Ophthalmology General Notes

Ophthalmology General Notes Development Eyes develop from neural plate approx day 22 Synapses form at 4-5 months Photoreceptors at 5m Vessels from 16 wks to birth For the image to focus on retina needs: Transparent vitreous Fully formed retina Lens/cornea with appropriate focusing power Hypermetropia = long sighted (eye is too short for refractive power) = most children, but can compensate. To correct use convex (+ve) lens à enlarges eye Myopia = short sighted (eye is too long for refractive power) = correct with concave (ve) lens à eye appears smaller Astigmatism – asymmetrical focus due to distorted refraction Amblyopia Lack of visual experience in developmental stages of vision Degree of severity depends on onset/duration/degree of obstruction of vision Can be refractive, strabismic, or sensory deprivation (e.g. cataract) Younger the child the more severe Rx: correct refraction, patching / drops Examination Visual levels 0-2wks – limited visual attention, inaccurate fixation 2-6wks – attention to faces, pursuit movements develop, 6-12wks – good central fixation, accurate smooth pursuit, smiling responsively 6m + - reaching for toys, accurate saccades and stereopsis Direct Ophthalmoscopy Red reflex & retina Papilloedema – raised ICP = tumour, meningitis, hydrocephalus or bleed Cherry red spots Niemann Pick – accumulation of sphyingomyelin, Hepatosplenomegally & learning difficulties Farber’s – Inherited metabolic disorder (ceramidase deficiency) affecting lipid storage. Usually seen in neonate – impaired motor & mental ability & difficulty swallowing Tay-Sachs – Hexoseaminidase A deficiency – progressive neuro deterioration Blue Sclerae Can be seen in normal children Usually assoc with osteogenesis imperfecta – AD, osteoporosis, fragile bones, blue sclerae (from toddler years), conductive hearing loss from adolescence, bowing of lower limbs Fixation Should be central & steady If alternate eyes fixing then both eyes can see = less likely to develop amblyopia Acuity tests 0-2yrs – preferential looking = teller cards Child will preferentially look to the stripes as they are more interesting 2-4yrs – verbalising pictures 4yrs + - Snellen / logMAR Colour vision – Ishihara plates (6% of white males are red-green colour blind) Visual fields – toys from behind Pupils Anisocoria (differing seized pupils) is common, Up to 3-6 months there is minimal light response Leukocoria (white pupil) - IS NEVER NORMAL (common causes underlined) Lens – cataract, persistent hyperplastic primary vitreous, haemorrhage Retina – ROP, retinoblastoma, retinal detachment, toxocariasis, myelination of nerves Chorio-retinal – coloboma, toxoplasmosis Base down prism Eye moves up if it can see to correct for prism Cover Test – see below Squint (strabismus) Common in newborns as very short sighted 4% of < 6yrs à Amblyopia in 50% if not treated ALL squints over 2 month need investigation (can be retinoblastoma / cataract) Most squints are esotropia (inward) Rarely exotropia (more likely underlying neuro problem) Can be latent / manifest Latent squints are usually accommodative (usually hypermetropic) NB: sudden onset esotropia can be due to CN VI palsy NB – beware pseudo-squint due to prominent epicanthic folds/ prominent nasal bridge New squint at any age, or baby squint beyond 6m à referral 2 Types Concomitant (common) Refractive error Assoc with developmental delay Can be convergent / divergent but rarely vertical Paralytic Paralysis of motor nerves Rapid onset = ? SOL Assessment of squint Corneal light reflex Optical movements Acuity Cover test Fundoscopy Cover test - Squint Inward position = convergent Manifest left Outward position = divergent Manifest squint = seen all the time. On covering good eye, squinting eye will move back to midline Latent Squint = only seen on covering then uncovering bad eye – will see movement If no eye movement: then there is no squint OR the eye doesn’t see (amblyopia) Heterophoria = latent tendency to misalign Heterotropia = manifest Latent left e.g. exophoria – latent divergent e.g. esotropia – manifest convergent Majority of squints are convergent and are due to refractive errors Rx: Patch good eye à stimulates input from bad eye, corrective lenses, surgery to shorten muscles to align eyes Pupils Dilated – Holme’s Adie (myotonic), CN III palsy, Drugs e.g. atropine, Constricted – Horner’s, pontine haemorrhage, Argyl-robertson, Drugs e.g. opiates Visual Field Defects Retina à optic nerve à decussates at optic chiasm à optic tracts à lateral geniculate body à optic radiations à optic cortex Bitemporal hemianopia Lesion at optic chiasm Bitemporal superior quadrantinopia - pressure from below chiasm