Flashcards in Corneal Disease Deck (46)
What is astigmatism?
Irregular curvature of the cornea.
What does the typical corneal involvement of herpes simplex virus infection present? And what are some consequences?
Corneal dendritic ulceration.
Ulcers may be multiple. If infection confined to corneal epithelium, healing occurs without scarring. But, if stromal involvement, there is always some degree of scarring and there may also be anterior uveitis.
HSV may undergo latency in which ganglion?
A reactivation would then see the virus travelling along CNV to the eye.
Topical steroids applied to a herpetic corneal ulcer will result in what?
An amoeboid ulcer, which is slow to heal and very hard to treat.
Stromal disease and anterior uveitis require careful topical steroid use, after healing of any epithelial disease (for the above reason). It is also usual to administer aciclovir ointment and corneal scrape from ulcer edge to confirm dx.
What are the differences in ocular consequences between primary (chicken pox) and secondary (reactivated/shingles) VZV infection?
Primary VZV may cause a conjunctivitis, and rarely, a dendritic ulcer.
Secondary (reactivated) VZV may affect any ocular or adnexal structure (as was latent in trigeminal ganglion) -
eg. conjunctivitis, keratitis (principally affecting stroma, though dendritic & non-dendritic ulceration may occur), anterior uveitis with secondary glaucoma, scleritis, episcleritis.
Which division of the trigeminal nerve can be affected by VZV?
Any of the three, but V1 (ophthalmic) most common -> herpes zoster ophthalmicus.
Skin rash involves forehead to occiput and upper lid, tending to spare lower lid but usually affecting side of the nose (which is supplied by nerve fibres that course through the orbit).
What are the two most disabling sequelae of herpes zoster (VZV/shingles) ophthalmicus?
1. Recurrent keratitis with scarring
2. Post-herpetic neuralgia
Conjunctivitis and iritis may continue for many months but are less disabling than the above.
Treatment of ophthalmic shingles (herpes zoster ophthalmicus)?
Systemic aciclovir reduces duration and severity of acute disease as well as post-herpetic neuralgia.
Topical steroids significant in suppressing inflammation, but may lead to 'dependence' (inflammation returns as soon as steroids stopped).
What are three features of bacterial keratitis?
1. Purulent conjunctivitis
2. Corneal ulcer
3. Corneal opacity
Vision is reduced.
What can bacterial keratitis (corneal infection) progress to?
Intraocular infection (endophthalmitis), leading to blindness.
This is suggested by presence of a hypopyon (presence of white cells in the anterior chamber).
Name four common organisms causing bacterial corneal infection/keratitis.
1. Staph epidermidis
2. Strep pneumoniae
3. Enterobacter (coliforms, proteus, klebsiella)
4. Pseudomonas aeruginosa (this can cause particularly aggressive infection).
The contact lens wearer with redness and discomfort should carefully be examined for what?
The presence of corneal infection.
Should be referred for further assessment by ophthalmologist.
How is bacterial corneal infection managed?
Urgent Ix (conjunctival and corneal samples for M&C) and admission for intensive treatment.
Broad-spec ABx every 15 mins, 24 hrs per day, until response.
Sometimes, subconjunctival and systemic ABx prescribed.
Topical steroids used only when resolution of infective element is thought to have occurred.
Name a protozoan which causes corneal infection.
Ubiquitous organism, present even in tap water.
What are the features of acanthamoebic corneal infection?
1. Pain disproportionate to ocular signs
2. Stromal keratitis without ulceration. Keratitis is usually severe and unrelenting, and does not respond to standard ABx treatment.
3. Particularly associated with contact lens use.
Where does thinning (melting) of the cornea occur, and what does progressive thinning lead to?
Occurs adjacent to and usually parallel to the limbus, may proceed centrally and circumferentially.
May occur with or without epithelial loss (ulceration) and with or without inflammation.
Progressive thinning can lead to corneal perforation and intraocular infection, or to severe astigmatism (irregular corneal shape).
What is the long term prognosis for patients with a corneal melt associated with a systemic disease?
Name 3 non-autoimmune causes of peripheral corneal thinning (melt).
1. Marginal keratitis (usually a sterile hypersensitivity reaction to bacterial toxins. Blepharitis +/- acne rosacea = common cause of marginal corneal ulceration).
2. Infection (Ix corneal scrapes)
3. Dellen (a localised swelling of the conjunctiva, such as post-surgical inflammation or a pterygium, which prevents normal transit of tears across the adjacent cornea, which becomes thinned as a result).
Name two organ-specific autoimmune causes of peripheral corneal thinning.
1. Primary Sjögren's (dryness of mucous membranes incl. conjunctiva) - painless melting may begin insidiously and progress inexorably.
2. Mooren's ulcer - rare, painful progressive melting process which results in marked astigmatism.
Name four generalised autoimmune diseases which can cause peripheral corneal thinning.
1. Rheumatoid arthritis (can cause secondary Sjögren's).
3. Wegener's granulomatosis
4. Polyarteritis nodosa
The latter three are rare recognised causes of corneal melting.
Local and systemic management of autoimmune peripheral corneal thinning?
Local: reversal of tear insufficiency by frequent instillation of artificial tears and punctal occlusion, and treatment of infection.
Systemic: Ix and Rx of any underlying disorder, usually in conjunction with a rheumatologist or dermatologist.
