Cornea - Ulster University PDF

Cornea Ulster University School Biomedical Sciences – Optometry Dr Julie-Anne Little ulster.ac.uk College of Optometrists Clinical Management Guidelines https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines.html Content Revision of anatomy Corneal problems – the signs Corneal c...

Cornea Ulster University School Biomedical Sciences – Optometry Dr Julie-Anne Little ulster.ac.uk College of Optometrists Clinical Management Guidelines https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines.html Content Revision of anatomy Corneal problems – the signs Corneal conditions Acute problems – covered in Lecture 7 (Differential diagnosis of the Red Eye) Corneal Ectasias Corneal degenerations Corneal dystrophies Corneal surgery Corneal Foreign Bodies and abrasions Cornea - Anatomy All photos from Spalton, Hitchings & Hunter Slide altas of clinical ophthalmology Corneal Layers 1. Epithelium- 50um thick, basal, wing then desquamating cells 2. Bowman’s 10-20um thick 3. Stroma- accounts for over 90% of corneal thickness. Contains keratocytes, type 1 collagen & proteoglycans 4. Descemet’s Membrane 5. Endothelium – single layer of cells – don’t replicate but enlarge to account for cell loss Cornea – how to look at it! Slit lamp – several illumination techniques Keratometer/keratoscopy Corneal Topographer Specular microscope Pachymetry What is normal? 11-12mm horizontally 9-11mm vertically 500um thick centrally and 650um peripherally Central 3mm virtually spherical, peripherally aspheric profile. Standard refractive index 1.3375. Average radius of curvature about 7.8mm (+43D) What is normal? Light transmission is maximal at 700nm (98%) decreases to 80% at 400nm Often some regular astigmatism correctable by spectacles with spheres and cylinders. Irregular astigmatism often found with disease processes Clinical signs of corneal problems Punctate epitheliopathy – where? Epithelial oedema Corneal filaments Punctate epithelial keratitis Stromal infiltrates Stromal oedema Stromal vascularisation Breaks/folds in Descemet’s membrane Endothelial problems Clinical Signs Signs can point to inflammation and/or infection Thorough history & symptoms is required Need to distinguish between acute and chronic problems Chronic signs include neovascularisation and scarring Pinguecula Very common, yellow-white deposit on bulbar conjunctiva. Temporal and/or nasal to limbus Degeneration of collagen fibres in conjunctival Stroma See CMG https://www.college-optometrists.org/guidance/clinical-managementguidelines/pinguecula.html No treatment required (usually) Pterygium Triangular sheet of fibrovascular tissue encroaches cornea More common in hot climates Treatment: surgery, lamellar keratoplasty See CMG https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines/pterygium.html Corneal Ectasias Keratoconus Keratoglobus Pellucid marginal degeneration Keratoconus Fairly common. Thinning and ectasia of the cornea Central and paracentral stromal thinning, apical protrusion and irregular astigmatism (scissor reflex on retinoscopy) Onset around puberty and then slowly progresses Bilateral but often asymmetrical More frequently occurs in Down syndrome, Marfan’s syndrome etc. Keratoconus Keratoconus Ocular associations include Leber congenital amaurosis, retinitis pigmentosa, aniridia etc. Autosomal dominant with variable penetrance? Apical protrusion called a ‘cone’. These can be different shapes,.e.g. nipple (5mm), oval (5-6mm), or globus (>6mm, up to 75% of cornea) Cones usually in inferior position. Nipple displaced nasally, Oval displaced temporally Keratoconus Signs Scissor reflex on retinoscopy Irregular astigmatism Fine deep stromal striae (Vogt straie) visible on Slit lamp. Progressive corneal thinning centrally Steep Keratometry measurements Bulging of the lower lid on downgaze (Munson’s sign) Epithelial iron deposits around base of cone (Fleischer’s ring) Acute Hydrops can result as Descemet’s membrane ruptures and fluid leaks into stroma – sudden drop in VA. This heals but causes stromal