Corneal Anatomy and Physiology

Flashcards covering key vocabulary and concepts related to corneal anatomy and physiology for exam preparation.

Cornea

Transparent, avascular structure that makes up the anterior 1/6th of the eyeball.

Function of the Cornea

Protection and optical function, providing ~2/3rds of the eye’s optical power.

Keratoconus

A condition characterized by the thinning and conical shape of the cornea.

Pellucid Marginal Degeneration

A condition causing a non-inflammatory thinning of the cornea that can lead to visual distortion.

Corneal Thickness

The central thickness of the cornea is about 0.536 mm, with peripheral thickness being ~20% thicker.

Corneal Curvature

The radius of curvature measures 7.8 mm anteriorly and 6.5 mm posteriorly.

Diurnal Variation in Corneal Thickness

Thickest in the early morning, with changes due to overnight swelling.

Epithelial Cell Types

Corneal epithelium consists of squamous cells, wing cells, and basal (columnar) cells.

Bowman's Layer

Anterior limiting lamina, thin layer of collagen located beneath the corneal epithelium.

Stroma

The thickest layer of the cornea, composed of collagen, ground substance, and proteoglycans.

Endothelium

A monolayer of squamous cells that lines the posterior cornea, playing a role in corneal hydration.

Corneal Metabolism

Dependence on oxygen and nutrients supplied from the atmosphere and aqueous humor for cell health.

Corneal Transparency

Ability of the cornea to transmit ~90% of light in the visible spectrum, maintained by regular arrangement of collagen.

Corneal Innervation

Richly innervated by sensory nerve fibers that help in sensing pain and reflex actions such as blinking.

Corneal Wound Repair

Rapid repair mechanism involving cell migration and mitosis in response to injury.

What is the cornea?

The cornea is a transparent, avascular structure that makes up the anterior 1/6th of the eyeball.

What are the key functions of the cornea?

The key functions of the cornea include refracting light to help focus it on the retina and providing a protective barrier against dirt, germs, and other particles.

How does the cornea receive nutrients?

The cornea receives nutrients through the tear fluid and from the aqueous humor, as it is avascular and does not have blood vessels.

What is the significance of the cornea's transparency?

The transparency of the cornea is crucial for clear vision as it allows light to enter the eye without obstruction.

What role does the cornea play in vision?

The cornea plays a vital role in vision by bending (refracting) light rays that enter the eye, aiding in the formation of clear images on the retina.

What are the layers of the cornea?

The cornea consists of five layers: the epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium.

What is the epithelium's role in the cornea?

The epithelium serves as the outermost layer, providing a barrier against injury and infection and aiding in the hydration of the cornea.

What is the stroma in the cornea comprised of?

The stroma is made up of collagen fibers, providing strength and structure to the cornea.

How does the endothelium contribute to corneal function?

The endothelium regulates fluid and ion transport, maintaining the cornea's transparency by preventing excessive swelling.

What is keratoconus?

Keratoconus is a condition in which the cornea thins and bulges into a cone shape, leading to distorted vision.

What is the function of Bowman's layer?

Bowman's layer provides stability and strength to the cornea.

What is the role of the aqueous humor in corneal health?

The aqueous humor provides necessary nutrients and maintains intraocular pressure for the cornea.

What are common symptoms of corneal diseases?

Common symptoms include blurred vision, pain, redness, and sensitivity to light.

What is corneal abrasion?

Corneal abrasion is a scratch on the surface of the cornea, often causing pain and discomfort.

What causes corneal opacities?

Corneal opacities can be caused by injury, infection, or degeneration, leading to cloudy areas in the cornea.

What is a corneal transplant?

A corneal transplant is a surgical procedure to replace a diseased or damaged cornea with healthy tissue.

How does UV light affect the cornea?

UV light can damage the cornea and lead to conditions like photokeratitis and cataracts.

What is the significance of tear film for the cornea?

Tear film is crucial for lubrication, nutrient supply, and removing debris from the corneal surface.

What are the signs of corneal infection?

Signs include redness, swelling, pain, and vision impairment.

