The anterior eye Flashcards
what are the tear film layers in order from outer to inner
- lipid layer
- aqueous layer
- aqueous phase (MUC 5AC)
- glycolax (MUC1), (MUC 4), (MUC 16)
- mucinous phase
- epithelial surface with microvilli
what can ocular surface and tear film disorders cause?
DED
MGD
CL DISCOMFORT
what are two types of dry eye disease? what are there symptoms?
dry eye syndrome (DES) and keratoconjunctivitis sicca (KCS)
-dryness
-discomfort
-irritation
-reduced vision
what are the two types of dry eye?
-aqueous deficiency where is affects the lacrimal gland function
-evaporative dry eye
what is the most frequent cause of DED?
MGD
why is it important to prevent DED
-it is very expensive to treat i.e.. cost of referrals, Px etc
what are the 4 inter-related mechanisms responsible for DED
-tear instability
-tear hyperosmolarity
-inflammation
-ocular surface damage
what is evaporative dry eye?
related to causes from
-lids such as MDG and blink problems
-ocular surface such as mucin or CL-related
what is another name for MGD
posterior blepharitis
how is obstructive MGD caused?
- terminal duct obstruction
- caused by hyperkeratinisation of the ductal epithelium, keratinised cell debris and increased meibum viscosity
- causes normal clear oily secretions to become semi-solid, toothpase like plaques
what kind of populations are most likely to have MGD?
mainly asian populations
what is the vicious cycle for dry eye disease?
- damage to ocular surface
- goblet cell loss
- mucin loss
- tear film instability
- excessive tear evaporation
- hyperosmolarity
8.inflammation - keratinisation of gland orfices
which causes inflammation and the cycle repeats
what is the cycle for MGD?
- bacterial proliferation causes increased exotoxin release
- lipases and esterases destabilise the tear films lipid layer
- this causes a rise in meibum melting point
- which causes meibomian gland dysfunction
which leads to proliferation of bacteria and the cycle repeats
What are the consistent risk factors for Dry eye?
-increasing age
-CL wear
-being female
-Asian ethnicity
what are the signs of dry eye?
-fluorescein staining, small tear meniscus height, TBUT <10
what are the symptoms of dry eye?
-discomfort
-dryness
-irritation
-grittiness
-fluctuating vision which may get worse throughout the day
-vision that gets worse with wind, smoke, heat and prolonged near activities
how do you diagnose dry eye?
-use the dry eye questionnaire to determine if they have symptoms of dry eye (difficult if time is limited)
-check tear film stability, tear film osmolarity or ocular surface staining
-check tear meniscus
how do you manage dry eye?
-dietary advice of eating more oily fish for omgea 3
-recommend ocular lubricants such as preservative free artificial tears
-wear protective glasses/ moisture chamber glasses
-use specialist care methods if these don’t work
-refer to secondary care if nothing else works
what specialist care methods can be used when treating dry eye?
-punctum plugs
-scleral / bandage contact lenses
-pharmacological management like topical steroids
what could be differential diagnoses to dry eye?
computer vision syndrome and digital eye strain
what are the risk factors for MGD?
-wearing CLs
-prolonged screen use (as it reduced blink rate)
what are the signs of MGD?
-changes to secretion of the gland
-saponification of tears
-gland plugging/ paste like yellowish secretion
diagnosis of MGD
-inspect the glands for the signs
-push on the meibomian glands to clear the blockage
MGD treatment?
squeeze the meibomian glands to clear the blockage
MGD management?
- use products to heat your eyes like heated eye mask
- massage the eyelids to clear the blockages
- clean the eyelids
in MGD when should you refer to secondary care?
-sometimes when you have peads px
-if they may have suspected underlying conditions or unidentified systemic diseases
-secondary complications like vascularisation, corneal scarring and infection
-abnormal lid anatomy/ function
-persistent/ severe Sx that dont want to respond to primary management after 4-12 weeks
Name two types of corneal inflammation
-marginal keratitis
-CL associated infiltrative events (CIE’S)
what is the aetiology of marginal keratitis?
an inflammatory response of the peripheral cornea to bacteria exotoxins instead of direct inocculation
what are the predisposing factors
-bacterial blepharitis
-sometimes contact lenses
what are the signs of marginal keratitis?