scarring https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines/corneal-hydrops.html Keratoconus 19 Keratoconus Treatment/Management Patients should be advised to avoid eye rubbing Spectacles initially correct vision As astigmatism gets more irregular this becomes more difficult. RGP contact lenses then can give better vision. These can be specially designed for steep cones Scleral contact lenses Keratoconus Treatment/Management Intra-stromal rings - INTACS Epikeratoplasty or Penetrating keratoplasty required in10-20% of cases Corneal collagen crosslinking Keratoconus Corneal collagen crosslinking (CXL) Useful treatment for early KC Riboflavin drops (Vit B2) exposed to UV light (365nm) Encourages collagen crosslinking and stiffening of cornea. Mimics age-related corneal stiffening Surgical procedure: 10-30 mins UV – 1 week healing time. Will still need spectacles/contact lenses afterwards to optimise VA Recent clinical trials provide evidence that it stops progression Video here: http://www.moorfields.nhs.uk/condition/keratoconus Keratoconus Advanced Keratoglobus Onset of this extremely rare condition is usually at birth Signs: Oval keratoconus Protrusion and thinning of entire cornea Acute hydrops may develop Keratoglobus Pellucid Marginal Degeneration Very rare condition. Onset 20-40 years of age. High increasing regular astigmatism Crescent shaped area of inferior corneal thinning extending from 4 to 8 o’clock Whole central cornea tilts forward Treatment: scleral lenses or corneal surgery Corneal Degenerations Arcus Senilus Vogt White limbal girdle Crocodile Shagreen Cornea Guttata Band Keratopathy Lipid Keratopathy Salzmann nodular degeneration Arcus Senilus Most common peripheral corneal opacity Hyperlipoproteinaemia frequently associated with bilateral arcus Age-related, most people over 80 have it. Signs are bilateral lipid deposition which starts in the superior and inferior perilimbal cornea and then progress circumferentially Asymptomatic Arcus Senilus Vogt White limbal girdle Very common, harmless, age-related finding Bilateral narrow crescentic lines composed of chalklike flecks at the interpalpebral fissure on the nasal and temporal limbus Crocodile Shagreen Characterised by greyish-white polygonal stromal opacities separate by clear spaces Opacities usually involve the anterior 2/3 of the stroma Rarely the opacities are found more posteriorly Patient has no symptoms so condition usually diagnosed by chance. Cornea Guttata Focal accumulations of collagen on the posterior surface of Descemet’s membrane ‘Raindrops on a windowpane’ ‘Beaten metal’ appearance Arise from fault in endothelial cells which causes local thickening. Often discussed with Fuch’s endothelial dystrophy Band Keratopathy Relatively common Deposition of Ca+ salts in sub epithelial space, the anterior Bowman’s layer and the anterior stroma. Can arise from ocular conditions, metabolic conditions or be hereditary Nasal & temporal peripheral calcification which progresses centrally to produce a ‘band’ Treatment by chelation which surgically removes the band, or by excimer laser (phototherapeutic keratectomy) Lipid Keratopathy Primary Secondary Commonly seen in vascularised corneae. This could be due to other corneal problem, e.g. herpes simplex. Abnormal vessels leak lipid into the stroma Corneal Dystrophies Most inherited abnormalities – bilateral. Tend to develop slowly through life (progressive) Dystrophies which predominantly involve the epithelium and anterior stroma tend to present with recurrent epithelial erosions and worsening vision from subsequent scarring. Those in deeper cornea present with acuity loss Types of Corneal Dystrophies Cogan Microcystic dystrophy Reis-Bucklers dystrophy Meesman dystrophy Schnyder dystrophy Lattice dystrophies (Types 1, 2 & 3) Granular dystrophies (Types 1, 2 & 3) Macular dystrophies (Types 1 & 2) Fuch’s endothelial dystrophy Posterior polymorphous dystrophy Epithelium Endothelium Cogan Microcystic dystrophy ‘Map Dot Fingerprint’ or ‘epithelial basement membrane’ dystrophy is the most