Lecture 2 - Ocular Pathology - pre-fit considerations Flashcards
Why can diabetes cause problems when fitting contact lenses?
- Reduced Corneal Sensitivity
- Corneal Oedema, risk of neovascularisation
- Delayed Healing, epithelial fragility
- Susceptibility to infection (bacterial, fungal)
- Dry Eye ~ 50% (so expect staining)
- Unstable Refraction
- Keratitis
- Blepharitis
- Xanthelasmata
- -> poor lipid metabolism
Diabetes should not interfere with contact lens wear
What should you consider when fitting diabetic px?
Informed Consent
Liase (co-operation) with other professionals involved in the care of the patient
Consider glycaemic control
More frequent aftercare
High permability and transmissiblity of Oxygen
Reinforce Hygiene & Handling
Proceed with caution…
Why can Hyperthyroidism or exophthalomas cause problems when fitting contact lenses?
The exophthalmos causes lid lag, reduced blink rate and dry eye contraindicate contact lenses.
Why can Chronic Catarrh & Sinusitis cause problems when fitting contact lenses?
There is an increased risk of infection when corneal abrasions occur. There may be excess mucus in the tears which will be visually distracting. A blocked naso lacrimal system may encourage epiphora.
Why can Cold sores cause problems when fitting contact lenses?
The Herpes Simplex Virus may be transferred from the mouth to the eyes via the fingers that touch the cold sores and then are used to insert contact lenses. Another source of infection arises from licking the contact lenses prior to insertion. Herpes keratitis leads to dendritic ulcers. The virus lies dormant in the nervous system and can be re-activated at any time.
No CL wear with an active ulcer!
Why can Skin conditions and allergic reactions cause problems when fitting contact lenses?
Allergic reactions to the contact lens solution preservatives and to lens surface deposits are common.
Allergic reactions tend to show a gradual build up of signs and symptoms whereas a toxic reaction is usually accompanied by a rapid onset of symptoms.
Why can Atopic eczema cause problems when fitting contact lenses and how can it be managed?
This is often linked with hay fever and/or asthma. The condition encourages surface deposits.
If contact lenses are fitted, the material should have good wetting properties.
Lid irritation can be minimised by fitting a large lens with minimal edge clearance and minimal edge thickness (radial edge thickness 0.12 mm).
Why can Keratoconjunctivitis sicca (Sjogren’s syndrome) cause problems when fitting contact lenses and how can it be managed?
This is associated with rheumatoid arthritis. It is characterised by a poor lacrimal secretion.
Dry eyes and contact lenses don’t go together.
The sealed or channeled scleral lens may help to protect the cornea.
An alternative would be a soft contact lens with artificial tears instilled at regular intervals.
Why can Xerophthalmia (vitamin A deficiency) cause problems when fitting contact lenses?
This can cause keratomalacia. It may be worth checking on patient’s diet.
Typically the corneal ulcer is centrally located and bilateral, Grey and indolent (little pain, slow to heal).
The cornea becomes soft and necrotic (death of cells) (hence the term keratomalacia). Perforation (holes in the cornea) is common.
Why can Seborrhoeic eczema cause problems when fitting contact lenses and how can it be managed?
This manifests as dandruff and blepharitis.
Any lenses must induce minimal lid irritation.
There is a risk of staphylococcal keratoconjunctivitis.
The blepharitis may be treated with tetracycline, taken orally: 250 mg twice daily for six weeks. This will be inactivated if taken with milk and is not advised for pregnant women or young children.
Why can Acne Vulgaris cause problems when fitting contact lenses and how can it be managed?
Occurs at puberty and is generally not aggravated by contact lens wear.
There may be problems of greasing and frothing of lenses.
Solutions containing polyvinyl alcohol may help with the greasing of lenses.
Why can Acne rosacea cause problems when fitting contact lenses?
There will be accentuated blood vessel dilatation in the conjunctiva and the skin of the eye regions of the face.
Ocular involvement more severe in males
Often get posterior blepharitis
Punctate keratitis is associated with this condition and may become worse by contact lens wear.
Why can Epidermolysis bullosa cause problems when fitting contact lenses?
This is a rare inherited skin disease which may produce anything from mild blepharitis and conjunctivitis to pronounced vesicle formation over the anterior eye.
High water content soft lenses worn on a daily basis are recommended.
Why can Psoriasis (skin disease showing a red patchy appearance) cause problems when fitting contact lenses?
Contact lenses are not likely to aggravate this condition but the associated nervous disposition may cause problems during adaptation.
Why can Surgery cause problems when fitting contact lenses?
Surgery performed on the extraocular muscles may produce scar tissue on the bulbar conjunctiva which may affect the fit of a soft lens. Scar tissue on the cornea does not usually cause problems unless the scar is raised above the normal corneal contour.
Why can Keratitis and conjunctivitis cause problems when fitting contact lenses?
Active keratitis makes contact lens wear impossible.
