cornea and lens histopathology refractive surgery cataracts high myopia
DESCRIPTION
Chi-Chao Chan, M.D. Immunopathology Section Laboratory of Immunology National Eye Institute National Institutes of HealthTRANSCRIPT
Cornea and LensCornea and Lens
Chi-Chao Chan, M.D.
Immunopathology Section
Laboratory of Immunology
National Eye Institute
National Institutes of Health
HistopathologyRefractive Surgery
CataractsHigh Myopia
ClassificationClassificationClassificationClassification
Conjunctiva Cornea Lens Optic Nerve Orbit/Extraocular Muscles Retina Sclera Trabecular meshwork Uvea (Iris, Ciliary body, Choroid) Vitreous
corneacornea
conjunctivaconjunctiva
sclerasclera
irisirisCiliary bodyCiliary body
lenslens
retinaretina
choroidchoroid
sclerasclera
optic nerveoptic nerve
vitreousvitreous
Ocular Tissue (a z)
Trabecular meshworkTrabecular meshwork
retinaretina
The average size of a normal adult eye: 25 mm (h) x 24.5 mm (v) x 24 mm (AP) The average size of a normal adult eye: 25 mm (h) x 24.5 mm (v) x 24 mm (AP)
ConjunctivaConjunctivaConjunctivaConjunctivaGross (Macroscopic structure):
» Palpebral (Tarsal) Conjunctiva » Fornical Conjunctiva» Bulbar Conjunctiva
Microscopic Structure:» Epithelium (two or more layers)
– Stratified epithelia, goblet cells
» Substantia propria (fibrovascular tissue including nerves and lymphatics)
epitheliumepithelium Substantia propriaSubstantia propria
CorneaCorneaCornea
Epithelium
Bowmanlayer
Stroma
Keratocyte
Descement membrane
Endothelium
CorneaCorneaCorneaCornea
Diameter: 11.5 x 10.5 mm (adult)
Layers (520-540 mm centrally):» Epithelium (5-6 layers)» Bowman’s Layer (8 -14 nm)» Stroma (90% thickness)» Descemet’s Membrane (10-12 mm)» Endothelium (single layer)
Nerve: unmyelinated nerves
Avascular tissue
Refractive Surgery
An eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses
Remodeling of the cornea The most common methods today use excimer
lasers to reshape curvature of the cornea Successful refractive eye surgery can reduce or
cure common vision disorders such as myopia (near sight), hyperopia (far sight) and astigmatism (non-perfected spherical cornea).
Refractive Surgery Radial Keratotomy (RK) Astigmatic Keratotomy (AK) Automated Lamellar Keratoplasty (ALK) Laser Refractive Surgery
– Phototherapeutic Keratotomy (PTK) – Photorefractive Keratectomy (PRK)– Laser In Situ Keratomileusis (LASIK)– EPI-LASIK– Customized Transepithelial No-touch (C-TEN)
Intrastromal Corneal Ring (Intacs)
LASIK
LASIK: Laser Assisted In Situ Keratomileusis A type of refractive surgery Wound healing only at the periphery of micotome incision Stromal reaction less after LASIK than PRK Requires a long time for wound healing
Perz-Santonja, et al. Refract Surg 1998;14:601-9. Wachtlin, et al. Refract Surg 1999;15:451-8.Park, et al. Cataract Refract Surg 1999;25:842-50. Kato. Br J Ophthalmol 1999;83:1302-5.
Photorefractive Keratectomy (PRK) LASIK
LASIK
LASIK
Intralamellar scar
• Origin of lamellar binding:• Binding of collagen fibrils• Interweaving of lamellae• Stabilization by ground substance
(extracellular matrix)Maurice & Monroe. Exp Eye Res 1990;50:59-63.
