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Questions and Answers
What percentage of patients with type 2 diabetes mellitus of 20 years' duration or more develop diabetic retinopathy?
What percentage of patients with type 2 diabetes mellitus of 20 years' duration or more develop diabetic retinopathy?
What is the leading cause of blindness in middle-aged individuals in the United States?
What is the leading cause of blindness in middle-aged individuals in the United States?
What is a complication of diabetic retinopathy that can cause blindness?
What is a complication of diabetic retinopathy that can cause blindness?
What is a factor that can accelerate the progression of diabetic retinopathy?
What is a factor that can accelerate the progression of diabetic retinopathy?
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What is the term for the abnormal growth of blood vessels and fibrous tissue in diabetic retinopathy?
What is the term for the abnormal growth of blood vessels and fibrous tissue in diabetic retinopathy?
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What is the ophthalmoscopic examination used to detect?
What is the ophthalmoscopic examination used to detect?
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Which muscle originates from the lesser wing of the sphenoid bone?
Which muscle originates from the lesser wing of the sphenoid bone?
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Which nerve innervates the inferior oblique muscle?
Which nerve innervates the inferior oblique muscle?
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What is the primary action of the superior rectus muscle?
What is the primary action of the superior rectus muscle?
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Which muscle inserts into the sclera deep to the lateral rectus muscle?
Which muscle inserts into the sclera deep to the lateral rectus muscle?
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What is the common origin of the superior rectus, inferior rectus, medial rectus, and lateral rectus muscles?
What is the common origin of the superior rectus, inferior rectus, medial rectus, and lateral rectus muscles?
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Which muscle is innervated by the trochlear nerve?
Which muscle is innervated by the trochlear nerve?
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What is the primary action of the lateral rectus muscle?
What is the primary action of the lateral rectus muscle?
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Which muscle inserts into the tarsal plate and skin of the upper eyelid?
Which muscle inserts into the tarsal plate and skin of the upper eyelid?
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Which bone contributes to the orbit and has an orbital surface that forms part of the inferior orbital fissure?
Which bone contributes to the orbit and has an orbital surface that forms part of the inferior orbital fissure?
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Which nerve passes through the superior orbital fissure and is responsible for_eye movement?
Which nerve passes through the superior orbital fissure and is responsible for_eye movement?
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Which structure separates the orbit from the cranial cavity?
Which structure separates the orbit from the cranial cavity?
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Which bone forms the posterior aspect of the orbit?
Which bone forms the posterior aspect of the orbit?
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Which nerve supplies the lacrimal gland?
Which nerve supplies the lacrimal gland?
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What is the purpose of the superior orbital fissure?
What is the purpose of the superior orbital fissure?
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Which vessel passes through the optic canal?
Which vessel passes through the optic canal?
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What is the name of the bony structure that borders the superior orbital fissure?
What is the name of the bony structure that borders the superior orbital fissure?
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Which muscle attaches to the inferior orbital fissure?
Which muscle attaches to the inferior orbital fissure?
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Which nerve is responsible for sensation in the forehead region?
Which nerve is responsible for sensation in the forehead region?
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Which artery supplies the lateral nose and lacrimal sac?
Which artery supplies the lateral nose and lacrimal sac?
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Through which notch does the Supraorbital artery pass?
Through which notch does the Supraorbital artery pass?
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Which part of the ear contains the three middle ear ossicles?
Which part of the ear contains the three middle ear ossicles?
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What is the function of the stapedius muscle?
What is the function of the stapedius muscle?
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What is the name of the tube that connects the middle ear to the pharynx?
What is the name of the tube that connects the middle ear to the pharynx?
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What is the name of the veins that drain the orbit?
What is the name of the veins that drain the orbit?
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What is the origin of preganglionic sympathetic fibers in the spinal cord?
What is the origin of preganglionic sympathetic fibers in the spinal cord?
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What type of photoreceptive cells are more sensitive to low light conditions?
What type of photoreceptive cells are more sensitive to low light conditions?
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What is the pathway of postganglionic sympathetic fibers to the eyeball?
What is the pathway of postganglionic sympathetic fibers to the eyeball?
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What is the function of the dilator muscle of the pupil?
What is the function of the dilator muscle of the pupil?
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What is the location of the photosensitive region of the neural retina?
What is the location of the photosensitive region of the neural retina?
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What is the destination of the axons of ganglion cells?
What is the destination of the axons of ganglion cells?
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What type of cells are interspersed between the photoreceptive cells in the neural retina?
What type of cells are interspersed between the photoreceptive cells in the neural retina?
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What is the location of the ciliary ganglion in relation to the eyeball?
What is the location of the ciliary ganglion in relation to the eyeball?
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Study Notes
Diabetic Retinopathy
- Develops in almost all patients with type 1 diabetes mellitus (DM) and in 50% to 80% of patients with type 2 DM of 20 years’ duration or more.
- Number-one cause of blindness in middle-aged individuals and the fourth leading cause of blindness overall in the United States.
- Complications include retinal detachment, vitreous contraction, and fibrovascular proliferation and hemorrhage.
Bony Orbit
- Formed by seven bones: frontal, sphenoid, zygomatic, maxillary, lacrimal, palatine, and ethmoid bones.
- Openings in the orbit include the superior orbital fissure, inferior orbital fissure, and optic canal.
- Muscles attached to the orbit include the levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, lateral rectus, and superior oblique.
Orbital Muscles
- Levator palpebrae superioris: elevates the upper eyelid
- Superior rectus: elevates, adducts, and rotates the eyeball medially
- Inferior rectus: depresses, adducts, and rotates the eyeball laterally
- Medial rectus: adducts the eyeball
- Lateral rectus: abducts the eyeball
- Superior oblique: medially rotates, depresses, and abducts the eyeball
- Inferior oblique: laterally rotates and elevates the eyeball
Neural Retina
- Composed of an outer retinal pigmented epithelium and a photosensitive region consisting of photoreceptive cells: rods and cones.
- Rods are more sensitive to light and respond to low light conditions, while cones are less sensitive to low light but respond to red, green, and blue regions of the visual spectrum.
Sympathetic Innervation of the Eye
- Postganglionic sympathetic fibers course along the internal carotid artery and ophthalmic nerve, and pass through the ciliary ganglion or along the long and short ciliary nerves to the eyeball.
- Innervate the dilator muscle of the pupil and the eyeball.
Blood Supply of the Orbit
- Ophthalmic artery supplies the orbit, including the eyeball, lacrimal gland, and eyelids.
- Muscular arteries supply the skeletal muscles of the orbit and smooth muscles of the eyeball.
- Supraorbital, dorsal nasal, and medial palpebrae arteries supply the forehead, nose, and eyelids.
Eye Structure
- Consists of the cornea, iris, lens, zonular fibers, and retina.
- The human ear consists of the external ear (auricle, external acoustic meatus, and tympanic membrane), middle ear (tympanic cavity, middle ear ossicles, and stapedius and tensor tympani muscles), and internal ear (labyrinthine wall and auditory tube).
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Description
Diabetic retinopathy develops in almost all patients with type 1 diabetes mellitus and in 50% to 80% of patients with type 2 DM of 20 years’ duration.
