6.1.4: Identify external pathology & offers appropriate advice to pxs Flashcards
What is dry eye and what are the functions of each layer of the tear film?
A disorder of the tear film due to tear deficiency or excessive evaporation, which causes damage to the interpalpebral ocular surface and is associated with symptoms of ocular discomfort.
1. Lipid Layer – Reduces water evaporation from the aqueous layer
Secreted by: Meibomian gland, glands of Zeiss, glands of Moll.
Evaporation – 10% of the aqueous layer evaporates as the lipid layer prevents evaporation.
2. Aqueous Layer – Carries nutrients and oxygen to the eye and carries away waste. Hydrates the cornea and prevents it from drying out.
Secreted by: Main lacrimal gland for reflex secretion, Basal secretion by accessory lacrimal glands of Krause and Wolfring
3. Mucus Layer – Trap debris and epithelial cells, which are then removed through blinking. Also allows for tear stability and adheres to the epithelial corneal cells and conjunctival goblet cells.
Drainage – through the puncta, through canaliculi, into lacrimal sac. Pumped into there from lid action and gravity feed to lower punctum.
o Function – Optical, Nutritional, Waste Removal, Transparency, Mechanical, Antibacterial
What are the symptoms of dry eye and px characteristics?
o Itchiness
o Irritation
o Increased Blinking
o Burning
o Grittiness
o Excess Watering
o Redness
o Blurred vision disappearing on blink
Age, Gender, Systemic condition, medication, environment, smoking, bilateral, dry eye vs allergy.
Describe secretion, staining, stability and examination in assessment of dry eye?
Secretion
* Schirmer’s Test
o Greater than 20mm is normal. <10mm DED, <5mm query Sjogren’s
* Tear Meniscus height
o G1: >0.3mm
o G2: 0.2 mm
o G3: <0.1mm
Staining of the Ocular Surface
* Fluorescein Sodium (Biofluoro has 1.0mg of it, 1% Minims)
* Lissamine Green (I-dew green Strip has 1.5mg)
* Fluorescein – is a weak acid. It doesn’t stain, it fluoresces in the presence of more alkaline fluid (such as mix of tear fluid and aqueous humor) and ‘stains’ corneal epithelial cells by pooling in areas of dead or shedded cells. It fluoresces at 525-
530nm (use yellow filter).
* Lissamine Green – stains membrane degenerate and dead cells. viewed in white light.
o In dry eyes, the nasal conjunctiva stains more than the temporal and the cornea stains less the conjunctiva. Observe 1 eye at a time (use red filter)
Tear Film Stability:
Less than 10 seconds is clinically abnormal
* TBUT
* NIBUT
Anterior Examination:
Lashes (Bleph/MGD, Skin, blink pattern, palpebral fissure width)
Describe aqueous layer deficiencies?
Adequate production and drainage of the aqueous layer is necessary for the
maintenance of:
1. tear nutrients (e.g. oxygen and electrolyte supply to the cornea) and antibacterial
agents (i.e. lysozyme produced by the major and accessory lacrimal glands).
2. moist conditions on the eye surface (evaporation reduces surface temperature)
3. the mechanical flushing action of tear movement
Aqueous deficiencies may be partial or absolute but invariably produce marked
symptoms of soreness or burning.
The osmolarity of the aqueous increases in dry eye and the resulting hypertonicity leads
to ocular damage
Describe mucin layer deficiencies?
o Mucus-secreting cells create a mucin layer which coats the cornea and protects its surface.
o An unstable tear film will result from deficiencies in secretion of the soluble surfactant mucin even if there is sufficient aqueous (surfactants are surface-acting agents that reduce surface tension).
o A reduction in goblet cell density will alter the integrity of the mucous layer and lead to abnormal tear-break-up-times (TBUTs).
o TBUTs normally range between 15 and 45s; less than 10s is considered clinically abnormal but substantial variation occurs with normal TBUTs.
Describe lipid layer abnormalities?
- The lipid layer reduces the evaporation of aqueous. - Meibomian gland secretions can be diminished by hydrolysis due to the secretion of the enzyme lipase by certain bacteria.
- A characteristic of lipid abnormality is a decrease in the rate of spreading of the tear film which results in a rapid TBUT.
- Lipid abnormality has been associated with chronic blepharitis.
Described impaired lid function as factor in DED?
The forces associated with lid-globe contact during blinking is important for mucus
distribution. Restricted lid movement can lead to serious tear deficiency and exposure
keratitis.
What is epitheliopathy and how does it relate to dry eye?
An irregular corneal epithelium (due to corneal lesions or keratoconus) can produce a
thin and unstable tear film.
What medications could dry eye be secondary to?
A number of systemic medications can cause dry eye by reducing epithelial cell turnover
e.g. CNS acting drugs and beta-blockers for heart conditions.
Contraceptive pill
HRT
Roaccutane - isotretinoin
What conditions could dry eye be secondary to?
