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Cornea & Lens Osman Younus Ophthalmology ST2Objectives • Basic anatomy • Common clinical conditions • Practice questions (if time allows)Cornea •structure in the anterior segment of the eye • Thicker peripherally than centrally • Average central corneal thickness is approximately 550 micrometresMiscroscopic anatomy • 5 layers: • Epithelium • Bowman’s layer • Stroma • Descemet’s membrane • EndotheliumFunctions • Light refraction • Total refractive power is 43D • Protection • Light transmission • which removes fluid from the stroma and the tightly packed nature ofl pump collagenous stroma with minimal blood vessels and pigmentNerve supply • Cranial nerve V • Ophthalmic division • Long posterior ciliary nerveChemical injury • Ocular emergency • Potentially blinding • Acid or alkali • Acid burns  coagulative necrosis  remain localised to the surface of the eye • Alkali burns  liquefactive necrosis  penetrate to a deeper extentComplications Acute Chronic • Abrasion • Ocular surface • Perforation • cicatricial conjunctivitis, dry eyes • Glaucoma • Cornea • Persistent epithelial defects • Limbal stem cell failure • Stromal scar • Intraocular • Glaucoma • CataractManagement • Acute • Irrigate, irrigate, irrigate! • Remove particulate matter • Debride • Start antimicrobials and topical steroids • Maximum 2 weeks steroids because decrease fibroblast and collagen synthesisCicactricial conjunctivitis: Picture showing symblepharon: adhesions between the palpebral (eyelid) conjunctiva and cornea / bulbar (central) conjunctivaCauses of cicatricial conjunctivitis Infectious Non-infectious • Autoimmune • Adenovirus • Ocular cicatricial pemphigoid • SJS/TEN • HSV • AKC / VKC • Dermatological • Trachoma • Rosacea • C.diphtheria • Scleroderma • Neoplasia • Strept spp • OSSN • Trauma • Mechanical, chemical injury • Other • Long-term timolol useCorneal ulcer • Definition of an ulcer: defect of the cornea involving • Epithelium • Bowman’s layer • Stroma • Commonly caused by a corneal abrasion that subsequently becomes infectedAetiology Central Peripheral • Infective • Peripheral ulcerative keratitis • Bacterial, viral, fungal, protozoa • Mooren’s ulcer • Non-infective • Terrien’s marginal degeneration • Neurotrophic keratopathy • Exposure keratopathy • Marginal keratitis • Bullous keratopathySymptoms • Eye pain or ache • Redness • Foreign body sensation • Photosensitivity • Lacrimation • Decreased visionWork up • A: saboraud agar • Fungal culture • B: chocolate agar • Anaerobes • C & D: Blood agar and thioglycolate broth • Aerobes and anaerobes • E: viral PCR • G: gram stain • Not shown: non-nutrient E.coli • acanthamoebaManagement • Most corneal ulcers are polymicrobial in nature (even where a culture may show a single predominant organism) hence treatment is usually polymicrobial • Additional cyclopegia for comfortBacterial infections • Pseudomonas (contact lens wearers) • Staph aureus • stept pneumoniae • Enterobacteriaceae • Epithelial defect • Underlying infiltrate • HypopyonHerpes simplex virus keratitis • Herpetic disease may affect any layer of the cornea • Epithelial disease • shallow ulceration and swelling of epithelial cells called a ‘dendrite’ • Stromal • Produces an interstitial keratitis (see later) • Leaves stromal scarring +/- vascularisation • Endothelium / disciform • Endotheliitis • Granulamatous reaction at the level of the descemets membrane • Associated with ‘mutton’ fat keratic precipitates & raised intraocular pressure • Post-herpetic • Neurotrophic keratopathy leading to corneal anaesthesiaMutton fat KPs • Keratic precipitates are white precipitates of inflammatory cells which deposit on the corneal endothelial or anterior chamber inflammatory activity • Mutton fat describes fatter, greasier appearance that is characteristic of granulomatous disease • Sarcoid • TB • HSV • Syphilis • Vogt-Koyanagi-Harada syndromeHerpetic eye disease: simplex vs varicella HSV VZV • Young to middle aged • Elderly • Recurrent • Immunosuppressed • Dermatomal • Rarely bilateral • No associated neuralgia • Unilateral • No skin scarring • Postherpetic neuralgia and skin scarring • Dendritic keratitis • Pseudodendritic keratitis • Large, central well defined dendrite • Peripheral, small, plaque-like lesion • Treat with topical aciclovir • Treat with oral aciclovirLeft: a ‘pseudodentrite’ – peripherally located branching ulcer Right: central ulceration with brancing pattern and terminal bulbs in keeping with true dendritic ulcerFungal • Predisposing factors • Ocular trauma (organic matter) • Ocular surface disease and systemic immunosuppressionClinical features • Greyish, white ulcer • Elevated • Indistinct, feathery borders • Satellite lesions • Ring infiltrate • Endothelial plaqueAcanthamoeba • Most common cause of infection in soft contact lens wearers who do not take appropriate precautions in maintain CL care • Association with contaminated, stagnant water (hot tubs) • Indolent infection that is usually missed in the early stages • May be mistaken for herpetic keratitisClinical features • Pain (severe and disproportionate to lesion) • Multifocal infiltrates and microabscesses • Ring infiltrate • Keratoneuritis • Complications • Scleritis, secondary bacterial keratitisPerineural infiltrates Ring infiltrate Corneal perforationTreatments: combination therapy • Biguanides • Chlorhexidinelene biguanide (PHMB) • Diamidines • Propamidine • Hexamidine • Imidazoles • econazoleInterstitial keratitis: chronic inflammationof the stromawithout primaryinvolvement of the epitheliumor endothelium, leading to scarringand vascularisation of the stroma Infective Non-infective • Syphilis • Cogan’s disease (associated with • Congenital or acquired PAN) • TB • Autoimmune disease affecting eyes and ears • Leprosy • Sarcoidosis • Herpes • LymeNeurotrophic keratopathy • Loss of trigeminal innervation to the cornea resulting in partial or complete loss of sensation • Aetiology: • L• Herpes zoster keratitis • Neurological • Acoustic neuroma • Generalised • Diabetes, leprosyDiagnosis • Corneal sensation tested with whisp of cotton or an anaesthesiometer • Interpalpebral punctate keratopathy • Persistent epithelial defect in which the appears thickening and rolled lesion • May progress to stromal oedema, infiltration, melting and perforationTreatment • Protect ocular surface • Taping of lids at night • Botox induced ptosis • Tarsorrhaphy • Bandage contact lens (close monitoring) • PF topical lubricants • Amniotic membrane patchingExposure keratopathy • Inadequate lid closure (lagophthalmos) leading to inadequate corneal wetting • Aetiology • Facial nerve palsy • Reduced muscle tone (coma / PD) • Severe proptosisPresentation • Dry eye • Mild inferior third punctate epithelial changes progressing to breakdown • Secondary infectionTreatments • Daytime artificial tears • Ointment and lid taping at night • Bandage contact lens • Tarsorrhaphy • Upper lid gold weight insertionPeripheral ulceration • Peripheral ulcerative keratitis • Mooren’s ulcer • Terrien marginal degeneration • Marginal keratitisPeripheral ulcerative keratitis • limbal-based inflammatory disease • immune complexes activate the complement system resulting in chemotaxis of inflammatory cells  collagenase and protease that destroy corneal stroma. • Proinflammatory cytokines induce stromal keratocytes to produce matrix metalloproteases which contribute to the breakdown of the cornea. • Systemic or local causesCauses Systemic Ocular • Connective tissue disease • Infective • RA (most common) • Bacterial, viral, acanthamoeba, fungi • SLE • GPA • PAN • Non-infective • RP (ears, nose, trachea) • Marginal keratitis • Acne rosacea • Sarcoidosis • leukaemiaClinical findings • Crescentic ulceration and stromal infiltration at the limbus • Limbitis, episcleritis, scleritis • Circumferential spread which may involve the scleraT reatments • Systemic • Acute • High dose oral corticosteroids in the acute phase • Chronic • Cytotoxic therapy for long-term management • Tetracycline to halt thinning • Local • Lubricants • Topical steroids avoided because they may worsen thinningMooren’s ulcer • Rare form of PUK • Association with hepatitis C • Bi-modal incidence affecting young or old • Early-onset  progressive, bilateral (afro-carribeans) • Later onset  limited, unilateral (Caucasians) • No associated scleritisTreatment • Topical steroids (unlike PUK) • Oral steroids and immunosuppression • Conjunctival excision / recession • Lamellar keratectomy • Dissection of residual central island in advanced disease to remove stimulus for further inflammationTerrien marginal degeneration • Uncommon idiopathic thinning of the peripheral cornea • Usually bilateral • Older malesPresentation • Asymptomatic • Eye not inflamed • Epithelium intact • sloping edge of ulcer • Perilimbal clear zoneMarginal keratitis • Hypersensitivity reaction to staphylococcal exotoxins and cell wall proteins • Presents with mild discomfort, redness and lacrimation • Features: • Marginal subepithelial infiltrates separated from the limbus by a clear zone • Epithelial defects • Superficial scarring and vascularisation • Pannus • Associated blepharitisTreatment • Weak topical steroid in combination with antimicrobial • FML & chloramphenicol • Oral tetracycline for repeated episodes • Treat underlying blepharitisBand keratopathy • Corneal degeneration characterized by calcium deposition in the central cornea • Horizontal, band-like appearance • Often in the presence of hypercalcaemiaAetiology Hypercalcaemia Chronic ocular disease • Hyperparathyroidism • Uveitis • Renal failure • JIA with uveitis • Paget disease • Herpetic keratitis • SarcoidosisInvestigations • Bone profile • PTH levels • Renal profile • Creatinine • Urinalysis • ACE, CXRTreatment • Address underlying cause • Topical EDTA • Superficial debridement • Lamellar keratectomy with excimer laserFuch’s endothelial corneal dystrophy • Autosomal dominant or sporadic • Non-inflammatory dystrophy of the endothelial layer of the cornea • Endothelial dysfunction causes corneal swelling  glare and haloes • Usually from age 30+Presentation • Reduced contrast sensitivity • Reduced visual acuity • Fluctuation vision • Glare, haloes • Pain if bullae developExamination • ‘beaten metal’ appearance of guttata on slit lamp • Can be an age-related finding but in this case the distribution is usually peripheral only (Hassal- Henle bodies) • Swollen, opaque corneaT reatment • Medical • Corneal oedema • Hypertonic sodium chloride (5%) drops • Ruptured bullae • Antibiotics and lubricating drops • Bandage contact lens • Surgical • Penetrating keratoplasty • Endothelial replacement surgeryPseudeophakic bullous keratopathy • Development of irreversible corneal oedema after cataract surgery • Due to loss of corneal endothelial cells pre, intra- and post-operatively • Characterized by the presence of corneal subepithelial bullae • Usually develops 8 months to 7 years after surgery • 1-2% of surgeriesRisk factors • Advancing age • Pre-existing Fuch’s dystrophy • Implantation of anterior chamber intraocular lens • Shallow anterior chamber • Glaucoma • Previous intraocular surgery / trauma • Systemic conditions (diabetes, COPD)Symptoms • Reduced visual acuity • Reduced contrast sensitivity • Glare or haloes around lights • Eye discomfort of pain • tearingT reatment • Medical • Corneal oedema • Hypertonic sodium chloride (5%) drops • Ruptured bullae • Antibiotics and lubricating drops • Bandage contact lens • Surgical • Penetrating keratoplasy • Endothelial replacement surgeryKeratoconus • ‘Keras’ means cornea • ‘Conus’ means conus • progressive thinning of the central and paracentral cornea such that the it becomes cone-shaped  irregular astigmatism • bilaterallyood or early adulthood,Risk factors Genetic Mechanical • Down syndrome • Eye rubbing • Contact lens wear • Atopy • Eczema • Asthma • Ocular • Hayfever • VKC • Connective tissue disorders • Floppy eyelid syndrome • Ehlers-danlos • Retinitis pigmentosa • Marfans syndrome • Retinopathy of prematuritySymptoms • Progressive decline in visual acuity due