commonly pituitary tumours (adenomas) Bitemporal inferior quadrantinopia - pressure from above chiasm e.g. craniopharyngioma (in young) Meningioma (over 30’s) Incongruous hemianopia Lesion in the optic tract before the lateral geniculate body Uneven hemianopia, usually larger defect on temporal side The lesion is on the contralateral side to the field defect Superior Quadrantinopia After the LGB the inferior fibres (superior image) rotate 90o to lateral The fibres must pass through the temporal lobe to bypass the temporal horn of the lateral ventricle A lesion in the temporal lobe will affect these fibres (also often causes paresis / paralysis) The lesion is on the contralateral side to the field defect Inferior Quadrantinopia After the LGB the superior fibres (inferior image) rotate 90o to medial The fibres pass through the parietal lobe A lesion in the parietal lobe will affect these fibres The lesion is on the contralateral side to the field defect Homonymous hemianopia The fibres rejoin & rotate back in the occipital lobe A lesion in the occipital lobe (“geniculocalcine tract”) before the cortex will cause a homonymous hemianopia The lesion is on the contralateral side to the field defect Macula sparing homonymous hemianopia The macula area of the cortex receives blood supply from both the middle and posterior cerebral arteries A vascular lesion will produce a macula sparing homonymous hemianopia, as the macula receives supply from the other (providing only one area affected) The lesion is on the contralateral side to the field defect Congenital malformations Anopthalmia - absent eyes = failure of optic vesicle formation Micropthalmia – optic vesicle has formed but subsequent incomplete development Optic Nerve Hypoplasia E.g. in septo-optic dysplasia (with absent corpus callosum) – suspect if severe neonatal low BM = pituitary problem Double ring sign Coloboma Notch / break / fissure in any ophthalmic structure. Often assoc with chromosome (T13) / other physical malformations e.g. CHARGE syndrome / Goldenhar Syndrome / isolated family occurance Morning glory syndrome – axial defect of distal optic stalk as it meets optic vesicle à large defect in disc. Assoc with basal encephalocele, midline & facial anomalies Persistent hyperplastic vitreous – due to persisting embryonic fibro-vascular tissue, draws the cilliary process inwards. Assoc with cataracts and causes white pupils Aniridia – absent iris, usually bilateral, assoc with lens problems e.g. cataracts, nystagmus, photophobia, poor vision. 50-70% will develop glaucoma Lacrimonasal duct obstruction – should self clear by 12 months. If not then surgical Congenital Horner’s Syndrome – ptosis & enlarged pupil & anhydrosis Delayed visual maturation – appears to be looking through objects. Present at 3m, self-resolve by 56m Ptosis Lens Upper lid elevated by levator mm (CN III + sympathetic input) Causes: CNS lesion, sympathetic chain (e.g. neuroblastoma à Horner’s), structural (congenital disinsertion of mm), muscular (e.g. MG) Horner’s: ptosis due to sympathetic lesion Damage to sympathetic supply Partial ptosis Constricted pupil Unilateral anhydrosis (can be caused by any lesion along the path of the nerve e.g. tumour, trauma) 3rd nerve palsy Ptosis Fixed dilated pupil looking down & out (can be due to posterior communicating artery aneurysm, cavernous sinus thrombosis etc) Is vulnerable to intrauterine insults such as rubella à cataracts Congenital cataracts Absent red reflex 20% of childhood blindness in children with severe visual loss Will lead to children being amblyopic = emergency in children Causes Congenital rubella Other infections – e.g. CMV & toxoplasma Prematurity – usually transient & require no treatment Galactosaemia = oil drop cataract Wilsons = Sunflower cataract Hypocalcaemia Lowe Syndrome (occulo-cerebro-renal syndrome) – X linked Recessive Congenital cataracts (bilateral), glaucoma, buphthalamos à visual impairment Fanconi syndrome Mental retardation (severe & progressive) with behavioural problems Rickets, osteopenia and path #s due to metabolic acidosis & PO4 depletion Ix: enzyme deficiency in skin fibroblasts / demonstrate DNA problem Rx: Supportive, cataract surgery etc Downs – 5-10% of T21 have cataracts Inherited – usually AD Idiopathic – 50% of all congenital cataracts Hurlers = Corneal Clouding. (Hunters = clear eyes) Lens dislocations - Assoc with marfans Nystagmus Disorder of fixation Apparent at > 2/12 Can be due to problem in anterior visual system/central motor (midbrain/cerebellum) Can be due to ocular albinism, retinal dystrophy, optic nerve glioma Commonly congenital idiopathic nystamus Pendular – loss of macular vision or brain stem Jerking – brain stem / cerebellum One eye – local muscle / nerve problem Up gaze – midbrain at level of superior colliculus Down gaze – lower medulla e.g. Arnold Chiarii malformation Glaucoma (Buphthalmos) 1/10,000 births, Can be familial Disorganised drainage angle à raised intra-occular pressure Usually bilateral = can be missed Commonest presentation = cloudy cornea Can à Optic nerve damage due to increased intraocular pressure Buphthalmos in ¼ of infants with glaucoma = enlarged eyes Sx: photophobia + epiphoria (watering), enlarged corneal diameter, clouding & decreased red reflex Most common cause is congenital error in anterior chamber formation à requires surgery Assoc with: Chronic uveitis, Acute Uveitis, Sturge Weber syndrome, T 21, Rubenstein-taybi, NF1, Lowes Rx - surgical Retinopathy of prematurity (prev known as retrolental fibroplasia) Pathophysiology VEGF (vascular endothelial growth factor) is normally stimulated by relative hypoxia in fetus In ROP is down regulated at birth due to O2 excess à Vaso-obliteration & no new growth à Hypoxia of non-perfused area à 2o up regulation of VEGF à increased neovascular & retinal fibrosis & detachment Diagnosis Clinical Opthalmoscopy Staging (1& 2 = mild, 3-5 = severe) 1 = demarcation. Thin white line splits vascular from non vascular area 2 = ridge – a ridge forms between the 2 above areas 3 = proliferation = occurs posterior (medial) to the ridge 4 = subtotal retinal detachment 5 = total retinal detachment Then subdivided into zones 1 = disc to 2x disc-fovea distance 2 = larger area to periphery of nasal equator 3 = everything Extent Described by hours of the clock Plus disease Is engorgement of vessels, rigid iris, vitreous haze or pupil rigidity Threshold disease 5 continuous clock hours (or total of 8) of stage 3, in zones 1, 2 and “plus” disease Incidence <1250g = 65-70% (5% need treatment, 1-2% end up registered blind) Screening If < 1.5kg OR <31/40 Start screening at 31/40 corrected, stop at 45/40 corrected (no new sight threatening disease will develop by then) Prevention Maintain pO2 of 6-8kPa O2 target of 70-90% = 4x less ROP than 88-98% Red eye Neonatal conjunctivitis (opthalmia neonatorum) Due to various organisms e.g. chalmydia, gonorrhoeae, herpes 2/52 of Abx will resolve most bacterial conjunctivitis (although will be self limiting anyway Bilateral usually bacterial, unilateral = viral Chloramphenicol + gent can à allergy & are toxic to ocular surface RX – STOP topical therapy for 48 hrs & look for improvement If not improving in 48 hrs? Dendritic ulcers (herpes), uveitis, foreign body, retinoblastoma Conjunctiva Conjuctivitis (sticky eye) at birth can be normal. Only infected if red / swollen. Can affect one or both eyes In 1st 48 hrs think Gonococcal After 1st week think Chlamydia (systemic rx & rx both parents). Opthalmia neonatorum – at brith from genital tract. Most commonly gonorrhoea /Chlamydia. Can à ulcers. Swab parents & baby Bacteria – haemophilus, pneumococcus – rx chloramphenicol Chlamydia Virus – adenovirus is usually self limiting but highly contagious Inflammation Blepharoconjuctivits, trauma, foreign body, chemical, lacrimonasal duct obstruction, allergy, molluscum contagiosusm Acute oedema – urticaria Corneal Abrasions Feeling of discomfort and “something there” Fluorescine to show abrasion under slit lamp Visual acuity can be decreased if lesion is central (resolves as heals) Rx – chloramphenicol eye drops and RV Swollen optic disc Optic neuritis – decreased vision (esp colour vision) with central scotoma. Can occur post infection and rapid decrease in acuity (days). Usually recovers over several months Raised ICP – normal colour, normal acuity, enlarged blind spot + peripheral field constriction Papilloedema – bilateral pathological swelling, due to raised ICP, disc oedema, local capillary dilatation, splinter haemorrhages at disc margins Apparent disc swelling – elevated small disc, no cup, good vision, no change on serial obs Optic disc drusen – small disc, absent cup, abnormal vascular trifurcations, good vision, no initial field loss Proptosis Forward displacement due to mass behind Space occupying lesion in orbit Usually primary malignant tumour (e.g. rhabdomyosarcoma/neuroblastoma) Can also be haemangioma, lymphangioma, orbital pseudotumour (inflammation) or thyroid eye disease Proptosis suddenly after cough / valsalva = vascular Perioccular cellulitis- erythema, eyelid swelling, febrile unwell child, INFECTIONS Cellulitis Both can be due to S.aureus, Gr A Step, Pneumococcus & H.Influ Orbital (a.k.a post septal) Can extend proximally to cause sinusitis & meningitis SIGHT THREATENING Eye movements affected, proptosis, eyelid swelling 14d