Contact lenses may however be of exceptional benefit to a patient who develops corneal irregularity or scarring from a past ulcer but it must be noted that the irritation in the presence of a contact lens may encourage the condition to recur.
Active conjunctivitis minimises the possibility of successful contact lens wear although lenses may successfully be worn during the quiet phases.
Why can Iritis, iridocyclitis or uveitis cause problems when fitting contact lenses?
Patients should not be fitted because the added irritation of a contact lens may activate the condition. It must be remembered that the disease may flare again spontaneously and contact lens wear could be blamed as the trigger.
Why can Keratitis sicca cause problems when fitting contact lenses?
This dry eye condition may make the wearing of contact lenses difficult.
However some patients welcome the reduced evaporation of tears from the cornea when a lens is worn, especially a scleral RGP - CL may act as a bandage.
Why can Trachoma cause problems when fitting contact lenses and how can it be managed?
Chronic keratoconjunctivitis caused by Chlamydia trachomatis (obligate intracellular organism)
Repeated episodes cause chronic follicular conjunctival inflammation (active trachoma), which leads to tarsal conjunctival scarring
Scarring distorts the upper tarsal plate and leads to entropion and trichiasis (cicatricial trachoma)
Results in corneal abrasions, corneal scarring and opacification, and, ultimately, blindness
Endemic in Africa, Asia, Middle East, Australian Aboriginals
Old, inactive cases may find that a contact lens helps protect the cornea against scarring which is often present on the lids.
A scleral RGP lens may be the best option.
Why can Glaucoma cause problems when fitting contact lenses?
Scleral and soft contact lenses rest on the anterior cillary veins which constitute a major drainage route for the aqueous.
These lenses may, therefore, influence the intraocular pressure (IOP). It could be argued that this will be raised or lowered (due to the massaging effect of a moving lens).
The situation is no clearer for corneal lenses. It may well be that contact lenses do not affect the IOP but the conservative practitioner would probably advise against contact lens wear.
Why can Pinguecula and pterygium cause problems when fitting contact lenses?
A large pinguecula may disturb the fit of a soft or scleral contact lens and can be responsible for extra discomfort in a corneal lens wearer. Contact lenses are precluded when a pterygium is present and should not be advised even after surgical removal of the pterygium because recurrence is a possibility.
Why can Herpes zoster ophthalmicus cause problems when fitting contact lenses?
Shingles (a painful acute inflammation of the nerve ganglia, with a skin eruption often forming a girdle around the middle of the body. It is caused by the same virus as chickenpox.)
Nerve infection -1st div of Trigeminal Nerve
Varicella Zoster Virus
Chicken Pox
By age 80, 50% of people who have had chicken pox have had shingles
Associated Keratoconjunctivitis
It is probably best to avoid contact lenses when there has been a past history of Herpes Zoster although there have been cases where contact lenses have been successfully fitted after a corneal graft.
Why can Amblyopia cause problems when fitting contact lenses?
Amblyopes don’t have a very good Spare Eye
Must be aware they are putting their good eye at risk
Must ensure informed consent
More frequent aftercare?
Any complications in the good eye may result in inability to work/drive until recovery
Only fit the good eye?
Depends on acuity, binocularity
Why can Class A Drugs cause problems when fitting contact lenses?
Cocaine, Crack, Amphetamines, LSD, Ecstasy
-‘Glassy’ eyes
-Dilated pupils, so photophobic
-Amongst other things…
Heroin
-Miotic pupils
-Epiphora? (excessive watering of the eye.)
Unlikely to Comply with care instructions!!
Would you fit a person with Albinism?
Recessive inheritance 1 in 17000 Ocular Albinism Usually X-linked, therefore mainly males (though can be autosomal recessive) Reduced VA (6/18 – 3/60) Nystagmus, Strabismus, Photophobia Opaque iris CLs may be useful?
Would you fit a person with Nystagmus?
CLs will not improve vision unless the patient is also a high myope
Increased retinal image size
Or if the CLs enable better use of the Null Point
CL’s often rejected due to discomfort
Would you fit a person with Corneal Ulcers?
No CL wear with an active ulcer!
CL may be useful if cornea is irregular following a corneal ulcer
Must minimise irritation
Would you fit someone with Entropion & Ectropion?
CL may act as bandage to protect cornea in entropion
Ectropion may lead to dry eye, may be helped or not by CL
Would you fit someone with Hordeolum?
Bacterial infection
Internal – Meibomian Glands
External – Glands of Zeis & Moll
Acute problem – lens wear best avoided until recovered
Would you fit someone with Chalazion?
Lipogranuloma of meibomian gland or gland of Zeis
Subsequent to Hordeolum
Again, lens wear best avoided
Would you fit someone who just had LASIK surgery?
Corneal topography not normal
If not emmetropic, then patient may seek CL wear
Difficult to fit, but no contraindications as long as flap secure
Also applies to PRK and LASEK
What are the two forms of Anterior Blepharitis?
