 \201\201 1 Mood aff ects Snellen reading. If we feel \200\234strong , active and proud \200\235 we perform better. 6 Children may give inconsistent answers, eg \200\230unable \200\231 to read big type (hoping for spe ctacles, or a spectacle case all of their own) while correctly reading very small type (una ble to resist a challenge!).JBL; personal communication 1 meter from the eye. In the normal eye there is a red glow from the choroid (the red re \202 ex). Any lens opacity (cataract) will be seen as a black pattern obstructing the red re \202 ex. Blood or loose \202 oaters in the vitreous are seen as black \202 oaters. To determine their position, move your head horizontally, to and fro, like a cobra waiting to strike. The opacity will either move in the same direction as you (so lies behind the le ns), in the opposite direction (so lies in front of the lens) or will not move at all (so i n the lens). 413 Red re \202 exes are absent with dense cataract and intraocular bleeding. When the retina is in focus, ask the patient to look at the Snellen chart or anything right ahead in the di stance. This may bring the optic disc into the view. It should have precise boundaries and a central cup (p440). Signi \201 cant cupping means an excavated appearance (seen in glauc oma). A pale disc suggests optic atrophy (eg chronic glaucoma, multiple sclerosis, et al., p438). Examine radiating vessels and the macula (ask the patient to look at the light). Aid s to successful ophthalmoscopy: Ensure the batteries are fully charged. \200 Darken the r oom; remove spectacles; dial up a lens to correct the resulting y g o o m l a h t h p O l refractive error ( \200\223 lenses correct myopia, + correct hypermetropia). \200 If very myopic, try examining with spectacles on (disks appear small). \200 If you \201 nd oph thalmoscopy diffi cult using your non-dominant eye, try us- ing your dominant eye for exami ning both fundi \200\224while standing behind the seated patient, whose neck is fully exten ded. \200\207Start looking for the disc by making the twinkle of the ophthalmoscope \200 \231s light strike the pupil \200\231s margin at 9 o \200\231clock for the right eye and 3 o \200\231clock for the left. Then move the beam medially and you will \201 nd the disc s omewhere along that line. Always check the lens for opacities before trying to examine the fundus. \200 Get close e nough to the patient, even if one of you has had garlic for lunch. \200 Consider using a short-acting mydriatic to dilate the pupil (see p456). \200 Remember that most retinal te ars are peripheral and are diffi cult to see. It isn \200\231t possible to see the margin of the retina with an ophthalmoscope. Slit lamp examination This instrument has a bright light source and a hori- zontally mounte d microscope to examine the structures of the living eye. The light source can be converted to a slit (hence the name). Tonometric attach- ments allow intraocular pressure measuremen t. The indirect ophthalmoscope This instrument is a bright light source mounted on the exam iner \200\231s head, which allows a binocular view of the eye. The patient lies down and th e examiner holds a convex lens (14, 20 or 30D) to examine the retina. The sclera is indente d using a blunt instrument to view the whole retina. This is a dynamic form of retinal exam ination and is the ideal way of identifying retinal tears or detachments. External eye Lids : Symmetrical? Normal retraction on upward gaze (abnormal in thyroid disease), pto- sis (p4 16), spasm, in \202 ammation or swellings (p416)? Conjunctiva: Look for in \202 ammation (if circumcorneal, suspect anterior uveitis; injection of the bulbar, for- nix, and the tar sal surfaces suggests conjunctivitis; focal injection adjacent to cornea means a problem on the cornea). Is there discharge, follicles, or upper Courtesy of Prof J Trobe. lid cobbles tone patterning, or any sub-conjunctival hemorrhage (p432)? Cornea: Use a torch. Any opacit y, abrasion/ulcer (the latter stains green with 1% \202 uorescein), or oedema? Anterior c hamber: Its clear aqueous humor can be cloudy in anterior uveitis (p430), may have sterile pus (hypopyon) with corneal ulcer, or blood (hyphaema) after injury ( \201 g 1). Lens: Wit h a normal lens a pupil is black; cataract may make it white. Pupils should be equal and re act to light and accommodation (written \200\230PERLA \200\231). They are small and irregu lar in anterior uveitis (dilated, oval and \201 xed in acute glau- coma, p430). For other pupil signs, see p424. Fig 1. Hyphaema. 