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What are the two main functions of the ciliary body?
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How wide is the ciliary body?
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Ciliary Body, etc
Ciliary Body, Crystalline Lens, Iris
| Question | Answer |
|---|---|
| What are the two main functions of the ciliary body? | 1) secrete aqueous humor; 2) control accommodation of crystalline lens |
| How wide is the ciliary body? | approximately 6 mm wide |
| The ciliary body extends from the _________ to the ___________. | ora serata to the scleral spur |
| What is the outermost layer of the ciliary body? | Supraciliaris |
| What other name is the supraciliaris known as? | supraciliary lamina |
| Which part of the ciliary body is adjacent to the sclera? | supraciliaris |
| What is the supraciliaris made up of? | Loose, connective tissue arranged in ribbon-like layers |
| What three things does the supraciliaris contain? | pigmented melanocytes; fibroblasts; collagen bands |
| Why are the collagen bands in the supraciliaris important? | they allow the ciliary body to slide against the sclera without breaking |
| What is the flatter region of the ciliary body that extends from the posterior of the pars plicata to the ora serata? | Pars Plana |
| Which part of the ciliary body contains the ciliary processes? | The pars plicata |
| How many ciliary processes are in the ciliary body? | 70 to 80 |
| What is the length of the ciliary processes? | 2 mm |
| What are the regions between the ciliary processes called? | valleys |
| The zonule fibers attach to the pars plana or the pars plicata? | Both |
| The pigmented epithelium of the ciliary body is continuous with? | Iris epithelium and the retinal pigmented epithelium |
| The non-pigmented epithelium is composed of what type of cells in the pars plana? | Columnar |
| The non-pigmented epithelium is composed of what type of cells in the pars plicata? | Squamous |
| Posteriorly the non-pigmented epithelium becomes...? | retinal nervous tissue |
| Which epithelial cells are active and secrete aqueous? | The non-pigmented epithelial cells |
| What type of tissue is the ciliary muscle made up of? | Involuntary, smooth muscle tissue |
| The ciliary muscle is used for...? | focusing at near |
| When the ciliary muscle contracts the lens gets a _______ front and back surface. | steeper |
| When the muscle contracts it takes the tension off of the ____________, allowing the lens to get rounder for ____________. | zonule fibers; accommodation |
| What are the three types of muscle fibers in the ciliary muscle? | Longitudinal; Radial; Annular |
| Which muscle type lies adjacent to the supraciliaris? | Longitudinal |
| Which muscle type is the middle transition? | Radial |
| What is the innermost region of the ciliary muscle? | Annular tissue |
| The ciliary stroma is highly vascularized, true or false? | true |
| What type of tissue is the ciliary stroma made of? | Loose, connective tissue |
| The ciliary stroma lies between which layers of the ciliary body? | Between the muscle and epithelial layers |
| What forms the core of each of the ciliary processes? | The ciliary stroma |
| Is the crystalline lens vascular? | No, it is avascular. |
| What is the location of the crystalline lens? | In the posterior chamber, anterior to the vitreous chamber. |
| Is the crystalline lens biconvex or biconcave? | biconvex |
| What is the thickness of the unaccommodated lens? | 3.5-5 mm |
| What is the diameter of the lens at infancy? | 6.5 mm |
| What does the diameter of the lens reach during the teenage years, and then doesn't change much? | 9.0 mm |
| How much does the thickness of the lens increase each year? | .02 mm |
| What is the power of the unaccommodated lens? | 20 diopters |
| What the eye accommodates it __________ the power of the lens. | increases |
| At what age do we have the max accommodative amplitude? | Ages 8-12 |
| What is the max acommodative amplitue? | 14 diopters |
| At what age do you have zero accommodative power | 50 |
| What is the lens capsule? | A transparent envelope that surrounds the entire lens |
| What is the lens capsule classified as? | A basement membrane |
| What is the capsule primarily made of? | collagen |
| The anterior capsule ________ with age. | Thickens |
| What is the anterior capsule secreted by? | anterior lens epithelium |
| The anterior lens capsule is how thick? | 1 mm |
| Does the anterior lens epithelium produce new cells? | Yes |
| The new cells in the anterior lens epithelium form the _______, when they elongate and the nuclei move with the cytoplasm. | lens bow |
| Old cells go towards the ________________? | embryonic nucleus |
| What are the primary lens fibers that form the very center of the crystalline lens? | Embryonic nucleus |
| When are the fetal nucleus fibers laid down? | Before birth |
| Which fibers are formed between birth and sexual maturation? | Adult Nucleus |
| When is the lens cortex formed? | After sexual maturity |
| Do cells in the lens get larger as the get older? | No, they shrink |
| What else happens to cells in the lens as they get older? | loose their nuclei; migrate towards the center; become compressed |
| What happens to the nucleus of the lens as it ages? | It becomes larger and less transparent |
| How much bigger is the lens at age 65, than at age 20? | 1/3 larger |
| What is the primary function of the lens? | Refracting light |
| In the center of the lens (light path) there are many or few cells? | Very few cells |
| What does the lens contain that allows it to be transparent? | An orderly arrangement of collagen fibers |
| What is the index of refraction of the lens? | 1.42 |
| The crystalline lens transmits light including which wavelengths? | 400 to 1000 nm |
| The cornea absorbs wavelengths below ___nm? | 300 |
