What are the three layers of the eyeball?
External - sclera and cornea
Intermediate - anterior (iris and ciliary body) and posterior (choroid)
Internal - retina
What is the anterior chamber of the eye?
Between the cornea and iris
Filled with aqueous humor
What is the posterior chamber of the eye?
Between the iris, zonule fibers and lens
Filled with aqueous humor
What is the vitreous chamber of the eye?
between lens and retina
Filled with vitreous humor
What does the aqueous humor do?
Nourishes the cornea and lens
What does the vitreous humor do?
Exerts pressure to maintain the shape of the eye
Define the limbus
The junction between the sclera and the cornea
Define canthi refer
Junction between the upper and lower eyelids
Where does the iris and posterior structures of the eye (with the exception of the lens) originate from?
Neuro-ectodermal layers
Where does the lens and all the structures anterior to the iris originate from?
Embyonic ectodermal layer
What causes a coloboma?
Failure of the neuro-ectodermal tissue to wrap around the lens placode and fuse in a double layer inferiorly
What causes infantile glaucoma or buphthalmos?
Failure of the development of the iridocorneal angel and/or the Canal of Schlemm
Where does the nasolacrimal duct open into?
Inferior meatus of the nose
What secretes aqueous humor? Where is is located?
Ciliary body behind the iris
What is the circulation of aqueous humor?
drains through the pupil, then into the iridocorneal angle where it is reabsorbed into the Canal of Schlemm
What causes of aqueous humor drainage fails?
Glaucoma
Increased intraocular pressure
Can cause retinal damage and blindness
Define ptosis. What can cause it?
Drooping of the eyelid.
CN III nerve palsy, sympathetic dysfunction (Horner’s), neuromuscular disease (Myasthenia Gravis)
Define lid retraction
Patient will have wide eyed starring appearance. Superior sclera is visible on opening of the eyes fully.
Define ectropion
Turning outward (sagging) of the eye margin. It is often associated with aging. There is a constant flow of tears down the medial side of the face.
Define entropion
Turning inward of the lid margin.
This can cause abrasion of the cornea.
Define a stye
AKA hordeolum
Red, swollen and tender
Pus discharge
Define blepharitis
Margin is red and irritated
Covered with scales
Define a chalazion
Cyst like
No acute signs of inflammation
Due to inspissated secretions of the mibomian glands
Define Xanthelasma
Discrete, waxy, yellowish deposit on the medial aspect of the lid
What are the signs of allergic reaction of the eye?
Pale, boggy swelling of all four eyelids
Define Chemosis
Swelling
Fluid in the episcleral space
Define pinguecula
Whitish-yellow, triangular, nodular growth on the nasal portion of the bulbar conjuctiva adjacent to the corneal-scleral junction (limbus)
Does NOT invade the cornea
Define pterygium
Similar in location to a pinguecula, but more vascular.
Begins at the medial canthus and extends beyond the corneal-scleral junction
Define arcus senilis
White ring in the cornea
Normal >40yo
< 40yo is a sign of hypercholesterolemia
Define Kayser-Fleisher ring
Greenish-yellow rings in the cornea
Seen in Wilson’s disease - copper deposition in Descemet’s membrane of the peripheral cornea
What impact does pneumococcal infection have on the eye?
Ulceration
What impact does pseudomonas infections tend to cause on the eye?
Rapidly progressive, leading to perforation
What impact does Herpes simplex infection cause on the eye?
Herpes simplex ulcers are a common cause of corneal related blindness (usually unilateral)
Define keratitis
Inflammation of the cornea
Symptoms include conjunctival hyperemia, tearing, photophobia
Define Keratoconus.
What is Munson’s sign?
Cornea protrudes as a cone, with the apex becoming thin and scarred. Bilateral but asymmetrical. Presents with slow deterioration of vision
Looking downwards makes the cone more obvious - Munson’s sign
Define miosis
Constriction of the pupil
Under parasympathetic innervation
Define mydriasis
Dilatation of the pupil
Under sympathetic innervation
Define iritis
Inflammation of the iris
Define cyclitis
inflammation of the ciliary body
Define choroiditis
Inflammation of the choroid
Define Posterior uveitis
Combined cyslitis and choroiditis
Define anterior uveitis
Combined iritis and cyslitis
What are the symptoms of eye inflammation?
