COMPLETE HOW TO TREAT QUIZZES ONLINE ( to earn CPD or PDP points.

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1 HowtoTreat PULL-OUT SECTION COMPLETE HOW TO TREAT QUIZZES ONLINE ( to earn CPD or PDP points. inside Childhood Assessing the child with possible Treatment of children Assessing adults with squint Treatment of adult The authors DR SHANEL SHARMA consultant ophthalmologist, Eye and Laser Surgeons, Wollongong and Sydney, and South Eastern Eye Care, Miranda; senior lecturer, University of Wollongong; conjoint lecturer, University of NSW and University of Sydney, NSW. DR GILL ADAMS director, and neuro-ophthalmology, Consultant Ophthalmologist Paediatric Service, Moorfields Hospital, London, UK. Background STRABISMUS is the term used to describe eyes that are not simultaneously fixing on a target of interest. It is commonly referred to as crosseyed, squint or a lazy eye and it affects 2.5-4% of the population. may present in childhood or adulthood. If undetected and untreated in childhood, it can result in amblyopia, which is the reduced visual acuity in one or both eyes caused by disruption of normal visual development. In both children and adults, the development of may indicate serious underlying pathology. When faced with the patient presenting with squint, the family physician needs to decide whether they require routine referral, urgent referral or possibly do not need referral at all. This article updates the GP on assessment, management and appropriate referral of children and adults with. Visual development and amblyopia At birth the visual system is immature and it develops by forming neural connections and pathways over the first 7-8 years of life. This period of visual development is called the critical period and, once it is completed, the pathways essentially cannot be altered. Before the critical period starts there is a sixweek latent period during which the baby s visual system is not damaged by stimulus deprivation. Colour vision and depth perception also develop during the critical period, but because of the latent period, early detection and treatment offers the chance of restoring vision. If the visual cortex does not receive clearly focused, aligned images from each eye, the child will not develop high-quality vision with depth perception. This is the reason that early treatment of squint and significant refractive errors is required to ensure good visual development. Factors needed for ocular alignment For alignment of the eyes to occur and be maintained, there needs to be simultaneous visual perception of an object by both eyes, with the images transmitted to the visual cortex, where they are fused together. Finally due to the slight disparity of the images reaching the brain, depth perception (stereopsis) can be appreciated. Fusion of the images is important and involves both sensory aspects of image integration and motor control to keep the eyes physically aligned. If a patient does not have fusion, or stereopsis, and they undergo corrective squint surgery, the chance of their maintaining a good ocular position long term is reduced. For this reason there has been a shift in the management of with the goal of regaining ocular alignment in children more promptly after they develop a squint, while they still have the potential to achieve stereopsis. The shorter time a child has a squint, the more likely they are to maintain long-term alignment after surgical correction. cont d next page 4 November 2011 Australian Doctor 29

2 from previous page Amblyopia Disruption of normal visual neurodevelopment during the critical period results in reduced vision in one or both eyes, called amblyopia. There are several causes of amblyopia. Refractive errors. Amblyopia most commonly occurs because the child has an undiagnosed refractive error, which impairs the focusing of images on the retina and hence reduces the quality of the visual stimulus to the neural pathways. The greater the refractive error, the more amblyogenic it is to the child. Refractive amblyopia usually develops in one eye, when there is a significant difference in the refractive error between the two eyes; this is termed anisometropic amblyopia. If vision is reduced in both eyes due to uncorrected high focusing errors, it is termed ametropic amblyopia.. is the second most common cause of amblyopia. When a child has a squint, the visual information from the squinting eye is cortically suppressed to avoid confusion and diplopia. If the squint alternates between the two eyes, both eyes are providing sensory stimulation to the brain and amblyopia does not develop, but the brain will still suppress a second image when both eyes are open. In the older child and adults who develop misaligned eyes, the typical complaint is the development of diplopia. Visual obstruction. Amblyopia can also occur with visual deprivation caused by conditions that obstruct the visual axis, which prevents a clear visual image reaching the retina. These include ptosis, corneal pathology, congenital cataract and retinoblastoma. Amblyopia from stimulus deprivation often results in a secondary squint. In the case of congenital cataract, unilateral cases are very amblyogenic and urgent treatment is crucial, emphasising the importance of being sure that the infant has a good red reflex at the time of the newborn screening. Surgery and visual rehabilitation during the latent period of visual development before the onset of the critical period gives the child the potential for developing good sight. Importance of early treatment Early treatment in childhood of refractive errors, and visual obstruction, and the resultant amblyopia, allows for the development of good vision. If these conditions remain undetected and untreated, they can lead to permanent uncorrectable visual loss. Good vision during a child s early years is vital as about 80% of learning is acquired through sight. If good vision is not developed in childhood, it cannot be acquired as an adult. Poor vision, even if unilateral, can have significant and long-term consequences for future employment and quality of life. In addition, there is an increased risk of further visual handicap if there is damage or disease to the good eye. It has been shown that the risk of losing the healthy eye is two per thousand in children with monocular amblyopia, of which more than 50% is due to trauma. 