ANATOMY OF THE HUMAN EYE

Anatomy of the eye includes lacrimal gland, cornea, conjunctiva, uvea (iris, choroid & ciliary body), lens, blood supply, retina, vitreous & optic-nerve. For ophthalmologists, optometrists, medical, dental, and optometry students, eye-anatomy forms the basis for eye-pathology in diseases: dry eye, retinal detachment, macular degeneration, diabetic retinopathy, eye-trauma etc.

About Mission for Vision

 
Web www.missionforvisionusa.org

Monday, March 06, 2006

What is the choroid?

The choroid is that part of the uveal tract extending from the edge of the optic nerve head to the ora serrata. The choroid underlies the retinal pigment epithelium and is continuous anteriorly at the ora serrata with the ciliary body.
ATTACHMENTS:
The choroid is part of the uveal tract which includes the iris and ciliary body as well. The uveal tract is attached at 3 sites:
1. the scleral spur
2. internal scleral exit channels of the vortex veins
3. optic nerve
The usually heavily pigmented posterior or choroidal portion of the uveal tract is loosely adherent to the overlying sclera. This plane of loose attachment is a zone of potential separation known as the suprachoroidal space that is common to both the choroidal and ciliary portions of the uveal tract. The suprachoroidal space has relevance for massive choroidal edema, clinically referred to as "choroidal detachments" or in local parlance as "choroidals". Attachment of the longitudinal (meridional) ciliary muscle to the scleral spur limits the space . The enlargement is limited posteriorly by attachment of the choroid to the sclera, augmented by the outward passage of the vortex veins, by the perforating short posterior ciliary arteries and by border tissue at the scleral aperture for the optic nerve.
VASCULATURE: The choroid is richly vascular and provides nutrients for the outer portion of the retina including the photoreceptors and the retinal pigment epithelium . It has an extremely rapid blood flow which is provided by the choriocapillaris, inner vascular layer and outer vascular layer. The capillary layer of the choroid, the choriocapillaris, lies directly under Bruch’s membrane and is critical to supply retinal photoreceptors. The larger arteries are found most readily in the outer layers of the posterior choroidal stroma. The long posterior ciliary arteries and their corresponding long ciliary nerves lie within the suprachoroidal space in the horizontal plane, encased by collagenous tissue. Branches from the nerves to the adjacent choroid form small net-like arrangements where large ganglion cells may be observed. The venous drainage system is seen as four vortex systems each located in a posterior quadrant. Each system converges to form a single vestibule, the ampulla, which then exits through the sclera by a vortex vein.
STROMA: The choroid contains flattened or interconnecting collagen lamellae that give the melanocytes a spindle shaped appearance. These melanocytes have a stellate shape and contain pigment granules. The cells contain small oval nucleoli. They are usually accompanied by the fibrovascular stroma of the choroid. The melanocytic cells cells are considered to be the source for the most common primary malignant neoplasm of the eye- melanoma.



REFERENCES

  1. Jakobiec FA. Ocular anatomy, embryology, and teratology. Philadelphia: Harper & Row, 1982
  2. Hogan MJ, Alvarado JA, Weddell JE. Histology of the human eye. Philadelphia: W.B. Saunders, 1971.
  3. Last RJ. Eugene Wolff’s anatomy of the eye and orbit. Philadelphia: W.B. Saunders, 1961.
  4. Fine BS, Yanoff M. Ocular histology, a text and atlas. New York: Harper and Row, 1972
  5. Strenstrom S. Untersuchungen uber die variation unk kovariation der optishen elemente des menshlickhen auges. Acta Ophthalmol 1946;26:1.
  6. Duke-Elder WS. The anatomy of the visual system. In: System of ophthalmology. St. Louis: CV Mosby, 1961;2:410-413
  7. Greiner JV, Covington HI, Allansmith MR. Surface morphology of the human upper tarsa conjuctiva. Am J Ophthalmol 1977;83:892-905.
  8. Dark AJ, Durrant TE, McGinty F, Shortland JR, et al. Tarsal conjuctiva of the upper eyelid. Am J Ophthalmol 1974;77:555-564.
  9. Hogan MJ, Alvarado JA, Weddell JE. Histology of the human eye. Philadelphia: W.B. Saunders, 1971.
  10. Blumcke S, Morgenroth K Jr. The stereo ultrastructure of the external and internal surface of the cornea. J Ultrastruct Res 1967;18:502.
  11. Hogan et al., Histology of the human eye, 202-255.
  12. Glasgow BJ. Intraocular fine needle aspiration of coronal adenomas. Diagn Cytopathol 1991;7:239-242.
  13. Tolentino FI, Schepens CL, Freeman HM. Vitreoretinal disorders, diagnosis and management. Philadelphia: W.B. Saunders, 1976;1-43.
  14. Sebag J, Balazs EA. Morphology and ultrastructure of human vitreous fibers. Invest Ophthalmol Vis Sci 1989;30:1867-1871.
  15. Foos RY. Vitreoretinal juncture: topographical variations. Invest Ophthalmol Vis Sci 1972;10:801-808.
  16. Foos RY. Anatomic and pathologic aspects of the vitreous body. Trans Am Acad Ophthalmol Otolaryngol 1973;77:OP171-OP183.
  17. Gartner J. Histologische Beobachtugen uber physiologische vitreovaskulare. Adharenzen Klin Mbl Augen 1962;141:530-545.
  18. Foos RY. Vitreous base, retinal tufts, and retinal tears: pathogenic relationships. In: Pruett RC and Regan CCJ, ed. Retina Congress. New York: Appleton-Century-Crofts, 1974.

7 Comments:

Anonymous Anonymous said...

It's good to have the right resources when it comes to medical terms. This helps when you have questions about tucson dentists and their practice.

11:42 PM  
Blogger Unknown said...

Very good work! Thanks for sharing this post.
thesis examples

1:15 AM  
Blogger Unknown said...

The considerable thing about such advances is that the organizations as of now comprehend that you have had some current hits surprisingly report, else you would not approach them for help in any case. cash advance

11:36 AM  
Blogger Chris Greenwalty said...

According to dissertation proposal writing service, the choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye (at 0.2 mm), while in the outlying areas it narrows to 0.1 mm.

10:56 PM  
Blogger John said...

yeezy shoes
michael kors outlet online
canada goose coats
soccer jerseys
coach outlet online
chrome hearts outlet store
jordans
coach factory outlet online
kate spade outlet
minnesota vikings jersey
yolo

2:27 AM  
Blogger Gregory J. Trujillo said...

This comment has been removed by the author.

12:03 AM  
Blogger Plasma centre near me said...

I just wanted to express my heartfelt appreciation for the informative explanation of the choroid. Netflix Vs Lookmovie Compare Differences Reviews Your concise and clear description of its anatomy, function, and importance in the eye has helped.

5:27 AM  

Post a Comment

<< Home