to irregular astigmatism • Nyctalopia • Photophobia • Monocular diplopiaSigns • Central / paracentral stromal thinning • Red reflex ‘oil droplet’ • Vogt striae  vertical corneal stress lines • Fleisher rings (epithelial iron deposits around the base of cone) • Munson sign  bulging of the lower lid on downgazeManagement • Optical • Toric contact lenses • Surgical • Corneal transplant • Corneal collagen cross-linking • Riboflavin drops to photosensitize the cornea followed by exposure to UVAComplications • Acute hydrops • Rupture in descemets membrane allows influx of aqeous, causing acute discomfort and blurring • Treat with hypertonic saline +/- bandage contact lensNormal lens • Avascular • Biconvex • 9-10mm in diameter • 5mm anterior to posterior • 1/3 (20D) refracting power of the eyeStructure • Capsule • Nucleus and cortex • Surrounds the entire lens • Oldest lens fibres (embryonic and fetal) are most central • Composed of collagen • Thickest anteriorly • Lens fibres are continuously laid • Thinnest posteriorly down peripherally • As lens epithelial cells de-differentiate • Epithelium into lens fibres, they lose all cellular • Single layer cuboidal cells organelles and nucleus • Present only anterior to lens equator • Zonules • Support the lens • Attach from the lens mid-periphery to the ciliary body processesLens pathologies • Cataracts • Cataract surgery complications • Lens dislocationsNuclear sclerotic • Most common type of cataract • Normal maturation of the lens • Slow progression • Causes lens to become more brunescent and large • Increase risk of angle-closure glaucoma • Distance vision often affected causing difficulty with drivingRisk factors • Age • UV radiation • Smoking • Trauma • myopiaSymptoms • ‘second sight’ • Increased refractive power improves presbyopia • Haloes / glare • Difficulty focusing • Trouble seeing at nightMorgagnian • Inferior sinking of nucleus in a liquefied cortexCortical spoking • Usually bilateral; asymmetric • Opaque, white wedge shaped tendrils in the periphery of the lens • Initially inferonasal • Works their way toward the centre like spokes on a wheelPosterior subcapsular • Lie infront of the posterior capsule • Younger patients • Progress more quickly • Chronic steroid use, diabetes, uveitis • Appear granular and vacuolated • Usually are within the visual axis and so produce rapid reduction in visual acuityTraumatic cataract • Characteristic flower-shaped opacity • May result from various trauma • Mechanical • Electric • radiationComplications of cataract surgery • Intra-operative • Late post-operative • Posterior capsule rupture and • Late endophthalmitis vitreous loss • Wound astigmatism • Suprachoroidal haemorrhage • Glaucoma • Dropped nucleus • Bullous keratopathy • Posterior capsule opacification • Early post-operative • Retinal detachment • Endophthalmitis • Wound leak • IOP problems (high, low) • Corneal oedema • Cystoid macula oedemaAcute endophthalmitis • Most feared post operative complication • Incidence = 0.1% • Potentially blinding • Risk factors • Intra-operative complications • Clear corneal incision • Temporal incision • Wound leak • Diabetes • Adnexal disease • 90% of isolates are gram positive (S. epidermidis, S.aureus) • Most common source are the flora or the eyelids and conjunctivaPresentation • First few days of surgery with acute onset pain, reduced vision, eyelid swelling • Examination showed a red eye, with fibrinous anterior uveitis with hypopyon, corneal haze and oedema, RAPD and loss of the red reflexManagement • Vitreous tap for microscopy and culture • Intravitreal antibiotics • Oral antibiotics • Topical antibiotics & steroids • Oral steroids after 12-24 hours • Vitrectomy • Beneficial when VA is worse than HM • Prevention: • Pre-operative application of povidone-iodine (betadine) is the single most effective • Intracameral antbiotics at the end of the operationLoss of red reflex • Intra-operatively  • Post-operatively  suprachoroidal haemorrhage endophthalmitis (in the context • Painful, tense and firm eye of