Ординатура / Офтальмология / Английские материалы / Eye Surgery in Hot Climates_Sanford-Smith, Hughes_1994
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3. Endophthalmitis
After a drainage operation, aqueous passes from the eye into the sub-conjunctival space.There is always a risk that infection will pass in the opposite direction, from the conjunctiva into the eye. The infection may just reach the drainage bleb, sometimes called “bleb-itis” with pus and inflammation around the drainage bleb (see plate 17). It may spread further into the eye causing endophthalmitis. (See page 163 and plates 9 and 10 for a description). Any episode of unexplained inflammation or iritis in an eye after a drainage operation might signify an intraocular infection needing urgent treatment.
If the infection is just in the bleb then intensive topical, sub conjunctival and systemic antibiotics should be given (see page 167). If there is an endophthalmitis, then intravitreous antibiotics should be given (see page 164–6).
4. Excessive drainage of aqueous and hypotony
Excessive drainage of aqueous causing a very low intraocular pressure (hypotony) is quite common in the first few days after the operation. It nearly always recovers by itself. If a very large drainage bleb and a very soft eye persist for more than a few weeks, a long mattress suture of 10“0” nylon may make the drainage bleb smaller and restore the intraocular pressure to normal levels (fig. 6.33). These may be placed on one side or both sides of the bleb.
Fig. 6.33 A mattress nylon suture placed to reduce the size of the drainage bleb if it is too large
Note: If the reader is uncertain of the significance of the relative afferent pupil defect or how to test for it, please see “Eye Disease in Hot Climates” 4th edition published by Elsevier India or available from the International Centre for Eye Health (for address see page 324).
CHAPTER 7
SURGERY OF THE EYELIDS
Eyelid disorders are common and their treatment is often surgical. Most eyelid diseases will produce three possible effects:
1.Cosmetic deformity. This may vary from being mild to quite severe causing serious disfigurement.
2.Conjunctivitis. Eyelid diseases often cause conjunctivitis if the conjunctiva is exposed or irritated by the eyelid deformity. The patient will complain of irritation and discharge from the eye.
3.Corneal ulcers and scarring. The eyelid protects the cornea and severe eyelid disease can damage the cornea. The cornea may become progressively more scarred and opaque from keratitis and corneal ulcers eventually causing loss of sight. Obviously loss of sight is the most important consequence of any eyelid disease.
There are many different operations that can be performed on the eyelids. This book cannot begin to describe them all, and there are already many excellent textbooks available describing eyelid surgery. Only common conditions will be described, especially those which cause loss of sight by damaging the cornea. Upper lid entropion and trichiasis as a result of trachoma is the most important cause of corneal scarring. It is more common than all other eyelid disorders in tropical countries. Facial palsy is also important particularly in leprosy. Surgical treatment of other eyelid conditions will be discussed here in much less detail.
As with any other surgery, the surgeon must first understand the structure of the tissues (surgical anatomy) and the nature of the disease (surgical pathology) before considering the details of the individual operations.
Surgical Anatomy of the Eyelids
The eyelid tissues can be divided into four layers from front to back (figs. 7.1 and 7.2).
1.The skin
2.The orbicularis oculi muscle
3.The tarsal plate
4.The conjunctiva.
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Fig. 7.1 A cross section of the upper eyelid to show its four layers. Note also the position of the orbital septum, the levator muscle and its aponeurosis, and the position of the main blood vessels
Fig. 7.2 A cross section of the lower eyelid to show its four layers. Note the position of the orbital septum and lower lid retractors
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The Skin
There are several important features about eyelid skin:
•Eyelid skin, especially in the upper lid, is thinner, more elastic and more mobile than skin anywhere else in the body. It is also very loosely attached to the underlying connective tissue, so that oedema fluid or blood can easily collect under the eyelid skin. Eyelid swelling is very common after surgery or trauma and may develop following infection or inflammation near the eyelid. Eyelid oedema may also occur in systemic diseases which cause fluid retention particularly when the patient lies flat.
•There is little or no subcutaneous fat under the eyelid skin especially in the upper lid. This means the upper eyelid is a good source of skin for a free skin graft. Because the upper lid skin is so mobile and loose there is often enough to spare to fill a defect in another eyelid.There is usually no spare skin in the lower lid. In old age or after some chronic diseases like leprosy the eyelid skin, especially upper lid skin, may hypertrophy and stretch. Excess skin can easily be excised if it is causing problems.