1 This is about 20 times the blindness rate of children without amblyopia of 0.11 per thousand. This risk increases if one considers the whole length of the child s life. In the UK about 185 people with monocular amblyopia (with acuity less than 6/12) have vision loss in their non-amblyopic eye annually; 75% of these patients are left visually impaired or blind. More than half of those in paid employment are unable to continue due to the visual loss, with significant impact on their quality of life. They also have an increased risk of death or morbidity including hip fractures after fall and tend to suffer from social isolation as a consequence of their visual loss. 2 Childhood Risk factors for developing a squint in a child Family history Premature birth and low birthweight Drugs taken during pregnancy eg, sodium valproate Refractive error Intraocular pathology, eg, cataract, retinoblastoma Neurological disease, eg, cerebral palsy Craniofacial disease Risk factors THE key risk factors predisposing a child to are listed in the box, right. Obstruction of the ocular media can cause a secondary squint. Particular vigilance is also required for children with developmental delay or cerebral palsy. A child with cerebral palsy has a 50% chance of developing a squint, and a child with a syndrome has about a one in three chance of developing. Premature birth is a significant risk factor for developing ophthalmic problems. A child born prematurely is five times more likely to develop by age 10 compared with children born at term. 3 Similarly, significant refractive errors have been documented to be about four times higher in children born prematurely than in full-term infants. 4 Many children have intermittent neonatal ocular misalignments, usually convergent, which disappear by 15 weeks of age. Infantile esotropia is a large-angle convergent squint developing within the first six months of life in a normal child. Children with underlying neurological problems may also present with an early-onset squint. The presence of a large-angle divergent squint in the young child is uncommon, and the possibility of neurological or ophthalmic disease should be considered. Some children are suspected of having a squint when in fact their eyes are straight. In most children these pseudo-squints are due to epicanthic folds of skin at the inner canthi, which give the appearance of convergent deviation. However, 5% of children thought to have a pseudo-squint at the first attendance will progress and be found to have a squint by age four. It is therefore recommended that children be followed until good linear acuity can be obtained in each eye with no evidence of squint. Assessing the child with possible CHILDREN can be difficult to assess, particularly very young infants, and more than one assessment may be required. The family physician should try to ascertain the child s vision, ocular alignment, ocular movements and presence of a red reflex when assessing a child with possible. Figure 1: The top image demonstrates an exotropia, with the light reflex centrally located in the left eye and visible over the nasal iris on the right. In the central image the patient is orthotropic, as the light reflex is noticeable in the same position in both eyes. In the lower image the patient is esotropic. Figure 2: How to perform a cover uncover test. As the right eye (fixing eye) is covered, the left eye takes up fixation on the target and an inwards movement is noted as the exotropic eye takes up fixation. The flash reflex in the pupil of the left eye is initially nasal and after the cover is applied, it moves centrally. Testing vision When testing vision in a child an ageappropriate test should be used. At birth, visual acuity is normally 1-2/60. It improves significantly up to age two years when acuity of 6/6-6/9 would be expected. It is often helpful to start testing the vision with both eyes open, which will give you the vision in the better eye, and this is often easier for the child as an initial test. Then check the eye you suspect has the worst vision before moving on to what you believe is the better eye. If the child resists the covering of one eye, this suggests you are occluding the better-seeing eye and the other eye is amblyopic. When checking vision uniocularly, make sure the other eye is well covered, for example, with an occlusive patch. In a baby, assess if they can fix and follow a toy or light. See if they smile back when you smile at them. Another helpful test for assessing vision in infants and very young children without the use of specialist testing is to use a mirror, as children like looking at their own reflection in mirrors. The child is held about 20cm from a mirror until they look at their own reflection, and then is moved slowly backwards until they lose fixation. This can be used as a measure of acuity; the further the distance from the mirror before fixation is lost, the better the infant s vision. In non-verbal children, preferential looking tests are used, knowing that a child prefers to look at a picture rather than a blank background. Cardiff cards are an example of this type of test. It uses pictures that will interest a child (house, car, duck, etc) located either at the top or at the bottom of an otherwise plain card. There are 11 visual acuity levels, with three cards at each level. In the verbal child, crowded tests are preferable because, particularly in amblyopia, children can perform better with single letter tests than with a line of text (the so-called crowding effect). By presenting a single image to the child it is easier to ensure they are looking and describing the letter or picture being presented. However, to simulate the effect of having more than one letter on a page, the letter is surrounded by a black blocking bar. This gives a more accurate assessment of vision. The older child can be checked with letter tests or using an adult logmar or Snellen chart. Alignment The alignment of the eyes can be assessed using light reflexes or with cover tests. Use a torch to shine a light on both eyes; if they are aligned, the corneal reflexes sit in the same position in both eyes. If the child is esotropic (has a convergent squint), the light reflex will be more temporal in one pupil compared with the other side. An exotropic child (has a divergent squint) will have one light reflex more nasal compared with the other (figure 1). The cover uncover test will identify a manifest