Dalia G. Said

BASICS

DESCRIPTION

Recurrent corneal erosion syndrome (RCES) is characterized by episodes of spontaneous breakdown of the corneal epithelium associated with symptoms ranging from ocular discomfort to severe pain. It is usually unilateral and is associated with awakening from sleep. It may be primary or secondary.

EPIDEMIOLOGY

Incidence

The incidence is unknown as the milder forms of the condition may go undiagnosed.

Prevalence

The disease is reported to occur more commonly in women, is more in the third and fourth decades, and is bilateral in 10% of cases.

RISK FACTORS

• Tiredness, menstruation, menopause, and alcohol intake are aggravating factors.

• Nocturnal lagophthalmos

• Trauma

• Corneal dystrophies

• Diabetes

Genetics

• A familial tendency has been reported among patients with map dot fingerprint epithelial basement membrane dystrophy (EBMD).

• A dominant inheritance has been reported to occur in 3% of cases in one study.

GENERAL PREVENTION

Avoidance of eye injury by wearing protective eyewear during activities such as gardening

PATHOPHYSIOLOGY

• Tear hypotonicity and corneal epithelial edema are implicated.

• Increased activity of matrix metalloproteinases (MMP-2 and -9) resulting in enzymic dissolution of epithelial anchoring structures including hemidesmosomes and anchoring filaments (1)[C].

• Abnormal basement membrane, abnormal or deficient hemidesmosomes, defective anchoring system, and accumulation of collagenous debris between and beneath epithelial cells result in easy slippage or tearing of the basal cells from the underlying connective tissue.

• Ocular saccades associated with rapid eye movement phase of sleep can exert shearing forces on the loose or poorly attached epithelium causing erosions to occur, the pain thus waking the patient, which is subtly different from experiencing pain on waking or eye opening.

• The relative reduced tear secretion during sleep may contribute by inducing greater friction between the apposing conjunctival and corneal epithelia on eye lid opening.

ETIOLOGY

• Primary: These include conditions that affect the basement membrane of the corneal epithelium.

– EBMD of which map dot fingerprint dystrophy (MDF) is the most common. Reis Bucklers and Thiel-Behnke dystrophy.

– Stromal dystrophies such as granular and lattice dystrophy

– Idiopathic

• Secondary: Trauma to the corneal surface with organic matter such as twigs, leaves, paper and finger nails is the commonest cause of RCES.

DIAGNOSIS

HISTORY

• Corneal trauma, which may be some time in the past.

• Recurrent attacks of pain, redness, photophobia, and watering which may last from a few minutes to several days. The frequency and intensity of episodes can be variable in the same patient.

• The frequency of episodes (number of times in a day, week, or month); duration of pain (minutes, hours, or days) and intensity of pain (on a scale of 1 = slight discomfort to 10 = severe pain) should be recorded in all cases. This helps in monitoring response to treatment and progression.

PHYSICAL EXAM

• Lid edema

• Conjunctival injection

• Impaired vision

• Cornea:

– Tear film debris and reduced tear break-up time

– Intraepithelial and subepithelial microcysts

– Punctate erosions staining with fluorescein (microform erosions)

– Large epithelial defects staining with fluorescein (macroform erosions) with the surrounding hazy loose epithelium

– A tag of epithelium attached to one edge of a frank defect

– Features of underlying dystrophy, e.g., fingerprint lines, maps, and dots; granular stromal deposits and lattice lines

– Very often areas of EBMD changes, loose epithelium, epithelial detachment and intraepithelial cysts present as “negative fluorescein staining.” These are dark areas (where the tear film is deficient or breaks instantaneously) seen after instilling fluorescein dye and visualized with cobalt blue light.

– A frank erosion or epithelial defect (staining positively with fluorescein) is often surrounded by an area of negative staining, which indicates the full extent of the defective epithelium.

– Most of the erosions occur in the lower third to half of the cornea. Following trauma, the erosions tend to recur at the same site but primary RCES may recur at different sites.

– Subtle corneal changes are best visualized by retroillumination or indirect illumination on the slit lamp.

DIAGNOSTIC TESTS & INTERPRETATION

Imaging

In vivo confocal microscopy can be used to demonstrate features of the underlying pathology, but these are not specific to RCES. For example, intraepithelial cysts, deposits in basal epithelial cells, subbasal microfolds, reduplicated basement membrane, damaged subbasal nerves, and altered morphology of anterior stroma can be seen in MD without erosions.

Diagnostic Procedures/Other

Diagnosis is essentially based on history and clinical features. Specific lab or other tests are not required.

Pathological Findings

• Histopathology:

– Epithelium: Intercellular edema, accumulation of connective tissue debris, flattening of basal cells, intraepithelial polymorphonuclear cells, intraepithelial cysts containing cellular debris, and degenerating cells

– Hemidesmosomes: Abnormal morphology; reduced in number. Deficient anchoring fibrils

– Basement membrane: Discontinuous and fragmented, multilaminar reduplication with extensions into the epithelial cell layers

– Collagenous debris interposed between basal epithelial cells and Bowman’s zone.

