Section

Management FIVE

complicationsAftercare 29CHAPTER

29.1 Emergencies and infections

Emergencies, either perceived or real, are a fairly routine occurrence in contact lens practice. It is a common assumption by patients that the lenses are the invariable cause of any ocular problem and it may require all of the practitioner’s skill to differentiate between contact lens and non-contact lens emergencies.

29.1.1 Infections and inflammatory responses

Infections may be either connected or unconnected with contact lens wear. In serious cases, immediate medical treatment is required to minimize any risk of permanent visual loss.

Microbial keratitis (suppurative keratitis)1,2,3

Microbial keratitis is a potentially sight-threatening condition and requires urgent diagnosis and referral. It is caused by bacteria such as the Gram-negative

Pseudomonas aeruginosa or the Gram-positive Staphylococcus aureus or Streptococcus pyogenes. Patients typically present with unilateral:

•Severe pain, photophobia and lacrimation.

•Epithelial defect.

•Central lesion over 1.0 mm in diameter.

•Corneal suppuration (ulceration) which can be rapidly progressive.

•Uveitis.

•Lid oedema.

©2010 Elsevier Ltd, Inc, BV

DOI: 10.1016/B978-0-7506-7590-1.00011-X

Section FIVE Management

If patients are observed early, before ulceration occurs, epithelial disturbance or superficial punctate keratitis may be the only signs. Corneal ulcers associated with Gram-positive bacteria are usually smaller and less purulent. The Gramnegative Pseudomonas, in particular, is highly virulent and characteristically produces large epithelial defects with dense anterior stromal infiltrates. Treatment usually commences with a broad-spectrum antibiotic until the specific microorganism has been identified.

Microbial keratitis in contact lens wearers is associated with soft  extended wear,4 poor patient hygiene, poor compliance and contaminated lens cases.5

Contact lens peripheral ulcer (CLPU)

CLPUs are also mainly unilateral and found with extended wear.6 They are considered to be the result of an inflammatory response of the peripheral cornea. Frequently, no causative microorganism is found on culturing and they have been referred to as sterile ulcers. Compared with microbial keratitis, patients usually present with:

•Mild pain sometimes described like a foreign body.

•Small peripheral lesions in the anterior stroma separated from the limbus. These focal infiltrates are dense, round and usually less than 1.2 mm in diameter.

•An overlying epithelial defect that rapidly takes up fluorescein.

•Bulbar and limbal injection, worse in the region of the infiltrate.

•Non-progressive corneal suppuration.

•No uveitis.

•Normal visual acuity.

Sterile keratitis should be treated as possibly microbial in origin until proved otherwise. The condition responds to topical steroids but, frequently, no medication is required and it resolves after a few days on ceasing lens wear. Normally, an anterior stromal scar remains which takes a minimum of 6 months to disappear.

PRACTICAL ADVICE

If a CLPU is suspected and the patient is not referrred for medical opinion, re-examine after 24 hours to ensure that the condition is not actually microbial keratitis.

Contact lens acute red eye (CLARE); acute red eye reaction

The red eye reaction is an acute inflammatory response usually occurring with soft extended wear lenses on waking. There is gross unilateral hyperaemia of the bulbar conjunctiva and limbus, associated with varying degrees of pain, photophobia, lacrimation and limbal infiltrates. Corneal staining is either absent or mild punctate in character. The condition has been associated with:

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•Gram-negative bacterial contamination.

•A tight lens trapping endotoxins and debris.

•Upper respiratory tract infection.

The contact lens must be removed immediately after which CLARE usually resolves without any medical intervention. There is, however, a significant possibility of recurrence in which case extended wear should be discontinued.

Infiltrative keratitis (IK and AIK)

The term ‘infiltrative keratitis’ tends to be used in respect of inflammatory infiltrative events which are not microbial keratitis, peripheral ulcers or acute red eyes. Patients have symptoms of mild pain, redness and lacrimation. There may be signs of minor corneal trauma such as that caused by a foreign body or a poorly fitted lens. Small diffuse or focal infiltrates are usually found in the corneal periphery but may also occur more centrally. IK occurs with both daily and extended wear and may be caused by bacterial toxins trapped beneath the contact lens.7

In some cases, patients are completely unaware of the condition which is discovered by chance at a routine aftercare examination. It is then called ‘asymptomatic infiltrative keratitis (AIK)’.

The additional term ‘asymptomatic infiltrates (AI)’ is used where the cornea shows a mild infiltrative response with one or more small focal infiltrates 0.2 mm or less in size. These are also observed in asymptomatic patients at routine aftercare examination.

PRACTICAL ADVICE

•Corneal ulceration can progress with great rapidity so that serious visual loss can occur within 12–24 hours. Immediate referral direct to an ophthalmologist is absolutely essential.

•Chloramphenicol which is currently the only antibiotic available to optometrists as a first aid treatment, is ineffective against Gramnegative microorganisms such as Pseudomonas aeruginosa.

Acanthamoeba keratitis

Acanthamoeba keratititis is an uncommon but devastating ocular condition. There are several reports that associate it with the use of contact lenses,8 so that the practitioner should always be open to its possibility in a patient presenting as a painful emergency.

Acanthamoeba is a non-flagellate protozoon occurring in trophozoite and cyst forms. The double-walled nature of the cyst accounts for its strong resistance to treatment. The organism is widely distributed in air and water so that tap water should never be recommended for rinsing contact lenses or cases. Patients should also be advised to be particularly careful with cleaning and disinfection after swimming with lenses. Alcohol based cleaners are particularly effective against

Acanthamoeba.