-redness and inflammation of limbus and bulbar conjunctiva due to excess blood in the vessels
- stromal infiltrate ( typically adjacent to the limbus and separated
by an interval of clear cornea)
-ulcers (they stain with fluorescein)
what are the symptoms of marginal keratitis
-ocular discomfort
-lacrimation
-red eye
-photophobia
what is the non pharmacological management of marginal keratitis?
-initially address predisposing factors e.g. contact lenses
-regular lid hygiene for associated blepharitis
what are the pharmacological managements for marginal keratitis?
-ocular lubricants for symptomatic relief
-systemic analgesia when needed (painkillers)
-topical antibiotic use to reduce bacterial load plus topical steroid to reduce inflammation
Name three CIEs
-contact lens-associated peripheral ulcer (CLPU)
-contact lens associated infiltrative keratitis
-contact lens associated acute red eye (CLARE)
what is the aetiology for CIEs?
a self limiting inflammatory response of the cornea affecting the anterior stroma
what are the patient related pre disposing factors of CIEs?
-blepharitis
-male sex
-being <25 years old
-smoking
-having previous Hx of CIEs
what are the predisposing factors of CIEs for patients who wear CLs?
-long term lens wear
-overnight wear
-silicon hydrogel material
-tight fit lens
-MSPs
-poor lens hygiene
what are the symptoms of CIEs?
-red and watery eye
-foreign body sensation
-photophobia
(some cases are even asymptomatic)
what are the signs of CIE’s?
-peripheral anterior stromal infiltrates, usually small
-ulcer formation
-conjunctival hyperaemia
-adjacent limbal hyperaemia
-epiphoria
-anterior chamber inflamed to some degree
-usually unilateral
Give the non-pharmacological management of CIE’s
- address the modifiable risk factors
-temporarily discontinue lens wear as this can resolve signs and symptoms within 48 hrs
-advise against extended CL wear
-evaluate lens fit and care regime
-reinforce education concerning lens hygiene and wearing schedules
-warn about possibility of recurrence as if condition recurs, then switch to daily disposables
-lid hygiene if blepharitis is present
give the pharmacological management of CIEs
-ocular lubricants for symptomatic relief
-topical antibiotic may be indicated if blepharitis present
what is the aetiology of bacterial keratitis
sight threatening infection of the cornea
what are the most commen bacterial corneal pathogens with their types
-Pseudomonas sp. (Gram -ve)
-Staphylococcus sp. (Gram +ve)
-Streptococcus sp. (Gram +ve)
What are the predisposing factors of bacterial keratitis?
- Contact lens wear
- Ocular surface disease, ocular trauma/surgery
- Immunocompromised
- Lid margin infection
What are the most common fungal corneal pathogens?
-Candida sp. (yeast-like)
-Fusarium sp. (filamentous)
- Aspergillus sp (filamentous)
what are the predisposing factors of fungal keratitis specifically?
-being immunocompromised
-having had a trauma involving organic materials
what are signs that are specific to fungal keratitis?
-deep lesions with a feathery edge
-raised profile
-satellite lesions
-endothelial plaque
what are the symptoms of bacterial/ fungal keratitis?
-pain (usually acute onset and quickly gets worse)
-redness
-photophobia
-blurred vision (if lesion is on visual axis)
-discharge
-yellow spot on cornea
what are the signs of both bacterial/ fungal keratitis?
*Lid oedema
* Epiphora
* Discharge (mucopurulent or purulent)
* Conjunctival hyperaemia and infiltration
* Corneal lesion usually single (central or mid-
peripheral)
* Excavation (cavity) of epithelium, Bowman’s layer, stroma
(tissue necrosis)
* Stromal infiltration beneath lesion
* Stromal oedema with folds in Descemet’s
membrane
* Anterior chamber activity (flare, cells, hypopyon or
coagulum if severe)
what is the non-pharmacological management of bacterial/ fungal keratitis?
remove CLs but keep them and the case to determine the culture)