Eye Pathophys Flashcards by Tyler VanNoord

What is the basic anatomy of the sclera?

Thick, white, transparent at the cornea

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What is the basic anatomy of the choroid?

Deeply pigmented, contains blood vessels, and the Iris is part of the choroid

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What is the basic anatomy of the Retina?

Has rods and cones, converts light energy into nerve impulses

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What is present at the Fovea centralis?

Only cones. This is where the greatest visual acuity occurs.

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Which bones make up the orbit?

Zygomatic
Sphenoid
Frontal
Ethmoid
Lacrimal
Palatine
Maxillary

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Which bone making up the orbit is the thinnest and what can result from this?

Ethmoid- orbital cellulitis can result if infection erodes through from the sinus

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What is the origin of the occular muscles?

Annulus of Zinn

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What does the annulus of zinn encircle?

optic n.

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What is characteristic of the lower canaliculus in children?

It’s smaller= inc risk for infection.

Massage can keep the duct open.

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What is the mechanism for thyroid-related orbitopathy(Graves Dz)?

T cells secrete cytokines(TNF, interferon) which stimulates fibroblast proliferation. Fibroblasts synthesize extracellular matrix proteins to 1)inc hydrophilic glycosaminogycans (Hyaluronic acid) and 2) inc osmotic pressure= fluid accumulation.

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What is the manifestation of thyroid related orbitopathy?

Proptosis
Strabismus/muscle-restriction
Exposure problems
Compressive optic neuropathy.

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Thyroid related orbitopathy Tx?

Steroids
Radiation therapy
Surgical decompression (opening the orbital walls into the sinuses)

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What are the most frequent primary tumors of the orbit?

Most are vascular in origin
Capillary hemangioma
Cavernous hemangioma
Lymphangioma

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What are characteristics of capillary hemangiomas?

“spider”, thinner

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What are characteristics of cavernoushemangiomas?

more dense/dilated

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What is the most common primary malignancy of the orbit in children?

rhabdomyosarcoma

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What is the most common metastatic tumor in children?

neuroblastoma- 20% develop orbit metastasis

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Where will the gaze likely be in orbital floor fx?

Restricted upgaze if there is muscle entrapement

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How critical are orbital floor fx?

Typically require hospitalization

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What are the tarsal glands AKA?

Meibomian glands

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What are the malignant tumors of the eyelids?

Basal cell carcinoma – most common
Sebaceous carcinoma
Squamous
Melanoma

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What can occur if basal cell carcinoma is not completely removed?

inc risk of becoming squamous cell carcinoma

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What causes a Chalazion?

chronic inflammatory lesion of the meibomian gland

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What secretes the mucinous components of the tear film?

goblet cells

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What causes conjunctivitis?

viral(adenovirus), bacterial, or allergic cause

What can result from chlamydial conjunctivitis?

scarring causing a dec in goblet cells leading to dec in mucin

Bacterial conjunctivitis Tx?

usually self limited in 10-14 days

Allergic conjunctivitis Tx?

antihistamines, vasoconstrictors, and steriods

What does conjunctiva intraepithelial neoplasia(CIN) often preceed?

Squamous cell tumor

What is the Limbus?

Border of the cornea and the sclera. The limbus is a common site for the occurrence of corneal epithelial neoplasm.

Where do lymphoidic conjunctiva tumors arise from?

mucosa-associated lymphoid tissue (MALT)

What are conjunctiva squamous papilloma and conjunctiva intraepithelial neoplasia(CIN) associated with?

HPV 16 and 18

Is the cornea vascularized?

