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Congenital corneal disorders
- 1. Page 1 CONGENITAL ANOMALIESOF CORNEA Dr. Sneha Thapliyal
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- 3. Page 3 • 4-5weeks: surface ectodermal cells cover the defect primitive corneal epithelium • Primary acellular stroma or post epithelial layer (random fibrils) • ~5th week : 1st wave of mesenchymal cells just beneath the primitive epithelium primitive endothelium (double layer) • ~7th week: 2nd wave b/w endothelium and epi cellular stroma (keratocan) • 7-10th week: mesenchymal cells differentiate into sclera/cornea + corneal curvature>scleral curvature
- 4. Page 4 • 8thweek: endothelium becomes monolayer and starts producing decemets membrane • 12-26 weeks: epi stratified squamous epi • 20 weeks: Condensation of acellular anterior stroma bowman’s membrane • 3rd month: corneal nerves invade stroma • 5th month: tight junction around endothelial cells • 5-7th month: transparent in utero Na-k ATP pump
- 5. Page 5 •Forms theanterior 1/6th of the globe •DIA: H 11.5-12, V 10.5-11 •CURVATURE: Anterior: 7.8mm; Posterior: 6.5mm •REFRACTIVE POWER:43D •CORNEAL THICKNESS: Central: 0.52mm Peripheral: 0.67mm
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- 8. Page 8 INTER CELLULAR JUNCTIONS •DESMOSOMES •ADHERENSJUNCTIONS •TIGHT JUNCTIONS •GAP JUNCTIONS CYTOPLASMIC FILAMENTS •KERATIN •ACTIN •MICROTUBULES SOURCE OF CORNEAL EPITHELIAL CELL: Limbal progenitor epithelial cell k/a adult corneal epithelial cell Located peripherally in palisades of vogt
- 9. Page 9 Acellular ,formsan interface between basal lamina of epithelium and the lamellar stroma Secreted by both epithelial cells and stromal keratocytes Randomly arranged collagen fibrils Considerable resistance to infection and injury. Once destroyed can not regenerate Collagen types:type1 and type 5
- 10. Page 10 90% thicknessof the cornea Predominantly water Structural network of insoluble and soluble ECM and cellular components CELLULAR COMPONENTS Collagen Keratocytes Proteoglycans and GAG Histiocytes/wandering macrophages Corneal nerves
- 11. Page 11 FUNCTIONS OFTHE STROMA •Maintain proper curvature •Mechanical resistance to IOP •CORNEAL TRANSPARENCY
- 12. Page 12 CORNEAL LAMELLAE Randomlyarranged in anterior stroma Orthogonal to one another in posterior stroma ANTERIOR 1/3RD POSTERIOR2/3RD The type 1 fibrils and corneal lamellae stretch across the cornea from limbus to limbus in a belt like fashion where they turn and for a circumferential annulus 1-2.5mm wide around the cornea maintaining the curvature of the cornea
- 13. Page 13 CORE PROTIEN DECORIN LUMICAN KERATOCAN MIMECAN Attachedcovalently to GAG’S Non covalently to collagen fibrils
- 14. Page 14 FUNCTIONS •Tissue volume •Maintainthe spatial order of collagen fibrills •Resist compressive forces •Viscoelastic properties to tissue GAG: •Keratan sulphate (60%) posterior stroma •Dematan sulphate (40%) anterior stroma
- 15. Page 15 •Are fibroblastsfound through out stroma •Are active in neonatal life and during trauma •Large nucleus and less cell organelles •KERATOCYTE PROGENITOR CELLS subpopulation of adult stromal stem cell present in periphery near the limbus
- 16. Page 16 •Also knownas pre descemets layer •Simulating DALK air bubbles were injected into the cornea after descemets membrane was surgically removed •It formed two types of air bubbles type 2 which dissipated and type 1 which did not. •Further experiments showed that all air bubble free specimens could be reinflated with a type 1 bubble •Indicating bubble was being trapped by a distinct layer of material which is not a normal variation of corneal stroma •Results were studied by optical and electron microscopy that revealed a thin layer of corneal collagen between corneal stroma and descemets membrane
- 17. Page 17 •Anterior bandedzone is present at birth •Posterior 2/3rd is the non banded zone formed by endothelium •Regenerates post trauma •Highly elastic •Consists of collagen type4 ,laminin, fibronectin and collagen type 8 •Schwalbe’s line •Hassel henle bodies •Guttae
- 18. Page 18 •Single layerof flat polygonal cells •Hexagonal cells attached to descemet’s membrane via hemidesmosomes and to each other by desmosomes •Metabolically active with abundant granules •6000 at birth falls by 26% in 1st year falls by 26% in next 11 yearsstable, 2400- 3000cells/sqmm •Polymegathism •70-80%cells are hexagonal if not is none as pleomorphism
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- 20. Page 20 •AVASCULAR •Small loopsderived from anterior cilliary vessels that invade periphery for about 1mm and provide nourishment
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- 22. Page 22 Congenital anomaliesof cornea.....
