A watery eye means tears overflow onto the eyelid or cheek more than expected. It is commonly described in clinics as “excess tearing” or “epiphora.” It can happen because the eye makes more tears, because tears do not drain normally, or both. The term is used by patients and eye-care professionals to describe a symptom, not a single disease.

UV keratitis is a short-term injury to the clear front surface of the eye (the cornea) caused by ultraviolet (UV) light exposure. It is also commonly called photokeratitis, “snow blindness,” or “welder’s flash.” It typically shows up hours after exposure with eye pain, tearing, and light sensitivity. Clinicians use the term to describe a recognizable pattern of symptoms and exam findings after UV exposure.

photokeratitis is an acute injury to the cornea caused by ultraviolet (UV) radiation. It is sometimes described as a “sunburn of the eye,” mainly affecting the corneal surface. It commonly occurs after exposure to UV sources such as sunlight reflected off snow or water, welding arcs, or tanning devices. The term is used in eye care to describe a recognizable pattern of symptoms and exam findings after UV exposure.

A thermal burn is tissue damage caused by heat. In eye care, it can affect the eyelids, conjunctiva, cornea, or deeper eye structures. The term is also used for controlled heat injury created on purpose during some ophthalmic procedures. This overview explains the concept in a patient-friendly, clinically precise way.

An acid burn is a chemical injury caused by contact with an acidic substance. In eye care, the term usually refers to acid exposure to the eye surface (cornea and conjunctiva). Acid burns can occur in homes, workplaces, laboratories, and industrial settings.

An alkali burn is a chemical injury caused by a basic (high‑pH) substance contacting the eye or surrounding tissues. In eye care, it most often refers to a chemical burn of the cornea and conjunctiva. Alkali chemicals are commonly used in household cleaners, industrial products, and construction materials. These exposures are clinically important because alkalis can penetrate eye tissues quickly.

A chemical burn is tissue damage caused when a chemical substance contacts the body and injures cells. In eye care, a chemical burn most often refers to injury of the ocular surface (cornea and conjunctiva) after exposure to liquids, powders, or fumes. It is a clinical term used in emergency triage, eye clinic documentation, and follow-up care. Common exposure settings include household cleaning, workplace chemicals, and industrial accidents.

ocular cicatricial pemphigoid is a chronic autoimmune condition that can scar the conjunctiva, the thin lining over the white of the eye and inner eyelids. It is part of a broader group called mucous membrane pemphigoid, which can affect the eyes and other mucosal surfaces. In the clinic, the term is used when eye findings suggest immune-driven conjunctival inflammation with progressive scarring. It matters because scarring can threaten comfort, the ocular surface, and vision over time.

Stevens-Johnson syndrome is a rare, severe inflammatory reaction that affects the skin and mucous membranes. It is most often discussed as a medication- or infection-triggered condition that can become a medical emergency. In eye care, it matters because it can injure the conjunctiva and cornea and threaten vision. The term is commonly used in hospital medicine, dermatology, and ophthalmology to describe this specific syndrome and its complications.

conjunctival scarring means fibrous healing changes in the conjunctiva, the thin, clear tissue covering the white of the eye and lining the eyelids. It can follow inflammation, infection, injury, chemical exposure, autoimmune disease, or eye surgery. Clinicians use the presence and pattern of conjunctival scarring as an important sign when evaluating “ocular surface disease” (conditions affecting the eye’s surface). It may be mild and focal or severe enough to change eyelid shape, tear function, and vision.

symblepharon is an abnormal adhesion between the eyelid lining (palpebral conjunctiva) and the surface lining of the eye (bulbar conjunctiva). It forms when conjunctival tissues heal together after injury or inflammation and create scar bands. The term is used in eye exams, surgical planning, and ocular surface disease documentation. It can affect comfort, eye movement, tear function, and sometimes vision depending on severity.

corneal perforation means a full-thickness break in the cornea, the clear “window” at the front of the eye. It creates an abnormal opening between the outside surface and the inside of the eye. Clinicians use the term when describing urgent corneal disease or eye injury. It is commonly discussed in emergency eye care, cornea clinics, and eye surgery settings.

A Descemetocele is a severe corneal ulcer in which the cornea has thinned down to Descemet’s membrane. It often appears as a clear, dome-like bulge at the base of a deep corneal ulcer. It is considered an ophthalmic emergency because it can progress to a corneal perforation. The term is most commonly used in cornea clinics, emergency eye care, and surgical decision-making.

corneal scarring is a loss of normal corneal clarity caused by healed injury or inflammation in the cornea. In plain terms, it is a “mark” in the eye’s clear window that can scatter light and affect vision. It is commonly discussed in eye exams when people have blurred vision, glare, or a history of infection or trauma. Clinicians document corneal scarring to guide diagnosis, monitoring, and treatment planning.

corneal neovascularization means new blood vessels growing into the cornea. The cornea is normally clear and does not contain blood vessels. This finding is commonly discussed in eye exams, contact lens care, and corneal disease management. Clinicians use the term to describe a sign of stress, inflammation, low oxygen, or injury affecting the cornea.

limbal stem cell deficiency is a disorder of the eye surface where the cornea loses enough stem cells to renew its outer lining. It can lead to chronic irritation, blurred vision, and recurrent breakdown of the corneal surface. Clinicians use the diagnosis to explain persistent “non-healing” corneal problems and to plan surface-focused treatment. It is most often discussed in cornea clinics, dry eye/ocular surface care, and ocular surface reconstruction.

pinguecula is a common, usually benign growth on the conjunctiva, the clear tissue covering the white of the eye. It often appears as a small yellowish, slightly raised spot near the edge of the cornea. The term pinguecula is used in eye clinics to describe a typical ocular surface change related to irritation and environmental exposure.

pterygium is a common growth of conjunctival tissue that extends onto the cornea. It is often described as a “wing-shaped” fibrovascular (fibrous and blood vessel–rich) lesion. It most commonly appears on the nasal (nose-side) white of the eye and grows toward the pupil. The term is used in eye clinics to describe a specific ocular surface condition that may be monitored or treated.

bullous keratopathy is a condition where the cornea (the clear front window of the eye) becomes swollen and develops fluid-filled blisters. It usually happens when the cornea’s inner “pump” layer (the endothelium) is not working well. People may notice blurred vision, glare, and episodes of pain when blisters break. The term is commonly used in eye clinics to describe corneal edema with epithelial bullae and to guide treatment planning.

map-dot-fingerprint dystrophy is a common corneal surface condition that affects the clear front window of the eye. It is also known in clinics as epithelial basement membrane dystrophy (EBMD). It can cause fluctuating vision and episodes of painful “corneal erosions” in some people. The term is commonly used in eye exams, contact lens care, and pre-surgical screening.