414 N. 48 He moved forward a few N. 36 N. 24 fine chattering gems. y g o o m a h t h p O l N. 18 He knew exactly who would l N. 14 now sneeze calmly through an open door. Had there been another year N. 12 of peace the battalion would have made a floating system of perpetual drainage. N. 10 A silent fall of immense snow came near oily remains of the purple-blue supper on the table . N. 8 H A L T N C O L H A E C T N O C L O H N A A E N L O M C T I S Q W E N L D E P O We drove on in our old sunless walnut. Presently classical eggs ticked in the new afternoon shadows. N. 6 We were instructed by my cousin Jasper not to exercise by country house visiting unless acc ompanied by thirteen geese or gangsters. T C L A H L O C N T L A H N. 5 The modern American did not prevail over the pair of redundant bronze puppies. The worn-out principle is a bad omen which I am never glad to ransom on purpose. H T O Y H U V A T Y M 415 y g o o m l a h t h p O l X O W U H Y U V T X O A W I M H Y T Use distance glasses \200\2306/6 \200\231 \200\2306/9 \200\231 \200\2306/12 \200\231 \200\2306/18 \200\231 \200\2306/24 \200\231 \200\2306/36 \200\231 \200\2306/60 \200\231 \200\230CF \200\231 \200\230HM \200\231 \200\230PL \200\231 \200\230no PL \200\231 Lines on the Snellen chart1 are as follows 6 Able to read at 6m what can normally be read a t 6m 9 Able to read at 6m what can normally be read at 9m 12 Able to read at 6m what can no rmally be read at 12m 18 Able to read at 6m what can normally be read at 18m 24 Able to rea d at 6m what can normally be read at 24m 36 Able to read at 6m what can normally be read at 36m 60 Able to read at 6m what can normally be read at 60m Counts \201 ngers; counts \201 ngers held m distance Hand movement; perceives hand moving m distance Perceives li ght; can see a torchlight when shone into eye No light perception, abbreviated to \200\230 no PL \200\231, ie blind 1 Be sure to use a proper Snellen chart! The above is just to give an idea of what a Snelle n chart looks like. The height and width of each optotype (letter) is \201 ve times the t hickness of the line (nib width). This thickness equals the thickness of the white spaces b etween lines and the thickness of the gap in the letter C. The British Standard BS 4274-1 : 2003 speci \201 es a uniform luminance of >120cd/m2. Any variation across the test chart shall not exceed 20%. \200\235 Only C, D, E, F, H, K, N, P, R, U, V, and Z can be used, as they are assumed to have equal legibility (probably wrongly: Errors were 7.5 times more com mon with certain letters (B, C, F, S) than with A, L, Z, T, this diff erence increasing to 18-fold at threshold, hence the move to systems (eg Dyop) which do not employ let- ter reco gnition; see doi:10.1001/archophthalmol.2010.369). Visual acuity = distance at which test i s made distance at which the smallest optotype identi \201 ed subtends an angle of 5 ar cminutes. The external eye 416 \200 Styes \200\230Stye \200\231 is a word used more by patients than doctors for referring to in \202 ammatory lid swellings. Hordeolum externum is an ab- scess or infection, usually s taphylococcal, in a lash follicle; these may also involve the glands of Moll (sweat glands) and of Zeis (sebum- producing glands attached directly to lash follicles). They \200\230p oint \200\231 outwards and may cause much in \202 ammation. Treat with local antibi- otics , eg fusidic acid. ( \200\230Stye \200\231 implies infection: if this is not present, the t erm marginal cyst \200\224of Zeis or Moll \200\224may be used.) Less common is the hordeolu m internum, an abscess of the Meibomiam glands (hordeolum is Latin for barley- corn). These \200\230point \200\231 inwards, opening on to conjunctiva, cause less local reaction but leave a residual swelling called a chalazion ( \201 g 1) or a Meibomian cyst (tar- sal cys t) when they subside. Vision may be \200\201 if corneal \202 attening occurs (rare). 7 T reat residual swellings by incision & curettage under local anesthesia. Blepharitis (Lid in \202 ammation eg from staphs, seborrhoeic dermatitis, or rosacea). Eyes have \200\230bur ning \200\231 itching red margins, with scales on the lashes. Treatment: Cleaning crusts of f the lashes is essential (use cotton-wool buds) Tears Naturale , fusidic acid, steroid drops (or creams) or oral doxycycline. In children with blepharokeratitis, consider oral e rythromycin too. 8 Pinguecula ( \201 g 2) Degenerative vascular yellow- gray nodules on th e conjunctiva either side of the cornea (esp. nasal side). Typical patient: Adult male. Ass ociations: \200\200Hair and skin pig- ment; sun-related skin damage. 