common dystrophy seen in practice. Neither familial or progressive Signs: four types of lesions are seen in the epithelium. – Dots – Microcysts – Fingerprint-like lesions – Map-like lesions Lesions can change over time Cogan Microcystic dystrophy Most patients are asymptomatic, and don’t require treatment Vision unaffected Contraindication of C/L wear? 10% will develop recurrent corneal epithelial erosion syndrome (REE), usually after 30 years of age. REE needs treatment Cogan Microcystic dystrophy Reis-Bucklers dystrophy Rare. Autosomal dominant inheritance. Severity can vary greatly from person to person Fine ring-shaped or polygonal opacities produce a ‘honeycomb’ or ‘fishnet’ appearance in the epithelium Most dense in central cornea. Causes REE If Vision is affected, partial corneal transplant (lamellar keratoplasty) may be necessary However, condition will re-occur in the graft Reis-Bucklers dystrophy Meesman dystrophy Autosomal dominant Very rare. Onset in first decade of life Irritation and minor visual symptoms Many very small epithelial cysts, most dense centrally Treatment not normally required Meesman dystrophy Schnyder dystrophy Autosomal dominant Onset in second decade of life Vision reduced, particularly with glare Central corneal haze is an early feature An oval area in the central cornea of scintillating subepithelial crystalline opacities Treatment: Excimer laser keratectomy Histology shows lesions are made up of fat and cholesterol Lattice Dystrophy Type 1 Autosomal Dominant. Onset at end of first decade of life with REE REE precedes stromal changes so often mis-diagnosed Subepithelial dots which coalesce into fine spidery branching lattice lines Lesions get deeper and outwards from central cornea VA progressively worsens as stromal haze increases. This can obscure the lattices. Penetrating keratoplasty (corneal transplant) usually required by fifth decade of life Histology shows lattices are deposits of amyloid between the stromal lamellae Lattice Dystrophy Type 2 Autosomal Dominant. Onset in middle age with progressive facial palsy and lattice corneal dystrophy (like Type 1) Systemic features: Cranial and peripheral neuropathy, facial paresis, skin laxity, occasionally renal and cardiac failure Cornea more rarely needs treatment due to later onset but systemic amyloidosis (metabolic disease) affects general health Lattice Dystrophy Type 3 Autosomal Dominant. Onset in fourth decade of life Thick ropy lines of lattice-work. Stroma relatively clear in between Can be very asymmetrical initially Rapid progression. Penetrating keratoplasty required Granular Dystrophy Type 1 Autosomal Dominant. Onset at end of first decade of life with REE Signs: white snowflake like opacities in stroma, especially anterior stroma and mostly central – tend not to reach limbus These increase in prominence over the year and are bilaterally symmetrical VA gradually reduces. Can fall below driving standard in fourth decade of life Histology shows hyaline deposits Penetrating keratoplasty sometimes required, but can reoccur in graft Granular Dystrophy Type 2 Autosomal Dominant. Onset in forth or fifth decade of life with mild or no REE Small, white crumb-like opacities in stroma. Same histology as Granular Dystrophy Type 1. Penetrating keratoplasty may be required late in life? Granular Dystrophy Type 3 Onset late in life. Patient mostly asymptomatic A few superficial and small white ring shaped lesions. Gradually increase in size and density Keratoplasty rarely required Macular Dystrophy Types 1&2 Autosomal recessive Metabolic dysfunction: failure to produce keratan sulphate. In Type 1 no keratan sulphate is detectable in serum. In Type 2 a little keratan sulphate is present. Only clinical manifestation is in the cornea Reduced VA usual presenting symptom (not REE) Onset second decade of life. Fail driving standard by third or fourth decade Macular Dystrophy Types 1&2 Macular Dystrophy Types 1&2 Spots of greyish opacity in the stroma gradually spread from anterior to posterior stroma. Corneal guttata may also