IV Abx Pre-septal (peri-orbital) Anterior to fibrous septum which runs through eyelid = NOT involving orbital structures = NORMAL eye movements Rx 5d IV & 5d oral Abx Toxoplasmosis Toxoplama gondii Unilateral mild ocular pain, blurry vision and new onset floating spots. “Hazy” vision. Retinoblastoma 1 / 20,000 Gene product is phosphorylates by CDK à binds to transcription factors Malignant Ca of immature retinal cells Bilateral in 30% of cases Genetics If sporadic mutation with no FH affects 1 eye with later onset (2 hit hypothesis) If familial affects both eyes at young age (AD with variable penetrance) = Rb1 gene on Chr 13q in inherited Sx - Leucocoria (white reflex) or heterochromia iridis, strabismus & poor vision Early diagnosis à 90% survival Rarely metastasise prior to presentation Rx – chemo (new therapy = intra-arterial chemo) Assoc with increased risk of other cancers e.g. osteosarcoma and pineal tumours Retinitis Pigmentosa Retinal degeneration Pigment changes with optic atrophy & progressive visual loss Starts with loss of night vision, then peripheral Can AR / AD / XL Assoc with: Hurlers syndrome – retinitis pigmentosa + corneal clouding Abetalipoproteinaemia = rare AR à steatorrhoea, diarrhoea, progressive ataxia, neuro-musc degeneration & retinitis pigmentosa. Presents by age 10. Due to defect in intestinal apolipoprotein B production à decreased LDL, VLDL and chylomicron synthess à failed lipid transport from intestine to liver. Blood film shows acanthocytes. Treatment with medium chain triglycerides & fat soluble vitamins Cystinosis – lysosomal storage disorder - also causes fanconi syndrome & hypothyroidism. Diagnosis by bone marrow biopsy, white cell enzymes and slit lamp exam of cornea. Treatment with mercaptamine Laurence-Moon-Biedl syndrome – AR – obesity, learning diffs, polydactyl and hypogonadism Post infectious Refsum’s disease PHACES syndrome Posterior fossa malformations (70%)– e.g. Dandy Walker, cerebellar hypoplasia, absent midline structures e.g. corpus callosum / septum pellucidum Haemangioma (90%)- large area on the skin of the head or neck (greater than 5 cm). Can affect vision Arterial lesions (41%) - large arterial malformation s (e.g. cerebrals), stenosis, aneurysms, sinus malformations, stroke Cardiac abnormalities (26%) – coarctation / aneurysm / duplication / right sided aortic arch, vascular ring, PFO, dextrocardia, TOF etc Eye abnormalities (23%) – morning glory disc, optic nerve hypoplasia, micropthalmia, congenital cataracts etc Cerebral visual impairment Abnormality of the brain à functional blindness OR other brain problem meaning child cant process images Causes Brain malformations PVL HIE Hydrocephalus Meningitis & Encephalitis Decreased/loss of vision Anterior pathway problems (between eye & chiasm, includes cataracts) Retinal dystrophy – progressive inherited decreased function. Can be selective for rods or cones. e.g. retinitis pigmentosa (rods > cones affected). Poor night vision, good central vision Overall changes – pigment changes, narrowed retinal vessels, pale disc Optic nerve damage/problem Congenital, inherited, neoplastic, toxic, metabolic, trauma, raised ICP Posterior pathway problems = cortical visual impairment OR delayed visual maturation Cortical visual impairment – due to seizures, metabolic, ischaemic, neuronal migration problems. Some improvement with age. Timings of improvement depends on cause Delayed visual maturation - decreased vision from birth. No other PMH. Apparent spontaneous improvement. Retrospective diagnosis. Delay in myelination of posterior pathway BUT does develop with time (3-6m) à full visual function Visual Impairment Signs & symptoms Pendular nystagmus Roving, purposeless eye movements Abnormal interactions – failing to fix & follow Poverty of facial expression Poking their own eyes / looking at bright / hot objects Apparently blind 500 new children registered each year Prevalence of 1/2500. 50% will have other handicap Most babies fix & follow from 6 wks – if not look for cause (fix if cataracts etc) Criteria <3/60 3-6 / with decreased field >6/60 with severe decreased field Causes – mostly non treatable 18% optic atrophy 16% congenital cataracts – treatable if found early enough 15% chorio-retinal degenerations ROP has increased in recent years, but now decreasing again 45% = genetic causes 33% = perinatal causes Failing vision – usually best noticed at change-overs – new school etc. Often only noticed when 2nd eye affected Aniridia Rare, usually bilateral, can have small rudimentary iris AN1 = isolated (AD) AN2 = (AD) assoc with wilms tumour, GU abnormalities & low IQ AN3 = (AR) assoc with cerebellar ataxia, congenital cataracts and low IQ