What technique is commonly used to assess corneal thickness?

Pachymetry is the technique used to measure corneal thickness.

What does the term 'astigmatism' refer to in relation to the cornea?

Astigmatism refers to an irregular curvature of the cornea, affecting how light is focused on the retina.

What are the potential complications of corneal surgery?

Potential complications include infection, scarring, and rejection of transplanted tissue.

What is the role of the limbus in the eye?

The limbus is the border area between the cornea and sclera, playing a role in stem cell regeneration.

What is keratitis?

Keratitis is inflammation of the cornea, often due to infection or injury.

What tests are used to diagnose corneal issues?

Common tests include slit-lamp examination, corneal staining, and keratometry.

What is the anatomy of the cornea?

The cornea consists of five layers: epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium.

What role do corneal nerves play?

Corneal nerves provide sensory information and are involved in tear production.

How does age affect corneal health?

With age, the cornea may become less elastic and more prone to conditions like dry eye.

What is a corneal ulcer?

A corneal ulcer is a sore on the corneal surface, typically caused by infection or injury.

What is the recovery time after a corneal transplant?

Recovery time can vary, but visual improvement may take several months.

What is Fuchs' dystrophy?

Fuchs' dystrophy is a progressive condition where the endothelium deteriorates, leading to corneal swelling and vision loss.

How does contact lens wear affect the cornea?

Improper contact lens use can lead to complications like hypoxia and infections.

What condition can occur due to excessive sun exposure to the cornea?

Pinguecula is a condition resulting from UV exposure, causing yellowish, raised lesions on the cornea.

What is the role of the corneal endothelium in fluid regulation?

The corneal endothelium pumps out excess fluid to maintain corneal clarity.

What is allergic conjunctivitis and its relation to the cornea?

Allergic conjunctivitis can cause inflammation that affects the cornea, leading to discomfort and vision changes.

What is the function of the corneal stroma?

The stroma provides structural integrity and strength to the cornea.

What is the pH level of healthy tear film?

Healthy tear film typically has a slightly alkaline pH around 7.0 to 7.4.

How can environmental factors affect the cornea?

Dry air, smoke, and pollution can irritate the cornea and lead to dryness or discomfort.

What is the purpose of corneal cross-linking?

Corneal cross-linking is a procedure to strengthen the corneal structure in conditions like keratoconus.

What can happen if the corneal nerves are damaged?

Damage to corneal nerves can lead to reduced sensation and potential complications like corneal ulcers.

What is the difference between myopia and hyperopia related to the cornea?

Myopia (nearsightedness) occurs when light is focused in front of the retina; hyperopia (farsightedness) occurs when light is focused behind the retina.

What is a corneal dystrophy?

A corneal dystrophy is a genetic condition that causes cloudy or distorted vision due to the buildup of material in the cornea.

What are the main causes of corneal scarring?

Corneal scarring can be caused by infections, injuries, or inflammatory diseases.

What is a common treatment for corneal inflammation?

Topical steroids are commonly used to reduce inflammation in the cornea.

What role does the cornea play in laser eye surgery?

Laser eye surgery reshapes the cornea to correct refractive errors and improve vision.

What is the anatomy of a healthy cornea?

A healthy cornea is clear, smooth, and maintains proper hydration levels for optimal function.

What is the purpose of the corneal reflex?

The corneal reflex protects the eye by triggering a blink response to potential threats.

How does diabetes affect corneal health?

Diabetes can lead to conditions like diabetic keropathy, which impairs corneal health and healing.

What is the significance of corneal epithelial cells?

Corneal epithelial cells are important for the protective barrier function of the cornea.

What is the recommended treatment for corneal swelling?

Hypertonic saline solutions can be used to reduce corneal swelling.

How can systemic diseases affect the cornea?

Systemic diseases like autoimmune disorders can lead to corneal inflammation and degeneration.

What factors influence corneal curvature?

Genetics, age, and environmental factors can all influence corneal curvature.

How do corneal nerves regenerate?

Corneal nerves can regenerate after injury, but this process may take weeks to months.