LASIKMicrokeratome
Courtesy of J. Douglas Cameron, MD
LASIKMicrokeratome
Courtesy of J. Douglas Cameron, MD
LASIKFemtosecond Microkeratome: Flap Hinge
Courtesy of J. Douglas Cameron, MD
LASIK
Microkeratome:
Flap hinge
Courtesy of J. Douglas Cameron, MD
LASIK
Microkeratome:
Flap hinge
Courtesy of J. Douglas Cameron, MD
INTACS• A 47-yr-old man with a history of keratoconus and failure of using a Rigid Gas Permeable (RGP) contact lens, O.S.
• Implantation of Intacs, O.U.
• 10 mons later: Multiple, whitish, small crystalline deposits around the edges and the border of the superior Intacs segment nasally
• Penetrating keratoplasty, O.S.
Cao, et al. J Med Case Rep 2011, 5:398.
INTACSA. A space containing residue
plastic (Intacs) material is surrounded by a dense acellular/ hypocellular collagen scar. The channel haze is observed at the inner edge of Intacs.
B. The severely attenuated corneal endothelial cells.
C. The acidophilic densification and mild inflammatory cell infiltration at the inner edge of Intacs.
D. Immunochemistry of CD68 shows macrophage (CD68+) infiltration at the inner edge of Intacs.
Cao, et al. J Med Case Rep 2011, 5:398.
Neovascularization
Contact lens causing» Soft contact lens wearers - micropannus
Inflammation» Vascularized pannus» Stromal keratitis – e.g., Cogan syndrome
Stem cell deficiency Poor wound healing
» Corneal transplantation under 2 yr.
• Corneal neovascularization is an unwanted vascular growth into the avascular cornea.
Neovascularization
Stem cell deficiency due to graft vs host disease
Neovascularization
Cogan Keratopathy
Courtesy of. David G. Cogan, MD
LensLensLensLens
Lens
Cornea
Cornea
Lens
LensLensLensLensGross (Macroscopic structure):- Soft, elastic, avascular, transparent, highly refractile, biconvex
structure composed of mainly crystallins
- Anterioposterior: 3.5 - 5 mm (birth-adult) Equatorial: 6.4-9.0 mm (birth-adult)
Microscopic Structure:- Capsule
- Zonules- Lens Cells: Epithelium
- Anterior
- Equatorial
- Cortex and Nucleus
capsulecapsule
epitheliumepithelium
cortexcortex
nucleusnucleus
LensLensLensLensMicroscopic Structure: Capsule Zonules Lens Cells: Epithelium
- Anterior - Equatorial
Cortex and Nucleus
capsulecapsule
epitheliumepithelium
cortexcortex
nucleusnucleus
Posterior lens
C.B.
Zonules
Photographs using a fish-eye lens
Transparent tissues:• Cornea• Lens
LensLensLensLens
Lens epithelial cellLens epithelial cell
Lens Equator:Lens Equator:• CapsuleCapsule• EpitheliaEpithelia• Lens fiberLens fiber
Bow regionBow region
LensLensLensLens
Lens: Congenital Cataracts
• Congenital cataract: opacity present at birth• Infantile cataract: opacity during 1st year life • Spherophakic
• Lamellar, Polar, Sutural, Coronary, Cerulean, Nuclear, Capsular; Complete, Membranous
• Rubella
Lens: Congenital Cataracts
Pierre Robin Trisomy 18 PHPV
*
Trisomy 13
Lens: Adult Cataracts
Aging– Nuclear, Cortical, Posterior Subcapsular– In theory, everyone would get cataract if one lives long enough
Drug-induced– Corticosteroids, Phenothiazines, Miotics, Aminodarone, etc.
Trauma– Contusion, Injury: mechanical, chemical, radiation, etc.
Metabolic– Diabetes Mellitus, Galactosemia, Wilson Disease, etc.
Nutritional
Lens: Adult Cataracts
Exfoliation Syndrome – True Exfoliation – Exfoliation Syndrome (Pseudoexfoliation)
Cataract Associated with Uveitis Cataract & Skin Diseases
– Atopic Dermatitis Glaukomflecken Cataract Associated with Degenerative
Disorders– Retinitis Pigmentosa, Essential Iris Atrophy, etc.