occur Stromal thinning and reduced corneal sensation. Cornea reduces to 2/3 its original thickness Penetrating keratoplasty often required. Fuch’s Endothelial Dystrophy Behaves like a degeneration rather than dystrophy. Autosomal dominant 4 times more common in females. Onset Descemet’s membrane greatly thickened as the result of an abnormal layer of fibrillar collagen in between Descemet’s membrane and the endothelial cells. Associated with Cataract and open angle glaucoma CMG https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines/fuchs-endothelial-cornealdystrophy.html Fuch’s Endothelial Dystrophy Stage 1 Asymptomatic Central posterior cornea shows guttata changes and pigment dusting Descemet’s membrane appears grey and thickened Corneal thickness same and VA normal Stage 2 VA drops, with diurnal variation Stromal oedema Wrinkles in Descemet’s membrane Epithelial oedema leading to bullous keratopathy and pain Stage 3 Less pain as collagen is deposited deep in the epithelium VA drops further Fuch’s Endothelial Dystrophy Fuch’s Endothelial Dystrophy Treatment: Hypertonic agents, e.g. 5% sodium chloride drops Bandage contact lens reduces pain Pentrating keratoplasty eventually required. Often also extract crystalline lens and replace with IOL Posterior Polymorphous dystrophy Onset from birth or early life Subtle vesicular, geographical or band-like lesions on endothelium Usually asymptomatic and innocuous Miscellaneous Keratopathies Exposure keratopathy Neurotrophic keratopathy Recurrent corneal erosion syndrome Thygeson superficial punctate keratitis Crystalline keratopathies Vortex keratopathy Metabolic keratopathies Exposure keratopathy Cornea normally covered by tear film. Epithelial cells front layer have microvilli to hold mucus and make cornea hydrophillic. If cornea isn’t covered by tear film, exposure results Drying, erosion, thinning, vascularisation Sometimes exposure keratopathy occurs if lids are abnormal e.g. poor blink, ectropion or if eye is proptosed. Some people sleep with eyes open Exposure keratopathy Treatment/management Hydrate the cornea Artificial tears/ointment Taping eye closed Temporal ptosis of cornea Tarsorrhaphy Scleral contact lens Neurotrophic keratopathy Arises when cornea loses nerve supply Denervated cornea develops abnormal epithelium and resists normal wetting by mucus Can be congenital, or arise from previous Herpes Simplex or Herpes Zoster infections or diabetes Punctate epitheliopathy, cells become grey and oedematous Treatment Recurrent corneal erosion syndrome Epithelial basement membrane responsible for adhering the epithelium to Bowman’s layer Defective adhesion results in recurrent breakdown of epithelium Presents typically on waking – sudden onset unilateral pain, lacrimation, photophobia and blurred vision If mild, symptoms may resolve by themselves More common if Px has had trauma, or a dystrophy. Diabetic patients may be slow to heal. Treatment https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines/recurrent-corneal-epithelial-erosionsyndrome.html Thygeson superficial punctate keratitis Rare bilateral remittant condition Round or oval lesions – granular and grey-white Elevated dots push the epithelium up Some epithelial haze sometimes Conjunctiva quiet Treatment Relieve symptoms with lubrication Topical steroid may be effective Soft contact lens? Thygeson superficial punctate keratitis Crystalline keratopathies Chrysiasis – gold in stroma. No affect on vision Cystinosis – crysteine crystals. Rare, metabolic (systemic) Vortex keratopathy Corneal verticillata Symmetrical, bilateral, grey/golden deposits in epithelium Occurs below pupil, swirls outwards Drugs: amioderone, chloroquinine, tamoxifen, indomethacin etc Fabry disease, glycolipidosis, purple skin lesions, cardio and renal lesions, pain in fingers and toes Vortex keratopathy Metabolic keratopathies Mucopolysaccharidoses – Severe corneal clouding Wilson disease – Depositions of copper in tissues – Copper in cornea – Sunflower lens opacity Contact lenses There are some therapeutic reasons