squint. The alternate cover test will identify latent squint. Cover uncover test This is the test used to assess for the presence of a manifest squint. The terminology used to describe a squint indicates the position of deviation: eso- for inward deviation, and exo- for outward. The term -tropia indicates that the squint is manifest (not latent). Thus an inwards-turning squint is termed an esotropia, and an out-turned eye an exotropia. To perform a cover uncover test in an infant, use a light or a bright toy. In the older child, use a detailed fixation target to perform the test. Start by covering the suspected squinting eye and observe the other eye for any movement. If there is no squint and the patient is using central fixation, the eye will remain still when the cover uncover test is performed on each eye in turn. No movement means the eyes are straight, unless the eye being tested has extremely poor vision and cannot take up fixation. An outward movement of the uncovered eye to take up fixation indicates a manifest esotropia, and an inward movement indicates an exotropia or divergent squint (figure 2). A downward movement indicates a hypertropia and an upward movement indicates a hypotropia of the uncovered eye. 30 Australian Doctor 4 November

3 Alternate cover test This test dissociates the eyes by occluding vision in one eye at a time. It is used to identify a phoria, or latent squint, which is seen when the fusion of the two images is disrupted. This is achieved by rapidly moving the occluder from one eye to the other. The eye under the occluder drifts out of alignment but is seen to recover when dissociation stops (figure 3). Figure 3: An alternating cover test. Figure 4: A: A normal red reflex. B: An abnormal left red reflex. A Ocular movements Check eye movements by getting the child to follow either a torchlight or a moving toy, keeping the head still. Doll s head rotations can be used to rapidly rotate the head to one side, initiating deviation laterally to the opposite side. In particular, check that abduction is full. The presence of nystagmus or wobbly eyes is abnormal and requires early referral for ophthalmological evaluation. Red reflex test This is best done by turning the room lights down and using an ophthalmoscope at a distance of about 45cm from the child. The ophthalmoscope dial is set at zero if the examiner has no refractive error or is wearing glasses, or the dial can be set to correct for the examiner s refractive error if the examiner is testing without wearing glasses. The pupil red reflex will be redder in Caucasian infants and slightly paler in dark infants (figure 4). If there is uncertainty about the red reflex, dilate the pupils with tropicamide or cyclopentolate (a cycloplegic that both impedes accommodation and dilates the pupil) 0.5% and re-examine. The red reflex should be clear. If there is any disruption to this clarity or if any smudging is still present after cleaning the ophthalmoloscope viewing lens, this suggests the child has a significant obstruction in their visual axis such as a cloudy cornea, congenital cataract or retinal problem. In particular, beware the white pupil, which might suggest the diagnosis of retinoblastoma. The child with an absent or white red reflex should be referred to an ophthalmologist to be seen within a couple of days. Even a short period of unilateral asymmetric retinal stimulation will result in dense amblyopia, as can be seen in children with unilateral dense congenital central cataract of over 2mm, who will have permanent deprivation amblyopia if they are not treated within the first two months of life. If there are any doubts as to the findings, these children should be referred for urgent assessment. Further tests When an older child is seen by a paediatric ophthalmologist, as well as vision testing and assessment B for squint, the child can be tested for the presence of stereopsis. The child s pupils will then be dilated to assess for the presence of refractive error, to check the media and to allow fundoscopy to be performed to exclude any underlying retinal pathology such as retinoblastoma, macular scarring or optic nerve hypoplasia. As children are unable to concentrate for a prolonged period of time and fix on a distant target and cannot reliably indicate which lens gives clearer vision, retinoscopy is performed as it is an objective means of measuring the refractive error. Topical cyclopentolate is instilled to enable retinoscopy to be performed. In most cases cyclopentolate takes about minutes to have its effect. In some children, retinoscopy is performed after instillation of atropine (an anticholinergic that is a strong cycloplegic) nightly for 2-3 nights before assessment. Parents often find it easiest to instill the drops after the child is asleep. As atropine has a long half-life, it can take up to a week for the dilation to wear off completely. During this period the child should wear sunglasses and a hat outdoors, as their pupil is unable to constrict when they go into bright light. Treatment of in children THE aims of managing any child with squint are to achieve the best vision in each eye, to optimally align the eyes, to correct any abnormal head posture which is adopted to alleviate double vision and, if possible, to obtain binocular function. Treatment usually includes that for any amblyopia and for correction of malalignment. It may involve glasses, occlusion therapy, and sometimes surgery. Treatment may have to be continued until the age of visual maturity (6-7 years). Amblyopia treatment The aim of amblyopia treatment in a child is to obtain equal and good vision in both eyes. This may be achieved with glasses, occlusion therapy or a combination of both. Glasses When glasses are prescribed in children, they are given to ensure accurate focusing of visual images on the retina and to allow clear focused images to be transmitted along the neural pathways to the visual cortex. The lenses must be large enough to ensure that the child looks through and not above them. Glasses should be worn all the time except for during sport or activities where they may get damaged. Prescription goggles can be obtained for swimming. Occlusion Glasses alone are often insufficient to improve the acuity maximally and occlusion may also be required. Occlusion may be in the form of patching or atropine drops. Patching involves applying an adhesive patch over the