DIFFERENTIAL DIAGNOSIS

• Meesmann’s corneal dystrophy: Intermittent rupture of epithelial microcysts as they reach the surface of the cornea, causing symptoms.

• Bullous keratopathy: Rupture of fluid filled epithelial vesicles or bullae can cause pain.

• Band keratopathy: When the calcific plaques are thick and erode through the epithelium, the eye becomes symptomatic.

• Salzmann’s nodular degeneration: The nodules often sit proud of the tear film causing poor wetting of the surface epithelium which is prone to breakdown and become symptomatic.

• Eyelid abnormalities: Trichiasis and tarsal concretions that have eroded through the covering epithelium can cause repeated mechanical abrasions of the cornea.

• Meibomian gland dysfunction and dry eyes.

• Ocular surface syndrome: Following photorefractive keratectomy or LASIK. Usually attributed to aberrant re-innervation with tear film instability and punctuate keratitis.

• Viral keratitis: A few cases of recalcitrant RCES have eventually manifested clinical features of herpes simplex viral keratitis. This association is known but unexplained.

• Multiple corneal foreign bodies: Following blast injury, insect hair, leather fibres (snooker or pool cue injury). The embedded foreign particles may intermittently make their way to the corneal surface and extrude causing “foreign body sensation” and irritation.

• Systemic conditions such as epidermolysis bullosa and Juvenile X-linked Alport’s syndrome have inherent basement membrane abnormality that makes the epithelium vulnerable to repeated breakdown.

• Munchhausen syndrome: Self-inflicted trauma to the cornea.

TREATMENT

MEDICATION

• Simple conservative measures such as eye padding and use of lubricating drops, gels, and ointment help to provide relief from symptoms and prevent or reduce occurrence of erosions in most cases. The regular use of ointment, immediately before going to sleep is beneficial.

• Eyelid margin cleansing helps if associated with blepharitis.

ADDITIONAL TREATMENT

General Measures

• When the above conservative measures provide partial relief or none at all, a therapeutic extended wear (bandage) contact lens should be considered. It provides symptomatic relief and encourages healing of the epithelium by affording projection against the rubbing action of the lids. The lens can be changed daily, weekly, or monthly depending on the patient’s preference, environmental pollution, and prevailing practice. It should be used for at least 6–8 weeks to allow for remodeling of the basement membrane and consolidation of hemidesmosomal attachments.

– The eye should be examined within 24–48 h to ensure that the lens does not tighten on the eye. This can cause exacerbation of pain, corneal edema, and sloughing of the epithelium due to hypoxia.

– Use of ointment should be avoided whilst using the contact lens.

Issues for Referral

RCES not responding to the above measures necessitating surgical intervention

Additional Therapies

• Sodium chloride 2% drops or 5% ointment helps to dehydrate the epithelium.

• Oral tetracyclines (e.g., doxycycline 100 mg b.i.d.) as a metalloprotease inhibitor. This provides additional benefit in cases with posterior blepharitis and rosacea.

• Autologous serum eye drops in recalcitrant cases to facilitate closure of epithelial defects and afford lubrication.

SURGERY/OTHER PROCEDURES

• The area of positive and negative fluorescein staining should be treated:

– Superficial keratectomy, mechanical debridement, or diamond burr polishing of the loose epithelium and affected area.

– Anterior stromal puncture: Multiple punctures through the affected epithelium into Bowman’s zone/superficial stroma with a 23–25 gauge needle. This can also be achieved with a Nd:YAG laser. Can leave behind tiny scars and affect vision if in the visual axis.

– Phototherapeutic keratectomy: With the excimer laser ablating the epithelium and 5–7 μm of Bowman’s zone. Can induce a hyperopic shift especially if it has to be repeated.

– Alcohol delamination: With 18–20% ethanol applied to the affected area for 30 s with the help of a hollow cylindrical well (e.g., optical zone marker) of appropriate diameter. The sheet of epithelium removed can be used for histological examination (2).

• Postoperatively a Bandage Contact Lens (BCL) may be applied for 1 or 2 weeks and the eye treated with antibiotic and lubricant drops. Regular instillation of eye ointment before sleeping may have to be continued for a while.

ONGOING CARE

PATIENT EDUCATION

Instructions should be given to maintain therapeutic contact lens hygiene, to avoid eye rubbing, and excessive alcohol intake.

PROGNOSIS

Most patients achieve symptomatic relief and freedom from recurrence with conservative and/or surgical management. Reported success rate is between 80 and 90%.

COMPLICATIONS

• Secondary bacterial infection: Corneal ulcer or abscess. The risk is higher with use of a therapeutic extended wear contact lens. Can also occur following an interventional procedure.

• Localized corneal stromal haze related to the wound healing response associated with persistent and recurrent epithelial breakdown.

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