The later, characteristic feature of Acanthamoeba keratitis is an extensive ring infiltrate in the cornea. There is often hypopyon and secondary glaucoma. The

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condition produces a high incidence of corneal scarring requiring keratoplasty and immediate referral is therefore essential. The earlier the diagnosis, the more successful the treatment, and a referral note should include the practitioner’s suspicions.

Early features of Acanthamoeba infection are:

•Severe ocular pain or aching, out of all proportion to any initial signs of infection or inflammation.

•Red eye.

•Reduced acuity.

•Central punctate epithelialopathy which often breaks down to an erosion. The lesion may well be dendritiform and therefore mistaken for ocular herpes simplex.

•Perineural infiltration of corneal nerves, extending from the centre to periphery.

•Superficial nummular keratitis.

Various treatments have been developed but Brolene drops (propamidine) and ointment (dibromopropamidine) both have some efficacy. Steroids are usually contraindicated.

Viral keratitis

The contact lens practitioner may encounter two main types of viral keratitis, although there is no particular association with contact lenses. Viral infections typically produce a profuse serous discharge.

•Herpes simplex. Very painful and typically showing dendritic lesions or disciform keratitis. There is generally scarring with the risk of recurrence. Aciclovir is used in treatment.

•Adenovirus. Mildly painful, showing multiple subepithelial infiltrates which may fade very slowly. The condition is extremely infectious but self-limiting with only a small chance of visual loss.

29.1.2Overwear syndrome (acute epithelial necrosis;

3 am syndrome)

This was commonly associated with PMMA, although not unknown with either rigid gas-permeable or soft lenses. The patient is typically awakened in the middle of the night with extreme pain (’red-hot needles’ is the usual description), photophobia and lacrimation. It is an extreme response to gross corneal oedema as a result of excessive contact lens wear. Typical causes are:

•Too fast an initial wearing schedule.

•Patient forgetting to remove lenses at a specified time.

•All-day use after a gap in lens wear because of loss.

•Falling asleep with lenses in.

•Chronic oedema with longer than normal wear in a hot and stuffy atmosphere.

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Examination, where feasible, shows large areas of corneal staining. Treatment may well require local anaesthetic and antibiotics to minimize the risk of secondary infection. In extreme cases, medical treatment is necessary with ‘pad and bandaging’ in a darkened room for 24 hours. The epithelium usually recovers within 2–3 days, although contact lens wear should not be resumed for at least a week and not until the practitioner has confirmed that the cornea is clear. A very slow wearing schedule is then indicated. Patients require considerable reassurance that they will not suffer permanent damage to their eyes.

PRACTICAL ADVICE

•Local anaesthetics tend to retard epithelial healing and should only be used in cases of extreme pain. The preferred analgesic is aspirin with whisky.

•After recovery, to prevent recurrence, the patient should be refitted with a more permeable lens.

29.1.3 Foreign bodies

These are much more common with rigid lenses. The damage to the corneal epithelium, however, can sometimes be greater with soft lenses because the foreign body remains trapped behind the lens for a longer period of time. Patients complain of sudden, acute pain during the wearing day.

The lens must be removed and fluorescein instilled to assess the depth of staining with slit lamp optic section. Treatment consists of antibiotics, with ‘pad and bandaging’ in severe cases.

29.1.4 Corneal abrasions

Severe abrasions cause symptoms similar to those resulting from foreign bodies. They may be caused by poor lens handling, typically by fingernails, inserting or wearing damaged lenses, lenses breaking in the eye, and fitting problems.

29.1.5 Solutions problems

A high proportion of soft lens emergencies relate to solutions reactions. Careful questioning is sometimes necessary to reveal either patient error or the offending solution. Typical problems are:

• Genuine allergic response.

• Thimerosal keratopathy, also known as contact lens-induced superior limbic keratoconjunctivitis (CLSLK).

•Using rigid lens solutions with soft lenses.

•Not neutralizing lenses stored in hydrogen peroxide.

•Confusing soaking and cleaning solutions.

•Reaction to enzyme tablets.

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•Using enzyme tablets in conjunction with an incorrect solution.

•Adverse reaction after intensive cleaning.

•Using preserved comfort drops in an otherwise non-preserved regimen.

•Using preserved therapeutic drops.

•Patients changing to a brand different from that originally recommended by the practitioner.

•Patients being sold an incorrect solution.

•A solution bought overseas with the same name but a different formulation.

PRACTICAL ADVICE

In some instances (e.g. where patients have instilled unneutralized peroxide or used rigid lens solutions with soft), a very severe corneal response is seen. There may be extensive corneal staining with considerable discomfort. In these cases:

•Ensure immediate removal of the lens.

•Use copious irrigation, preferably with 0.9% saline.

•Use chloramphenicol because of the risk of infection in a cornea with compromised epithelium.

•Consider a topical anaesthetic but only for those patients in severe pain.

29.1.6 Broken and displaced lenses

Novice patients often lose a lens in the upper fornix. It is therefore important to explain at initial collection (see Section 27.2) the procedure for recovering such a displaced lens, although this can happen even to experienced wearers. The problem usually occurs with rigid gas-permeables but thin soft, particularly disposables, can sometimes fold up and slip off the cornea.

Most daily disposable lenses are thin and fragile. High water content varieties are therefore more prone to breakage and this can easily happen on insertion or removal from the eye. There may be a portion remaining which, despite discomfort, patients are unable either to locate or remove from the sclera or upper fornix so that they present as an emergency. Lid eversion is frequently required and lens wear can usually be resumed immediately on removal of the broken fragment.

PRACTICAL ADVICE

Instill fluorescein into the eye before attempting removal of a broken disposable because:

•A stained lens is more easily and quickly seen.

•Any corneal abrasion is observed at the same time.

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