Severe pain, photophobia, lacrimation, decreased vision
Adhesion between iris and cornea, and iris and lens can lead to glaucoma
What systemic diseases are associated with uveitis?
Sarcoidosis Ankylosing spondylitis Tuberculosis Lyme's disease HIV
What is the pupillary response in blindness?
Pupils are equal in size
Defective eye stimulation - no response
Normal eye stimulation - both respond
Near reflex is normal
Define Argyll Roberston Pupil
Hallmark of neurosyphilis
Effects the pupils
Vision is normal
What is the pupillary response in Argyll Robertson Pupil?
Pupils are small and irregular in shape Bilateral, asymmetrical No response to light Brisk response to near reaction Dilate poorly in response to mydriatics
Define Adie’s (Tonic) pupil
Lesion in the ciliary ganglion - sphincter and the ciliary muscles are affected (pupils and accommodation)
Unilateral
Women, young adults
Random association - reduction in the knee jerk reflex
What is the pupillary response in Adie’s pupil?
Accommodation is sluggish
Impaired impaired pupillary response
Affected pupil is dilated in bright light and relatively constricted in dim light
Contracts vigorously with pilocarpine (minimal effect on good pupil)
What are the features of Horner’s syndrome?
Miosis
Ptosis
Anhidrosis
Apparent enophthalmos
Define Anisocoria
Pupils of unequal sizes
Define Afferent Pupillary Defect (AKA Marcus Gunn pupil)
“Pupillary escape”
Defect in optic nerve conduction
Pupillary response normal when shined in normal eye
Pupillary response weaker when shined in abnormal eye
Diagnose using “swinging flashlight” test
What are causes of cataracts?
Down's syndrome Cretinism Ocular diseases, such as iritis Systemic disease (Diabetes, hyperparathyroidism) Penetrating eye wounds
Define red lesions of the retina
Hemorrhages (round, linear or flame-shaped)
Define black lesions of the retina
Shaped like bone spicules that are associated with retinitis pigmentosa
Define white lesions of the retina
Soft, cotton-wool or dense
Seen with diabetes and hypertension
Define Roth’s spots
Clear white center surrounded by hemorrhage
Seen in endocarditis, HIV retinitis and leukemia
What are the signs of diabetic retinopathy?
Early: nonproliferative
- Capillary microaneurysms
- Dilated and torturous vessels
- Non-perfusion or areas
- Rupture of microaneurysms, capillaries and venules results in hemorrhages (flame-shaped or blot)
- Exudates (Due to leaky capillaries) as clusters, streaks or rings around the fovea
Later: proliferative
- Neovascularisation (new vessels)
- Hemorhage, retinal tears and detachment
What are the signs of hypertensive retinopathy?
Irregularities in arteriolar size (narrowing) Tortuosity of arteries Changes in arteriovenous crossing (a-v nicking) Cotton wool exudates Macular exudates Macular star Flamed-shaped hemorrhages Retinal edema Papilledema
Define Papilledema
Swelling of the optic disk
blurring of the disc margin, loss of spontaneous venous pulsation, hyperemia hemorrhgage and exudates of the disc
Due to raise ICP
Describe primary ophthalmoscopic classification
Disc is chalky white, sharply demarcated, and with normal retinal vessels
Optic nerve degenerates in an orderly fashion
Causes: pituitary tumor, optic nerve tumor, traumtic optic neuropathy and MS
Describe secondary ophthalmoscopic classification
Architecture of the nerve is lost Disc is grey with poorly defined margins Drusen and tortuous veins Progressive contraction of the visual fields Due to papilledema
Describe consecutive optic ophthalmoscopic classification
The disc is waxy pale with normal disc margin
Arteries are markedly attenuated
Causes: retinitis pigmentosa, myopia, central retinal artery occlusion
Describe glacomatous ophthalmoscopic classification
Marked cupping of the disc
Bayonetting and nasal shifting of the retinal vessels
Splinter hemorrhages may be observed at the disc margin
Describe temporal pallor ophthalmoscopic classification
The disc is pale (more pronounced on the temporal side)
Clear, demarcated margins
Vessels are normal
Seen in traumatic or nutritional optic atrophy, most often seen in MS