9 If in \202 amed (p ingueculitis) topical steroids are tried. If invading the cornea, as it may in dusty, wind- blown life-styles, the word pterygium ( \201 g 5) is used; surgery may be needed. Entropi on ( \201 g 3) Lid inturning is typically due to degeneration of lower (rare- ly upper) li d fascial attachments and their muscles. It is rare if <40yrs old. The inturned eyelashes i rritate the cornea. Taping the (lower) eyelids to the cheek, or botulinum toxin injection t o the lower lid gives temporary relief; more last- ing relief needs surgery. Ectropion ( \201 g 4) Lower lid eversion causes eye irritation, watering (drainage punctum malaligned) exposure keratitis. Associations: Old age; facial palsy. Plastic surgery may correct the deformity. If facial palsy is the cause, consider surgical correction of with gold weight implant in upper lid to aid closure. Upper lid malposition results from the globe \200\231s hypotropic position ( \200\203 \200\230pseudo- ptosis \200\231) or intrinsic levator weakn ess ( \200\203true ptosis) from: \200 Congenital (ab- sent nerve to levator muscle; poorl y developed levator) \200 Mechanical (oedema, xanthelasma or upper lid tumor) \200 Myog enic (muscular dystrophy, myasthe- nia) \200 CNS (III nerve palsy, p422; Horner \200\231s , p424). Congenital ptosis is corrected surgically early if the pupil, ie the visual axis i s covered (risk of amblyopia, p422). Dermatochalasis denotes excess lid tissue (may obstruc t sight). Lagophthalmos is diffi culty in lid closure. Causes: Exophthalmos; mechanical imp airment of lid movement (eg injury or lid burns); leprosy; paralyzed orbicularis oculi givi ng sagging lower lid. Corneal ulcers and keratitis may follow. \201\227: Lubricate eyes wi th liquid paraffi n ointment. If corneal ulcers develop, temporary tarsorrhaphy (stitching lids together) may be needed. Dendritic ulcer (Herpes simplex corneal ulcer) Signs: Photoph obia & wa- tering. If steroid drops are used without aciclovir cover, corneal invasion and scarring may occur, risking blindness. 1% \202 uorescein drops stain the lesion. \201 \227: Aciclovir 3% eye ointment 5 \211\210 daily. Get help if aciclovir resistance possible . 10,11 Fig 1. Chalazion. Courtesy of Bristol Eye Hospital. y g o o m a h t h p O l l Fig 2. Pinguecula. 417 y g o o m l a h t h p O Fig 3. Entropion. Fig 4. Ectropion. Courtesy of Bristol Eye Hospital. Courtesy of Bristol Eye Hospital. l Fig 5. Pterygium. Note the new vessels cross- ing over the boundary between the sclera and the cornea. Courtesy of Jon Miles. Fig 6. Xanthelasma (from dyslipidaemia). Courtesy of Jon Miles. Eyelid tumors Benign tumors Skin papillomas and seborrhoeic keratoses (basal cell papil- lo mas) are common, as are naevi. Congenital vascular naevi such as straw- berry naevi and por t wine stains may also involve lids. Pyogenic granulomata may occur as a response to injury . Keratoacanthomas may require excision to con \201 rm diagnosis. Malignant tumors Basal c ell carcinoma (BCC): These nodular lumps with pearly edges \201 ne telangiectasia, or morphea-like sclerosing forms with more extensive in \201 ltration require excision (Mohs micrographical techniques are sometimes used). 12 They comprise 90% of malignant tumors. Se baceous gland carcinomas: (1 \200\2232% lid malignancies) are commoner on the upper lid, in \200 , and with \200\200 age. They arise from Meibomian glands or glands of Zeis (they c an resemble chronic blepharoconjunctivitis, so refer if unilateral for ?biopsy), or nodular chalazions (so refer if recurrent). Mortality: 10%. Malignant melanomas require wide excis ion. Kaposi \200\231s sarcoma (purple nodules usually in those with AIDS is treated by radi otherapy. In the elderly, a rapidly growing purple nodule may be a Merkel cell cancer. Tears and lacrimation The lacrimal glands are on the superior temporal side of the orbits. The tear \201 lm excreted over the eye drains via the lacrimal puncta (found at the media l side of the upper and lower eyelid) through the lacrimal sac, lacrimal duct and inferior meatus (just lateral to the inferior turbinate) into the nasal passages. Dry eyes may be du e to insuffi cient tear secretion, and watering eyes may be due to blockage of the drainage system \200\224or pump failure ( \201 g 2). Acute dacryocystitis ( \201 g 1) is acute in \202 am- mation of the tear sac which is located medial to the medial canthus. This may s pread to sur- rounding tissues (cellulitis) and result in sys- temic upset. Immediate antib iotic therapy may resolve the infection. Failure leads to local ab- scess formation. Nasola crimal duct non-canalization The nasolacrimal duct may not be canalized at Courtesy of Bris tol Eye Hospital. birth and may not open fully until 1 year old. The child will have a pers istent watery eye(s) and may be prone to attacks of conjunctivitis. If the duct fails to ca nalize, probing of the duct under general anesthesia is done. Chronic dacryocystitis This t ypically occurs in the middle-aged and elderly. The lacrimal sac distends, discharges mucop us (=gound) into the eye naso- lacrimal duct block. Treat any infection promptly. CT of the orbit is needed if orbital cellulitis. If the nasolacrimal duct is permanently blocked, dacryocys- torhinostomy (DCR) establishes