good eye then placing the glasses on top to force the weaker (amblyopic/more amblyopic) eye to do more visual work. The patching regimen depends on the child s vision and is prescribed and monitored closely, usually starting with three hours each day, with at least one hour of near work, which can include reading, doing jigsaws or (often more acceptable to the child) handheld computer games. Compliance with patching is often difficult to achieve, particularly when the sight in the amblyopic eye is very poor and the child is frightened or distressed by covering up their betterseeing eye. In these cases, using atropine penalisation is often helpful. This involves the use of atropine 1% drops instilled into the better eye on two evenings a week. The atropine drops are long-lasting and produce dilation with visual blurring in the good eye, encouraging the weaker eye do more visual work. The side effects include light sensitivity, allergic reactions and possible tachycardia and facial flushing if too much atropine is instilled, resulting in significant systemic absorption. The vision should be monitored regularly to ensure that acuity is improving. Once the maximum vision is achieved, the patching or atropine is tapered off slowly to prevent visual regression. The child must continue to be monitored, as vision can deteriorate for up to one year after treatment has ended. Most children will complete their amblyopia management by age six. Treatment of the older child with occlusion or atropine can result in loss of the suppression of the amblyopia, with resultant double vision. This is not appropriate in most cases unless specialist tests confirm that there is a low risk of inducing diplopia. Achieving alignment After maximising the vision using glasses and/or occlusion, the next step is to align the eyes. In most cases this will improve the aesthetic appearance, but in some children accurate alignment may also achieve binocularity, or reduce a compensatory head posture that has been adopted to reduce double vision. The presence of a squint can have a significant impact on a child s psychosocial development. A recent study explored the perception of children aged 5-6 years towards pictures of peers who were ocularly aligned compared with those who were digitally modified to have a noticeable exotropia. 5 The children were asked to choose the child they preferred and with whom they would share their favourite toy. A similar study has been done asking children which child they would invite to a birthday party one with, or one without, a squint. The children were found to have a negative social reaction towards their peers with a noticeable squint, demonstrating that children with noticeable may be subjected to social alienation and social biases that can lead to negative psychosocial development, particularly when experienced at a young age. 5 Children are now operated on earlier, as this gives the best potential for the development of three-dimensional vision and long-term ocular alignment. Two methods can be used to align the eyes either surgery or botulinum toxin A injection(s), or a combination of both. Surgery In children surgery is the most common treatment of choice. Squint surgery is performed under general anaesthesia and the muscle being operated on is detached from the globe and reattached at a new position, through a conjunctival incision, either tightening or weakening the action of the muscle. Surgical risks include: Under- or over-correction of the deviation. The patient requiring further squint correction during their life. A red eye. Slipped muscle. Discomfort. Wound infection. Suture complications. Vision-threatening problems such as endophthalmitis and scleral perforation are rare but can lead to profound visual loss. Patients need to understand that surgery aims to improve alignment but does not treat amblyopia, and thus the child usually needs to continue wearing their glasses and patching as treatment for amblyopia. The risk of amblyopia has been shown to spike postoperatively. If this is not emphasised as sometimes happens, parents may believe that as the alignment has improved, their child has been fixed and hence they think follow-up is optional. As a general rule, no more than two of the recti muscles are operated on simultaneously in the same eye, as this is associated with a risk of anterior-segment ischaemia, a visionthreatening complication. However the oblique muscles may safely be operated on in addition to the recti. Botulinum toxin Botulinum toxin (BTX) type A is produced by Clostridium botulinum. If injected into an extraocular muscle it produces temporary muscle weakness. It works by irreversibly blocking the acetylcholine receptors on the muscle end of the neuromuscular junction. Acetylcholine released from the nerve is unable to bind with the acetylcholine receptors, as they are bound to the toxin. The muscle generates new acetylcholine receptors and the muscle action is restored. cont d next page 4 November 2011 Australian Doctor 31

4 from previous page This usually takes about three months to occur in the recti muscles. In young children, BTX is injected under general anaesthetic. It has been used to treat infantile esotropia, in the hope that early realignment would allow the brain to maintain long-term alignment. Variable success has been reported. Referral of children with Timely referral for may significantly alter visual outcomes. The box, right, summarises when to refer. When to refer children with Accurate ophthalmic examination in infants and children is not easy, even for ophthalmologists. If the GP has any doubt about visual normality in a child, the child should be referred to an ophthalmologist, or if possible, to a paediatric ophthalmologist. If the young child has a neonatal malalignment or pseudo-squint, they can be observed. However, some children with pseudo-squints may develop squint, so they should be observed until good uniocular acuity can be obtained, with evidence of straight eyes and stereopsis. Refer any child in whom there is still a squint at 15 weeks of age, and if the squint is noticeable, then refer earlier. Refer a young child with a divergent squint. A child with a sudden-onset squint, particularly if there is restricted eye movement, or a child with a dull or absent red reflex should be referred urgently. Children with but with full ocular movements and a normal red reflex