blood vessels
Later on:
–Scattered haemorrhages
–Retinal necrosis and retinal detachment
–Usually no vitritis
What condition is being shown in the following fundus photo?
CMV Retinitis with granular ‘pizza pie’ appearance
What condition is being shown in the followijg fundus photo?
CMV retinitis advanced.
Here we can see haemorrhages, dilated veins, cotton wool spots too
What are examples of retinitis caused by fungal infections?
- Presumed Ocular Histoplasmosis
- Candida Endophthalmitis
- Aspergillus
What is Presumed ocular histoplasmosis syndrome?
A Fungal Infection following inflammation of the yeast form of the fungus
What is the mode of transmission of Ocular histoplasmosis syndrome?
- Fungal spores inhaled as child
- Reactivation 20-30 years later
(Common in AIDS patients)
What are signs of Presumed ocular histoplasmosis syndrome?
- 60% Bilateral
- White atrophic chorio-retinal “histo” spots -Histo spots are small circular punched-out spots in the retina at a site where spores of the fungus histoplasma (histo) are seeded in the eye. Histo spots may be multiple, found in both eyes, and scattered throughout the retina.
- Peripapillary atrophy - i.e. atrophy around the optic disc
- Macula involvement can occur e.g.–Choroidal neovascularisation
- Absence of Vitritis or anterior Uveitis
What condition is the following fundus photo showing?
What is endophthalmitis?
Endophthalmitis is a rare but potentially sight-threatening disease characterized by marked inflammation of the intraocular cavities (aqueous and/or vitreous humour)
What are the exogenous causes of Endophthalmitis?
- Infection by microorganisms from the external environment
- most commonly occurs as a complication of ocular surgery, trauma, or intravitreal injections
What are the endogenous causes of Endophthalmitis?
[Endogenous causes are less common]
•Spread of infectious organisms through the blood from distant sites of the body associated with
–IV drug use, diabetes, immunocompromised patients
How would Endogenous Endophthalmitis present? (i.e what symptoms?)
- Decreased Vision
- Floaters
- Pain, photophobia
- Headache
- Redness
- Discharge
- Only 50 % have systemic symptoms
How would bacterial endophthalmitis appear?
Anterior chamber inflammation, corneal oedema, and hypopyon in bacterial endophthalmitis
What is candida endophthalmitis?
Endophthalmitis caused by a fungal infection.
What are the exogenous causes of Candida endophthalmitis?
–trauma or surgery
–spread from fungal keratitis
What are endogenous causes of Candida endophthalmitis?
–E.g. Metastatic spread from chronic lung disease
What are signs of Candida Endophthalmitis?
- Vitritis – fluffy cotton ball
- Chorio-retinitis
[In the picture Cotton ball colonies in vitreous can be seen]
What is Aspergillus endophthalmitis?
How does it differ from Candida endophthalmitis?
It is Endophthalmitis caused by Aspergillus fungi.
It has a More rapid disease progression
Visual outcome worse
What is the managment of Fungal Endophthalmitis?
- Urgent referral
- Antifungal treatment:
–E.g. Intravitreal amphotericin
–E.g. Oral flucytosine
- Pars plana vitrectomy
- Keep treatment going for 2 – 4 weeks
Which of the following is NOT an ocular condition associated with HIV ?
- Retinal Haemorrhages
- CMV Retinitis
- Cotton Wool Spots
- Cataract
Cataract