communication between the lacrimal sac and the n asal cavity. \201\231 \201\231 : Squamous cell ca of the lacrimal drainage system. Dacroad enitis Lacrimal gland in \202 ammation causes pain and swelling on the temporal side of th e upper eyelid, which may become S-shaped. Cause: Viral (mumps, measles, in \202 uenza) or gonococcal. Chronic swelling can occur in sar- coid, TB, lymphatic leukemia, or lymphosarc oma. Tear production The volume of tears normally in the eye is 6 L, the turnover rate bei ng 1.2 L/min. Tears are similar in electrolyte concentration to plasma, but rich in protei ns, especially IgA. They also contain lysozyme and \200 -lysin which have antibacterial pr operties. Meibomian glands, conjunctival glands, goblet cells, and lacrimal glands produce tear \202 uid, but re \202 ex secretion is from the lacrimal gland alone via the parasym pathetic system (trigeminal nerve). Dry eye syndrome/keratoconjunctivitis sicca may be due to \200\201tear produ- ction by lacrimal glands in old age, or, rarely in: Sj gren \200 \231s syndrome (associat- ed with connective tissue disorders, esp. RA); mumps; sarcoidosis ; amyloidosis; lymphoma; leukemia; haemochromatosis. Other causes: excess evaporation of te ars (post-exposure keratitis); or mucin de \201 ciency in tears (avitaminosis A, Stevens \200\223Johnson syndrome, pemphigoid, chemical burns). Schirmer \200\231s test (strip of \201 lter paper put overlapping lower lid; tears should soak >15mm in 5min) reveals \200 \201production. Arti \201 cial tears give symptomatic relief. Watery eyes/excess lacrimati on Causes: Emotion (joy; sorrow),1 cor- neal injury/FB (these tears contain \200\200nerve growth factor, which aids healing, which is rather neat), entropion, conjunctivitis, iritis , acute glaucoma. Often the cause is normal tear volume, but improperly drained (epiphora; \201 g 1), eg from ectropion, drainage system blockage (idiopathic, mucocele at the media l canthus, or rarely from head and neck tumors). 13 \201\227: Dacryocystorhinostomy (eg en doscopic) for nasolacrimal duct obstruction; surgery for other causes. 14 1 Emotional tears are a breakthrough in the evolution of the human face as a platform for emotional signalin g. Faces with tears removed by doctoring the image seem to others to be of neutral emotiona l valence: without tears we tend to misinterpret these faces as expressions of awe, concern , or puzzle- ment. 15 NB: skeptics argue that tears of joy don \200\231t exist. Sandor Feld man claims they are really tears of anticipated loss. 16 In support of this, the \200\230f act \200\231 is cited that children do not cry with tears of joy. Were such psychoanalysts too absorbed to have noticed infant tears of joy at family reunions? 418 Fig 1. Acute dacryocystitis. y g o o m a h t h p O l l 419 y g o o m l a h t h p O l Fig 2. Is your patient \200\231s watery eye from decreased drainage eg from punctal stenosi s/ obstruction or canaliculitis? Use the ophthalmoscope as a magni \201 er to see if the p unctum is stenosed. Surgery may help. Look for any obstructing lump at the medial canthus: an exuding mucocele is commoner than a lacrimal sac tumor: pain is a red \202 ag here. If from increased lacrimation (the 2nd category of causes), ask: are both eyes aff ected? I s the environment dust- or irritant-laden? Lubricating drops will help here (eg Lacri- Lube ). Is lid hygiene impaired? (suggesting blepharitis; note any redness). On blinking, positive and negative pressure is created in the lacrimal sac which accord- in gly sucks tears into it. This is the tear pump. Gravity helps keep the sac empty. If the ca use if pump failure (the 3rd category of causes) look for causes such as entropion, ectropi on or CNS causes (myasthenia, VII palsy). Refer for consideration of corrective surgery. NB: the lacrimal glads are in the upper outer area of the orbit (lacrimal fossa of the fron tal bone) and have autonomic innervation. Parasympathetics start in the lacrimal nucleus of the facial nerve in the pons. Sympathetic postganglionic \201 bres start in the superior cervical ganglion and travel as a periarteriolar plexus with the middle meningeal artery. DP Austin. Orbital swellings Lesions in the bony orbit typically present with proptosis (ie exophthalm os), whatever the pathological origin. Proptosis (protrusion of orbital contents) is also a cardinal sign of intraorbital problems. If pressure is eccentric within the orbit there wi ll be deviation of the eyeball diplopia. Orbital cellulitis Spread is typically via para nasal sinus infection (or eyelid, dental injury/infection, or external ocular infection). T ypical patient: A child with in \202 ammation in the orbit, fever, lid swelling, and \200 \201eye mobility. Causes: Staphs, Strep pneumoniae, Strep pyogenes or milleri. \201\227: A dmit for prompt CT, ENT and ophthalmic opinion + antibiotics1 surgery \200\224to prevent extension to meninges or cavernous sinus. Blindness is a risk from pressure on the optic n erve or thrombosis of its vessels. 