What are the 5 layers of the Cornea?

``` Epithelium Bowmans Membrane Stroma Descemet's membrane Endothelium ```

What is the anatomy of the Cornea epithelium?

Continuous with conj, richly innervated by CN-V1

What is the anatomy of the Corneal Stroma?

The thickest central portion (90%). | Primarily made up of Type 1 Collagen in uniformly-spaced lamellar bundles.

Where does copper deposition occur in Wilsons disease (Kayser-Fleischer ring)?

Descemet's membrane layer of the cornea

What is the function of the endothelial layer of the cornea?

pumps the water out of the cornea and keeps it clear

Where does LASIK/Refractive surgery happens?

Corneal Stroma

What is Keratitis?

inflammation of the cornea

What is the most common cause of bacterial keratitis?

Pseudomonas

What is the most common cause of viral keratitis?

HSV

What are the signs of HSV Keratitis?

epithelial "dendritic" lesions

What are the signs of Bacterial Keratitis?

Hypopyon

What is Stromal dystrophy?

a heritable disorder resulting in abnormal tissue morphology, function, or abnormal depositions of material into the cornea.

What is ectasia?

progressive deformation of the cornea

What is the most common ectatic dystrophy?

Keratoconus

What can be a complication of refractive surgery?

Ectasia

ectasia Tx?

refer to ophthalmology

What composes the Uvea?

Iris, ciliary body, and the choroid

What is the function of the iris?

diaphragm for light

What is the function of the ciliary body

suspends and flexdes the lens, also makes the aqueous humor

What is the function of the choroid

nourishes the outer retina

where is the angle of the uvea?

where the iris meets the cornea

What is the function of the angle of the uvea?

regulates the outflow of aqueous humor through the canal of Schlem. This determines intraocular pressure.

What serious systemic Dzs can uveitis be associated with?

arthritis, IBD, vacuities, torch syndrome

What is commonly seen in anterior uveitis?

WBC's floating in aqueous humor

What is seen in posterior uveitis?

active toxoplasmosis choroiditis, old scars

Why is the choroid a potential target site for metastasis?

It is highly vascularized

What has the highest protein content in the body and what is the significance of this?

Lens- creates a high refractive index

What focuses light on the retina

The lens in concert with the cornea

What happens the the central fibers of the lens with aging?

they become sclerotic and opaque making the lens flatten with time

What are pathogenic factors of cataracts

UV light, steroids, and inflammation

What type of cells are in the retina?

Photoreceptors-detect light Bipolars-transmit signal to ganglion cells Ganglion cells- send signal by long axon through optic n.

Which side of the optic disc do retinal arteries and veins emerge from?

nasal side

Which direction do arching retinal vessels go?

toward the temple

which direction do radial retinal vessels go?

toward the nose

Do retinal arteries contain a muscular coat?

What do retinal arteries drain?

innner retina(retinal ganglion cells and their axons and the bipolar cells)

What drains the outer retina(rods and cones)?

choroidal circulation

Where does retinal detachment occur?

between the retinal pigment epithelium(RPE) and photoreceptor(neurosensory) segments

What causes Macular degeneration?

Bruch’s membrane damaged by deposition of drusen, allowing leaky choroidal vessels to grow into retina (exudative type).

What causes Drusen?

mucoproteins and mucopolysaccarides that progressively calcify, leaving remnants of axonal transport system of degenerative retinal ganglion cells. Occurs in both wet and dry macular degeneration

What are the 2 types of retinal detachment?

Tear (most common), seperation

What are characteristics of atrophic macular degeneration?

Discrete deposits in the Bruch membrane(drusen)

What are characteristics of neovascular macular degeneration?

Presence of angiogenic vessels originate from choroid capillaries Penetrate Bruch membrane and may penetrate the RPE. Vessels may leak causing macular scars.

Neovascular macular degeneration Tx?

VEGF antagonists(antibodies to growth factors)

What is characteristic of hemorrhage form of macular degeneration?

sudden onset of painless, blurred, or warped vision called metamorphopsia.

What can cause microvascular Dz in the retina?

Dm, Sickle cell, radiation

What occurs in the preproliferative phase of diabetic retinopathy?

Glu and sorbitol levels are high=Retinal blood vessels thicken= 1)dec O2 perfusion=up regulation of VEGF and 2)vessles become flimsy=microaneurysusms occure

What occurs in the proliferative phase of diabetic retinopathy?

retinal angiogenesis=retina becomes thicker

Consequences of Diabetic Retinopathy?

Vitreous humor detachment “posterior vitreous detachment” May precipitate massive hemorrhage Organization of retinal neovascular membrane may wrinkle the retina Traction retinal detachment

What is the best prevention of Diabetic Retinopathy?

blood glucose control

Diabetic Retinopathhy Tx?

lasers can stop progression

What are Roth spots

Cotton wool spots surrounded by hemorrhage

If a person has chronic hypertension, what is likely to be seen on the optic disc?

AV nicking due to stiffened arteries

What is the classic pediatric tumor of retina?

Retinoblastoma

What causes Ischemic Neuropathy?

due to arteritic (Giant Cell Arteritis) or non-arteritic causes. Vessle walls become inflammed= dec diameter= dec blood supply to optic n.

What causes Optic Neuritis?

Many causes, but demyelinating (Multiple Sclerosis) causes are most important

What causes Papilledema?

swelling due to increased intracranial pressure