•The eyelid has an extremely good blood supply. This means that wounds following surgery or trauma heal well and quickly without infection. Because of the good blood supply it is rarely necessary to excise traumatised or damaged eyelid tissue. It also means that free skin grafts applied to the eyelids will usually “take” satisfactorily.
In general, incisions into the eyelids should be made horizontally along the line of the skin creases. In this way they will heal well with minimal scarring.There is often spare skin in the upper lids, but by contrast there is usually none to spare in the lower lids.Therefore if any skin needs to be excised from the lower lid (for example to remove a skin tumour) it is best to make vertical not horizontal incisions to prevent contraction and ectropion.
The Orbicularis Oculi Muscle (figs. 7.1, 7. 2 and 7.3)
This muscle is responsible for closing the eyelids. It forms a circular sheet of fibres that pass around the eyelids, and is inserted into the medial canthal tendon and surrounding bone of the lacrimal crest and the medial wall of the orbit. It is divided into 3 parts:
Fig. 7.3 The orbicularis oculi muscle
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1.Orbital.The muscle fibres sweep around the orbital rim and are responsible for forced closure of the eye.
2.Palpebral. These muscle fibres pass over the orbital septum (the pre-septal fibres) and also over the tarsal plates (the pre-tarsal fibres). Together they are responsible for the movement of blinking. Sometimes in old age the fibrous tissue septa between these muscle fibres atrophy, so that when the muscle contracts the pre-septal portion rolls up over the pretarsal portion contributing to senile or spastic entropion in the lower lid (See fig. 7.7).
3.Lacrimal. These are a few fibres surrounding the lacrimal sac. They have a pump action sucking tears into the lacrimal sac and down to the nose.
The orbicularis muscle is supplied by the Facial nerve (the 7th. cranial).The nerve fibres enter the muscle from its deep surface. Local anaesthetic injections should be placed deep to the muscle in order to paralyse it.
Incision through the muscle layer should be made horizontally in the line of the fibres. Vertical incisions will damage the muscle fibres and the wound edges will tend to gape from contraction of the muscle.
The Tarsal Plates
The tarsal plates are composed of dense fibrous tissue and keep the eyelids rigid and firm.They are attached at each end to the medial and lateral canthal ligaments which join the eyelids to the bone of the orbit.The upper tarsal plate is larger than the lower.The upper lid is lifted by the Levator Palpebrae muscle which is supplied by the third cranial nerve.The muscle ends in a thin fibrous sheet or aponeurosis. This inserts into the upper border and anterior surface of the tarsal plate. It also breaks up to be inserted into the upper lid skin. Muller’s muscle which is supplied from the cervical sympathetic nervous system also helps to lift the upper lid. It lies between the Levator aponeurosis and the conjunctiva and is inserted into the upper border of the tarsal plate.The lower lid has a few weak muscle fibres, called the “lower lid retractors”, which also help to retract it.The Meibomian glands are embedded in the tarsal plate and produce an oily secretion which forms part of the tear film. Each gland opens on to the lid margin with a row of tiny ducts.
The Conjunctiva
The conjunctiva forms a mucous membrane lining the inside of the eyelids. It stretches from the limbus, round the conjunctival fornix and to the eyelid margin. It is very firmly attached to the tarsal plate, and chronic inflammation particularly from trachoma will cause fibrosis and contracture here, so that the tarsal plate buckles and thickens. This makes the eyelid turn inwards.
The eyelid margin where the conjunctiva joins the skin is an important area. In the middle of the eyelid margin is a line of thin skin called the “grey line” because of its colour (fig. 7.1 and fig. 7.4). It runs on the eyelid margin from the outer canthus to the inner canthus. Just in front of the grey line the eye lashes emerge through the skin of the eyelid margin. Just behind the grey line on the conjunctival side of the lid margin there are the openings of the Meibomian glands. If the eyelid
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Fig. 7.4 The margin of the eyelid. The position of the grey line is shown by the dotted line
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Fig. 7.5 The artificial division of the eyelid into an anterior and posterior lamella by an incision at the grey line
is massaged small beads of Meibomian secretion will appear.The tears flow along the eyelid margin from lateral to medial where they drain into the lacrimal puncta. The oily Meibomian secretions prevent overflow of tears and help form the tear film on the surface of the cornea.