17,18 Rule out underlying rhabdomyosarcoma. Carotico-cav ernous \201 stula may follow carotid aneurysm rupture with re- \202 ux of blood into th e cavernous sinus. Causes: Spontaneous; trauma; post- septorhinoplasty. There is engorgemen t of eye vessels + lid & conjunctival oedema. Exophthalmos may be pulsatile, with a loud br uit over the eye tin- nitus. Arterial ligation or embolization may occasionally be tried . 19 \200\22321 Orbital tumors Primary neoplasia is rare (angioma, dermoid, meningioma, or optic nerve glioma). 3% of orbital lesions are metastatic (from breast, lung, prostate, gut , kidney: examine liver, spleen, nodes). In children, unilateral prop- tosis may be the 1st sign of a neuroblastoma. Nasopharyngeal tumors can invade the orbit, as may mucocoeles and pyocoeles of ethmoid and frontal si- nuses. CT scan pictures give a clear representation o f the orbit. Hyperthyroid- ism may cause exophthalmos: Graves \200\231 ophthalmopathy (OHCM p210). 420 y g o o m a h t h p O l l Ophthalmic shingles This is zoster of the 1st (ophthalmic) branch of the trigeminal nerve a nd accounts for 20% of all shin- gles. See \201 g 1. Only thoracic nerves are more aff ec t- ed (55%). Pain and neuralgia in the distribution of cranial nerve V1 dermatome (p762 \200\2233) precedes a blis- tering in \202 ammed rash. In 50% of those with HZO the globe is aff ected (corneal signs iritis in >40% \200\224 sectoral iris atrophy, p425 \201 g 1). Nose-tip involve- ment (Hutchison \200\231s sign) means involvement of the nasociliary branch of the trigeminal nerve which also supplies the globe, and makes it likely that the eye will be aff ected. (herpes zoster ophthalmicus, HZO) Presentation \200 Purulent conjunc- tivitis Visual loss/keratitis \200 Episcleritis/scleritis \200 Iritis ( atrophy) \200 Crania l nerve palsy \200 Pupillary distortion \200 Limbal lesions \200 Pre-auricular node tenderness \200 Optic atrophy The eye can be aff ected with little rash elsewhere. immunocompromised. 22 if Beware dissem ination Varicella zoster virus (VZV) may persist in the eye. The diff erent patterns of ret inal disease caused by VZV relate to immune status. \201\227: Oral antivirals improve symp toms (additional antiviral drops are not needed) but cannot be relied on to prevent post- h erpetic neuralgia.2 Famciclovir off ers the best dose Bristol Eye Hospital. schedule (750mg once daily for 1wk; SE vomiting; headache) but is much more expensive than aciclovir (800m g 5 times daily PO for 7 days \200\224it has more serious SE such as hepatitis and renal fa ilure). Start within 4 days of onset. It is wise for all to see a specialist if the nose-ti p is involved, or the eye turns red within 3 days, to exclude anterior uveitis with a slit lamp. Prolonged steroid eyedrops may be needed. Fig 1. Ophthalmic shingles. 1 Adults: cefotaxime 2g/6h IVI + metronidazole 500mg/8h IVI vancomycin. 23 Pediatric dos es: p204. 2 Incidence of neuralgia is 16% if >65yrs (risk \200\200 if rash is extensive). I t causes insomnia, and depression \200\224 even suicide. Amitriptyline 25mg at night may he lp \200\224or gabapentin (max 3.6g/day; 24 see BNF). 25 421 Retinoblastoma This is the most common primary intraocular tumor in children. Incidence 1 i n 15,000 live births. Signs Strabismus and leukocoria (ie a white pupil). Always suspect re tinoblas- toma when the red re \202 ex is absent (the mother may come with a photo show- i ng only one eye reddened during \202 ash photography); NB: multiple tumors may be present . 26 Inheritance Hereditary retinoblastoma is diff erent from the non-hereditary type: ther e is a mutation of the RB gene located at 13q14. Inheritance is auto- somal dominant with 8 0% penetrance. The RB gene is present in everyone, and is normally a suppressor gene or ant i-oncogene. Those with hereditable retinoblastomas typically have one altered allele in eve ry cell. If a developing retinal cell undergoes mutation in the other allele, a retinoblast oma results. The retinoblastoma gene is the best characterized tumor suppressor gene. Its p roduct is a nuclear phosphoprotein which helps regulate DNA synthesis. Associations 5% occu r with a pineal or other tumor (=trilateral retinoblas- toma). Secondary malignancies such as osteosarcoma and rhabdomyosar- coma are more frequent, and they are the main causes of d eath of patients with hereditary retinoblastoma. 