- 23. Page 23 Congenital anomalies 1.Anomalies of size and shape 2. Mesenchymal dysgenesis of anterior ocular segment- anterior cleavage syndrome 3. Corneal dystrophies
- 24. Page 24 Developmental corneal anomaliesof size and shape • Absence of the cornea • Anomalies of corneal size • Anomalies of corneal shape
- 25. Page 25 Absence ofcornea • True absence • True cryptophthalmos/ablepharon • Pseudocryptophthalmos
- 26. Page 26 True absence •Very rare • Always accompanied by agenesis of various other anterior segment structures
- 27. Page 27 Cryptophthalmos • AR,B/L • Skin (dermoid transformation) replaces normal eyelid architecture • Connect to the underlying globe and anterior segment grossly abnormal • Absence of lashes, brows, lacrimal gland and cannaliculi • Small or absent AC
- 28. Page 28 Diagnostic criteriafor cryptophthalmos syndrome FRASER SYNDROME Major criteria Minor criteria 1. Cryptophthalmos 2. Synctactyly 3. Abnormal genital 4. Sibling with cryptophthalmos syndrome 1. Congenial malformation of the nose 2. Congenital malformation of the ears 3. Congenital malformation of the larynx 4. Cleft lip and/or palate 5. Skeletal defects 6. Umbilical hernia 7. Renal agenesis 8. Mental retardation Atleast 2 major criteria and one minor criteria or one major and 4 minor criteria
- 29. Page 29 Pseudocryptophthalmos • Totalankyloblephron • Eyelids form but fail to separate • Normal cornea and conjunctiva covered by skin • Both lashes and brows are present • Vision restored by surgery creating a palpebral fissure
- 30. Page 30 Anomalies ofSize Microcornea ‡ Megalocornea ‡
- 31. Page 31 Microcornea Clearcornea of normal thickness H Diameter is < 10 mm (or 9.5-10 mm in a newborn 10- 12.5 MM IN ADULTHOOD) Non progressive, u/l or b/l, no sex predilection ‡ Anterior microphthalmos: whole anterior segment is small ‡ Microphthalmos: entire eye is small and malformed Nanophthalmos: eye is small but otherwise normal MIDAS: DELETION OF SHORT ARM OF X P 22 MICRO+ DERMA APLASIA+ SCLEROCORNEA
- 32. Page 32 Pathogenesis • ‡Causeunknown • Fetal arrest of growth of the cornea in the 5th month • ‡Overgrowth of the anterior tips of the optic cup, which leaves less space for the cornea to develop.
