Conjunctiva Flashcards
What is the blood supply of the conjunctiva?
supplied by the anterior ciliary and palpebral arteries.
What is the conjunctiva?
a transparent mucous membrane that lines the inner surface of the eyelids and the anterior surface of the globe, terminating at the corneoscleral limbus.
What are the divisions of the conjunctiva?
- The palpebral conjunctiva starts at the mucocutaneous junction of the lid margins and is firmly attached to the posterior tarsal plates. The tarsal blood vessels are vertically orientated.
- The forniceal conjunctiva is loose and redundant.
- The bulbar conjunctiva covers the anterior sclera and is continuous with the corneal epithelium at the limbus.
What is the epithelium of the conjunctiva?
non-keratinizing and around five cell
layers deep. Basal cuboidal cells evolve into flattened polyhedral cells, subsequently being shed from the surface. Mucus-secreting goblet cells are located within the epithelium,
being most dense inferonasally and in the fornices.
What is the stroma of the conjunctiva?
richly vascularized loose connective tissue. The accessory lacrimal glands
of Krause and Wolfring are located deep within the stroma. Secretions from the accessory lacrimal glands are essential components of the tear film.
What is Conjunctiva associated lymphoid tissue (CALT)?
critical in the initiation and regulation of ocular surface immune responses. It consists of lymphocytes within the epithelial layers, lymphatics and associated blood vessels, with a stromal component of lymphocytes and plasma cells, including follicular aggregates.
What are some clinical features of conjunctival inflammation?
Discharge- watery (viral/allergic conjunctivitis), mucoid (chronic allergic conjunctivitis and dry eye), mucopurulent (chlamydia/bacterial conjunctivitis), moderately purulent (acute bacterial conjunctivitis), severe purulent (gonococcal infection)
Conjunctival reaction- hyperaemia (diffuse and beefy red seen in bacterial infection and away from limbus). Haemorrhages in viral conjunctivitis, Chemosis (local from TED, Allergic conditions, SVC syndrome and nephrotic syndrome). Membranes (pseudomembranes, true membranes of which removal causes tearing caused by severe adenoviral conjunctivitis, gonococal and bacterial infections, diptheria. Infiltration- papillary response and chronic inflammation. Subconjunctival cicatrization- scarring from trachoma. Due to loss of goblet cells and can lead to entropion. Follicles- viral and chlamydial conjunctivitis. Parinaud oculoglandular syndrome. Papillae- bacterial/allergic conjunctivitis/chronic blepharitis/CL wear, SLK, FES.
Lymphadenopathy- viral infections. Can occur in Chlamydial/severe bacterial infection (gonococcal) and parinaud oculoglandular syndrome. Preauricular lymph node affected.
How to macroscopially differentiate between a follicle and papillae?
Papillae- a vascular core is present.
Micropapillae form a mosaic-like pattern of elevated red dots as a result of the central vascular channel,
Follicles are multiple, discrete, slightly elevated lesions resembling translucent grains of rice, most prominent in the fornices. Blood vessels run around or across
rather than within the lesions.
Histological difference between follicle and papillae?
Follicle- Histology shows a subepithelial lymphoid germinal centre with central immature lymphocytes and mature cells
peripherally
Papillae- folds of hyperplastic conjunctival epithelium with a fibrovascular core and subepithelial stromal infiltration with inflammatory cells
What are the causes of acute bacterial conjunctivitis?
The most common isolates are Streptococcus pneumoniae,
Staphylococcus aureus, Haemophilus influenzae and Moraxella catarrhalis. A minority of severe cases are caused by the sexually transmitted organism Neisseria gonorrhoeae, which can readily invade the intact corneal epithelium. Meningococcal (Neisseria meningitidis) conjunctivitis is rare and usually affects
children.
Symptoms and signs of bacterial conjunctivitis?
Redness, grittiness, burning and discharge.
Usually bilateral and 1 eye infected 1-2 days before the other.
Eyelids stuck together on waking.
Vision usually normal.
Eyelid oedema/erythema (gonococcal)
Conjunctival injection
Hyperacute purulent discharge
Superficial corneal PEE’s
PUK in gonococcal and meningococcal infection progressing to perforation
What investigations can be performed for bacterial conjunctivitis?
Ix not routinely performed but indicated in:
1) Severe cases (binocular swabs and scrapings to excude Gonococcal and Meningococcal conjunctivitis
2) Culture on chocolate agar/Thayer martin for N. gonorrhoea
3) PCR for less severe cases such as chlamydial/viral infections
What is the treatment for bacterial conjunctivitis?
Topical antibiotics QDS for upto 1 week such as CPL, Quinolones, Macrolides, fusidic acid.