27 Treatment There is a trend away from en ucleation (eye removal). Aim to- wards focal procedures to preserve eye and sight, if possi ble. Chemotherapy Useful in bilateral tumors. Combination of carboplatin, etoposide and vin cristine. Ciclosporin helps reduce multidrug resistance. Enucleation may be needed with lar ge tumors, long-standing retinal detach- ments, and optic nerve invasion or extrascleral ex tension. External beam radiotherapy has a role (may cause secondary non-ocular cancers in t he radiation \201 eld, esp. if carrying the RB-1 germline mutation). Ophthalmic plaque br achytherapy has a more focal and shielded radiation \201 eld, and may carry less risk, bu t is limited to small \200\223medium retinoblastomas in accessible locations. Cryotherapy a nd transpupillary thermotherapy (TTT) can give control of selected small tumors. \200\230C hemoreduction \200\231 is achieved by IV or subconjunctival chemotherapy to allow TTT, cryo therapy, and radiotherapy. Screening parents and siblings This is needed for accurate genet ic coun- selling and to allow presymptomatic treatment. Germ-line mosaicism must be conside red as a genetic transmission pattern. If a parent is germ-line mosaic, the possibility of bearing more babies with retinoblastoma is high- er than conventionally believed. 28 y g o o m l a h t h p O l Eye movements and squint To maintain single vision, \201 ne co-ordination of eye movement of both eyes is necessary. Abnormality of the co-ordinated movement is called squint. Othe r names for squint: strabismus; tropia. Exotropia is divergent (one eye turned out) squint: esotropia is (one eye turned in) convergent squint. Prominent epi- canthic folds (diagram) may produce pseudosquint. Non-paralytic squints These usually start in childhood. Squints may be con- stant or not. All squints need ophthalmological assessment as vision may be dam aged if not treated. Diagnosis Diffi cult, eg in uncooperative children. Screening tests: 1 Corneal re \202 ection: re \202 ection from a bright light falls centrally and symmet- 422 \200 rically on each cornea if no squint, asymmetrically if squint present. 2 Cover test: movement of the uncovered eye to take up \201 xation as the other eye is co vered demonstrates manifest squint; latent squint is revealed by movement of the covered ey e as the cover is removed (see \201 g 2). Convergent squint (esotropia) This is the commonest type in children. There may be no cause , or it may be due to hypermetropia (p426). In strabis- mic amblyopia the brain suppresses the deviated image, and the visual path- way does not develop normally.1 Divergent squint ( exotropia) These tend to occur in older children and are often intermittent. Management Rem ember 3 \200\230O \200\231s: Optical; Orthoptic; Operation. Treatment starts as soon as th e squint is noticed. Optical: Assess the refractive state af- ter cyclopentolate 1% drops; the cycloplegia allows objective determination of the refractive state; the mydriasis allow s a good view into the eye to exclude abnormality, eg cataract, macular scarring, retinobla stoma, optic atrophy. Spectacles are then provided to correct refractive errors. Orthoptic: Patching the good eye encourages use of the one which squints. Orthoptic review charts pro gress. Operations (eg resection and recession of rectus muscles): These help align- ment an d give good cosmetic results. NB: use of botulinum toxin has helped some patients with squi nts (see p460). 29,30 Paralytic squint Diplopia is most on looking in the direction of pull of the paralyzed muscle. When the separation between the two images is greatest the image from the paralyzed eye is furthest from the midline and faintest. Third nerve palsy (oculom otor) Ptosis, proptosis (as recti tone \200\201), \201 xed pu- pil dilatation, with the eye looking down and out. Causes: p424. Fourth nerve palsy (trochlear) There is diplopia an d the patient may hold his head tilted (ocular torticollis). The eye looks upward, in adduc tion and can- not look down and in (superior oblique paralyzed).2 Causes: Trauma 30%, dia- betes 30%, tumor, idiopathic. Sixth nerve palsy (abducens) There is diplopia in the horizon tal plane. The eye is medially deviated and cannot move laterally from midline, as the lat- eral rectus is paralyzed. Causes: Tumor causing \200\200intracranial pressure (com- press es the nerve on the edge of the petrous temporal bone), trauma to base of skull, vascular, or multiple sclerosis. 31 \201\227: Botulinum toxin can eliminate need for strabismus surg ery in selected VI palsies. 32n=19 Medial rectus: \200\230Look at your nose \200\231 (addu ction). Lateral rectus: \200\230Look away from your nose \200\231. 33 1 In anisometropic a mblyopia, each eye has diff erent refractive powers. The brain favors the eye with the clea rer image, ignoring the other. Other types of amblyopia: congenital cataract; uncorrected m yopia or hypermetropia in one or both eyes; severe ptosis. Amblyopia ex anopsia means \200 \201acuity from failure of development of visual pathways due to lack of a sharp image on t he macula at a critical stage of development. 