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Cornea and Lens Histopathology Refractive Surgery Cataracts High Myopia
1. Cornea and Lens
Histopathology
Refractive Surgery
Cataracts
High Myopia
Chi-Chao Chan, M.D.
Immunopathology Section
Laboratory of Immunology
National Eye Institute
National Institutes of Health
2. Classification
Ocular Tissue (a
z)
cornea
Trabecular meshwork
Conjunctiva
conjunctiva
Cornea
sclera
Lens
Optic Nerve
retina
Orbit/Extraocular Muscles
Retina
vitreous
Sclera
Trabecular meshwork
Uvea (Iris, Ciliary body, Choroid)
Vitreous
iris
Ciliary body
lens
retina
choroid
sclera
optic nerve
The average size of a normal adult eye: 25 mm (h) x 24.5 mm (v) x 24 mm (AP)
3. Conjunctiva
Gross (Macroscopic structure):
» Palpebral (Tarsal) Conjunctiva
» Fornical Conjunctiva
» Bulbar Conjunctiva
epithelium
Microscopic Structure:
» Epithelium (two or more layers)
– Stratified epithelia, goblet cells
» Substantia propria (fibrovascular tissue including
nerves and lymphatics)
Substantia propria
6. 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).
8. LASIK
Photorefractive Keratectomy (PRK)
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.
Park, et al. Cataract Refract Surg 1999;25:842-50.
Wachtlin, et al. Refract Surg 1999;15:451-8.
Kato. Br J Ophthalmol 1999;83:1302-5.
16. 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.
17. INTACS
A. 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.
18. Neovascularization
• Corneal neovascularization is an unwanted
vascular growth into the avascular cornea.
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.
29. 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
38. Cataract: Exfoliation
•
•
•
•
Age related disease
Accumulation of abnormal fibrillar extracellular material
Anterior segment involvement
Cause cataract and glaucoma
SEM
a. SEM: lens capsule
b. TEM: lens capsule
c. TEM: lens epithelium
Z: zonular fiber/lamella
Ritch, Schlotzer-Schrehardt.
Surv Ophthalmol 2001;45:265315.
41. 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
42. 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
46. Posterior Staphyloma
• 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
47. 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
48. 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
•
49. Macular Foveoschisis
Tnag, et al. J Ophthalmol 2010, 2010:1-4.
• interbridging strands in the outer plexiform layer of the
macular region
• located mainly in the outer plexiform layer
50. 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
51. 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
52. 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
The cornea is the transparent anterior part of the eye’s tough fibrous outer coat and is the eye’s principal refractive element. The bulk of the cornea is comprised of interweaving lamellae of type I collagen fibers, which are spaced in an exquisitely regular fashion. Artifactitious clefts separate the stromal lamella in routine histologic sections. Cornea is composed of a nonkeratinized epithelium which usually five cells in thickness corvers the anterior surface of the cornea, , Bowman layer is a hyaline band of modified stroma, stroma Descemet’s membrane and a delicate monolayer of flattened endothelium. The stroma contains flattened dendritiform fibroblastlike cells called keratocytes.
Molecular analyses revealed 10 fold lower IP-10/CXCL10 mRNA and two fold higher CCL5 mRNA in the fibrous tissue surrounding the Intacs channels, as compared to the central corneal stroma. IP-10/CXCL10 is a fibrotic and angiostatic chemokine produced by macrophages, endothelial cells and fibroblasts. IP-10/CXCL10, a CXC chemokine, which promotes chemoattraction but inhibits angiogenesis, is secreted by monocytes, endothelial cells, fibroblasts and keratinocytes. IP-10/CXCL10 regulates wound healing and inhibits fibrosis in the lung. IP-10/CXCL10 also induces apoptosis in several cell types. Therefore, it is not surprising that only occasional apoptotic cells are detected in the collagen scar tissue.
Patient: Thomas McDonough
Left: Thomas McDonough
Right: Jacqueline Tran
Lattice degeneration: occurs more frequently in myopic than non-myopic eyes, however its incidence is greater in moderate than severe myopia
Lattice degeneration: occurs more frequently in myopic than non-myopic eyes, however its incidence is greater in moderate than severe myopia
Lattice degeneration: occurs more frequently in myopic than non-myopic eyes, however its incidence is greater in moderate than severe myopia
Margaret Bon
Study by Benhamou and colleagues and Fujimotoe et al.structure of macular retinoschisis inner and outer schisis, need for ILM detachment (21 eyes, 10 had foveal detachment, 9/10 had ILM detachment)
ILM detachment
ELM to OPL detachment
Margaret Bon
Study by Benhamou and colleagues and Fujimotoe et al.structure of macular retinoschisis inner and outer schisis, need for ILM detachment (21 eyes, 10 had foveal detachment, 9/10 had ILM detachment)
ILM detachment
ELM to OPL detachment
30-50% of eyes will go on to develop CNV over the next 10 years