Gonococcal and meningococcal conjunctivitis treated with quinolone, gentamicin, CPL or bacitracin 1-2 hourly
Systemic abx in gonococcal infection. Refer to GUM. H influenza in children treated with Co-amoxiclav orally.
Topical steroids can reduce scarring in (pseudo) membranous conjunctivitis
CL wear discontinued for at least 48 hours after complete resolution
What percentage of bacterial conjunctivitis resolve in 5 days without treatment?
60%
What is Giant fornix syndrome and how is it treated?
uncommon entity causing chronic pseudomembranous purulent conjunctivitis due to retained debris in a big upper fornix leading to colonization with S. aureus. in an elderly patient with levator disinsertion.
Treatment involves repeated fornix sweeps with cotton bud and topica/systemic abx. Intense topical steroid may be appropriate.
What are the 2 forms that Chlamydia Trachomitis exist in?
They exist in two principal forms: a robust infective extracellular ‘elementary body’ and a fragile intracellular replicating ‘reticular body’.
Which chlamydial serotypes is Adult chlamydial inclusion conjunctivitis caused by?
serovars (serological variants) D–K of C
What % of Chlamydial conjunctivitis transmission is ‘eye to eye’
10%
Which chlamydial serovars cause Trachoma
A,B,Ba,C
What are the symptoms and signs of chlamydial conjunctivitis?
Symptoms
Subacute unilateral/bilateral redness/watery eyes and discharge
Signs
Watery or mucopurulent discharge
Tender preauricular lymphadenopathy
Large follices inferior fornix
SPK
Perilimbal subepithelial corneal infiltrates after 2-3 weeks
How to investigate suspected Chlamydial conjunctivitis?
Tarsal conjunctiva scrapings for NAAT PCR
Giemsa staining for basophilic intracytoplasmic bodies
Enzyme immunoassay
McCoy cell culture- highly specific
Swabs for bacterial culture and serology
How to treat chlamydial conjunctivitis?
Refer to GUM specialist.
Systemic Azithromycin/Doxycycline/Erythromycin/ Amoxicillin/Ciprofloxacin
Topical abx Erythromycin/tetracycline ointment
Reduce transmission risk until 1 week after azithromycin
Retest in 6-12 weeks
What is the pathogenesis of Trachoma?
recurrent infection with Chlamydia serotypes A-C elicits a chronic immune response consisting of a cell-mediated delayed hypersensitivity (Type IV) reaction to the intermittent presence of chlamydial antigen and
can lead to loss of sight.
2 stages of Trachoma?
Active inflammatory stage
Cicatricial chronic stage
WHO grading of Trachoma?
TF = trachomatous inflammation (follicular): five or more follicles (>0.5 mm) on the superior tarsal plate
TI = trachomatous inflammation (intense): diffuse involvement of the tarsal conjunctiva, obscuring 50% or
more of the normal deep tarsal vessels; papillae are present
TS = trachomatous conjunctival scarring: easily visible fibrous white tarsal bands
TT = trachomatous trichiasis: at least one lash touching the globe
CO = corneal opacity sufficient to blur details of at least part of the pupillary margin
What happens in active trachoma?
○Mixed follicular/papillary conjunctivitis associated with a mucopurulent discharge. In children under the age of 2 years the papillary component may predominate.
○Superior epithelial keratitis and pannus formation
What happens in Cicatricial trachoma?
○Linear or stellateconjunctival scars in mild cases, or broad confluent scars (Arlt line) in severe disease.
○Although the entire conjunctiva is involved, the effects are most prominent on the upper tarsal plate.
○Superior limbal follicles may resolve to leave a row of shallow depressions (Herbert pits)
○Trichiasis, distichiasis, corneal vascularization and cicatricial entropion
○Severe corneal opacification.
○Dry eye caused by destruction of goblet cells and the ductules of the lacrimal gland.
What is the SAFE strategy for managing Trachoma?
Surgery for trichiasis,
Antibiotics for active disease,
Facial hygiene
Environmental improvement.
Whys are systemic tetracyclines not used in children under 12 years of age?
Tooth staining
What is ophthalmia neonatorum?
as conjunctival inflammation developing within the first month
of life. It is the most common infection of any kind in neonates, occurring in up to 10%.
What are the causes of Ophthalmia Neonatorum?
*Organisms acquired during vaginal delivery: C. trachomatis, N. gonorrhoeae
*Staphylococci are usually responsible for mild conjunctivitis.
*Topical preparations used as prophylaxis
*Congenital nasolacrimal obstruction. Despite poor neonatal tear production
What are the timing of onset for different organisms causing Ophthalmia Neonatorum?
○Chemical irritation: first few days.
○Gonococcal: first week.
