Recurrent Corneal Erosion Syndrome

The cornea is made up of three layers: the internal, single-layer cell of endothelium, the central stroma which makes up the bulk of the cornea and the multi-layered external epithelium. Recurrent corneal erosion syndrome (RCES) refers to the situation where there is disturbance of the epithelial basement membrane resulting in defective adhesion of the epithelium to the stroma so recurring cycles of epithelial breakdown. Multiple recurrences are common, because the basal epithelial cells require at least 8 to 12 weeks to regenerate or repair the epithelial basement membrane.¹

Aetiology

• The most common cause that triggers the process off is superficial trauma to the cornea (including micro-trauma caused by contact lens wear).² RCES may not develop until several months after the original insult.
• It may arise spontaneously but in the presence of risk factors relating to the cornea such as corneal dystrophies (notably epithelial basement membrane dystrophy but large number of others too), dry eye syndrome and exposure keratopathy.
• There may be more unusual trigger factors (all involving disruption of the epithelial basement membrane) such as following cataract surgery or refractive surgery. Other iatrogenic causes include vitrectomy (surgical removal of the vitreous) and photocoagulation.³
• Systemic diseases which may predispose to this condition include diabetes¹ and junctional epidermolysis bullosa.³ More unusually, patients with Alport's syndrome can develop RCES.⁴ It may also be a manifestation of Munchausen's syndrome.⁵ Malnutrition is thought to play a role.³
• Drugs associated with the development of RCES include thiomersal (found in contact lens solutions), high dose topical neomycin, topical paromomycin, topical diamidines and propamidine.³ To a certain extent, all topical anaesthetic medication causes some degree of epithelial cell damage but this is most marked with cocaine which is associated with RCES more than others.
• A variety of RCES associated with autosomal dominant inheritance has been described but is rare.¹

• There are no accurate statistics relating to the exact incidence and prevalence of this condition as it often goes un- (or mis-) diagnosed.
• It tends to occur slightly more commonly in females.
• It is a problem seen in adulthood, usually from the fourth decade of life onward, unless it is associated with one of the corneal dystrophies or Alport syndrome in which case it can arise in children.

History

Recurrent attacks of acute pain (typically towards the end of sleep or on waking) associated with lacrimation, photophobia and a foreign body sensation. There may be an associated blepharospasm (inability to open the lids) and blurring of the vision. The problem is almost always unilateral.¹ Symptoms may gradually subside over the course of the day and then start all over again the next morning. The unpredictability of these episodes may lead to an associated anxiety.

Assessment

• Check the patient's visual acuity (a drop of local anaesthetic will temporarily relieve the pain and the associated blepharospasm).
• Examine as much of the anterior segment of both eyes as your instruments allow you to. This includes fluorescein staining of the cornea. The idea is to rule out other possible differentials (see list below).
• If you think this is RCES, refer: the urgency depends on the degree of pain the patient is in. Same day referral is required for an acute attack.
• In the ophthalmology clinic, the anterior segment of the eye will be assessed with an emphasis on the state of the epithelium (macroerosions, microerosions or a roughening of the corneal surface). There may be associated oedema or disruption at deeper levels of the cornea. The degree and location of the disruption will affect the visual acuity. The fellow eye will also be examined for evidence of corneal dystrophy or other predisposing factors. There may be no signs to see at all in mild cases as the epithelium can heal within a few hours: the diagnosis can be made on history alone if this is typical. Severe cases can result in marked corneal changes which are quantifiable by corneal topography (a 3-dimensional mapping of the corneal surfaces giving gradients at each point so producing an ordinance survey map of the cornea).

• Corneal abrasion
• Corneal foreign body
• Contact lens related problem
• Dry eye syndrome
• One of a variety of corneal dystrophies
• Floppy eyelid syndrome
• Herpes simplex keratitis
• Other form of keratitis

Diagnosis is made on history and examination. Severe cases may warrant corneal topography (see assessment above) to outline the degree of corneal damage or help in the diagnosis of a corneal dystrophy (most of which are diagnosed on examination).

There is no formal staging of RCES but a note is made of the depth of corneal involvement as this dictates treatment options and prognosis.

Primary care

• The best time for a patient to be seen is first thing in the morning: in mild cases, signs will have resolved within a few hours.
• A patient suspected of suffering from RCES should be referred to the local ophthalmology unit. The degree of urgency depends on the severity of pain.
• Should a non-urgent referral be made and there be an interval between referral and ophthalmology consultation, do not be tempted to manage these patients with topical anaesthetic agents as these disrupt epithelial healing and aggravate the problem. Topical lubricants and oral analgesia are a reasonable initial plan.
• Avoid a pressure patch: this is best applied (if at all) in the eye clinic once the problem has been assessed.
• The patient may be discharged once the condition seems to have stabilized. However in some patients, this can be a recurring problem and should the treatment regime given not contain the symptoms any longer, re-referral is entirely appropriate.

Topical treatment

• The mainstay of treatment is intensive lubrication. This may need to go on for 3-6 months after epithelial healing.
• A mild cycloplegic and topical NSAIDs (such as topical diclofenac) may be added in the acute phase.
• If the defect is large, a pressure patch may be applied although use of patching is somewhat controversial and not favoured by all. These patients are reviewed daily and patching should not go beyond 72h.¹
• Alternatively, a bandage contact lens (a clear, non-refracting soft lens) can be used to allow the corneal surface to heal properly. In some patients, this may have to stay on for several months.

Debridement

• This is indicated in severe cases where there are extensive patches of loose epithelial flaps. It is carried out under local anaesthetic in the eye clinic and involves removal of the loose epithelium (which gets caught and pulled as the patient blinks) so leaving as smooth a surface as possible to promote healing.
• If there is no improvement long-term, anterior stromal puncture may be performed. Again, this is a minor procedure carried out under local anaesthetic in the eye clinic. Numerous tiny punctures are made away from the central visual axis which induces cicatrization and promotes more permanent epithelial adherence.

Keratectomy

• This is the removal of corneal tissue and is reserved for severe and recalcitrant cases (usually in patients with associated corneal dystrophies).
• This procedure involves either laser treatment or surgical removal (knife, diamond burr): the entire epithelium is removed and allowed to regrow from new over the following 5-7 days.
• This procedure can be carried out more than once if the problem recurs⁷ and also be combined with a refractive correction.⁸

• Infectious keratitis
• Corneal scarring
• Decreased visual acuity (due to either of the above)

With the right treatment, generally the prognosis is good with most patients responding well to topical treatment.³ This relies on any underlying conditions being diagnosed and treated and good patient education on the long-term management.¹ Few patients will have their vision permanently affected.

Prophylaxis revolves around long-term lubrication in the first instance. More severe cases may require a protective bandage contact lens to prevent new erosions and both anterior stromal puncture and epithelial keratectomy can be performed prohylactically. There is evidence to suggest that a 12 week course of systemic tetracycline (250mg bd) may be beneficial although the mechanism of action is not completely understood.