- 33. Page 33 Clinical Findings •‡Autosomal dominant or recessive • Equal sex predilection • ‡Cornea relatively flat: hyperopia & increased incidence of angle-closure glaucoma
- 34. Page 34 Clinical Findings Associated ocular anomalies: • ‡Persistent fetal vasculature • ‡Congenital catarcts • ‡Anterior segment dysgenesis • ‡Optic nerve hypoplasia Associated systemic conditions: • ‡Myotonic dystrophy • ‡Fetal alcohol syndrome • ‡Achondroplasia • ‡Ehlers-Danlos syndrome
- 35. Page 35 Management • ‡Excellentvisual prognosis if an isolated finding • ‡Spectacles to treat the hyperopia resulting from the flat cornea • ‡Specific treatment for concurrent ocular pathology
- 36. Page 36 Megalocornea • ‡Bilateral,nonprogressive corneal enlargement • ‡X-linked recessive • ‡Histologically normal cornea measuring >=12MM AT BIRTH AND AFTERV 2 YRS >13.0 mm • ‡Males are more typically affected
- 37. Page 37 Pathogenesis • ‡Failureof the optic cup to grow and of its anterior tips to close, leaving a larger space for the cornea to fill
- 38. Page 38 Three patterns 1.Simple megalocornea 2. Anterior megaophthalmos 3. Buphthalmos
- 39. Page 39 Simple megalocornea •Normal cornealdiameter >13mm • Non progressive • AD inheritance
- 40. Page 40 Anterior megaophthalmos •X linked recessive • Central cornea usually clear but may contain mosaic stromal opacity • Corneal curvature is normal • Deep anterior chamber • Hypoplastic iris stroma • Excess mesenchymal tissue in angle increased IOP • Lens subluxation and cataracts before 40 years
- 41. Page 41 Buphthalmos • Triadof: haab’s striae, increaesd IOP and optic disk changes • Milder case can be differentiated by sharply demarcated limbal region seen in megalocornea • A-scan : to measure axial length in which entire globe is increased along with cornea
- 42. Page 42 Clinical Findings Associated ocular anomalies: • Iris translucency (diaphany) • ‡Miosis • ‡Goniodysgenesis • ‡Cataract • ‡Ectopia lentis • ‡Arcus juvenilis • ‡Mosaic corneal dystrophy • ‡Glaucoma • Craniosynostosis • ‡Frontal bossing • ‡Hypertelorism • ‡Facial anomalies Associated systemic conditions‡ • Dwarfism • ‡Facial hemiatrophy • ‡Mental retardation • ‡Hypotonia • ‡Down Syndrome • ‡Marfan Syndrome • ‡Alport Syndrome • ‡Osteogenesis imperfecta • Mucolipidosis type II
- 43. Page 43 Management • Intraocularpressure testing and slit lamp biomicroscopy : to rule out congenital glaucoma ‡ • Ultrasonography: to determine short vitreous length , deep lens and iris position, and normal axial length that distinguish megalocornea from buphthalmos caused by congenital glaucoma ‡ • Careful cataract surgery: to implant the IOL in the lens capsular bag
- 44. Page 44 Anomalies ofshape of cornea 1. Cornea plana/sclerocornea 2. Posterior keratoconus: generalized/circumscribed 3. Keratoglobus 4. Congenital staphyloma and keratectasia
- 45. Page 45 Cornea Plana •‡Flat cornea, where the radius of curvature is less than 43 D, and readings of 30-35D are common • ‡Corneal curvature that is the same as the adjacent cornea is pathognomic • All cases have some degree of peripheral or central scleralization
- 46. Page 46 Sclerocornea • ‡Nonprogressive,noninflammatory scleralization of the cornea, may be limited to the corneal periphery, or the entire cornea may be involved.
- 47. Page 47 Pathogenesis • ‡Autosomalrecessive and dominant forms of cornea plana and sclerocornea, AR having more severe manifestation • 7th-8th gestational weeks when mesenchymal cells differentiate into sclera and cornea and also allows corneal curvature to exceed scleral curvature.
- 48. Page 48 Clinical Findings Associated ocular anomalies: • ‡Sclerocornea • ‡Microcornea • ‡Cataracts • ‡Anterior and posteriorcolobomas • ‡Hyperopia • ‡Angle-closure glaucoma • ‡Open-angle glaucoma Associated systemic condition: • ‡Ehlers-Danlos Syndrome
- 49. Page 49 Management • ‡Refractiveerrors are corrected • ‡Loss of central clarity may indicate penetrating keratoplasty, but cornea plana increases the risk of graft rejection and post keratoplasty glaucoma.