an inflamed eye) • Can result in expulsion of the intraocular contents • Stop surgery immediately and close the eyeDelayed-onset chronic endophthalmitis • Organisms of low virulence become trapped within the capsular bag  saccular endophthalmitis • Pathogens become sequestered within macrophages, protected from eradication but with continued expression of bacterial antigen • Most frequent isolate as Propionibacterium acnesPresentation • Several months following surgery with progressive visual deterioration and floaters • Low grade anterior uveitis • Mutton fat keratic precipitates • Treat with oral moxifloxacin or clarithromycin • Persistent cases may require removal of IOL and bagPCO • Most common complication after cataract surgery • Sometimes called a ‘secondary’ cataract • Posterior capsule undergoes secondary opacification due to migration, proliferation and differentiation of lens epithelial cells • Occurs in 20-50% of patients within 2-5 years of surgery • Children / infants have higher incidence and earlier onsetRisk factors • Younger age • Diabetes • Uveitis • Myotonic dystrophy • Retinitis pigmentosa • Traumatic cataractSlit lamp examination • Elshnig’s pearls • Capsular fibrosisTreatment • YAG capsulotomy Lens dislocations Marfan syndrome: lens dislocation Homocystinuria: lens dislocation upwards downwardsQuestionsKeratoconus… a. is a progressive condition True b. is associated with Down's syndrome True c. is caused by increased intraocular pressure False d. can be treated with contact lens True e. is made worse by eye rubbing TrueCorneal endothelial cells a. stimulated to divide by uveitis False. Endothelial cells do not divide a. do not divide after birth True a. easily damaged by trauma True. When damaged during cataract surgery can result in pseudophakic bullous keratopathy d. control the corneal water control True. Na/K ATPase pump in the endothelium continuously pumps water out of the stromaCauses of a cataract • A. radiation True • B. beta blockers False • C. Vincristine False • D. Chlorpromazine True • E. Amiodarone TrueDrugs that cause cataracts: ABCD • Amiodarone • Busulphan • Chlorpromazine • Dexamethasone (and other steroids)Causes of corneal neovascularisation a. interstitial keratitis True. By definition IK causes inflammation in the stroma resulting in scarring and vascularisation b. amiodarone False c. herpes zoster ophthalmicus True  corneal hypoasesthesiae can result in long-term development of neovascularisation d. trachoma YesCornea a. the central corneal thickness is about 550 micrometres True b. the adult diameter is about 14.5 mm False. Approx 11mm. Corneal diameter 14.5mm is termed megalocornea c. endothelium cells continue to divide after birth False d. has a diorite power of about 30 dioptres False. Approx 40-45D e. myopia is associated with increased curvature True. Increased curvature increases refractive power of the light focusing the rays to fall infront of the macula (rather than upon it)The immediate treatment of an alkali burn should be a. copious irrigation of eye with tap water True b. castor oil False c. oral vitamin C False – is part of the secondary treatment once pH of the eye has been neutralised d. rush to eye emergency rapidly True e. start oral steroids False. No role for oral steroidsLens abnormalities are associated with • Marfans • True. Upwards dislocation • Homocystinuria • True. Downward dislocation • Myotonic dystrophy • True. Early onset cataracts • Diabetes • True • Amyloidosis • True. Amyloid deposits may occur on the zonules and lensThe lens • a. is completely surrounded by a layer of cuboidal cells underneath the capsule False. Epithelial layer extends only to the equator b. becomes more spherical during accommodation True. Increased curvature  increased refractive power  better focusing ability c. provides most of the ocular refractive power False. 1/3 of the total power (approx. 18-20D) d. power increases with nuclear sclerosis for presbyopia and some patients may suddenly find they no longer require reading glasses