Corneal transparency
-
Upload
ikramdr01 -
Category
Health & Medicine
-
view
266 -
download
0
Transcript of Corneal transparency
![Page 1: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/1.jpg)
CORNEAL TRANSPARENCY
JAYADEVI.A
![Page 2: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/2.jpg)
Primary physiological functions of the cornea is to maintain its transparency and protect the intraocular contents
Cornea consists of three layers epithelium stroma endothelium
![Page 3: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/3.jpg)
FACTORS DETERMINING TRANSPARENCY Peculiar arrangement of corneal lamellae
Avascularity
Relative state of dehydration
Metabolism of cornea
Higher difference between refractive index of cornea and air
![Page 4: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/4.jpg)
STROMA
Transparency of cornea is related to the regularity of stromal components
Stroma is composed of type1 collagen fibers set in ground substance of mucopolysaccharides
This ribbon like bundle formation gives the laminated appearance
Collagen fibers are spaced equidistantly and form the hexogonal lattice
![Page 5: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/5.jpg)
LATTICE THEORY Lattice formation leads to interfibrillar
spacing of less than the wave length of light.
so that tangential rows of fibers acts as a diffraction grating resulting in destructive interference of scattered rays
![Page 6: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/6.jpg)
GOLDMAN AND BENEDEK THEORY It is based on dimension of refractive
elements in corneal stroma. There is least scattering of light till
spatial dimension of variations in refractive index remains <200 nm.
![Page 7: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/7.jpg)
Corneal avascularity is maintained by PAX6 GENE & DESTRIN
The main source of nutrition is atmospheric air-oxygen perilimbal capillaries aqueous humor The relative state of corneal dehydration is
mainly due to epithelial and endothelial pumps
![Page 8: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/8.jpg)
•
![Page 9: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/9.jpg)
Atmospheric oxygen dissolved in pre corneal tear film
perilimbal capillaries & aqueous provides solutes
Deeper parts of cornea obtains nutrition from aqueous
Endothelium needs oxygen and glucose for metabolic activity & proper functioning of pump
![Page 10: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/10.jpg)
Cornea derive their energy requirements from phosphorylation of carbohydrates and auto oxidative system
Glucose enters cornea either by simple diffusion or active transport
Breakdown of glucose in cornea occurs by aerobic & anaerobic process into carbondioxide & lactic acid
![Page 11: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/11.jpg)
Recent studies suggested that corneal keratocytes contain two water soluble proteins
transketolase aldehyde dehydrogenase class 1A1
![Page 12: Corneal transparency](https://reader035.fdocuments.us/reader035/viewer/2022070602/587c2b1c1a28aba0118b5501/html5/thumbnails/12.jpg)
Thank you