Ncle Basic Anatomy

7.7mm

6.8mm

0.5mm

11.5mm horizontally

11.2mm vertically

+43.00 diopters, or 70% of the eye’s total refractive ability

+48.8 diopters

-5.8 diopters

shorter = steeper curve

longer = flatter curve

1.376

AKA: corneal cap. Central portion of cornea with constant radius of curvature.

Nutrients and oxygen from the aqueous humor, tears, and vascular blood vessels in the limbus.

Epithelium, Bowman’s membrane, Stroma, Descemet’s membrane, Endothelium

10-12 seconds (with fluorescein staining)

Evaluates aqueous tear production in dry eye assessment. Performed WITH anesthetic.

Evaluates aqueous tear production (baseline AND reflex secretion) in dry eye assessment. Performed WITHOUT anesthetic.

Benign growth; small, round, yellow or yellow-brown

Benign growth; small and flat, tan or brown

Broken blood vessel under conjunctiva; blood in eye lasts 7-10 days and usually causes no permanent harm. Caused by trauma, sneezing, coughing, high BP, etc.

Meeting point of lid and globe of the conjunctiva. (plural: fornices)

Posterior chamber, behind iris.

Biconvex

10mm across, 3.5mm thick (when relaxed)

Maximum amount that the crystalline lens can accommodate (change shape) in diopters. Decreases with age.

Ciliary muscles and zonule fibers.

Gradual lessening of the power of accommodation caused by the stiffening of the lens. Occurs with age.

Caused by the thickening/clouding of the crystalline lens; occurs with age, radiation, toxicity, or can be congenital (rare).

“Middle” of retina, about 4.5mm across at the end of the visual axis.

Small pit in the center of the macula. This area contains only cones, so this is where the most acute vision occurs.

About 1.5mm.

Directly proportional; can be changed with prescription lenses.

Retinal blood vessels leak due to long-term diabetes. Affects macula or retina and causes blurred/distorted vision.

Chronic disease in which the macula deteriorates and central vision is lost. Usually caused by aging (may be genetically predisposed).

Condition in which the retina separates from the choroid, usually caused by trauma. Causes patient to see flashes and a “black curtain” across vision. Must be fixed by emergency surgery.

Hereditary condition where peripheral vision is lost, and night-blindness occurs, due to rods being affected. Can be minor to severe, causing eventual blindness. No cure.

Two eyes experience significant difference in retinal image sizes. Causes trouble in image fusion for the brain, and may result in diplopia (double vision). Manageable with contacts/glasses.

Two eyes have a significant difference in refractive powers. Managed with contacts (preferable) or glasses (less preferable due to unequal prismatic displacement).

Abnormal growth on the medial bulbar conjunctiva; triangular shape. Caused by UV exposure and may eventually invade cornea, thus causing loss of vision.

Two eyes have opposite signs (+/-). Does not necessarily dictate the amount of difference in power that comes with anisometropia (but could potentially be both if signs are opposite AND significantly different).

Part of eyelid; made of fibrous connective tissue that forms the supporting structure of the eyelid.

Defined by larger than normal micro/papillae on tarsal plates of eyelid. Normal is 0.3 - 0.5mm in diameter. Caused by irritation, infection, etc.

Point where top and bottom lid meet. Lateral canthi (temporal side) makes an acute angle, medial canthi (nasal side) have curved angle.

Found in medial canthi; pinkish part of eyelid with 2-5 accessory tear glands called Ciacco’s glands. Produce tears.

Tiny ducts in the inner corner of the eye; siphon fluid (i.e. tears) away from eye surface and into lacrimal sac.

Lining of tissue inside the eye, sensitive to light. Focuses images and sends to brain via optical nerve. Made of photoreceptor cells (rods and cones).

“Front” part of retina, comes right up to the ciliary body.

“Middle” of retina, yellowish in color and contains lots of cones (meaning vision from here is very clear).

Stroma: front pigmented fibrovascular tissue

Pigmented epithelial cells: found beneath stroma

Aka: sphincter muscle; contracts pupil in a circular motion

Aka: dilator muscle; pulls iris open in folds, and enlarges the pupil.

Pupillary zone: inner region, edges form boundary of pupil.

Ciliary zone: rest of the iris, extends to its origin at the ciliary body.

Thickest region of the iris, separates pupillary/ciliary zones. Also defined as the region where the sphincter and dilator muscles overlap.

The iris is missing/absent from the eye. Causes excessive sensitivity to light. Managed with iris contact lenses.

The iris is void of any pigmented cells (albino). Causes excessive sensitivity to light. Managed with iris contact lenses.

The iris and ciliary body are inflamed. Can be associated with arthritis.

Growth of abnormal blood vessels in the iris.

Covers any inflammation in the uvea. Includes iris, ciliary body, or choroid.

Sudden onset, not to be confused with chronic glaucoma. Most common cause is that the iris is pressed forward by an abnormal crystalline lens. Pupil dilates and iris may make contact with cornea, blocking off flow of aqueous humor. Emergency surgery required.

Rays of light entering pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that do not exit the narrow pupil.

Between 2.0 and 5.0mm (depending on lighting). Typically larger in younger people.

Glaucoma

Pupils are a different size in each eye.

Pupils are a different size in each eye.

When the pupil constricts, or gets smaller. Caused by light, sleep, or when eyes converge. “Miotic” is a drug that causes pupils to constrict.

When the pupil dilates, or gets bigger. Caused by low light or high emotion. “Mydriatic” is a drug that causes pupils to dilate.

The white of the eye, made of opaque fibrous tissue. Six muscles attach here to control movements of the eye.

Large-diameter gas permeable lenses specifically designed to vault over the entire corneal surface and rest on the sclera. Functionally replace an irregular cornea with a perfectly smooth optical surface to correct vision problems such as keratoconus. Also helpful for patients with severe dry eye.

The choroid is the dark vascular layer of the eye that lies between the retina and the sclera. It goes from the optic nerve to the ciliary body. It provides oxygen and nutrients to the retina. This is what causes “red eye” in flash photos. Aka: choroidea; choroid coat

To provide nutrients to the retina.

Short posterior ciliary arteries: 10+ from optic nerve out to choroid.

Long posterior ciliary arteries: 2, from posterior part of globe and up to supply iris.

Anterior ciliary arteries: from front of eye and into rectus muscles. Pierce the anterior sclera and supply ciliary body and sclera.

When the choroid and retina are inflamed.

Anterior chamber, posterior chamber, vitreous chamber

Fluid-filled space inside eye between iris and corneal epithelium. Filled with aqueous humor that helps maintain shape of eye.

Smallest chamber, located behind iris and in front of vitreous chamber. Houses the crystalline lens and ciliary processes. Filled with aqueous humor.

Hyphema (blood) and glaucoma, due to blockage of the canal of Schlemm, causing build up of aqueous humor.

Located in the center of the retina, temporal to the optic nerve. Average size is 6mm in diameter. The fovea is found here, responsible for detailed central vision.

Takes up over 50% of the visual cortex (although it comprises less than 1% of the retina in size).