Eye Pathophys Flashcards
What is the basic anatomy of the sclera?
Thick, white, transparent at the cornea
What is the basic anatomy of the choroid?
Deeply pigmented, contains blood vessels, and the Iris is part of the choroid
What is the basic anatomy of the Retina?
Has rods and cones, converts light energy into nerve impulses
What is present at the Fovea centralis?
Only cones. This is where the greatest visual acuity occurs.
Which bones make up the orbit?
Zygomatic Sphenoid Frontal Ethmoid Lacrimal Palatine Maxillary
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
What is the origin of the occular muscles?
Annulus of Zinn
What does the annulus of zinn encircle?
optic n.
What is characteristic of the lower canaliculus in children?
It’s smaller= inc risk for infection.
Massage can keep the duct open.
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.
What is the manifestation of thyroid related orbitopathy?
Proptosis
Strabismus/muscle-restriction
Exposure problems
Compressive optic neuropathy.
Thyroid related orbitopathy Tx?
Steroids
Radiation therapy
Surgical decompression (opening the orbital walls into the sinuses)
What are the most frequent primary tumors of the orbit?
Most are vascular in origin
Capillary hemangioma
Cavernous hemangioma
Lymphangioma
What are characteristics of capillary hemangiomas?
“spider”, thinner
What are characteristics of cavernoushemangiomas?
more dense/dilated
What is the most common primary malignancy of the orbit in children?
rhabdomyosarcoma
What is the most common metastatic tumor in children?
neuroblastoma- 20% develop orbit metastasis
Where will the gaze likely be in orbital floor fx?
Restricted upgaze if there is muscle entrapement
How critical are orbital floor fx?
Typically require hospitalization
What are the tarsal glands AKA?
Meibomian glands
What are the malignant tumors of the eyelids?
Basal cell carcinoma – most common
Sebaceous carcinoma
Squamous
Melanoma
What can occur if basal cell carcinoma is not completely removed?
inc risk of becoming squamous cell carcinoma
What causes a Chalazion?
chronic inflammatory lesion of the meibomian gland
What secretes the mucinous components of the tear film?
goblet cells
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?
No
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.