[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Ophthalmology](https://durgical.com/en/ophthalmology/) › [Clinical anatomy and physiology](https://durgical.com/en/ophthalmology/areas/anatomy-physiology/) › The tear film and ocular surface # The tear film and ocular surface - Anatomy and physiology The tear film is a thin layer of oil, water and mucus that keeps the cornea smooth and clear. When it fails, eyes feel gritty and vision fluctuates. Updated Nov 5, 2026 **See it in 3D:** [Cornea](https://durgical.com/en/anatomy/cornea/) · [Eyelids](https://durgical.com/en/anatomy/superior-tarsus/) · [Lacrimal gland](https://durgical.com/en/anatomy/lacrimal-gland/) · [Orbicularis oculi](https://durgical.com/en/anatomy/orbital-part-of-orbicularis-oculi/) ## Key points - Three layers: lipid (meibomian), aqueous (lacrimal), mucin (goblet cells). - Commonest dry eye: evaporative, meibomian gland dysfunction. - Dry eye with dry mouth: think Sjögren. - Facial palsy: protect the cornea. ## What it is The ocular surface is the cornea, the conjunctiva, the lids and the glands that make the tears. The tear film covering it is only a few micrometres thick but is the first refracting surface of the eye. It lubricates, nourishes and protects the cornea, and each blink spreads it again. Dry eye disease, the commonest eye complaint after refractive error, is a failure of this system. ## Clinical anatomy - Outer lipid layer: made by the meibomian glands in the lid margins; slows evaporation. - Middle aqueous layer: made by the main lacrimal gland and small accessory glands; carries water, electrolytes, oxygen and antibacterial proteins. - Inner mucin layer: made by conjunctival goblet cells and the surface epithelium; lets the watery tears wet the cornea. - Blinking, driven by the orbicularis oculi (facial nerve), spreads the film and pumps tears towards the drainage system. ## Physiology - A smooth tear film gives a clear optical surface; when it breaks up, vision blurs between blinks. - Corneal nerves sense dryness and trigger reflex tearing and blinking. - Tears contain lysozyme, lactoferrin and antibodies that protect against infection. ## Clinical correlation - Evaporative dry eye from meibomian gland dysfunction is the commonest type; aqueous-deficient dry eye is typical of Sjögren disease. - Screens and reading reduce blinking; contact lenses, laser refractive surgery, antihistamines and isotretinoin worsen dryness. - Incomplete lid closure (facial palsy, thyroid eye disease, sedated patients) dries the lower cornea: exposure keratopathy. - Reflex tearing from a dry eye can make it water. ## Next step / Initial management - Gritty, burning eyes with normal vision: lubricant drops, warm compresses and lid hygiene, fewer screen hours; review in weeks. - Dry eye with dry mouth or joint symptoms: tests for Sjögren disease (anti-Ro and anti-La antibodies) and rheumatology. - Incomplete lid closure: lubricating ointment at night and protection of the cornea; refer if the cornea stains. - Pain, light sensitivity or reduced vision: same-day ophthalmology, as for a red eye with red flags. ## Test yourself Think of the answer, then tap the question to see it. ## Which glands make the lipid layer of the tear film? The meibomian glands of the lid margins. ## What is the commonest type of dry eye? Evaporative dry eye from meibomian gland dysfunction. ## Why can a dry eye water? Because irritation of the dry cornea triggers reflex tearing. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/ophthalmology/the-tear-film-and-ocular-surface/) ## Elsewhere in DurgiPedia - [Conjunctiva, eyelid glands and lacrimal gland](https://durgical.com/en/histology/conjunctiva-eyelid-glands-and-lacrimal-gland/) ## Connections ## See it in 3D 4 The structures of Durgical's 3D anatomy where it is found. - [Cornea](https://durgical.com/en/anatomy/cornea/) - [Eyelids](https://durgical.com/en/anatomy/superior-tarsus/) - [Lacrimal gland](https://durgical.com/en/anatomy/lacrimal-gland/) - [Orbicularis oculi](https://durgical.com/en/anatomy/orbital-part-of-orbicularis-oculi/) ## Related 4 - [The cornea: clarity, nerves and healing](https://durgical.com/en/ophthalmology/the-cornea-clarity-nerves-and-healing/) - [Tear production and drainage](https://durgical.com/en/ophthalmology/tear-production-and-drainage/) - [The watering eye (epiphora)](https://durgical.com/en/ophthalmology/the-watering-eye/) - [Fluorescein staining and the Seidel test](https://durgical.com/en/ophthalmology/fluorescein-staining-and-the-seidel-test/) ## Related conditions 4 - [Dry eye disease](https://durgical.com/en/conditions/dry-eye-disease/) - [Sjögren disease](https://durgical.com/en/conditions/sjogren-disease/) - [Bell palsy](https://durgical.com/en/conditions/bell-palsy/) - [Thyroid eye disease (Graves orbitopathy)](https://durgical.com/en/conditions/thyroid-eye-disease/) [← All of ophthalmology](https://durgical.com/en/ophthalmology/) Educational content; not a clinical guideline and no substitute for assessment by a health professional. For sudden visual loss, severe eye pain, a chemical burn or an eye injury, go to an emergency department at once. Sources: [Dry Eye Syndrome](https://www.ncbi.nlm.nih.gov/books/NBK470411/) (StatPearls Publishing (NCBI Bookshelf), 2024); [Anatomy, Head and Neck: Eye Lacrimal Gland](https://www.ncbi.nlm.nih.gov/books/NBK532914/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Anatomy, Head and Neck, Eye Conjunctiva](https://www.ncbi.nlm.nih.gov/books/NBK519502/) (StatPearls Publishing (NCBI Bookshelf), 2023). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/ophthalmology/the-tear-film-and-ocular-surface/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/ophthalmology/the-tear-film-and-ocular-surface/