P.G.C. Bedford, BVetMed, PhD, DVOphthal, DipECVO, FRCVS
Introduction
The disease conditions of the canine eyelid are many, variety and incidence combining to render them of considerable significance in this species, far outweighing their significance in other domesticated species. Congenital abnormality, traumatic defect and neoplastic disease are all seen, but it is the range of the breed related conformational anomalies that introduces the opportunity for surgical challenge. The actual diagnosis of eyelid disease does not hold too many mysteries, but the execution of the various blepharoplasties may stretch expertise in the pursuance of patient relief.
ANATOMY
The eyelids are two movable folds of tissue which close and cover the eye. They are composite structures built around an internal skeleton of compacted connective tissue, the TARSUS or TARSAL PLATE. The anterior aspect of the lid is covered by hair-bearing skin, then there is muscle and loose connective tissue, then the tarsal plate and then the lining of palpebral CONJUNCTIVA. Movement is primarily related to two muscles, the ORBICULARIS OCULI and the LEVATOR PALPEBRAE SUPERIORIS. The orbicularis oculi is a sphincter of muscle which runs around the entire palpebral tissue. It is tied down at the medial and lateral canthus, and constriction leads to closure of the lids. Its motor supply is by the palpebral branch of the facial nerve (VII). The levator muscle raises the upper lid and its motor supply is the oculomotor nerve (III).
Obviously lid movement protects and excludes excessive light from the eye, but movement is also important in the removal of foreign body material and the distribution of the pre-corneal tear film (PCTF). The lid also contributes to the PCTF with secretions from the goblet cells of the palpebral conjunctiva (mucus producing glands), the KRAUSE and WOLFRING glands (accessory lacrimal glands), the MEIBOMIAN glands (sebaceous secretion), the MOLL glands (modified sweat glands) and the ZEIS glands (sebaceous glands). The Meibomian glands (approx. 25-30) are found within the substance of the tarsal plate and open via ducts onto the eyelid margin, (MARGO-INTERMARGINALIS).
Thus there is both an anatomical and physiological relationship between the eyelids and the cornea : disease of the former invariably leads to disease of the latter, but treatment regimes require consideration of both components. Secondary corneal disease cannot be addressed adequately until the eyelid primary is corrected.
CONDITIONS
Congenital or neonatal, inherited and acquired eyelid conditions are of considerable significance in the dog and cat whereas disease of these structures is generally uncommon in large animals. Blinking is an important reflex serving to
distribute the precorneal tear film (PCTF) over the corneal surface. Anything which destroys the relationship of the cornea with the eyelid can result in ocular surface disease (i.e. either or both conjunctival and corneal disease).
A. Congenital and Neonatal Conditions
1. ANKYLOBLEPHARON
A failure of the palpebral fissure to open (in pups the lids are sealed for the first 7-14 days of life whilst in kittens it is 4-12 days). In addition to the obvious effect this condition can promote a neonatal conjunctivitis (ophthalmia neonatorum). Correction is simple, involving the careful use of scissors to open the palpebral fissure. Antibiotic ointment is then used to control infection and lubricate the eye (effective antibiosis requires microbiological assessment).
2. EYELID AGENESIS (ABLEPHARON, COLOBOMA)
An anomaly seen most commonly in the cat, with a possibility of being inherited in the Persian. Part of the upper eyelid is absent to varying degrees, but in the cat the lateral part of the lid is always involved. The cornea cannot be covered adequately and an exposure keratitis results.
Repair can be achieved by either utilising :
(a) a pedicle graft from the lower lid, the base of the pedicle being the lateral canthus.
(b) a sliding facial skin graft utilising skin adjacent to the lateral canthus.
The repair covers cornea and helps to complete the blink, although constant lubrication with an artificial tear preparation may prove a necessary adjunct.
3. SYMBLEPHARON
The acquired adhesion of conjunctival tissue either to another conjunctival surface or to the cornea. Although the condition may be seen congenitally it occurs much more frequently in the cat affected with neonatal conjunctivitis and upper respiratory tract infection. Surgical correction is difficult for re-adhesions complicate the repair. Resected conjunctiva can be anchored at the limbus and the use of soft contact bandage lenses can help prevent adhesions reforming.
4. BLEPHAROPHIMOSIS
A neonatal but occasionally acquired narrowing of the palpebral fissure. The neonatal form is seen in the Bull Terrier, the Chow, the Kerry Blue, and the Collie types, and it may predispose to ENTROPION. Treatment is by surgery - the lengthening of the lid margin by lateral canthotomy (canthoplasty). Here the canthus is split using scissors to obtain a longer palpebral margin, conjunctiva being sutured to skin to prevent cicatricial closure.
