cornea ulcer

Other related separate articles include: Recurrent Corneal Erosion Syndrome, Dry Eyes (keratoconjunctivitis sicca), Corneal Foreign Bodies, Injuries and Abrasions, Eye Trauma, Contact Lenses (Types and Care) and Contact Lens Problems.

Always remember that babies with suspected corneal abnormalities should be referred urgently, even if they appear to be otherwise well and, if there is likely to be a wait before the patient can see the ophthalmologist, you can do little harm by giving them some preservative-free ocular lubricants or artificial tears which are a good first step in helping to relieve initial discomfort for many conditions. Pain can be addressed with oral analgesics; avoid topical anaesthetics as these are toxic to the corneal epithelium if used repeatedly.

Sospecialist unit

• Pachymetry - this is the measurement of corneal thickness. It is a painless investigation involving placing a measuring probe lightly on the surface of the anaesthetised cornea.
• Specular microscopy - this is a photographic investigation that enables the corneal endothelial cells to be accurately assessed.
• Corneal topography - this is another painless investigation which maps the surface of the cornea rather like an ordnance survey map, showing the gradient at each spot and therefore highlighting asymmetries, such as are found in the dystrophic conditions, for example.
• Microbiological investigations - a corneal scrape (clinic) or biopsy (theatre) may need to be done.

Protozoal keratitis

• Nature - the most feared is the Acanthamoeba species - a ubiquitous free-living protozoan found in air, water (fresh, salty, tap, swimming pools and hot tubs) as well as dust, soil or sewage. It largely survives in freezing to boiling temperatures and the chlorination of swimming pools. Contact lens wearers are at risk (although anybody can be infected). It can cause a devastating, sight-threatening infection.
• Presentation - this ranges from asymptomatic to a foreign body sensation, reduced visual acuity and extreme pain (disproportionate to mild clinical findings). Punctate or dendritiform defects may be present with small, white satellite lesions.
• Management - refer. Topical amoebicides will be used in association with topical steroids. In severe cases, a therapeutic penetrating keratoplasty may be needed to preserve the globe.

Other infectious keratitis

• Luetic interstitial keratitis - stromal inflammation associated with, amongst others, syphilis infection.
• Microsporidial keratitis - bilateral diffuse keratitis or unilateral deep keratitis seen in the immunocompromised.
• Infectious crystalline keratopathy - a rare indolent infection associated with HSV, acanthamoebic keratitis, Streptococcus viridans and long-term topical steroid therapy.

Acute problems following keratoplasty^[4][5]

• Nature - corneal grafting (keratoplasty) is the most common and most successful of all procedures. It can be performed as an elective procedure to improve vision, or as an emergency in the case of corneal perforation. Early postoperative complications include:
  • Wound leak.
  • Raised intraocular pressure.
  • Persistent epithelial defect (>2 weeks).
  • Endophthalmitis.
  • Graft failure.
  • Graft rejection.
  • Urrets-Zavalia syndrome (iris ischaemia).
• Presentation - patients who have undergone a keratoplasty and present with any of the symptoms outlined above should be assumed to have one of the above complications until assumed otherwise. Each has a slightly different presentation: these patients will be under close ophthalmological review in the first year at least. It is worth noting that corneal graft rejection most often occurs within the first two years following the procedure.
• Management - refer. Ideally, the operating surgeon should see the patient but, if they are not available (eg out of hours), refer to the on-call ophthalmologist who will initiate the management and liaise with the team.

Disorders of the periphery of the cornea

Marginal keratitis

• Nature - a disorder caused by hypersensitivity to staphylococcal toxins, more commonly occurring in patients suffering from chronic staphylococcal keratitis or blepharitis. It is characterised by peripheral infiltrates and multiple epithelial defects which eventually coalesce. It is a recurring condition.
• Presentation - typically, the patient is all too familiar with their symptoms of mild irritation and discomfort associated with a red, watery eye. Occasionally, discomfort is severe.
• Management - refer for confirmation of diagnosis and a short course of topical steroids.