Staphylococcal
Infection of lash follicle
Seborrheic
Disorder of glands of Zeis or Moll
What is Staphylococcal anterior blepharitis?
Chronic infection of lash follicles
Secondary ulceration and tissue destruction
Often in atopic eczema
Females and younger patients
Hyperaemia, telengiectasia and scaling of lid margins
Scales leave bleeding ulcer if removed
Lashes may stick together, cuff or collarette around base of lash
Loss of lashes (madarosis)
Lid margin scarred or hypertophic
How can you manage Staphylococcal anterior blepharitis?
Antibiotic ointment (via GP) Lid hygiene Lid scrubs Baby shampoo Corticosteroids (again via GP/ophthalmologist) Artificial tears
What is Seborrheic anterior blepharitis?
Disorder of glands of zeis and Moll
Frequent association with seborrheic dermatitis
Symptoms similar to staphylococcal, but less severe
Signs
Shiny, waxy lid margin
Soft yellow greasy scales along margin, no ulcer on removal
Lashes greasy and stuck together
How can you manage Seborrheic anterior blepharitis?
Lid hygiene
Artificial tears
Keys compared lid scrubs, hypoallergenic soap and baby shampoo for lid hygiene
85% preferred commercial lid scrub
Would you fit someone with anterior Blepharitis?
Lens wear usually contraindicated Resolve problem before fitting Mild staphylococcal -Care with cleaning -Avoidance of cross-contamination -Use cosmetics with care -Daily disposable CLs?
What is posterior blepharitis?
Usually meibomian gland disorder
Common chronic condition
Duct obstruction or changes in gland secretion
Leads to alteration of tear film, inflammation, ocular surface disease
Quality of gland expression and expressability key in clinical assessment
MGD (meibomian glad dysfunction) important, under-estimated condition
Most frequent cause of dry eye?
How could you differentiate the difference between meibomian gland dysfunction from other disorders of the meibomian gland
External hordoleum (stye) Internal hordoleum (meibomian cyst) Eliminate other causes of tear film dysfunction -Schirmer? -Phenol red thread?
How would you manage Mites?
Aim - reduce infection to sub-clinical level
Vigorous lid hygiene, initially with CL cleaning solution
May need topical anaesthetic
Lid scrubs, hypoallergenic soap or dilute baby shampoo later
How would you manage Lice?
Refer Mechanical removal Slit lamp and forceps Argon laser Cryotherapy Mercuric oxide ophthalmic ointment Sanitise home environment Pubic lice regarded as STD
What is Kerataconus?
Corneal thinning IOP steepens cornea Cone forms Irregularity/aberrations increase Quality of vision deteriorates Old classification (prior to topography) Round or nipple cone Oval or sagging cone Ill-defined cone
What are the early signs of Kerataconus?
Rapid increase in myopia and astigmatism (ATR or oblique?) Frequent Rx change required Swirling ret reflex Indefinite Rx end point Steep K readings not at 90° to each other Irregular mires Typical asymmetric bow-tie topography CCT < 480um Low p-value Pinhole significantly improves vision Prominent corneal nerves Apparently low IOP
What are the later signs of Kerataconus?
Vertical striae (lines of Vogt) Disappear with pressure Fleischer’s ring round base of cone Best viewed with blue light Iron deposit around base of cone Munson’s sign Scarring Nebulae Hydrops Rupture of Descemet’s Aqueous flows in Gross oedema Scarring
What are the early symptoms of Kerataconus?
Gradual reduction in vision in one eye
Vision better near than distance
Distortion of vision
Glare at night
What are the later symptoms of Kerataconus?
Reduced contrast sensitivity Ghosting and/or monocular diplopia Hydrops Significant loss of vision Severe pain Cease CL wear
Why would you fit a px with Kerataconus with CLs?
Aim: -Provide adequate vision -Maximum comfort for a prolonged period -Do no harm Avoid fitting CLs until both eyes have Rx Often fit is a compromise Initially often RGP lenses
What are the problems of fitting a kerataconic px?
Touch on apex of cone (already thinned) may cause scarring Vision compromised if on visual axis Flare Poor comfort High dependence on CL Atopy-related complications -CLIPC -Solution sensitivity
When would you refer a kerataconic px for a corneal graft?
lens intolerance Poor fit (including frequent loss of lenses) Poor vision Peripheral thinning Risk of perforation
Summarise kerataconus.
Most common corneal ectasia.
Usually appears in the second decade of life
Affects both genders and all ethnicities
Prevalence approximately 54 per 100,000
Ocular symptoms and signs of keratoconus dependon disease
severity.
Cause(s) and mechanisms for development poorly understood.
Thought to be genetic, environmental, biomechanical and biochemical factors
Keratoconus management improved substantially recently
Contact lens wear most successful option for managing mild to moderate keratoconus
Also new surgical options eg corneal rings and collagen cross-linking to treat moderate to severe cases