5. MACROPALPEBRAL FISSURE (EURYBLEPHARON)
An excessively large palpebral fissure which may be associated an exaggerated exophthalmos (brachycephalics) or gross disparity between the small size of the globe and an exaggerated length of the lid. The former may result in LAGOPHTHALMOS and exposure keratitis, particularly in the brachycephalic breeds and the latter may be associated with ENTROPION and/or ECTROPION in breeds like the Cocker Spaniel, the Bloodhound and the St. Bernard. Treatment is surgical, by permanent reducing tarsorraphy at the lateral canthus in brachycephalics or other lid shortening techniques where looseness is the problem.
6. ENTROPION
The inversion or inward rolling of the eyelid so that lid hair is brought into contact with the cornea. The result is corneal irritation, keratitis and possible ulceration. The trigeminal pain is witnessed by BLEPHAROSPASM, PHOTOPHOBIA and excessive LACRIMATION. The condition may be inherited (breed predisposition) or acquired.
(a) The neonatal form of the condition is often not noticeable until 2-6 months of age, and therefore the term "anatomical" is perhaps more appropriate. Often a secondary spastic component may be present. It is usually bilateral and both lids may be involved, although usually only the lateral aspect of the lower lid. It is seen in several breeds including the Bulldog, Bloodhound, St Bernard, Irish Setter, Springer Spaniel, Labrador Retriever, Cocker Spaniel and the Chow, but though addressed as inherited, the mode of that inheritance has yet to be decided (? dominant, polygenic). Entropion is also seen in lambs and foals.
(b) Acquired entropion is classified as:
(a) cicatricial.
(b) spastic (all ages).
(c) atonic (old dogs).
Spastic entropion is caused by orbicularis oculi muscle spasm associated with painful ocular conditions. As noted above, anatomical entropion may also have a spastic component. For this reason all entropion should be assessed before and after the application of topical anaesthetic drops to the eye to remove the spastic component.
Atonic or senile entropion is common in the older English Cocker Spaniel associated with “slipped facial mask”. Entropion and trichiasis due to severe drooping of the upper lid often leads to chronic keratitis and may be sufficient to impair vision as the result of scarring and pigmentation.
Cicatricial entropion is less common and may be associated with previous surgery, trauma or chronic inflammation.
TREATMENT of entropion is surgical and many techniques have been described.
In puppies and lambs a temporary eversion of the lid margins using tacking sutures (vertical mattress) may be all that is required. Permanent surgical correction is probably best delayed until the puppy is 4 to 6 months of age.
Assessment of the degree of correction required should always be performed in the conscious, unsedated animal after the instillation of topical anaesthetic to abolish any associated blepharospasm, with no or minimal manual restraint.
In all cases, care should be taken not to over-correct the problem for this will lead to iatrogenic ectropion. It is easier to under-correct the entropion and then repeat the surgery if necessary. The owner should always be advised that a second bite of the cherry may be necessary.
Temporary tacking or the repeated manual eversion of the lid margins is usually all that is required when managing entropion in young foals. Techniques used in the management of entropion in lambs include the use of wound clips and tacking sutures or injections of bulking agents such as liquid paraffin or oily antibiotics into the lid skin to evert the eyelid margin. Such techniques should not be utilised in the dog.
Temporary tacking sutures to relieve entropion
(1)entropion of the lower eyelid.
(2)2 or 3 temporary everting (vertical mattress) sutures are
placed to evert the eyelid margin.
(3)The sutures are tightened. The suture ends may
be carefully superglued to the skin to prevent
premature loss.
Neonatal (anatomical) entropion in all breeds other than some Chows is perhaps best treated by the HOTZ-CELSUS skin/muscle resection technique. In the Chow some entropion can be related to blepharophimosis and lateral canthotomy (augmentation canthoplasty) should be the first move in correction.
Holtz-Celsus Procedure for the permanent
Correction of eyelid entropion
(1)Assess the degree of entropion in the
conscious patient. Instil a topical anaesthetic
to relieve blepharospasm (“spastic component”)
(2)Make the initial incision approximately 2 mm
from the lid margin. Remove a crescent-shaped strip
of skin/orbicularis muscle from the eyelid in the
region affected by entropion, using scissors or scalpel.
(3)Simple interrupted sutures (6/0 vicryl) are used to
close the wound with the knots directed away from the
cornea.
Atonic or senile entropion can be treated using the Stades’ procedure which creates an area of hairless skin on the upper lid as well as everting the lid margin. In severe cases where the “slipped facial mask” means that the palpebralfissure is located ventral to the position of the eye leading to ectropion of the lower lid and blindness, then a face-lift procedure will be required.