- 50. Page 50 Generalized posterior keratoconus •Increased posterior corneal curvature with a short radius of curvature • Normal anterior corneal surface • Central cornea is thinned but clear • Sporadic as a result of developmental arrest. • Less common
- 51. Page 51 Circumscribed Posterior Keratoconus •‡More common • Localized central or paracentral indentation of the posterior cornea without any protrusion of the anterior surface, as seen in typical keratoconus
- 52. Page 52 Pathogenesis • Abnormalmigration of the 2nd wave of mesenchymal cells that normally form corneal stroma • Represent mild variant of Peter’s anomaly therefore implying some intrauterine inflammation or anterior segment dysgenesis
- 53. Page 53 Clinical Findings •‡Variable amount of overlying stromal haze • ‡Loss of stromal substance can lead to corneal thinning approaching one third of normal. • ‡Descemet’s membrane and endothelium are usually present in the area of defect • ‡Focal deposits of pigmentation and guttae are often present at the margins of opacity. • ‡Astigmatism and/ or amblyopia may occur
- 54. Page 54 Keratectasia andCongenital Anterior Staphyloma • ‡Unilateral conditions that are both characterized by protrusion of the opaque cornea between the eyelids at birth. • ‡Differ only in the presence of a uveal lining of the cornea in congenital anterior staphyloma
- 55. Page 55 Pathogenesis • ‡Secondaryfailure of neutral crest cell migration results in dermoid transformation of the cornea to stratified squamous epithelium, sparing the eyelids and conjunctiva.
- 56. Page 56 • ‡Histopathologically,Descemet’s membrane and endothelium are absent, and a uveal lining is present (except in keratectasia). • ‡The cornea is variably thinned and scarred and the anterior segment disorganized, with the lens occasionally adherent to the posterior cornea, resembling unilateral Peters anomaly
- 57. Page 57 Management • ‡Exceptin very mild cases, visual prognosis is poor because of associated severe damage to the anterior segment. • Penetrating keratoplasty is rarely warranted, and enucleation may be required for a blind, glaucomatous, painful eye
- 58. Page 58 Keratoglobus • b/l,non inflammatory • Entire cornea is thinned out ( 1/3rd-1/5th the normal thickness) and takes globular shape • Keratomertry readings: 60-70 D • Strong association with Ehler-Danlos syndrome type VI
- 59. Page 59 Histopathology • Absent/fragmentedBowman’s membrane • Thinned stroma with normal lamellar orientation • Thin Decemet’s membrane with focal breaks • Normal endothelium • Thin sclera
- 60. Page 60 Clinical features •Globular shape of cornea • Thinning more pronounced in mid- periphery • Very deep anterior chamber • Otherwise normal anterior segment structures
- 61. Page 61 Management • Spectaclecorrection for high myopia to avoid amblyopia. • 2 stage procedure: epikeratplasty or tectonic lamellar corneo-scleral graft followed by penetrating keratoplasty weeks to months later • Protective eye wear is strongly encouraged and enforced.
- 62. Page 62 Anterior chambercleavage syndrome • Posterior embryotoxon • Axenfeld-Rieger syndrome • Peter’s anomaly • Iridogoniodysgenesis
- 63. Page 63 Posterior Embryotoxon •‡Thickened and centrally displaced anterior border ring of Schwalbe • ‡Schwalbe’s ring represents the junction of the trabecular meshwork with the termination of Descemet’s membranes. • ‡Usually inherited as a dominant trait
- 64. Page 64 Axenfeld-Rieger Syndrome •‡Represents a spectrum of disorders characterized by an anteriorly displaced Schwalbe’s ring (posterior embryotoxon), with attached iris strands, iris hypoplasia, and glaucoma in 50% of the cases occurring in late childhood or adulthood • Associated skeletal, cranial, facial, and dental abnormalities are often present
- 65. Page 65 • Transmissionis usually dominant (75%) for the Axenfeld-Rieger group, but it can be sporadic. • ‡Spectrum of mutations of transcription factors located in chromosome region 6p25, known as forkhead genes, are responsible for many developmental defects of the anterior chamber of the eye
- 66. Page 66 Peters Anomaly •‡3 anatomic components 1. Central posterior corneal defect in endo and DM with overlying corneal opacity 2. Keratoiridial adhesion 3. Corneaolenticular contact or cataract • Defective neural crest cell migration in 6th-8th week of gestation.