What type of corneal surgery could be indicated for superficial corneal scars? Two possibilities.
1. Lamellar keratoplasty (replaced by a layer of donor cornea)
2. Phototherapeutic keratectomy (excimer laser)
What is a penetrating keratoplasty and what is the indication for this type of surgery?
It is a full-thickness corneal transplantation to restore visual potential after dense corneal scarring.
Scarring as a result of herpes simplex infection is one of the main indications for corneal transplantation in the UK, but in this instance the risk of immune rejection is higher and so prognosis is poorer than for other reasons necessitating a corneal transplant.
Adenoviral keratitis causes which two symptoms after viral conjunctivitis?
Blurring and photophobia.
What is a dystrophy? Name five of the more common dystrophic disorders.
A primary intrinsic hereditary disorder, with bilateral manifestation.
1. Recurrent corneal erosion syndrome
2. Stromal dystrophies
3. Corneal guttata and Fuch's endothelial dystrophy
4. Congenital hereditary endothelial dystrophy (CHED)
What does corneal degeneration refer to?
Refers to changes occurring secondary to an insult in previously normal tissue, and includes ageing. The changes need not be bilateral.
Name six types of corneal degenerations.
2. Band keratopathy
3. Lipid deposition
4. Salzmann nodular degeneration
5. Crystalline keratopathy
6. Vortex keratopathy
What can cause recurrent epithelial erosion syndrome, and what would be three ways to treat it?
Caused by epithelial or stromal dystrophy, or by previous trauma.
Treat with regular lubrication, patching, or bandage contact lens.
What are two things endothelial failure can be caused by, and what two consequences (and main treatment) can endothelial failure lead to?
2. Cataract surgery
Progressive stromal oedema leads to loss of transparency and formation of epithelial bullae. It may require corneal transplantation.
What is keratoconus and how it is treated?
Keratoconus is a progressive myopic astigmatism caused by distorted corneal shape. Treated with transplantation when optical treatment is insufficient.
What is a pterygium and how is it treated?
Pterygium is a type of corneal degeneration. It is a interpalpebral fibrovascular growth which can be removed surgically.
It is non-neoplastic, extends from the conjunctiva into the cornea beneath the epithelium. May be nasal or temporal, but always interpalpebral. Rarely leads to significant visual Sx. May present a cosmetic problem or persistent foreign body sensation. Simple removal is usually effective.
What is a pinguecala?
Similar process to a pterygium, but involves interpalpebral conjunctiva only (without growth onto the cornea).
What is band keratopathy, and what may it be associated with?
In band keratopathy there is subepithelial deposition of calcium in the interpalpebral region.
It may be associated with systemic hypercalcaemia or chronic ocular inflammation.
Visual loss and pain are treated with debridement (with aid of a chelating agent). Excimer laser ablation is an alternative.
What is arcus senilis?
A narrow circumferential strip of lipid laid down in the peripheral cornea, separated from the limbus by a margin of clear cornea.
It is a common degeneration present in most elderly people, and may indicate hyperlipidaemia in young adults.
What is the characteristic pattern of vortex keratopathy, and what are 5 associations which may cause it?
Epithelial deposits in a whorled pattern. Does not usually present with any significant visual Sx.
1. Systemic amiodarone therapy (most common)
5. Fabry's disease (lysosomal storage disorder).
How is epithelial loss managed?
As for any corneal abrasion:
1. Persistent discomfort treated with regular lubrication
2. Chloramphenicol ointment
3. A mydriatic
If caused by trauma, the recurrent epithelial erosion eventually resolves, but if symptoms are persistent, a soft bandage contact lens (without refractive power) may be used.
What is deposited in a lattice (stromal) dystrophy, and in what pattern?
Amyloid, in a branching pattern (in the central corneal stroma, sparing periphery).
Presents in first decade of life with Sx of recurrent corneal erosion. The central cornea becomes cloudy, leading to visual loss. Rarely associated with systemic amyloidosis.
What is a full-thickness corneal graft called?
What are corneal guttata?
Areas of endothelial cell dysfunction or loss that are seen in the ageing cornea.
What is Fuch's dystrophy?
Progressive endothelial cell loss.
This may lead to decompensation, corneal oedema with loss of transparency and reduced vision. Painful epithelial blisters (bullous keratopathy) are typical. Scarring and vascularisation may occur. There is association with open and closed angle glaucoma, and with cataract.
Eyes with corneal guttata may decompensate following what?
Routine cataract surgery.
This may lead to aphakic and pseudophakic bullous keratopathy.
How would hypertonic (5%) saline be useful in endothelial cell dysfunction or loss?
It helps to dehydrate the cornea and is helpful with symptoms of discomfort and pain.
What is CHED?
Congenital Hereditary Endothelial Dystrophy.
A rare condition causing congenital or early-onset bilateral corneal oedema owing to a defective endothelium.
Name two systemic and one ocular condition associated with keratoconus.
1. Down's syndrome
2. Marfan's syndrome
3. Atopic keratoconjunctivitis
What is keratoconus?
An acquired abnormality of corneal shape of gradual onset. Usually bilateral, but asymmetrical.
Cornea protrudes forwards like a cone, the apex of which becomes thinned, scarred and distorted. Patients present with slow visual deterioration, often initially uniocular, owing to progressive myopia and astigmatism.