Stades Procedure
(1)Entropion-trichiasis affecting upper lid.
(2)With the first incision 1mm from meibomian gland
openings on the upper lid margin, remove a strip of skin
1 ½ -2cm wide from the upper lid. Ensure that all
hair follicles are removed from this area.
(3)Mobilise the skin at the upper edge of the incision
and suture to part of the wound corresponding to the
area of the bases of the meibomian glands – using
simple interrupted and continuous sutures.
The uncovered portion will heal by second intention.
Apply a topical antibiotic ointment post-operatively to
this area for approximately 10 days.
Cicatricial entropion is usually treated by a simple Y to V procedure with resection of any scar tissue.
7. ECTROPION
An outward rotation of the lid such that exposure conjunctivitis and keratitis may occur. Less serious than entropion, but a condition which still requires correction.
(a) Neonatal (anatomical) ectropion can be further classified as pathological or physiological (post exercise). This latter is transient, requires no correction and is usually seen in the working breeds of dog. It should not be corrected. The former is seen in the St Bernard, Bloodhound, Mastiff, Clumber Spaniel and Cocker Spaniel. It leads to chronic conjunctivitis, exposure keratitis, chronic ocular discharge and often discomfort.
(b) Acquired ectropion is classified as:
(i) cicatricial – due to previous surgery, trauma or chronic inflammation.
(ii) spastic – due to spasticity of the orbicularis oculi muscle.
(iii) atonic – due to lack of muscle tone.
(iv) paralytic (7th nerve damage).
TREATMENT is surgical and several techniques are available:
(i) a wedge resection to shorten the lid but this does not correct lid laxity at lateral canthus.
(ii) a triangular resection at the lateral canthus.
(iii) a modified Khunt Szymanowski resection - a lid split combined with triangular resection at the lateral canthus. This shortens the lower lid and lifts the lateral canthus into a fixed position.
(iv) a V to Y plasty can be used in the correction of cicatricial ectropion.
The modified Khunt-Szymanowski technique (ectropion)
Techniques which address the laxity of the canthus offer a better prognosis
when the ectropion is associated with marked euryblepharon. Excellent results are routinely obtained using a modified Khunt Szymanowski procedure in which the length of the lower eyelid is reduced and there is increased stability at the lateral canthus. A triangular flap of skin is raised at the lateral canthus and the lower eyelid is split along the grey line into anterior skin and muscle and posterior tarsoconjunctival flaps. The length of the split equates to the amount of lid shortening required. Using tenotomy scissors a triangular wedge of the tarsoconjunctival flap is removed and the defect closed by apposing its edges using a 6-0 interrupted absorbable suture. The lower eyelid anterior skin and muscle flap is then sutured into the triangular facial skin defect and excess facial skin removed. It is this translocation of lower eyelid tissue laterally to the canthus which lifts the shortened lower eyelid and helps stabilise the canthus. A further modification of this procedure avoids splitting the margo-intermarginalis and thus damaging the Meibomian ducts: here the initial skin and muscle incision is placed 3mm from the eyelid margin and runs parallel to it, starting some 10 to 15mm lateral to the canthus.
The modified Khunt-Szymanowski technique for the correction of
ectropion associated with marked euryblepharon.
(a) A triangular eyelid skin and muscle and facial skin flap is
prepared (A).
(b) A triangular wedge of the tarsoconjunctival flap is removed to
shorten the lower eyelid (B).
(c) The skin flap is lifted into the lateral facial wound and excess
skin is removed.
8. ENTROPION/ECTROPION COMBINATION
A "diamond eye" configuration in which there is a lower lid ectropion (middle) and a lower lid entropion (lateral) together with an upper lid entropion (lateral). The cause is a macropalpebral fissure combined with a lack of lateral traction and correction can be attempted by a modified canthoplasty in which muscle pedicles are used to obtain traction of the lateral canthus (after Wyman). However this does nothing about the excessive length of the palpebral fissure and produces exposure of the lateral aspects of the globe. A modified Khunt Szymanowski technique in which the upper eyelid is also shortened perhaps offers the best solution.
The original Khunt-Szymanowsky Resection modified to shorten the upper eyelid.
