EYE EXAM REVISION - USE SPACE REPETITION METHOD

What reflex is elicited by touching the cornea of one eye?

Bilateral blink response or corneal reflex.

What is the primary function of the corneal reflex?

To protect the eyes from harmful stimuli and maintain eye health.

How is the usual test for the corneal reflex performed?

By touching the cornea with a cotton wisp.

Which cranial nerve innervates four of the six extrinsic eye muscles?

The oculomotor nerve (CN III).

Where does the oculomotor nerve originate?

From the oculomotor and Edinger-Westphal nuclei in the midbrain.

What occurs when the ciliary muscle contracts?

It moves the ciliary body closer to the lens.

What muscles does the oculomotor nerve functionally innervate?

Superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris.

What condition can result from damage to the oculomotor nerve?

Ptosis (drooping of the eyelid).

What function does the trochlear nerve serve?

It innervates the superior oblique muscle.

What eye movement does the superior oblique muscle facilitate?

Moving the eye downwards and laterally(abduction) and rotating eyes inwards (intorsion) - top of eye towards nose.

What is the role of the abducens nerve (CN VI)?

To innervate the lateral rectus muscle, enabling lateral eye movement.

What movements do the oblique muscles assist with?

Rotating the eye; superior oblique moves it down depression and laterallyand intorsion, while inferior oblique elevates and rotates it up elevation and laterally and extorsion.

What are the four main movements of the eye?

Elevation, depression, abduction, and adduction.

What is a main symptom of superior oblique dysfunction?

Diplopia (double vision) when looking down.

What happens during internal rotation (intorsion) of the eye?

The upper part of the pupil rotates medially, towards the nose.

What does the abducens nerve do?

Facilitates the lateral movement of the eye via the lateral rectus muscle.

What compensatory motion may a patient with trochlear nerve palsy exhibit?

Tilting their head to compensate for eye movement or vision challenges.

What is the pathway for the abducens nerve (CN VI)?

Leaves the cranium via superior orbital fissure and extends to the lateral rectus muscle.

What is the middle layer of the eye called and what does it house?

The middle layer is called the uvea, which houses blood vessels, lymph vessels, and intrinsic muscles of the eye.

What are the three distinct regions that compose the uvea?

The three regions are the choroid, ciliary body, and iris.

What is the function of the aqueous humour in the eye?

The aqueous humour provides nutrients and oxygen to the avascular lens and cornea.

What maintains normal intraocular pressure (IOP)?

Normal IOP is maintained when the formation rate of aqueous humour equals the drainage rate.

What happens when the sphincter pupillae muscle contracts?

The pupil becomes smaller.

What is the role of the dilator pupillae muscle?

It contracts to make the pupil larger.

Where is the ciliary body located in relation to the choroid?

The ciliary body is located immediately anterior to the choroid.

What do ciliary processes do?

Ciliary processes secrete aqueous humour.

What is the function of the ciliary muscle?

It anchors the crystalline lens and adjusts its shape for focusing.

What condition is referred to as MD?

Macular degeneration (MD) is a degenerative condition affecting the macula lutea.

What are the symptoms of age-related macular degeneration (AMD)?

Symptoms include central vision blurriness.

What are drusen and their significance in AMD?

Drusen are extracellular deposits between the retina and choroid that disrupt retinal pigment epithelium (RPE) function.

What is the recommended lifestyle modification for managing AMD?

Smoking cessation and dietary changes.

What are rods and how do they differ from cones?

Rods are longer and narrower than cones and are more sensitive to dim light.

What is the photopigment found in rods?

The photopigment in rods is called rhodopsin.

What is the pathway of visual information from photoreceptors to the brain?

Photoreceptors -> CN II -> chiasm -> optic tract -> lateral geniculate nucleus -> primary visual cortex.

What is colour blindness and its genetic trait?

Colour blindness is an inherited trait involving a deficit in cone cells, commonly affecting red and green cones.

What is the Ishihara test used for?

The Ishihara test is used to detect colour blindness.

What is the pH range of normal tears? and the mean value

The pH of normal tears is between 7.3 to 7.7. and mean value of 7.4

Why is the pH of tears lowest upon awakening?

It is lowest due to carbonic acid by-products from anaerobic conditions during prolonged lid closure.

What changes the pH of tears after awakening?

The loss of carbon dioxide as the eyes open increases the pH of tears.

How many rods are typically found in each eye?

Each eye contains more than 100 million rods.