○Staphylococci and other bacteria: end of the first week.
○Herpes simplex virus (HSV): 1–2 weeks.
○Chlamydia: 1–3 weeks.
What are the characteristics of discharge in the organisms causing Ophthalmia Neonatorum?
○A mildly sticky eye may occur in staphylococcal infection, or with delayed nasolacrimal duct canalization (mucopurulent reflux on pressure over the lacrimal sac).
○Discharge is characteristically watery in chemical and HSV infection, mucopurulent in chlamydial infection, purulent in bacterial infection and hyperpurulent in gonococcal conjunctivitis.
○Pseudomembranes are not uncommon in chlamydial conjunctivitis.
Treatment for Ophthalmia Neonatorum?
Prophylaxis with 2.5% poviodine
Chemical conjunctivitis with artificial tears
Mild conjunctivitis broad spectrum topical abx like CPL.
Moderate-severe cases Ix with microscopy and treatment with broad spectrum abx liek CPL/Erythromycin
Severe conjunctivitis with systemic illness take samples and treat with broad spectrum abx like erythromycin. Cover for chlamydia
Chlamydial infection treated with PO erythromycin for 2/52
Gonococcal conjunctivitis treated systemically with 3rd gen Cephalosporin
HSV with high dose intravenous aciclovir under paediatrics
What are the common causes of viral conjunctivitis?
Viral conjunctivitis is a common external ocular infection, adenovirus (a non-enveloped double-stranded DNA virus) being the most frequent (90%) causative agent.
How can viral conjunctivitis present?
Non specific acute follicular conjunctivitis
Pharyngoconjunctival fever (PCF)
Epidemic Keratoconjunctivitis (EKC)
Acute haemorrhagic conjunctivitis
Chronic/relapsing adenoviral conjunctivitis
HSV
Systemic viral infections
Molluscum contagiosum
What is Non specific acute follicular conjunctivitis?
most common clinical form of viral conjunctivitis and is typically due to adenoviral infection by a range of serological variants. Unilateral watering, redness, irritation and/or itching and mild photophobia occur, the contralateral eye generally being affected 1–2 days later, often less severely.
What is Pharyngoconjunctival fever (PCF)?
caused mainly by adenovirus serovars 3, 4 and 7. It is spread by droplets within families with upper respiratory tract infection. Keratitis develops in about 30% of cases but is seldom severe. Symptoms are essentially as above, though sore throat is typically
prominent.
What is Epidemic Keratoconjunctivitis (EKC)?
caused mainly by adenovirus serovars 8, 19 and 37 and is the most severe
ocular adenoviral infection. Keratitis, which may be marked, develops in about 80%. Photophobia may be correspondingly prominent.
What is Acute haemorrhagic conjunctivitis?
occurs in tropical areas. It is typically caused by enterovirus and coxsackievirus, though other microorganisms may present similarly. It has a rapid onset and resolves within 1–2 weeks. Conjunctival haemorrhage is generally marked
What are the signs of viral conjunctivitis?
*Eyelid oedema
*Lymphadenopathy: tender preauricular
*Conjunctival hyperaemia and follicles
Keratitis (adenoviral). Epithelial microcysts, PEE’s, focal white subepithelial/anterior stromal infiltrates, small pseudodendritic epithelial formations
*Anterior uveitis- mild
*Molluscum contagiosum- pale waxy umbilicated nodule on lid margin
How to investigate viral conjunctivitis?
*Giemsa stain- mononuclear cells in adenoviral conjunctivitis and multinucleated giant cells in
herpetic infection.
* NAAT eg. PCR are sensitive and specific for viral DNA.
*Viral culture with isolation is the reference standard but is expensive and fairly slow. Sensitivity is variable but specificity is around 100%.
*A immunochromatography test takes 10 minutes to detect adenoviral antigen in tears; sensitivity and
specificity are excellent.
* Serology for IgM or rising IgG antibody titres to adenovirus
has limitations and is rarely used.
*Investigation for other causes such as chlamydial infection may be indicated in non-resolving cases.
How to treat viral conjunctivitis?
*Spontaneous resolution of adenoviral infection 2-3 weeks
*Reduction of transmission risk with hand hygiene
*Molluscum- lesions self limiting but remove in immunocompromised
*Topical steroids- Pred 0.5% QDS for severe membranous conjunctivitis. Use with caution suppress inflammation and corneal infiltrates recur after stopping.
*Discontinue lens wear
*Cold or warm compress
*Artificial tears
What is seasonal allergic conjunctivitis?
‘hay fever eyes’), worse during the spring and summer, is the more common. The most frequent allergens are tree and grass pollens, although
the specific allergen varies with geographic location.