2 Superior oblique and inferior oblique aid e ye abduction (ie lateral rotation), while superior and inferior recti adduct the eye. The s uperior oblique also lowers the gaze while the inferior oblique elevates it.34 y g o o m a h t h p O l l Superior rectus ( \201 g 1) primarily moves the gaze upward and secondarily rotates the to p of the eye towards the nose (in- torsion). Note its eccentric attachment. Inferior rectus primarily moves the gaze down (Secondary action: rotation of the bottom of the globe towar ds the nose.) Superior oblique primarily rotates the top of the globe towards the nose, sec - ondarily depresses gaze.3 Note its eccen- tric attachment. Inferior oblique primarily rot ates the bottom of the globe towards the nose3 & secondarily moves gaze upward. Tertiary ac tion of each oblique: abduction. 35 Best results are achieved in childhood strabismus by: \200 Early detection of amblyopia. If >7yrs old, amblyopia may be permanent. 36 \200 Con scientious and disciplined amblyopia treatment. \200 Optimal glasses (especially full plu s in esotropia). \200 Having the child see as straight as possible as soon as possible af ter amblyo- pia treatment is optimized. 37 Gobin \200\231s principles: Evaluate all aspects of the strabismus (horizontal, verti- cal and oblique); search for the obstacles to ocular movements which cause alteration of binocular vision; remove them. 38n=449 423 Right orbit seen from above Nose s u t c e r r o i r e p u S e u q i l b o r o i r e p u S y g o o m l a h t h p O l Fig 1. Superior oblique. Pseudosquint Wide epicanthic folds give the appearance of a squint in the eye looking towar ds the nose. That the eyes are correctly aligned is con \201rmed by the corneal re \202ec tion. Normal Corneal re \202ection shows correct alignment. Neither eye moves as they are altern ately covered. Left convergent squint Corneal re \202ection shows malalignment. As the right eye is cover ed the left moves out to take up \201xation. Left divergent squint Corneal re \202ection shows malalignment. As right eye is covered th e left moves in to take up \201xation. Fig 2. The cover test relies on the ability to \201 xate. If there is eccentric \201 xa tion (ie foveal vision is so poor that it is not used for \201 xation), the deviating eye will not move to take up \201 xation. Corneal re \202 ection shows that malalignment is present. 3 The primary muscle moving an eye in a given direction is the agonist. A muscle in that ey e that moves it in the same direction as the agonist is a synergist \200\224eg in abducting the left eye, the left lateral rectus is the agonist, the left superior and inferior obliq ues are synergists; the left medial, superior, and inferior recti are antagonists.39 Superi or & inferior obliques are the primary muscles of torsion. Pupils Pupil inequality Light detection by the retina is passed to the brain via the optic nerve (aff erent pathway) and pupil constriction is mediated by the oc- ulomotor (third) cr anial nerve (eff erent pathway). The sympathetic nervous system is responsible for pupil di latation via the ciliary nerves. Aff erent defects (absent direct response) The pupil won \200\231t respond to light, but constricts to a beam in the other eye (consensual response) . Constriction to accommodation still occurs. Causes: optic neuritis, optic atrophy, retina l disease. The pupils are the same size (consensual response unaff ected). Mar- cus Gunn sw inging \202 ashlight test: On beaming light to the normal eye, both pupils constrict (dir ect & consensual reaction); if, on swinging the light to the aff ected eye, the pupil dilat es it is a Marcus Gunn pupil. Eff erent defects The 3rd nerve also mediates eye movement an d eyelid re- traction. With complete palsy there is complete ptosis, a \201 xed dilated p upil, and the eye looks down (superior oblique still acts) and out (lateral rectus act- ing ). Causes: cavernous sinus lesions, superior orbital \201 ssure syndrome, dia- betes, pos terior communicating artery aneurysm. The pupil is often spared in vascular causes (diabete s; hypertension). Pupillary \201 bres run in the periphery, and are \201 rst to be invo lved in compressive lesions by tumor or aneurysm. Other causes of a \201 xed dilated pupi l Mydriatics, trauma (blow to iris), acute glaucoma, coning ie uncal herniation (OHCM p840) . Holmes \200\223Adie pupil Initially monolateral, then bilateral, pupil dilatation with de layed responses to near vision eff ort, with delayed redilation. Typical pa- tient: A young woman, with sudden blurring of near vision, and a dilated pupil, with slow responses to ac commodation, and, especially, to light (looks unreac- tive, unless an intense light is used for >15min), ie a tonic