should be referred for a full paediatric ophthalmological examination, including cycloplegic refraction and fundoscopy. Refer promptly any child with restricted eye movements. Refer urgently any child complaining of double vision. Assessing an adult presenting with squint History ADULTS with usually present complaining of diplopia or of the effect of the ocular misalignment on their appearance. The history helps guide the clinician to the underlying cause of the, in conjunction with the clinical findings. Childhood squints often recur in adulthood. These patients may have previously undergone surgery, or have decompensated a squint that they were previously able to control. Most of these patients who have a recurrence of previous do not have double vision. However, new-onset squint in an adult produces double vision, which may be constant or intermittent or only in some positions of gaze. New-onset adult may be caused by systemic conditions or problems isolated to the ocular muscles and orbit. Neurological conditions include: Neurogenic palsies caused by microvascular disease such as diabetes and hypertension. Demyelinating disease, including multiple sclerosis. Space-occupying lesions, with raised intracranial pressure and cranial nerve palsies (figure 5). Mechanical problems that interfere with normal extraocular muscular contraction and relaxation or that hinder global movement can give rise to diplopia. These can occur with thyroid eye disease and orbital lesions. Diseases that may weaken ocular muscle include myasthenia gravis or chronic progressive external ophthalmoplegia. With systemic conditions it is important to remember that the eye disease may occur without obvious systemic involvement and even with normal blood tests; this is especially true of myasthenia gravis and thyroid eye disease. If the patient is over 55, consider the possibility of giant cell arteritis (temporal arteritis), as this can be a blinding or occasionally fatal condition, and can present with a cranial nerve palsy. Ask if there is any associated pain, headache or other systemic symptoms such as weight loss or jaw claudication, possibly indicating giant cell arteritis. The clinical history should enquire about any prior childhood treatment for lazy eye or squint. The patient should be questioned about general health, in particular vascular risk factors such as blood pressure and diabetes. Microvascular cranial nerve palsies caused by Figure 5: MRI of a woman presenting with a new-onset, progressing fourth nerve palsy. The top panel is the sagittal section of MRI T2 weighted image. The lower panel is an axial section, both demonstrating an exophytic tumour of the dorsal midbrain. diabetes or hypertension would be expected to resolve within three months. Examination Check the vision. If it is reduced in one eye and does not improve with a pinhole test to exclude a refractive error, this may indicate that the patient has amblyopia due to a longstanding squint or that the patient has an optic neuropathy. Perform a cover test to identify the type of squint. Examine the ocular movements, in particular looking for restricted movements suggestive of a cranial nerve palsy. Asking the patient if the double vision is worse in particular positions of gaze is often helpful. Check the pupils, specifically looking for a fixed dilated pupil, which might suggest a compressive lesion of the third nerve caused by a posterior communicating artery aneurysm. Examine the discs, as discs swelling with a sixth nerve palsy can be a presenting sign of raised intracranial pressure. The presence of ptosis could suggest a third nerve palsy or, if fatigable, myasthenia gravis. When to refer adults with Immediate referral Patients with a fixed, dilated pupil indicating a third nerve palsy Patients with suspected giant cell arteritis Patients with disc swelling in association with a sixth nerve palsy Refer as soon as possible (within days) Patients with other cranial nerve palsies, including an isolated sixth nerve palsy or multiple cranial nerve palsies, should be considered for neurological and ophthalmological assessment within days particularly if intracranial pathology is suspected. Patients who have diplopia, which does not appear to be due to a cranial nerve problem, should be referred for assessment of possible systemic disease such as myasthenia gravis and thyroid eye disease. Non-urgent routine referral Adults who present with a worsening of known childhood squint without double vision can be referred routinely for specialist assessment. Adults who are not aligned but are unsuitable for surgery should be referred routinely for possible toxin injection if they are concerned by their appearance. New-onset adult may be caused by systemic conditions or problems isolated to the ocular muscles and orbit. Proptosis, either unilateral or bilateral, can be seen with thyroid eye disease, which can occur with or without a background of systemic thyroid disease. Other causes of unilateral proptosis include orbital lesions. Investigations If giant cell arteritis is suspected, the patient should have immediate blood tests looking for a raised ESR or CRP, and FBC looking for a thrombocytosis. These tests may be normal in a patient with giant cell arteritis, as this is a clinical diagnosis; if in doubt the patient should be referred for urgent assessment. Neuroimaging of the brain and orbit may be required. This will be needed urgently in patients with disc swelling and also in younger patients with no history of systemic disease. Investigations for systemic disease include thyroid function tests and thyroid antibodies, and for myasthenia gravis, tests for acetylcholine receptor antibody and muscle-specific kinase antibody. Tensilon testing (the use of edrophonium chloride, an anticholinesterase, to temporarily reverse the ptosis or diplopia of myasthenia gravis) is rarely used in testing for myasthenia but an icepack test is often useful, with ptosis or double vision improving after application of ice. When to refer Referral within an appropriate time frame can have important clinical implications. The box above summarises the indications for referral. cont d page Australian Doctor 4 November