9. DISTICHIASIS
A neonatal condition in which adventitious or accessory cilia emerge from the Meibomian ducts to impinge upon the cornea. Occasionally cilia arise from elsewhere on the margo-intermarginalis. They arise from within the meibomian glands as the result of abnormal differentiation. Their presence may not cause corneal irritation, but where such irritation occurs then blepharospasm, excessive lacrimation, superficial keratitis and corneal ulceration may be present. Either or both lids may be involved, but the upper lid is often the commonest site. The condition occurs in the Pekingese, Cocker Spaniel, Bulldog, Rough Collie, Shetland Sheepdog and the miniature long-haired Dachshund. However distichiasis may be seen throughout dogdom.
Treatment necessitates the removal of the root material either by:
(a) electrolysis for a few cilia,
(b) partial tarsal plate excision (PTPE) when the condition is extensive and the lid is of substantial thickness
or
(c) cryosurgery may answer most of the problems. Note that a temporary depigmentation of the skin and hair is possible and owners should be warned about this complication prior to surgery.
10. ECTOPIC CILIA
A variation of distichiasis in which the adventitious hair(s) emerge through the dorsal (usually) palpebral conjunctiva to impinge upon the cornea, usually in the 12 o'clock position. There is always pain and corneal ulceration is common. Treatment is by simple excision. This condition must be suspected in any dog presented with anterior segment pain.
11. TRICHIASIS
The eyelashes are angulated onto the corneal surface. It is frequently seen in elderly Cocker Spaniels. Correction may be by the Hotz-Celsus (entropion) technique or the Stades lid split can be tried in which the hairbearing eyelid skin is removed.
12. TRICHOMEGALY
Seen in the American Cocker Spaniel. Abnormally long eyelashes may contact the cornea to cause irritation. Treatment is by trimming and grooming.
B. Acquired Conditions
It should be noted that symblepharon, blepharophimosis, ectropion, entropion and other eyelid deformities can be acquired as the result of cicatrisation within lid tissue. Other acquired conditions include :
1. PTOSIS (Blepharoptosis)
A drooping of the upper lid either due to atonic entropion or to paralysing lesions of the cervical sympathetic trunk, a third cranial nerve lesion, mechanical lid lesions, masseter and temporal muscle atrophy and myasthenia gravis.
2. LAGOPHTHALMOS
Discussed as a breed related neonatal condition, but can be acquired as the result of seventh cranial nerve lesions, membrana gland prolapse, lid and orbital neoplasia, and exophthalmos (proptosis).
3. WOUNDS
Traumatic injuries are fairly common and they must be repaired promptly and accurately with minimal or no debridement. Healing is good where little or no tissue has been lost.
4. BLEPHARITIS
Inflammation and infection of lid tissue. Treatment involves the identification and correction of the causes. It may be simply a periocular problem or part of a generalised skin disorder.
i) Parasitic dermatitis – causes include sarcoptic and demodectic mange.
ii) Bacterial blepharitis – usually due to staphylococcal infection. Meibomianitis may occur when inspissated secretions retained in the gland leak into surrounding tissue and a granuloma or chalazion may form. These lesions are seen as yellow or white swellings through the palpebral conjunctiva. Surgical drainage through the palpebral conjunctiva is required.
Staphylococcal infection of an eyelash sebaceous gland is called a hordeolum. The swelling involves anterior eyelid tissues. Again surgical drainage is necessary.
iii) Fungal dermatitis – due to infection with microsporum or trichophyton species.
iv) Immune-mediated conditions include pemphigus and the uveodermatological syndrome. Secondary bacterial infection can be present. Treatment necessitates the use of corticosteroids, immune suppressants and possible antibiosis. Allergic skin disease (atopy) can involve the eyelid.
5. LID NEOPLASIA
Very common in the dog, and occasionally seen in the cat and horse. It is usually the middle aged/older dog and epithelial tumours predominate in a ratio of 5 to 1. Approximately 75% of all lid tumours are benign. The most common types of epithelial derived lid tumours are papillomas, adnexal tumours (adenomas) and squamous cell carcinomas. This latter is the commonest adnexal tumour in the horse and cat (conjunctiva and membrana nictitans). Melanomas, histiocytomas and fibromas are also seen. Biopsy is essential. Tumours may be removed by wedge resection, split thickness advancement flaps, and full thickness resection with skin and muscle advancement flaps.
References for further reading :
Moore, C.P. and G.M. Constantinescu (1997). “Surgery of the adnexa” Veterinary Clinics of North America:Small Animal Practice 27(5):1011-1066.
Bedford, P.G.C. (1990). “Surgical correction of facial droop in the English cocker spaniel” Journal of Small Animal Practice 31:255-258.
Bedford, P.G.C. (1998). “Technique of lateral canthoplasty for the correction of macropalpebral fissure in the dog” Journal of Small Animal Practice 39(3):117-120.