pupil. Slit lamp exam: Iris shows spontaneous wormy movements (iri s streaming). Holmes \200\223Adie syndrome: Tonic pupil, absent knee/ankle jerks and BP \200\201.1 The pupil \200\231s size may \202 uctuate, and get smaller than the other (if both pupils are involved they may be confused with Argyll Robertson pupils). See below for other tonic pupils.2 Horner \200\231s syndrome occurs on disrupting sympa- thetic \201 br es, so the pupil is miotic (smaller), and there is partial ptosis, and the pupil does not d ilate in the dark. Unilateral facial anhydrosis (sweating \200\201) may indicate a lesion p roximal to the carotid plex- us \200\224if distal, the sudomotor (sudor = sweat) \201 bre s will have separated, so sweating is intact. Congeni- tal Horners: iris heterochromia (see \201 g 1). Argyll Robertson pupil occurs in neurosyphilis is bilateral miosis, pupil and diabetes; there irregularity, and no response to light, but there is response to accommoda tion (the prostitute \200\231s pupil accommodates but does not react). The iris is spongy, the pupils dilate poorly, and there may be ptosis. Causes of light-near dissociation (LND, \200\223ve to light +ve to accommodation): Argyll Robertson pupil; Holmes \200\223Adie and Parinaud syndromes;3 meningitis; alcoholism; tectal lesions, eg pinealoma; mesencephalic o r thalamic lesions.4 424 \200 y g o o m a h t h p O l l Causes of Horner \200\231s \200 Posterior inferior cer- ebellar artery or basilar artery occlusion \200 Multiple sclerosis \200 Cavernous sinus thrombosis Pancoast \200\231s tumor \200 Hypothalamic lesions \200 Cervical adenopathy \200 Medi astinal masses \200 Pontine syringomyelia \200 Klumpke \200\231s palsy, p766 \200 Aor tic aneurysm 1 Selective impairment of monosynaptic connections of 1a aff erents \200\200presynaptic inhibition on aff erent 1a input to ventral horn motor neurons 40 \200\230 absent deep re \202 exes persist despite cord pathology. 41 There is auto- nomic dysfunction too with di sturbed vasomotor and sweating functions \200\224and cough. 42 2 Migraine; syphilis; diabet es; chickenpox; arteritis; sarcoid; myasthenia; hamartoma; anti-Hu autoantibod- ies to neur al nuclei; Sj gren \200\231s; Meige \200\231s syndrome; botulism; dermatomyositis; amyloid osis; paraneoplasia. 3 LND + nystagmus, upward gaze palsy and eyelid retraction (Collier \200\231s sign). 4 The path from the optic tract to the Edinger \200\223Westphal nucleus is disrupted but deeper cortical connec- tions remain intact, so accommodation is spared. 425 Irises What color are your eyes? y g o o m l a h t h p O l Fig 1. Heterochromia (sectoral above, central below). Both may be a normal variant; secto- ral heterochromia may be a feature of Waardenburg syndrome (WS, p548). Type 1 WS is an auto somal dominant disorder whose other signs are hearing loss, pigmental abnormalities of the hair and skin, and dystopia canthorum (wide nasal bridge due to sideways displace- ment of the inner angles of the eyes). NB: the top image also displays iris hypoplasia, further des cribed in Fig 2. Courtesy of Jon Miles. Fig 2. Iris hypoplasia. There are \201 bre separations in the stroma. It is associated wi th Wilms \200\231 tumor, cerebral gigantism, congenital rubella, and other rare syndromes. In developmen- tal glaucomas (eg Reiger syndrome) there is anterior segment dysgenesis. Refraction Refractive errors arise from disorders of the size and shape of the eye. Correct refraction depends upon the distance between the cornea and the retina, and the curvatures of the lens and cornea (see \201 g 1). Myopia (short sight) The eyeball is too long. In any eye, the nearer objects come to the eye, the further back their image falls. With myopi a, only close objects focus on the retina (short sightedness) unless concave spectacle (or contact) lenses are used. Causes: Genetic (chromosome 18P & 12Q). 43 Very close work in the early decades (not just at school) may lead to changes in the syn- thesis of mRNA and the concentration of matrix metalloproteinase, resulting in myopia. Acetylcholine, dopamine, an d glucagon are triggers for eye growth. 44 426 In normal growth, changes in eyeball and lens curvature compensate for the eye getting long er as it grows, but in myopic children, such compensations may not be occurring, so myopia worsens with age. Most do not become myopic until the age of 6yrs (a few are born myopic). Myopia will then usually continue to worsen until the late teens, when changes stop below 6 dioptres in most people. It is important, therefore, for children with myopia to have the ir eyes regularly checked, as spectacle changes are to be expected, perhaps every 6 months. Avoid over-correction as this can make myopia worse. 45 In later life, increasing myopia m ay indicate developing cataracts. y g o o m a h t h p O l l