5 Treatment of adult ONCE the underlying pathology has been determined and appropriate therapy instituted, further treatment for any persistent diplopia may be considered, using occlusion, botulinum toxin intramuscular injections, or surgical correction. Occlusion If it is thought that the double vision will resolve, for example, in diabetic sixth nerve palsy, the patient will be treated symptomatically. This is achieved either with a Fresnel stick-on prism on one spectacle lens, or occlusive tape if a prism does not achieve single vision. Longer-term options include prisms incorporated into spectacles if a temporary prism was found to be helpful but gave blurred vision. Authors case study A GIRL initially presented aged two-and-a-half with a childhood esotropia. She underwent her first squint operation aged four, on her right eye. Her eyes remained straight for some years before becoming divergent and requiring further squint surgery at age 15. She had a very large angle of deviation and despite two squint operations had a residual small angle exotropia. She therefore underwent a third operation later that same year. Her vision was 6/9 in the right eye 6/5 in the left. By age 17 her eyes had begun to diverge again. As she had already undergone three operations and had had surgery on all four horizontal muscles (with a redo operation on two of the muscles) she was offered BTX injections into her right lateral rectus muscle under electromyographical guidance. She has now had a BTX injection into this muscle 32 times over the past 17 years (figure 7). Figure 6: Ocular alignment of this patient before surgery and after adjustment. Botulinum toxin BTX is a temporary treatment that lasts on average three months and can be used to treat small to large angle squints. The toxin is injected into the ocular muscle under local anaesthetic with electromyographic guidance. It takes 2-3 days before any effect is noticed and about two weeks to reach full effect. The complications are usually temporary and can include underor over-correction of the, diplopia, ptosis, haematoma or infection. An extremely rare complication is ocular perforation with damage to the sight. In patients who have lost control of a previously well-compensated deviation, toxin treatment may only be required on one occasion, to enable the patient to regain satisfactory alignment without the need for formal squint surgery. BTX has a major use in assessing patients whose orthoptic tests have suggested that they have a risk of developing double vision if their eyes are straightened by operation. This risk is present because the visual cortex has adapted to having deviated eyes and realigning them overcomes cortical suppression and produces double vision. For other patients, toxin injections may be given repeatedly as a way of maintaining ocular alignment. This is often the best treatment option in a patient who is unfit or unable to undergo an operation, for example a patient with a sixth nerve palsy secondary to a brain tumour where the squint would recur after surgery. It is also a good option when the patient has poor vision or a blind eye on one side, as these patients do not have any visual drive to maintain long-term ocular alignment after surgery, and their squint tends to recur. BTX is also useful in patients who have a squint despite having undergone several previous operations. Surgery With the accuracy and precision that has been achieved in cataract and refractive surgery, patients often believe that the aim of surgery is to gain precise alignment. However, this is unachievable, as the position of the eyes is not purely related to the length of the muscles or the position of their insertions. The aim of surgery or BTX treatment is to reduce the angle of deviation. In patients who have stereopsis or fusion, by reducing the angle of deviation between the eyes and getting them into their fusional range, alignment may be achieved by the neural feedback loop to the brain, which normally controls the position and alignment of the eyes. In patients without fusion potential, reducing the angle of deviation makes the less obvious. Squint surgery is a good treatment option for many patients, particularly those with no or limited previous surgery (figure 6). In adults, an adjustable suture technique is often used, in which most of the surgery is performed with the patient under general anaesthetic, and the final muscle position is fine-tuned and tied off after the patient has been woken up. The patient is usually advised to take two weeks off work after the operation, with most of the scarring no longer visible by about Figure 7: The upper image demonstrates the exotropia in this patient. She underwent botulinum toxin injection into the right lateral rectus muscle. The bottom image demonstrates her eye position two weeks after injection. Comment Squint operations on average last 10 years, as was the case for the original surgery here. Squints in children tend to be esotropic, while those in adulthood tend to become three months. If required, further surgery can be considered at this time. Patients who have had repeated previous surgery have an increased risk of chronic redness postoperatively. There is increased associated scarring of the conjunctiva with each operation and for this reason in some patients BTX treatment is a better option. Both BTX and surgery have an important role to play in the treatment of patients with. Psychosocial impact Treatment of in adults who do not experience diplopia or who do not have binocular potential has sometimes been regarded as cosmetic. However, many adults with have stated that it has had a negative impact on their lives, including a negative effect on their interpersonal relationships and limiting employment opportunities. A number of publications have confirmed that the presence of an eye turn has a negative impact on the way that person is perceived with respect to their physical appearance, personality and perceived capability. It has a negative impact on the overall judgement of a potential employer, reducing the strabismic applicant s ability to obtain employment and therefore having an impact on their economic status It also has an impact on their personal lives, with potential partners perceiving a person with as significantly less attractive, erotic, likeable, interesting, successful, intelligent and sporty. 