Human Eye Anatomy and Function Quiz

The uvea is the middle layer of the eye. It is composed of the choroid, ciliary body, and iris.

The lens of the eye is avascular, meaning it doesn't have blood vessels. It's also derived from the ectoderm and has a single layer of epithelial cells.

The average axial length of the eyeball is approximately 24mm. This distance is measured from the front of the cornea to the back of the eye.

The lens has the highest refractive index in the eye, bending light more than the other structures.

The corneal stroma is the thickest layer of the cornea, composed of collagen fibers. Descemet's membrane is the innermost layer, containing type 2 & type 4 collagen. The endothelium maintains the cornea's dehydrated state.

A baby can typically follow objects with their eyes by 6-8 weeks of age. This is a sign of normal visual development.

Vigabatrin can cause progressive constriction of visual fields. This is a side effect that can occur with long-term use.

Avascularity means the absence of blood vessels, which is crucial for lens transparency. The lens also relies on hydration, antioxidants, and aquaporins to maintain its clarity.

The muscle responsible for depressing the eye and rotating it inwards. It originates from the orbital apex, passes through the trochlea, and inserts on the sclera.

Binocular single vision is the ability to see one single image with both eyes. It relies on fusion of two images from each eye into one perception. It is important for depth perception and spatial awareness.

Amblyopia, commonly referred to as lazy eye, is a condition characterized by reduced vision in one eye despite proper eye health. It is most commonly caused by misalignment of the eyes (strabismus) in childhood.

Treatment options for amblyopia vary depending on age and severity, but often involve patching the good eye to encourage the weaker eye to work harder.

Esotropia is a type of strabismus where one or both eyes turn inwards. When it occurs in infancy, it often has an accommodative component, meaning it is linked to focusing effort.

Prism adaptation testing is used to assess a patient's ability to adapt to a change in their vision. This helps predict the success of surgical correction for strabismus.

The vitreous humor is a gel-like substance that fills the space between the lens and the retina. It is normally transparent, and its changes can cause visual disturbances.

The Snellen chart is a widely used tool for measuring visual acuity, assessing sharpness of vision. It consists of rows of letters of varying sizes.

Pseudoesotropia is a condition where the eyes appear to be crossed, but the actual eye alignment is normal. It occurs when the angle kappa, which measures the angle between the visual axis and the pupillary axis, is negative. This means the visual axis is slightly turned inward, while the pupillary axis stays parallel.

Positive angle kappa means the pupillary axis is turned inward more than the visual axis, making the eyes appear slightly divergent. This is associated with pseudoextropia, where the eyes appear to be turned outward, but are actually properly aligned.

Accommodative strabismus occurs when the eyes turn inward (esotropia) due to excessive focusing effort (accommodation). It is often corrected by addressing the underlying refractive error using glasses or contact lenses.

A scleral perforation during strabismus surgery is a serious complication that requires immediate attention. It increases the risk of endophthalmitis (eye infection) and retinal detachment. Prompt antibiotic treatment and possibly surgical repair are essential.

Botulinum toxin injections are generally not suitable for treating large angle exotropia. This is because the effect of weakening the eye muscles with Botox is not strong enough to correct large deviations in eye alignment.

Applanation tonometry is a technique used to measure the pressure inside the eye (intraocular pressure). Errors in measurement can occur due to factors like tear film variation, high pressure on the eyeball, astigmatism (uneven corneal curvature), and variations in blood pressure.

A positive photostress test indicates that the eye is not properly responding to light stimulus. This can be a sign of various retinal conditions, such as central serous retinopathy, optic neuritis, ethambutol toxicity, and central retinal artery occlusion.

An indentation tonometer measures intraocular pressure by measuring the depth of indentation created by a plunger on the cornea. The depth of indentation depends on the stiffness of the eye. A softer eye will be indented further, while a harder eye will resist indentation more.

A sudden onset of floaters and decreased vision, often accompanied by a vitreous hemorrhage and retinal detachment. It can be caused by various factors, including trauma, but is most commonly associated with age-related changes in the vitreous.

This is a serious condition where the iris blocks the flow of aqueous humor, causing a rapid increase in intraocular pressure. Symptoms include severe eye pain, blurred vision, halos around lights, nausea, and vomiting.

This is a clouding of the natural lens of the eye, which can lead to blurry vision, halos around lights, and difficulty seeing in bright light.

This is an infection of the inner eye, which can occur after cataract surgery. It is a serious complication that can lead to vision loss. Symptoms usually start within 2 weeks of surgery.

This is a condition that causes nearsightedness, particularly in older adults. This means that they have difficulty seeing objects that are close to them.

This type of cataract forms at the back of the lens, often in people with diabetes or those taking certain medications. It can cause blurry vision and halos around lights, especially in bright light.

This refers to the difference in refractive error between eyes, which can occur due to the development of a cataract in one eye. This can cause blurry vision and difficulty with depth perception.

This condition is characterized by an increased pressure within the eye, which can damage the optic nerve and lead to vision loss, especially in the peripheral areas. This is often diagnosed by finding a deep cup-to-disc ratio and an elevated intraocular pressure.

The middle layer of the eye, composed of the choroid, ciliary body, and iris, responsible for providing nourishment and regulating the amount of light entering the eye.

Colliquation necrosis is a type of liquefactive necrosis characterized by the breakdown of tissue into a liquid mass. It's often caused by strong acids or alkalis, as they disrupt cell membranes leading to cell lysis and release of enzymes that further digest tissue.

Crepitation on palpation of the eyelid suggests air trapped within the subcutaneous tissue. This often occurs due to a fracture of the orbital walls, allowing air to escape from the sinuses into the surrounding tissues.

Retinoblastoma is a malignant tumor arising from the developing retinal cells in the eye. It typically originates from the primitive neuroectoderm that forms the neurosensory retina, the light-sensing tissue at the back of the eye.

Cryotherapy and photocoagulation are effective treatments for anterior retinoblastoma. Cryotherapy involves freezing the tumor with a cryoprobe, while photocoagulation uses a laser to destroy tumor cells.

Leucocoria, also known as 'white pupil,' is a hallmark symptom of retinoblastoma. It refers to an abnormal white reflection of light from the pupil, instead of the normal red reflex. This is often accompanied by strabismus, where the eyes are misaligned, as the tumor disrupts normal eye movement.

Transient visual obscurations, headache, and diplopia are common symptoms of increased intracranial pressure (ICP). This can be caused by various conditions, including cerebral venous thrombosis, which is a blockage of veins in the brain, leading to a backup of blood and increased pressure.

A cherry-red spot on the fundus, along with a sudden painless loss of vision in one eye and a heart murmur, strongly suggests central retinal artery occlusion. This occurs when the central artery supplying the retina becomes blocked, leading to vision loss. The cherry-red spot results from the healthy macula being visible against the surrounding ischemic retina.

Suprachoroidal hemorrhage usually occurs due to bleeding from the short posterior ciliary artery, which supplies the choroid. The blood pools in the suprachoroidal space, a potential space between the choroid and the sclera. This condition is associated with increased intraocular pressure (IOP).