- Rheumatoid Arthritis
- Acne rosacea
- Dermatitis
- Psoriasis
- Sjögen’s syndrome.
What are treatments for dry eye? What are contained in those drops?
- Carbomers (GelTears, Viscotears) – semi-solid formulations of high molecular
weight.
o Drop frequency reduced from 20x to 4x
o reduces natural elimination of tears
o retention time is 7x longer
o protective during sleep
o high viscosity can cause blurring - Hypermellose – traditional choice of treatment for tear deficiency. Requires
frequent instillation - Liquid Paraffin (Hycosan Night) – lubricates eye surface in case of recurrent
corneal erosion. May cause blurry vision - Macrogels (Systane) – uses pH sensitive component to become more viscous in
the eye - Paraffin (Ointment) – bland ointment are semisolid preparation of petrolatum
and mineral oil and lanolin. Melt in eye and retained. Only use at night - Sodium Hyaluronate (Hysosan) – Viscoelastic high molecular weight polymer, increases goblet cell density and reduces inflammation of ocular surface.
Improves tear stability and wettability. - Diet – Omega 3/6, fatty acids.
- Ocular Environment – central heating, air humidifier
What are other, more unusual, treatments for dry eyes?
- punctal plugs
- FML
- IPL (more for MGD)
- Tetracycline (Doxycycline, more for bad ant bleph)
- Topical ciclospoirin - Ikervis
- Topical autologous serum (px’s own blood)
- Azithromycin
- Acetylsystene (iLube) for filamentary dry eye - mucous strands - px’s hate it as it stings
Describe bleph - types, sxs, signs, differential, CMG advice, referral?
Anterior
* Bacterial (Staphylococcal - crusty),
* Seborrhoeic (Disorder of ciliary sebaceous glands - oily/greasy)
* Demodex (mites - collarettes)
Posterior
* Meibomian Gland Dysfunction (MGD)
Symptoms
* Ocular discomfort
* soreness
* burning
* itching
* mild photophobia
* dry eye
* CL intolerance
Signs
* Bilateral
Staphylococcal
* Lid margin hyperaemia
* margin swelling
* crusting of margin (scales on base of lashes)
* misdirection of lashes,
* Recurrent styes
* conjunctival hyperaemia
Seborrhoeic
* Lid margin hyperaemia
* Oily or greasy deposits on lid margins
* conjunctival hyperaemia
MGD
* Thick and/or opaque secretion at MG orifices
* foam in lower tear meniscus
* conjunctival hyperaemia
* evaporative tear deficiency
* unstable tear films
* Differential - Allergy, Dacryocystitis, Preseptal Cellulitis, HSV, HZO, MG carcinoma
College Management Guidelines
* Lid hygiene
* warm compress
* topical antibiotics
* systemic antibiotics (Posterior)
* Ocular lubricants
Refer
* Routine – if pharmacological therapy doesn’t produce significant response.
* Urgent if Unilateral: MG Carcinoma suspect
Describe dacryocystitis - sxs, signs, differential, CMG advice?
Bacterial infection of lacrimal sac – secondary to blockage on the nasolacrimal duct
Symptoms
* Sudden onset
* Pain
* tender swelling of lacrimal sac
* epiphora
* fever
Signs
* Red, tender swelling centred over lacrimal sac and extending around the orbit
* Purulent discharge from the puncta when pressure applied
* frequent conjunctivitis and pre-septal cellulitis
Differential
* Facial cellulitis
* pre-septal cellulitis
* orbital cellulitis
* frontal sinusitis
College Management Guidelines – ALL Children EMERGENCY REFERRAL,
Emergency referral if Severe case:px is systematically unwell, cases which do not respond to anti-biotics for 7 days
Urgent referral, mild cases responsive to systemic antibiotics – monitor for blockage of
duct. Manage to resolution
Describe entropion - cause, sxs, signs, differential, CMG advice, referral?
Inward rotation of the tarsus and lid margin, causing the lashes to come into contact
with the ocular surface
Cause
* Age related lid laxity
* build up scar tissue and contraction
* trachoma
* surgery
* Congenital
Symptoms
* Irritation (FB sensation)
* Epiphora
* Lid spasm (Lash rub on the cornea)
* Red watery eye
Signs
* Inward directing lower lid à can be intermittent
* irregular vertical corneal fb tract caused by lashes à corneal scarring and pannus
if left
* localised hyperaemia
* lid laxity
Differential
* Eyelid retraction (Graves’ disease)
* Distichiasis (extra row of lashes)
* Trichiasis (misdirection of lashes)
* Dermatochalasis (extra orbital fat)
* Epiblepharon (abnormal insertion of muscle fibres causing fold of skin)
College Management Guidelines
* Tape the lid to the skin of the cheek for temporary relief
* Epilation of lashes can be done where Trichiasis is localised (can leave spikey lashes though - sore)
* therapeutic CL to protect cornea
* Ocular lubricants
Refer – Initial management followed by routine referral for surgery