11 A physician therefore should not underestimate the psychosocial impact of such social biases, which can lead to social isolation and alienation. The benefit of treatment should also not be underestimated, as improvement of the patient s ocular alignment appears to herald major improvements in the quality of psychosocial functioning for most adults. exotropic. The main problem is that the patient is unable to hold the alignment of their eyes. This woman wrote a letter to express her feelings about the BTX treatment. Having the toxin treatment has allowed me to look at the world in the eye with confidence. Prior to my treatment, my squint was still bad enough that when I looked at someone, they sometimes thought I was looking at someone behind them which was pretty cringey! So much of professional life is down to whether your face fits, and I don t think I d have landed the jobs that I ve had over the years if my eyes had looked odd. I m happily married with a family and I have an interesting job at a major international law firm. I m not sure I would have such blessings in my life without the treatment, particularly because I wouldn t have been as confident to pursue opportunities that have come my way. References 1. Tommila V, Tarkkanen A. Incidence of loss of vision in the healthy eye in amblyopia. British Journal of Ophthalmology 1981; 65: Rahi J et al. Risk, causes, and outcomes of visual impairment after loss of vision in the nonamblyopic eye: a populationbased study. Lancet 2002; 360: Holmstrom G, et al. Prevalence and development of in 10-year-old premature children: a population-based study. Journal of Pediatric Ophthalmology and 2006; 43: Larsson EK, et al. A populationbased study of the refractive outcome in 10-year-old preterm and full-term children. Archives of Ophthalmology 2003; 121: Lukman H, et al. related prejudice in 5-6-year-old children. British Journal of Ophthalmology 2010; 94: Burke JP, et al. Psychosocial implications of surgery in adults. Journal of Pediatric Ophthalmology and 1997; 34: Coats DK, et al. Impact of large angle horizontal on ability to obtain employment. Ophthalmology 2000; 107: Olitsky SE, et al. The negative psychosocial impact of in adults. Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and /American Association for Pediatric Ophthalmology and 1999; 3: Mojon-Azzi SM, Mojon DS. and employment: the opinion of headhunters. Acta Ophthalmologica 2009; 87: Mojon-Azzi SM, Mojon DS. Opinion of headhunters about the ability of strabismic subjects to obtain employment. Ophthalmologica 2007; 221: Mojon-Azzi SM, et al. Opinions of dating agents about strabismic subjects ability to find a partner. British Journal of Ophthalmology 2008; 92: Online resources American Association for Pediatric Ophthalmology and : cont d page Australian Doctor 4 November

6 GP s contribution DR JON FOGARTY Point Clare, NSW Case study AT the time of Katie s sixth-month vaccination, Dr L wonders if she has an intermittent squint. Katie s mother feels that Katie s eyes are normal. She admits that some friends have suggested that Katie has a lazy eye. Dr L is unsure if she can confirm a squint. She is able to elicit a definite red reflex from the right eye but Katie is distressed during the examination and a left red reflex is not confirmed. Her mother declines referral to an ophthalmologist. She says that her oldest son had a squint but he grew out of it. At 18 months Katie re-presents, this time with her grandmother, who says that Katie s left eye turns when she is tired. The GP is concerned that Katie has a left convergent squint. Katie is referred to a local ophthalmologist, who recommends surgery to correct the squint. Katie s mother declines this therapy but agrees to a trial of eye patching. Two months later, Katie is again seen and her mother says that she would not tolerate patching and became distressed when the patch was applied to Katie. Katie s mother reluctantly agrees to further specialist review. Questions for the author Can you give some tips on how to determine whether a squint is caused by wide epicanthic folds, or genuine? Use a torch to shine a light on both eyes; if they are aligned and it is a pseudo squint, the corneal reflexes sit in the same position in both eyes. However continue to monitor the child, as 5% of children who are initially diagnosed as having a pseudo squint have a squint detected within a couple of years. When is the ideal time to repair squint in children? This depends on the child s vision, squint type and age at assessment. However, as a general rule, the longer the squint has been present, the less likely binocularity can be achieved. Will binocular vision be restored if squint treatment is delayed for several years? The chance of developing binocularity is higher in children who have had binocularity before developing a squint. The sooner the eyes are aligned, the better the chance of regaining binocularity. How to Treat Quiz 4 November 2011 Could you comment generally on Katie s management? This is a difficult situation for the general practitioner when the patient or carer refuses assessment. Patients can be referred to a public ophthalmology clinic for assessment if cost is an issue. At the initial consultation, as the left red reflex could not be elicited, it would be worth assessing this child for the red reflex at a subsequent GP visit if ophthalmic assessment is refused, at a time where the child is less distressed, such as at an early morning appointment. Further, patching has been commenced for this child, indicating that the child has amblyopia, and the child s distress with treatment, suggests that the amblyopia is significant. This child needs urgent referral in an attempt to improve the vision. If this opportunity is missed, the child will always have weaker vision in the eye. Using atropine treatment in the good eye may be helpful in a child who has found patching treatment difficult and is a good therapy for amblyopia. General questions for the author Considering that children are often seen by their GP for vaccination at six weeks, four months, six months, 12 months, 18 months and four years, which routine eye checks should we do and at what age? Vision should be assessed with an age appropriate test as this is a good screening test for visual development. A red reflex should be assessed at six weeks, and light reflexes assessed at six months, and beyond. What is the implication of ghosting of images? Some patients complain of ghosting when they have cataract, or occasionally it may describe double vision with the second image from an amblyopic eye very close to the main image. Some patients complain