Preocular Tear Film & Lacrimal System

Comprehensive vocabulary flashcards covering the structure, function, and drainage of the preocular tear film and lacrimal system, as well as dry eye disorders and diagnostic tests.

Preocular Tear Film (POTF)

A structure that provides a smooth refractive surface, protects the eye by removing foreign bodies, and maintains ocular surface integrity through lubrication.

Lipid Layer

The outer layer of the preocular tear film produced mainly by the Meibomian glands, with contributions from the Zeis and Moll glands.

Meibomian glands

The primary glands responsible for producing the lipid (outer) layer of the tear film.

Aqueous Layer

The middle layer of the tear film, making up about $90\%$ of it, produced by the main lacrimal gland and accessory lacrimal glands.

Krause and Wolfring

The specific accessory lacrimal glands that contribute to the production of the aqueous layer.

Mucin Layer

The inner layer of the preocular tear film produced mainly by conjunctival goblet cells.

Basal Tears

One of the three types of tears, serving to constantly lubricate the ocular surface.

Reflex Tears

Tears produced in response to irritants like foreign bodies or bright light.

Emotional Tears

Tears triggered by psychological and emotional states.

Lacrimal Puncta

Small openings at the medial eyelid margins that serve as the entry point for tears into the drainage system.

Valve of Rosenmüller

A structure in the canaliculi that prevents tears from flowing backward.

Lacrimal Sac

A temporary reservoir for tears located between the eye and the nose, receiving tears from the canaliculi.

Nasolacrimal Duct

The passage that carries tears from the lacrimal sac into the nasalcavity, opening into the inferior nasal meatus.

Valve of Hasner

A valve that prevents backflow from the nose into the nasolacrimal duct.

Lacrimal Pump Mechanism

The process where the orbicularis oculi muscle contracts during blinking to create negative pressure, pulling tears into the lacrimal sac.

Orbicularis oculi muscle

The muscle that contracts during blinking to facilitate the lacrimal pump mechanism.

Dry Eye Disease

A condition characterized by insufficient or unstable tears, leading to eye discomfort, blurry vision, and increased tear concentration (osmolarity).

Sjögren’s Syndrome

A chronic autoimmune inflammatory disease affecting the exocrine glands, commonly resulting in dry eyes and dry mouth.

Xerophthalmia

The clinical term for dry eyes resulting from Sjögren's Syndrome or other deficiencies.

Xerostomia

The clinical term for dry mouth, a common symptom of Sjögren's Syndrome.

Primary Sjögren Syndrome

A form of the syndrome that occurs without another autoimmune disease, directly affecting the lacrimal and salivary glands.

Secondary Sjögren Syndrome

A form of the syndrome that occurs in conjunction with another autoimmune disease, such as Rheumatoid arthritis or Systemic lupus erythematosus.

Tear Meniscus Height

An aqueous quantity evaluation with a normal range of $0.1 \text{ to } 0.6\,mm$.

Schirmer I Test

A test for aqueous quantity, where normal values are considered greater than $15\,mm$ in $5\,min$.

Schirmer basic secretion test

A test signifying aqueous deficiency when results are less than the normal value of greater than $5\,mm$ in $5\,min$.

Lactoferrin Normal Value

A measure of lacrimal gland function where $1.42\,mg/mL$ is normal, and values less than $1.00\,mg/mL$ are abnormal.

Tear Osmolarity Normal Value

A clinical measure of lacrimal gland function where the normal threshold is less than $312\,mOsm/L$.

Breakup Time (BUT)

A measure of tear film stability or mucus deficiency, with a normal value of greater than $10\,sec$.

Noninvasive Breakup Time (NIBUT)

An evaluation of microepithelial defects or aqueous adequacy, with a normal value of $40\,sec$.

Impression Cytology

A test evaluating epithelial cell appearance and goblet cell density, characterized by a normal microscopic appearance.

Punctal Plugs

Devices used to reduce tear drainage and keep tears on the ocular surface as a management strategy for dry eye.

Cyclosporine

A topical anti-inflammatory medication used in the management of Sjögren’s Syndrome and dry eye.