Rosacea keratitis

• Nature - occurs in patients suffering from acne rosacea but the severity of the ocular condition does not correlate with that of the skin condition. It is more common in middle-aged, fair-skinned females.^[5]
• Presentation - nonspecific irritation, burning and redness associated with inferior punctate epithelial defects and peripheral neovascularisation. There may be lid and conjunctival involvement too.
• Management^[5] - refer for topical steroids and a course of systemic antibiotics (eg doxycycline 100 mg od for twelve weeks). Concurrent blepharitis also needs addressing. In very severe cases where there is the threat of corneal perforation, systemic immunosuppression is used.

Ulcerative keratitis in systemic disease^[5]

• Nature - this is particularly associated with rheumatoid arthritis where there is severe, progressive corneal thinning (perforation may occur). Ulcerative keratitis also occurs in other conditions such as Wegener's granulomatosis, systemic lupus erythematosus, relapsing polychondritis and polyarteritis nodosa. It may be referred to as 'peripheral ulcerative keratitis' (PUK).
• Presentation - this recurrent condition presents with acute unilateral/bilateral exacerbations characterised by decreased visual acuity, variable pain and redness (there may be none).
• Management - treatment will involve systemic immunosuppression, topical immunosuppression, ocular lubricants and globe protection (such as an eye shield). Both ophthalmologists and rheumatologists will be involved in patient care.

Other disorders

• Mooren's ulcer - where PUK-associated ulceration occurs and is idiopathic, it is referred to as Mooren's ulcer.^[4] This is an ulcerative condition (usually unilateral) which arises as a result of an autoimmune response to corneal antigens. It is rare but serious, particularly in young Africans in whom the more aggressive form of the disease is seen, and treatment depends on subtype (ranges from topical steroids/antibiotics to aggressive systemic steroid treatment).
• Dellen - localised saucer-shaped thinning of the cornea caused by localised tear film instability. Managed with lubricants; it is a transient condition.
• Phlyctenulosis - small pinkish-white nodule develops with an associated red eye. It occurs as a result of a nonspecific delayed hypersensitivity reaction to bacterial and viral antigens. These lesions may resolve spontaneously or be treated with a short course of antibiotics or topical steroids.
• Terrien's marginal degeneration - uncommon, idiopathic bilateral thinning of the cornea, usually occurring in the third to fourth decade of life, more often in males. There may be pain, there is decrease in visual acuity and, eventually, surgery may be needed to excise the diseased tissue (results are limited).

 

al nerve palsy, severe proptosis, eyelid scarring).

Presentation - a progressively painful red eye if left untreated in the presence of reduced tear film. Look for loss of shiny reflection from the corneal surface.

Management - if recovery of the underlying problem is anticipated, aggressive lubrication will do. Otherwise, lid surgery will be considered (tarsorrhaphy- where the lids are partially sutured together).

Neurotrophic keratopathy

• Nature - this occurs when there is loss of sensation in the cornea (eg acoustic neuroma, diabetes, herpes simplex virus (HSV) affecting fifth cranial nerve) and a secondary intracellular oedema (the pathogenesis is unknown).
• Presentation - variable: a painless red eye with mild visual impairment secondary to corneal oedema through to epithelial defects leading to corneal ulceration. A decrease in corneal sensation is the key factor.
• Management - this depends on the severity but lubrication ± protection overnight will usually be enough.

Miscellaneous conditions

Astigmatism

This is when the shape is slightly rugby ball-shaped rather than truly spherical, so causing a refractive error. This is most commonly treated with corrective spectacles and contact lenses (in some cases, the latter may be the best way of improving sight). Surgery is also an option in the private sector.

Drug-induced keratopathies

The cornea can be affected by a number of systemically administered drugs, including gold (causing chrysiasis - deposition of gold deposits), and antimalarials and amiodarone - both of which give rise to vortex keratopathy characterised by whorl-like corneal deposits. Vortex keratopathy has also been seen associated with indometacin, tamoxifen use and clofazimine toxicity. Drug-induced keratopathy has been described in the use of certain oriental herbal medicines.^[10]