Management of ocular surface exposure
- Correspondence to Carol Lane, Consultant Ophthalmologist, Cardiff Eye Unit, University Hospital of Wales, Cardiff CF14 4XW, UK;
Contributors I was asked to write the article. I performed the literature search and wrote the article, and I am the guarantor (the contributor who accepts full responsibility for the finished article, had access to any data, and controlled the decision to publish).
- Accepted 17 January 2012
- facial paralysis
- corneal disease
- treatment surgery
- lacrimal gland
Appropriate management of ocular surface exposure depends on understanding the pathogenesis in terms of the adnexal tissues, epithelial surfaces, motor and sensory innervation, tear film and sometimes the treatment. A primary aim of the oculoplastic surgeon is to protect the ocular surface and preserve vision. Proptosis, eyelid defects or immobility, eyelid malposition, impaired lacrimal gland secretion or drainage, meibomian gland dysfunction and reduced corneal sensation all compromise the ocular surface.
Static and dynamic assessment of the eyelids is a vital part of the anterior segment examination. A simple examination routine for all patients should include comparison of orbital symmetry, infrequency of blink, excluding the presence of lagophthalmos on blink as well as gentle and forced eyelid closure with a check for orbicularis weakness. A test for the presence, direction and extent of the Bell's phenomenon followed by slit lamp examination for eyelid margin entropion or other malpositions, trichiasis, punctal patency and meibomian gland disease helps identify vulnerable corneal zones for exposure or staining.
Types of ocular exposure
Static eyelid defects may be congenital, such as coloboma, or acquired, as in surgical sequelae, facial palsy, periocular burns and ocular cicatricial pemphigoid. The detail of eyelid structure is important. Workshops on meibomian gland dysfunction have produced a series of reports, indicating a wide range of types of meibomian gland size, position and secretion; the report of the diagnosis subcommittee is particularly informative.1 The influence of upper eyelid position on the cornea is well recognised. As one would expect, upper eyelid entropion repair can improve visual acuity by increasing tear break up time and reducing corneal epitheliopathy.2 The full benefits of correction of eyelid malposition can take up to 90 days to take effect. Lower eyelid position is affected by proptosis or maxillary hypoplasia. The latter may be acquired with ageing and change the relationship between the globe and the orbital rim, predisposing to ocular surface exposure.3
Dynamic abnormalities are caused by coma or paralysis for ventilation in an intensive care unit, facial nerve palsy, lagophthalmos, reduced blink rate, proptosis and a poor Bell's phenomenon. A normal Bell's phenomenon is important when other protective mechanisms are compromised, such as after ptosis repair.4 Conversely, despite the presence of apparent ptosis and perhaps due to retroplacement of the eyelids and the loss of upper eyelid volume and weight influencing gravitational descent, enophthalmos-related lagophthalmos is well recognised as a potential cause of exposure keratopathy.5 Patients with ‘sunken upper eyelids’ orbital fat loss, enophthalmos and ptosis have been shown to exhibit more blink lagophthalmos, correlating with incomplete eyelid closure and corneal epithelial breakdown in comparison with controls.6 The authors also reported an abnormal Bell's phenomenon to correlate with early morning symptoms. These studies also reinforce the importance of recognising the impact of nocturnal lagophthalmos7 as well as careful consideration of the impact of enophthalmos in addition to ocular surface abnormalities in patients being considered for ptosis surgery.
Defective eyelid closure arising from orbicularis weakness can lead to corneal ulceration, scarring and visual loss if treatment is delayed. If the Bell's phenomenon is poor, ocular lubricants alone will usually not provide adequate corneal protection. If VIIth cranial nerve function is compromised, facial paralysis can usefully be graded using the House–Brackmann scale,8 ranging from I (normal) to VI (no function). At stage III blink, lagophthalmos may be present even if the eye can gently close (albeit often slowly), and, by stage IV, lagophthalmos is invariably present, being evident on gentle and forced closure. Systematic approaches, including lubricants, botulinum toxin injections to the upper eyelid,9 and surgery, should be tailored to the degree and anticipated duration of ocular exposure.10
Management of ocular exposure
When a short period of corneal exposure is unavoidable, as in critically ill children treated with neuromuscular blockade, a moist chamber over the eye has been found to be no more effective than lubricants and eye closure in preventing corneal abrasion.11 A similar UK study did not show any significant difference between the ocular lubricants (Lacrilube) and polyacrylamide gel (Geliperm) in preventing exposure keratopathy in the critically ill.12 The authors emphasise that nursing staff must be trained in the application of polyacrylamide gel for eye care.