| The lens absorbs wavelengths between ___ and __nm? | 300 and 400 |
| Light greater than ___ nm will transmit to the retina. | 400 |
| Any opacity of the crystalline lens is technically considered a ________? | cataract |
| What is the most common type of cataract? | Age related/senile |
| What are age related/senile cataracts linked to? | Long-term exposure of UV rays |
| What kind of cataracts are linked to German measles (rubella) in the mother during pregnancy? | Congenital |
| What can cause traumatic cataracts beside trauma to the eye? | Exposure to certain gasses |
| What is an opacity located in the embryonic or fetal nucleus? | Nuclear cataract |
| What is the most common type of nuclear cataract, characterized by a yellowing of the lens. | Senile Nuclear Sclerosis |
| Which type of cataract is an opacity located in the cortex? | Cortical |
| A cortical cataract is only problematic when...? | It spreads to the central vision |
| Where is a posterior subcapsular cataract located? | on the backside of the crystalline lens |
| What causes a posterior subcapsular cataract to form? | irregular migration of the epithelial cells |
| What has been linked to posterior subcapsular cataracts? | Long-term use of steroids |
| What type of cataract develops from elevated glucose levels and is characterized by decreased transparency. | Diabetic cataracts |
| What type of anesthetic is used for cataract surgery? | Local anesthesia |
| What type of incision is required for cataract surgery? | A small incision into the anterior chamber |
| What is opened during cataract surgery? | The anterior lens capsule |
| What is removed, and what is left intact during cataract surgery? | The epithelium and all lens fibers are removed, leaving only the capsule intact. |
| What is an IOL? | intra-ocular lens |
| What is the main function of the iris? | To regulate the light let in through the pupil |
| What divides the anterior chamber from the posterior chamber? | Iris |
| Where is the center of the pupil located in relation to the center of the iris? | Slightly medial (nasal) and inferiorly |
| The pupil can vary from _ to _ mm, depending on illumination. | 1 to 9 mm |
| The pupil is myotic (smaller) in what conditions? | brightly lit conditions |
| The pupil is mydriatic (bigger) in what conditions? | dimly lit conditions |
| What is the diameter of the iris? | 12 mm |
| Which epithelium lies nearest to the stroma in the iris? | Anterior epithelium |
| What is the anterior epithelium of the iris made uop of? | myoepithelial cells |
| The anterior epithelium is the only structure in the body that contains myoepithelial cells, true or false? | True |
| Which epithelium in the iris is heavily pigmented? | Posterior epithelium |
| What is the pupillary ruff (frill)? | When the epithelial cells curls around from the posterior iris to the anterior iris. |
| What does the pupillary frill encircle? | pupil |
| What color is the pupillary frill? | copper |
| The pupillary frill has a ________ appearance. | serrated |
| What is the collarette? | A circular ridge 1.5mm from the pupillary margin, that separates the iris into the ciliary and pupillary zones. |
| What is the outer edge periphery of the iris? | The iris root |
| How thick is the iris root? | .5 mm |
| What is the thinnest part of the iris? | iris root |
| The iris root joins the iris to the...? | ciliary body |
| What is iridodialysis? | a blunt trauma to the eye, where the root of the iris tears away from the ciliary body |
| What complications are caused from iridodialysis? | hemorrhaging and paralysis of the muscles in the eye |
| What does the stroma in the iris contain? | fibers and blood vessels and melanocytes which contain melanin |
| Where is the sphincter muscle located? | within the pupillary zone of the stroma |
| What type of cells is the sphincter muscle made up of? | smooth muscle cells |
| How wide is the sphincter muscle? | .75 to 1 mm |
| Contraction of the sphincter muscle causes...? | the pupil to constrict (myosis) |
| The sphincter muscle is innervated (activated) by the...? | parasympathetic nervous system |
| The parasympathetic nervous system is part of the _________ system, which means you don't have to think about it. | autonomic |
| Sympathetic nervous system, example dilation of the pupil, causes... | speeding up |
| The parasympathetic nervous system, example constriction of pupils, causes... | slowing down |
| The contraction of the dilator muscle...? | pulls the pupillary portion of the iris towards the root, enlarging the pupil |
| What is the contraction of the dilator muscle known as? | Mydriasis |
| Dilation is a ___________ muscle? | sympathetic |
| What are holes in the front of the iris that allow aqueous quick exit and entrance to the stroma of the iris. | crypts |
| What factor decide iris color? | The arrangement and density of connective tissue in the anterior border and stroma, and the amount of pigment. |
| If the iris is heavily pigmented, the anterior of the iris will appear...? | brown and smooth |
| Lighter irises will appear...? | Blue, grey, or green |
| What causes albinos to have red eyes? | There is no pigment in the epithelial layer |
| What is an area of hyper-pigmentation on someone's iris? | Nevus |
| What is it called when someone has two different colored irises, or if a portion of one's iris is different from the rest. | heterochromia |
| What is an iris synechiae? | An abnormal attachment of the iris surface to another surface. |
| What is an iridectomy? | A wedge-shaped, full thickness section of the iris is removed for aqueous flow. |
| What is an iridotomy? | Hole going through the iris to allow aqueous flow, performed by a laser. |
| Which is less invasive, an iridectomy or iridotomy? | iridotomy |
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griffiskr
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