- 67. Page 67 • ‡80%bilateral • Inheritance is mostly sporadic • ‡Associated ocular anomalies present in ~50%of cases • Associated with systemic malformations in60% of cases
- 68. Page 68 Clinical Findings Associatedocular anomalies: ‡ • Keratolenticular touch • ‡Cataract • ‡Congenital glaucoma • ‡Microphthalmos • ‡Aniridia • ‡Persistent fetal vasculature Associated systemic malformations • ‡craniofacial anomalies • ‡External ear abnormalities • Hearing loss ‡ • ‡Peter’s plus’: short-limbed dwarfism, cleft lip/palate,learning difficulties
- 69. Page 69 Histopathologic Findings •Localized absence of the corneal endothelium and Descemet’s membrane beneath the area of opacity
- 70. Page 70 Corneal Dystrophies •‡Congenital hereditary stromal dystrophy • ‡Posterior amorphous corneal dystrophy • ‡Congenital hereditary endothelial dystrophy
- 71. Page 71 Congenital HereditaryStromal Dystrophy (CHSD) • ‡Extremely rare AD stationary dystrophy presents at birth with bilateral central superficial corneal clouding. • Anterior corneal stroma exhibits an ill-defined flaky or feathery opacity. ‡ • Cornea is clear peripherally ‡ • No edema, photopobia or tearing, but the opacities can be sufficiently dense to cause a reduction in vision
- 72. Page 72 Posterior AmorphousCorneal Dystrophy • ‡Rare autosomal dominant stromal dystrophy is bilaterally symmetric. • Appears early in life and may be congenital • Grouped vesicles, refractile geographic lesions, scalloped bands and peripheral iridocorneal adhesions
- 73. Page 73 • ‡Gray-white,sheet like stromal opacities concentrated in the posterior stroma. • ‡Epithelium appears normal, but Descemet’s membranes shows involvement, with focal areas of endothelial disruption • ‡Central corneal thinning • ‡Hyperopia • ‡Flattened corneal topography • ‡Anterior iris abnormalities • ‡Fine iris process extending to Schwalbe’s line for 360 degree.
- 74. Page 74 Congenital hereditary endothelialdystrophy (CHED) • ‡A cause of bilateral congenital corneal edema • ‡Due to primary dysfunction of the corneal endothelium, characterized by increased permeability and abnormal Descemet’s membrane secretion • ‡No consistent associations with other systemic abnormalities
- 75. Page 75 • Dominantform (CHED 1) • ‡Presents in the first or second year of life • ‡Slowly progressive • ‡Accompanied by pain, photophobia, and tearing but nystagmus is not present • ‡Cornea exhibits a diffuse, blue-gray, ground-glass appearance • ‡Primary abnormality: degeneration of endothelial cells during or after the 5th month
- 76. Page 76 • AutosomalRecessive Type(CHED 2) • ‡Presents at birth, remains stationary and • Accompanied by nystagmus • ‡Bluish white cornea may be 2-3 times normal thickness and have a ground-glass appearance, but this finding is not associated with tearing or photopobia • ‡Diffuse non bullous epithelial edema • ‡Uniform thickening of Descemet’s membrane may be seen, but no guttae changes are present
- 77. Page 77 Iridocorneal Endothelial Syndrome •‡Spectrum of disorders characterized by varying degrees of corneal edema, glaucoma and iris abnormalities • Corneal edema that precluded visualization of the posterior cornea
- 78. Page 78 Pathogenesis • ‡Unknownbut appears to involve an abnormal clone of endothelial cells that takes on ultrastructural characteristics of epithelial cells • ‡Varying degrees of endothelialization take place in the anterior chamber angle and on the iris surface.
- 79. Page 79 Clinical Findings •Iris atrophy, corectopia, polycoria (hallmarks of the essential iris atrophy variant) • Cogan-Reese (iris-nevus variant) • Chandler variant: hammered silver endothelium
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- 81. Page 81 Management • ‡Penetratingkeratoplasty • ‡Long-term graft clarity depends on the successful control of the IOP
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