An incision into the eyelid margin along the grey line splits the eyelid into 2 parts (fig. 7.5).The anterior part is the skin and orbicularis muscle with the eye lashes. It is sometimes called the anterior lamella. The posterior part is the tarsal plate and conjunctiva, and is sometimes called the posterior lamella.This is a useful plane for making incisions into the eyelid margin. It does not damage the eye lash roots or the Meibomian glands and there is relatively little bleeding. As the incision is continued in this plane it will separate the orbicularis oculi muscle fibres from the front of the tarsal plate. This artificial division of the eyelid into an anterior and posterior lamella helps in understanding the principles of entropion surgery. If this splitting is continued still further upwards it splits the levator aponeurosis into 2 parts, the front part is attached to the eyelid skin and the back part with Muller’s muscle to the tarsal plate (fig. 7.5).
The eyelids have a very rich blood supply which comes from both the ophthalmic artery which is a branch of the internal carotid artery, and the facial arteries which are branches of the external carotid. The arteries run between the orbicularis muscle and the tarsal plate.There is a main artery at the lateral and medial edge of the lid, and in the upper lid these two arteries are joined together by two arterial arcades which run transversely across between the muscles and the tarsal plate. One is about 3 mm above the eyelid margin and the other just above the upper edge of the tarsal plate. In the lower lid there is one arterial arcade about 3 mm from the eyelid margin. The veins from the eyelid pass both into the facial veins which drain into the external jugular vein and the ophthalmic veins which drain into the cavernous sinus.
It is easy to anaesthetise the eyelids with local anaesthetic. Adrenaline 1:100,000 should always be added to the local anaesthetic because the lids are so vascular. For superficial surgery to the eyelids the local anaesthetic can be injected just
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under the skin. For surgery to the deeper parts of the eyelids topical anaesthetic drops to the conjunctiva should also be given. If there is still some pain the anaesthesia can be increased with an injection through the conjunctiva into the conjunctival fornix. This is easily done in the lower lid. However the upper lid should be everted in order to give this injection.
Post operatively the good blood supply to the eyelids ensures good healing. There is usually some post operative haemorrhage into the tissues because the lids are so vascular and the connective tissues in the lids are so loose. Therefore good haemostasis is important particularly if the arterial arcades have been cut. To minimise post operative haemorrhage and tissue swelling some surgeons like to apply a firm pad and bandage for 24 hours after eyelid surgery. It should not be necessary to keep the eye padded any longer except in special cases (e.g. a skin graft). Always make sure that the pad is not rubbing against the cornea.
Surgical Pathology of the Eyelids
It is important to have a clear understanding of the different words used to describe abnormalities of the eyelids.
Entropion
This means that the eyelid turns inwards so that the eyelid margin and eyelashes rub against the cornea. There are two common causes:
1.Contracture of the tarsal conjunctiva and distortion of the tarsal plate causing the eyelid to turn inwards (fig. 7.6). This is often called “cicatricial” entropion (a cicatrix is an old fashioned word for a scar). It is much more common in the upper lid than the lower. By far the most common cause in tropical countries is long-standing trachoma.Trachoma is an infection of the conjunctiva caused by
Fig. 7.6 Cicatricial entropion.The normal eyelid is shown on the left. Chronic inflammation, scarring and contracture in the tarsal plate and the conjunctiva deforms the eyelid
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Fig. 7.7 Senile or “spastic” entropion. The normal eyelid is shown on the left. As the orbicularis muscle contracts during eyelid closure the tarsal plate buckles inwards
the organism Chlamydia trachomatis. There is a chronic inflammatory reaction in the tarsal conjunctiva and sub-conjunctival tissues.This inflammation leads on to scarring, particularly in the upper tarsal plate and conjunctiva. As the scar tissue contracts it distorts the tarsal plate and causes it to buckle inwards. The tarsal plate often becomes thickened as well and the Meibomian glands may be destroyed or blocked.