of vertical diplopia. What tests should the GP do to assess this symptom? In adults, the most common causes of vertical diplopia are a fourth nerve palsy, thyroid eye disease and an orbital floor fracture. Assess the patient s vision, and look for signs of thyroid eye disease including conjunctival chemosis, proptosis, lid retraction, lid lag and limitations of ocular rotations. An orbital floor fracture is usually associated with a history of trauma. A fourth nerve palsy is best diagnosed using the Bielschowsky three-step test. Some patients complain of diplopia after facial or head injuries. What tests should the GP do to assess this symptom? Binocular diplopia is a symptom of loss ofocular alignment. For example, a patient with an orbital floor fracture, with inferior rectus entrapment can present with diplopia after a facial injury. These patients should be assessed within a few days. Children with a floor fracture and inferior rectus entrapment may present with a white eye and parasympathetic stimulation on upgaze. These children need to be seen immediately and have corrective surgery urgently. INSTRUCTIONS Complete this quiz online and fill in the GP evaluation form to earn 2 CPD or PDP points. We no longer accept quizzes by post or fax. The mark required to obtain points is 80%. Please note that some questions have more than one correct answer. ONLINE ONLY for immediate feedback 1. Which TWO statements are correct? a) A dense unilateral cataract may be left untreated during the first 16 weeks of life without resulting in amblyopia b) Visual pathways can be altered by therapeutic interventions until early adulthood c) Clearly focused, aligned images from each eye must reach the visual cortex for a child to develop high-quality vision with depth perception d) The slight disparity of the images reaching the brain from each normal eye allows for depth perception 2. A white red reflex is detected during the sixweek newborn screen. What TWO conditions could it be due to? a) Retinoblastoma b) Congenital cataract c) A pterygium of the eye d) Amblyopia 3. A three-year-old boy presents with right vision 6/6, and left 6/24 due to amblyopia. It is important to refer the child to a paediatric ophthalmologist for assessment. Which TWO statements are correct? a) This child has more than 10 times the risk of developing blindness in his right eye compared with other children b) The patient will not be able to get a driver s licence if his right eye vision drops to less than 6/12 c) Amblyopia treatment is beneficial until visual maturation, which usually occurs around puberty d) Amblyopia is a rare condition that is easy for the patient to identify 4. Which TWO statements relating to botox treatment for adult are correct? a) It is a good treatment option when the patient is not suitable for surgery and to reduce the turn to make it less noticeable b) It is a permanent treatment in most cases c) It cannot be used in someone if squint surgery is being considered in the future d) It may only require one injection for ocular alignment to be re-established in some patients 5. When assessing a sudden-onset squint in a 65-year-old man, which THREE conditions must be considered? a) Giant cell arteritis b) A space-occupying lesion in the brain c) Microvascular disease, including diabetes or hypertension d) Amblyopia 6. Which TWO statements are correct? a) When a cover uncover test is performed, if there is no squint, each eye will remain still b) When a cover uncover test is performed, if there is both a squint and very poor vision in one eye, that eye may remain still c) When a cover uncover test is performed, an outward movement of the uncovered eye to take up fixation indicates an exotropia d) A cover uncover test is the best way to identify a latent squint 7. In what TWO situations is neuroimaging of the brain and orbits needed? a) When the patient has optic disc swelling b) When the patient with squint has a fixed and dilated pupil suggesting a third nerve palsy c) To exclude giant cell arteritis d) If the patient had a childhood esotropia that was surgically corrected and they present with an adult-onset exotropia 8. Treatment for a childhood squint aims to achieve which TWO outcomes? a) Reduction of the psychosocial impact of the appearance of a turned eye on the child s development b) Achievement of binocularity in all children operated on within the first year of life c) Improvement of the child s vision d) Treatment of the compensatory head posture 9. In which TWO scenarios is urgent referral required? a) A child is noted to have a unilateral or bilateral reduced red reflex b) A child complains of double vision, as this indicates the eye turn is of acute onset c) A child has a head tilt d) A six-week-old baby noted to have a convergent squint and no other detectable ocular abnormality 10. Amblyopia treatment may involve which TWO of the following approaches? a) Glasses b) Squint surgery c) Patching or atropine dilation d) Botox therapy CPD QUIZ UPDATE The RACGP requires that a brief GP evaluation form be completed with every quiz to obtain category 2 CPD or PDP points for the triennium. You can complete this online along with the quiz at Because this is a requirement, we are no longer able to accept the quiz by post or fax. However, we have included the quiz questions here for those who like to prepare the answers before completing the quiz online. HOW TO TREAT Editor: Dr Giovanna Zingarelli Co-ordinator: Julian McAllan Quiz: Dr Giovanna Zingarelli NEXT WEEK The next How to Treat is a two-part series looking at stem cell therapies and the promise they may hold for treating presently incurable conditions. In Part 1, we explain stem cells and examine their clinical uses. In Part 2, we highlight clinical trials that are already underway. The authors are Dr Kirsten Herbert, consultant haematologist, Peter MacCallum Cancer Centre, East Melbourne, and Cabrini Medical Centre, Malvern; Professor Andrew Elefanty, joint head, embryonic stem cell differentiation laboratory, Monash Immunology and Stem Cell Laboratories, Clayton; Rebecca Skinner senior manager, communications, Australian Stem Cell Centre, Clayton; Dr Megan Munsie (PhD), director, education, ethics, law and community awareness unit, Stem Cells Australia, Melbourne, formerly senior manager, research and government, Australian Stem Cell Centre, Clayton, Victoria. 36 Australian Doctor 4 November