for C/L wear: – Correcting Irregular astigmatism (RGPs) – Persistent epithelial defects (promote healing) – Recurrent corneal erosions, bullous keratopathy (reduce pain, and protects cornea) However, C/L wear can lead to corneal problems – Giant papillary conjunctivitis – Overwear creating oedema, infiltrates, vascularisation, warping, MK Surgery In chronic conditions corneal transplant may be necessary Penetrating keratoplasty (full thickness corneal graft) Lamellar keratoplasty (partial thickness corneal graft) Refractive surgery RK, PRK, LASIK, LASEK Corneal Crosslinking RK – Radial Keratectomy PRK - complications LASIK - complications Penetrating Keratoplasty (complications) Penetrating Keratoplasty (complications) Ocular Foreign Body Range of DIY related or wind blown materials can get embedded on corneal surface Patient presents with painful, red, watering eye with possible blurred vision Signs will vary depending on nature of foreign body material CMG https://www.college-optometrists.org/guidance/clinicalmanagement-guidelines/corneal-or-other-superficialocular-foreign-body.html Ocular Foreign Body Careful Symptoms & History important Careful examination is imperative: Identify main FB Look under the lids for any other particles. If embedded in cornea, you need to be sure of the depth before considering whether you can safely remove it Vital to check VA Also ensure no signs of globe penetration and check for any A/C cells and flare Seidel’s test https://www.youtube.com/watch?v=GlFcAv0DR4c Ocular Foreign Body Ocular Foreign Body Superficial particles may be rinsed away with topical saline and perhaps a cotton bud A metallic or stone FB usually best removed with the tip of a hyperdermic needle with the aid of some topical anaesthetic. Try to remove rust ring also if present and not deep Give some topical anti-biotic in ointment form to help wound healing and give some protection. Consider topical cycloplegia for pain relief, and follow up until this heals. https://www.youtube.com/watch?v=rm_nAafFszs If in any doubt - refer Corneal Abrasion Increased risk with contact lens wear, situations of corneal exposure and recurrent erosion syndrome Symptoms of watering, reduced vision, photophobia and often considerable pain Patient may report a history of corneal insult Signs - corneal epithelial defect, conjunctival hyperaemia, watering, lid swelling, reduced vision and possible anterior chamber cells and flare CMG https://www.collegeoptometrists.org/guidance/clinicalmanagement-guidelines/cornealabrasion.html Corneal Abrasion Assess and examine the extent of the defect – try to photograph or measure. Measure VA Use topical anaesthetic if required for examination Rule out any foreign body Treatment may include, oral analgesic, topical cyclo for pain relief Topical chloramphenicol or fucithalmic ointment for at lest 5-7 days. Consider ocular lubrication without an anti-biotic beyond that Review until resolution Refer if not resolving References Kanski, J. Clinical Ophthalmology 4th Edition Butterworth Heinemann Sallustio B, Clincial Decision making II: the painful eye, Optometry Today , Aug 2008 Carnt N. Fungal keratitis – a cause for concern? Optometry Today , Nov 2014 Carnt N. Acanthamoeba keratitis – implications for contact lens wearers. Optometry Today, Aug 2014 Burnett-Hodd Corneal infiltrative Events. Optometry Today, July 2013 Shah & Rowe. Keratoconous: signs. Symptoms and management. Optometry Today 2015 Edwards M. Fuchs’ Corneal Endothelial Dystrophy. Optometry Today 2014 Wipperman JL, Dorsch JN. Evaluation and management of corneal abrasions. Am Fam Physician. 2013;87(2):114-20 References Illahi W, Keratoconus: Diagnosis, contact lens fitting and management, Optometry Today, Aug 2006 Buckley R, The cornea: differentiating sight threatening from non-sight threatening disease, Optometry Today, April 2006 Buckley R, Disorders of the cornea: Keratitis: clinical signs and management, Optometry Today, July 2005 Buckley R, Disorders of the cornea: Chronic corneal abnormalities, Optometry Today, Sept 2005