2.Laxity of the connective tissue and the tarsal plate of the lower lid in old age (fig. 7.7). Because the tissues are lax and the tarsal plate has lost its rigidity, when the Orbicularis Oculi muscle contracts to close the eyelids, the muscle fibres roll upwards and so the eyelid turns in.This is usually called “spastic” or “senile” entropion and only occurs in the lower lid.
Trichiasis
The normal eyelashes point forwards. Trichiasis means that some of the eyelashes are pointing backwards and so rub against the cornea. Obviously every patient with entropion will also have trichiasis. However there may be some misdirected lashes turning inwards without the whole eyelid turning in (i.e. trichiasis without entropion).
Trichiasis like entropion is usually a result of previous trachoma. Scar tissue from the chronic infection causes contracture around the eyelash roots and distorts them so the lashes point inwards.
Ectropion
This means that the eyelid is turned outwards (everted) so that the eyelid margin does not rest against the eyeball (fig. 7.8). In severe cases the eyelid will be so everted that the conjunctiva lining the inside of the lids will be exposed and face outwards. There are four causes of ectropion:
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Normal lower lid |
Cicatricial ectropion |
Paralytic ectropion |
Mechanical ectropion |
Fig. 7.8 The causes of ectropion |
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1. Cicatricial ectropion. A cicatrix is an old fashioned name for a scar. A contracture or loss of eyelid skin will cause the lid to turn outwards and is often called a “cicatricial” ectropion. It is fairly common in the lower lid because the lower lid has little or no excess skin. The lower lid does not cover the cornea, and therefore lower lid ectropion will only cause discomfort, irritation and discharge but rarely causes any damage to the cornea or loss of sight.
Cicatricial ectropion is rare in the upper lid because the upper lid has so much spare skin. If however it does occur, the cornea is unprotected and exposed, and there is a great risk of corneal ulceration and permanent damage to the sight.
There are several possible causes of eyelid skin contracture leading on to an ectropion. The commonest are:
•Burns–thermal or chemical causing destruction of the skin and subsequent scarring.
•Trauma from injury or surgery.
•Chronic skin infection or fistulas from infected nasal sinuses.
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2.Paralytic ectropion. Paralysis of the Orbicularis Oculi muscle which closes the eye will make the lower lid sag and fall away from the eyeball. This is called a “paralytic” ectropion and is caused by a paralysis of the Facial nerve.
3.Senile ectropion. This results from stretching of the lower eyelid tissues in old age.
4.Mechanical ectropion. This is caused by a tumour or thickening of the lower eyelid which by its weight pulls the eyelid away from the eyeball.
Once ectropion from any of these causes has occurred, the exposed conjunctiva becomes chronically inflamed, thickened and hypertrophic, and in this way makes the ectropion worse.
Lagophthalmos
This is the traditional word used when the eyelids will not close due to paralysis of the Orbicularis Oculi muscle.The word literally means “eye of a hare” because the ancients thought that hares went to sleep with their eyes open. The Orbicularis Oculi muscle is supplied by the Facial nerve and so a better name for lagophthalmos is Facial Palsy. In a mild case the eye will look normal, but when the patient tries to blink or close the eyes the weakness will become apparent. In severe cases the whole side of the face will be affected and droop from loss of function of the facial muscles. The lower lid will sag so it does not rest against the eye (paralytic ectropion). In this way facial palsy and ectropion often occur together. If the eyelids will not close properly there is a risk that the cornea will become ulcerated. This usually occurs when the patient is asleep and the eyelids are not closed. Corneal damage is particularly common in facial palsy from leprosy because the sensation of the cornea is also affected. In this way both the motor and sensory parts of the protective reflex for the cornea are absent. Most other causes of facial palsy do not also affect corneal sensation.
Ptosis
Ptosis means a drooping of the upper eyelid and it can have many causes.The most common are:
•A congenital abnormality of the levator muscle which elevates the upper lid.
•A paralysis of the third cranial nerve supplying the levator muscle, this usually causes a severe ptosis.
•A paralysis of the cervical sympathetic nerve supplying Muller’s muscle, which will cause a slight ptosis.
•Senile stretching of the insertion of the levator muscle into the upper lid.
•Myopathy or myaesthenia affecting the levator muscle.
•Trauma to the upper lid.