Temporary suture tarsorraphy13 is a simple technique, which can be performed in the clinic setting under local anaesthetic in acute facial paresis, for non-healing epithelial defects,14 and to prevent anticipated corneal exposure or eyelid contraction.13 15 A 4/0 or 5/0 monofilament suture, inserted just anterior to the grey line in the lower eyelid, passed through a partial thickness tarsal plate, out of the grey line 1 cm along the eyelid margin with a mirrored insertion in the upper eyelid. When this is tied, it will maintain eyelid apposition for weeks if required. This technique should be learnt and practised by all trainee ophthalmologists.
Upper eyelid levator recession with weighting
The insertion of gold weights into the upper eyelid particularly improves blinking in orbicularis weakness. However, upper eyelid loading also improves exposure keratopathy and ocular discomfort in patients without facial palsy found to have blink lagophthalmos.16
A retrospective review of 107 gold weight insertions using a high tarsal placement combined with levator muscle recession by Bladen et al17 in this issue showed that 86% of operations were successful. Revision surgery was only required in 14% of cases, mainly because of a poor eyelid contour. In six of these 15 cases, the gold weights were exchanged for platinum because of its greater density and low allergenicity. Platinum weights can be made thinner and less prominent than gold weights.18 Bladen et al also describe a useful photographic method of assessing eyelid position, blinking and lagophthalmos before and after revision. This method could form the basis for randomised controlled trials addressing the relative merits of gold and platinum eyelid weighting when combined with levator muscle recession.
The use of hyaluronic acid gel as a non-surgical method of upper eyelid loading also holds potential value in patients with paralytic lagophthalmos who are poor surgical candidates.19
Surgery for ocular burns
Ocular burns require immediate use of lubricants, with additional amniotic membrane grafts20 or eyelid surgery. If frequent corneal examination is required, a ‘drawstring’ tarsorraphy, as described in a detailed review of the management of eyelid burns by Malhotra et al,21 is a useful technique. Eyelid contracture often relates to the ‘middle lamella’ of the eyelids—the orbital septum. A short series of patients with second- and third-degree periocular burns have been treated with surgery within 3 days of injury with encouraging results.22 The orbicularis muscle was separated and mobilised between the tarsus and the inferior orbital septum in a ‘canthus to canthus’ release21 before application of a large full-thickness skin graft. When the patient's general condition permits, this suggests that early surgery may be beneficial.
Surgery for immune-mediated disease
Treatment of the underlying cause of ocular exposure should ideally prevent the need for surgery in an immune-mediated disease such as Graves' orbitopathy or ocular mucous membrane pemphigoid.23 However, in medically controlled ocular mucous membrane pemphigoid, oral mucosal grafting to the eyelid margin may improve the ocular surface by reducing corneal microtrauma from keratinisation or trichiasis and lengthening the eyelid to lessen lagophthalmos.24
Oculoplastic surgery plays an important role in the management of ocular surface exposure, particularly in its simplest form, suture tarsorraphy. The complex dynamics of tear composition25 and response to blinking26 are intimately related to eyelid position and function. Anterior segment therapy should be seen as a continuum from cornea to eyelid. Subspecialisation should not hinder an integrated approach to the treatment of the corneal surface disease; each subspeciality has much to gain from the other.
I am grateful to Mr D S Morris for reviewing the manuscript.
Linked article 300732.
Competing interests None.
Provenance and peer review Commissioned; internally peer reviewed.
Data sharing statement I agree to data sharing of the contents of my original research article.