What function do rods serve in vision?

They are activated by dim light for night vision and do not provide colour recognition.

At what wavelength is rhodopsin most sensitive to light?

Rhodopsin is most sensitive to light at a 500-nm wavelength.

What is 'accommodation' in eye physiology?

Accommodation is the process of adjusting the lens's shape for focusing on objects at various distances.

What is the function of the optic nerve (CN II)?

It conducts visual information from the retina to the brain.

Which three meningeal layers cover the optic nerve?

Dura mater, arachnoid mater, and pia mater.

What is the origin of the optic nerve (CN II)?

Retina of the eye.

What is anopsia?

Nerve damage that affects vision, often associated with CN II damage.

How do the right and left optic nerves communicate?

They unite at the optic chiasm.

What area of the brain does the optic tract extend to?

The lateral geniculate nucleus of the thalamus.

What does the oculomotor nerve (CN III) innervate?

Four of the six extrinsic eye muscles and intrinsic eye muscles.

Where does the oculomotor nerve (CN III) originate?

From the oculomotor and Edinger-Westphal nuclei within the midbrain.

What muscle does the abducens nerve (CN VI) innervate?

The lateral rectus muscle.

What is the primary function of the lateral rectus muscle?

To move the eye laterally.

What mnemonic helps remember the innervation of extrinsic eye muscles?

LR6(SO4)3, where LR = lateral rectus (CN VI), SO = superior oblique (CN IV), and other muscles = CN III.

What is the motion associated with eye elevation (moving the pupil superiorly)?

Elevation.

What is the motion associated with moving the pupil inferiorly?

Depression.

What is meant by abduction of the pupil?

Moving the pupil laterally.

What is meant by adduction of the pupil?

Moving the pupil medially.

What are intorsion and extorsion movements?

Intorsion is internal rotation of the pupil, and extorsion is external rotation of the pupil.

What is the primary contraction result of the superior rectus muscle?

Elevation of the eye.

What additional actions does the inferior rectus muscle perform?

Depression, adduction, and extorsion.

What is the innervation for the levator palpebrae superioris muscle?

Oculomotor nerve (CN III).

What is the function of the medial rectus muscle?

Adduction of the eyeball.

Which muscles are responsible for abduction of the eyeball?

Lateral rectus muscle (innervated by CN VI).

What do superior oblique and inferior oblique muscles have in common?

They both help in moving the eye but have different specific actions.

What contraction results from the superior oblique muscle?

Intorsion of the eye.

Extrinsic muscles

Muscles outside the eye that control eye movement, including superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique, and inferior oblique.

Conjunctiva

A continuous, transparent lining consisting of stratified columnar epithelium that lubricates and protects the eye.

Lacrimal glands

Glands that secrete tears to moisten the eye and help spread them across the conjunctiva and cornea during blinking.

Tear film

A thin layer of fluid (lipid, aqueous, and mucus layers) that lubricates and protects the eye, preventing corneal drying and aiding in oxygen transport.

pH of tears

Typically between 7.3 and 7.7, indicating slight alkalinity and can vary based on age and certain eye conditions.

Aqueous humor

A clear fluid produced by the ciliary processes that fills the anterior and posterior chambers of the eye, responsible for intraocular pressure.

Suspensory ligaments

Fibers that hold the lens in place and are involved in adjusting the lens shape for focusing.

Accommodation

The process of changing the shape of the lens to focus on near or distant objects.

Presbyopia

An age-related condition where the lens becomes less elastic, making it difficult to focus on close objects.

Cataract

A clouding of the crystalline lens in the eye, leading to blurred and cloudy vision.

Sclera

The outer fibrous white coat of the eyeball, contributing to shape maintenance and muscle attachment.

Cornea

The transparent front part of the eye that refracts light, protecting the inner layers of the avascular cornea.

Choroid

The layer of the eye that contains blood vessels and melanocytes, providing nutrients to the retina and preventing light scattering.

Iris

The colored part of the eye that controls the size of the pupil and regulates the amount of light entering the eye.

Photoreceptors

Specialized cells in the retina (rods and cones) responsible for converting light into electrical signals.

Fovea centralis

The area of the retina with the highest concentration of cones, responsible for sharp central vision.

Macula lutea

The yellowish area surrounding the fovea which contains a high density of cones for color vision.

Optic disc

The area where ganglion cell axons leave the eye to form the optic nerve, also known as the blind spot.