ABO Ophthalmology key terms

The outermost stratified squamous layer of the cornea, which blocks fluid entry, anchors the tear film, and regenerates rapidly from limbal stem cells after injury.

Loss or dysfunction of stem cells at the corneoscleral junction, causing conjunctival tissue to grow over the cornea with scarring, opacity, and recurrent epithelial breakdown.

Corneal damage caused by reduced sensation, in which impaired reflex tearing and blinking allow epithelial breakdown, poor healing, and possible ulceration or perforation.

A superficial scrape of the corneal surface that causes pain, tearing, and light sensitivity; it usually heals quickly unless infection or a retained foreign body develops.

A progressive condition in which the cornea thins and bulges into a cone shape, producing irregular astigmatism and declining vision that often requires rigid contact lenses or corneal crosslinking.

Abnormal thinning and outward bowing of the cornea that can occur spontaneously or after refractive surgery, leading to progressive irregular astigmatism and loss of best-corrected vision.

Measurement of corneal thickness, used to assess ectasia risk, plan refractive surgery, and monitor corneal edema or thinning over time.

A chronic optic neuropathy in which the drainage angle is open but outflow is impaired, causing progressive retinal ganglion cell loss and characteristic visual field defects.

The fluid pressure inside the eye, determined mainly by the balance between aqueous humor production and drainage; it is the primary modifiable risk factor for glaucomatous damage.

Enlargement and excavation of the central optic nerve head as retinal nerve fibers are lost, producing a widened pale cup that is a hallmark of glaucoma.

A form of glaucoma in which the iris blocks the drainage angle, causing sudden or chronic pressure elevation with risk of severe optic nerve damage if not relieved.

Examination of the anterior chamber drainage angle using a special contact lens and slit lamp, essential for distinguishing open from closed angles and identifying abnormal angle structures.

A filtering operation that creates a new drainage channel from the anterior chamber to the subconjunctival space, lowering intraocular pressure when medications and lasers are insufficient.

The raised conjunctival filtering area created by glaucoma surgery, through which aqueous humor exits the eye; its appearance helps predict surgical success or failure.

Swelling of the central retina from fluid accumulation, causing blurred or distorted vision and often arising from diabetes, vascular occlusion, or inflammation.

Microvascular damage to the retina from long-standing high blood sugar, ranging from small hemorrhages and exudates to abnormal new vessel growth that can bleed or detach the retina.

Growth of new, fragile blood vessels in the retina, optic disc, or iris in response to oxygen deprivation, which can leak, bleed, or cause traction and severe vision loss.

Separation of the light-sensing retina from its underlying support tissue, producing a shadow or curtain in the visual field and requiring prompt repair to prevent permanent loss.

Age-related separation of the vitreous gel from the retina, commonly causing floaters and flashes and occasionally leading to retinal tears or detachment.

A surgically placed band that indents the eye wall to bring it closer to the detached retina, used to treat certain retinal detachments.

A noninvasive imaging method using light to produce cross-sectional pictures of the retina and optic nerve, widely used to detect swelling, thinning, and fluid.

A weaker pupillary response when light is swung from the healthy eye to the affected eye, indicating asymmetric damage to the optic nerve or extensive retina.

Inflammation of the optic nerve causing painful vision loss, reduced color vision, and a relative afferent pupillary defect; it is often linked to demyelinating disease.

Swelling of the optic disc caused by raised pressure inside the skull, typically bilateral and often accompanied by headache, transient visual obscurations, and enlarged blind spots.

Reduced vision in one or both eyes caused by abnormal visual experience during childhood, such as strabismus or unequal refractive error, that is treatable if detected early.

Misalignment of the eyes in which one eye deviates inward, outward, upward, or downward, potentially causing double vision or loss of binocular vision.

An inward turning of one eye relative to the other, which may be constant or intermittent and can lead to amblyopia in children.

A significant difference in refractive error between the two eyes, which can cause unequal retinal images and lead to amblyopia in children.

Infection of the tear sac near the nose, producing pain, redness, and swelling below the inner corner of the eye, often due to blockage of the tear drainage channel.

Drooping of the upper eyelid that can reduce vision, cause eye strain, or signal underlying nerve or muscle disease.

Inflammation of the iris and ciliary body causing eye pain, redness, light sensitivity, and cells in the anterior chamber; it may be linked to systemic inflammatory disease.

An abnormal adhesion of the iris to the cornea or lens, which can distort the pupil, block fluid flow, and raise eye pressure.

Cataract surgery that uses ultrasound energy to break up and remove the clouded lens through a small incision, followed by implantation of an artificial lens.

Clouding of the thin membrane left behind after cataract surgery, causing gradual vision decline that is typically treated with a laser.

Severe infection inside the eye, often after surgery or injury, causing pain, vision loss, and inflammation that threaten sight and require urgent treatment.

A mismatch between the eye's focusing power and its length that prevents images from focusing clearly on the retina, producing blurred vision correctable with lenses.

A malignant tumor of the developing retina in young children that may present with a white pupil reflex or crossed eyes and requires urgent specialist care.

A white or abnormal pupil reflex in a child that can indicate serious intraocular disease such as tumor, cataract, or retinal detachment and always warrants urgent evaluation.

A powerful anti-inflammatory drug used in eye drops or other forms to control ocular inflammation, with risks including raised eye pressure, cataract, and infection.

Drugs injected into the eye that block a protein driving abnormal vessel growth and leakage, commonly used for macular edema and neovascular retinal disease.