Cataract: Anterior
Cataract: Equator
Cataract: Nucleus
Cataract: Posterior
Cataract: Soemmering’s Ring
• Dumbbell shape• Congenital• IOL
Cataract: Periphery
Cataract: IOL
• Cortical cleanup• IOL material• Optic edge
design• Anterior capsule
Cataract: Exfoliation
• Age related disease• Accumulation of abnormal fibrillar extracellular material• Anterior segment involvement• Cause cataract and glaucoma
a. SEM: lens capsuleb. TEM: lens capsulec. TEM: lens epithelium
Z: zonular fiber/lamella
Ritch, Schlotzer-Schrehardt. Surv Ophthalmol 2001;45:265-315.
SEM
Axial Myopia Average axial length of normal eye is
23.5-24.0 mm
Fundus Manifestations Tilted optic nerve Peripapillary chorioretinal atrophy Peripheral retinal changes Myopic Maculopathy
Posterior staphyloma Macular schisis Atrophic changes in the RPE and choroid Lacquer cracks Choroidal neovascularization Macular atrophy
Tilted Optic Nerve Head
• Because of the elongated eye, the nerve inserts obliquely• Most commonly, the nerve head is tilted toward the temporal side• This can make the assessment of the cup:disc ratio difficult and OCT nerve may be unreliable
Peripapillary Chorioretinal Atrophy
• Due to tangential tractional forces of the elongating globe, the RPE, Bruch’s membrane, and choroid fall short of reaching the entrance of the nerve into the eye, and bare sclera is seen
Peripheral Retinal Changes
Lattice degeneration Paving-stone degeneration Pigmentary degeneration Chorioretinal atrophy White without pressure Retinal holes Retinal tears Retinal detachments
Lattice Degeneration
• Can develop retinal tear, breaks/holes• May progress to retinal detachment
Paving-stone Degeneration
Cobblestone degeneration
• Abnormal elongation of the globe and the attenuation of the sclera are accompanied by a localized ectasia involving the sclera, choroid, and RPE (outward bowing)
• Histologically, staphylomas contain decreased amounts of scleral collagen bundles and decrease in caliber
• Axial length elongation and/or posterior staphyloma may generate inward tractional force which is opposed by the residual posterior vitreous cortex, ILM, and/or retinal vessels
• Detected in 9-35% of highly myopic eyes with posterior staphylomas
• Majority remain stable• Can lead to foveal detachment and/or macular hole
Posterior Staphyloma
• The prevalence and severity of staphylomas are found to increase with greater age, eye length, and myopic refraction
• Most commonly involves the posterior pole, extending from 2 to 5 disc diameters nasal to the optic nerve to an area involving the macula
• Best seen on B-scan ultrasound
Posterior Staphyloma
Macular Foveoschisis
• Detected in 9-35% of highly myopic eyes with posterior staphylomas
• Majority remain stable• Can lead to foveal detachment and/or macular hole
Macular Foveoschisis
• interbridging strands in the outer plexiform layer of the macular region
• located mainly in the outer plexiform layer
Tnag, et al. J Ophthalmol 2010, 2010:1-4.
Atrophic Changes in the RPE and Choroid
Early degenerative changes affect the choriocapillaris and RPE – Loss of choroidal melanocytes and RPE atrophy
'tessellated/tigroid' fundus
Atrophic Changes in the RPE and Choroid
In later stages, the neuroretina also becomes atrophic leading to generalized and/or patchy atrophy– Vision may begin to be affected at this stage
Lacquer Cracks
• Yellow-white linear or stellate lesions that are typically horizontal oriented and branched• Represent mechanical breaks of the RPE, Bruch’s membrane, and choriocapillaris from
elongation of the globe• Usually occur in eyes >26.5 mm in length and more common in males• Macular hemorrhages can sometime occur in the crack in the absence of CNV• Number usually increase over time and can be associated with the development of atrophy• Important prognostic factor for the development of CNV
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