Eyelids and tear film · AH
Lubricating drops and ocular surface lubricants
Three-layer tear film · ingredient classes · preservatives · link to dry eye
Last reviewed: 2026-10-06 · 潘家健醫生
Key points
- Lubricating drops are taught by ingredient class — no brands or price ranking.
- Lubricants do not replace prescription drugs and are not treatment for cataract, glaucoma or infection.
- Sudden vision drop or sudden blindness, or severe pain with headache and vomiting: A&E now.
- Severe pain, photophobia or vision drop after weeks of use needs examination to exclude inflammation or infection.
What they are
Lubricating drops (artificial tears), gels and ointments ease dryness, grit and intermittent blur. They support the tear film; they do not cure meibomian dysfunction or Sjögren syndrome, and this page is not a medicine advertisement. See the dry-eye overview and the dry-eye care ladder. Product names are not listed.
Three layers of the tear film
| Layer | Main role | When short |
|---|---|---|
| Lipid (outer) | Slows evaporation; mostly from meibomian glands | Evaporative dry eye / MGD; worse in wind and air-conditioning |
| Aqueous (middle) | Wets, oxygenates, rinses debris | Aqueous-deficient dry eye; drugs or autoimmune disease may contribute |
| Mucin (against the cornea) | Spreads tears evenly | Poor spread; film breaks early |
Many people have mixed patterns. Evaporative disease often tracks MGD; aqueous deficiency is less common but can be severe. Choice of lubricant is by type and surface findings — not “more expensive is better”.
Forms
| Form | When it is often used | What to expect |
|---|---|---|
| Watery drops | Daytime, mild–moderate dryness, with spectacles | Short dwell; may need frequent use; brief blur after a drop |
| Thicker drops / gel | Moderate–severe, wind, air-conditioning | Lasts longer; blur lasts a little longer |
| Night ointment / thick gel | Morning stickiness, lagophthalmos in sleep | Marked blur — usually bedtime only unless a doctor says otherwise |
Ingredient classes (not a shopping list)
- Aqueous / dwell: sodium hyaluronate (HA), carmellose, hypromellose, polyvinyl alcohol, polyethylene glycol / propylene glycol, hydroxypropyl guar and similar
- Lipid supplements: lipid or emulsion formulas — often discussed when MGD leaves the oil layer thin
- Ointment bases: liquid paraffin / petrolatum types for night sealing
- By situation: evaporative / MGD may lean lipid plus warm lid care; aqueous deficiency often needs frequent preservative-free watery drops — still a doctor’s assessment, not a DIY online order
Preservatives (including benzalkonium chloride / BAK)
BAK-containing multi-dose bottles are often tolerated in mild disease with occasional use. If you need long-term frequent drops, already have surface disease, are post-op, or use other drops at the same time, ask a doctor or pharmacist whether a preservative-free preparation is better. So-called “vanishing” preservatives are not preservative-free; suitability is decided after examination — not by swapping products yourself based on daily drop count. Do not keep an opened unit dose overnight.
How often (education, not your prescription)
- Lubricants ease dryness; they are not a cure. Frequency and preservative-free choice follow the surface and the clinician or pharmacist
- Night ointment is usually bedtime only; do not put thick ointment in before daytime driving
- Space two medicines; thin before thick — follow the label and the doctor’s demo (see the drops tool)
- Contact lenses: only lubricants allowed for that lens type; sleeping in lenses is a separate risk — see the contact-lens page
What you can expect
- Some people get less dryness, grit or blur after blinking, but the evidence quality is not high — not everyone improves, and this is not a cure. Tear break-up time does not necessarily lengthen; this does not heal meibomian glands.
- Aqueous deficiency (including Sjögren) often needs very frequent preservative-free drops; plugs or prescription anti-inflammatories may be discussed if drops are not enough
- Evaporative / MGD: lubricants help; warm compress and lid hygiene matter too
- Severe pain, photophobia or vision drop after weeks of drops: not ordinary dry eye — exclude inflammation, infection or neuropathic surface pain
Selected public references (not a full bibliography)
These are the public studies this page draws on. PMID links go to PubMed (US National Library of Medicine) so you can check them. Figures are from those studies — not your prognosis and not a clinic success rate. Links are not a shop.
- Craig JP, Nichols KK, Akpek EK, et al. TFOS DEWS II definition and classification report. Ocul Surf. 2017;15(3):276-283. PMID 28736335國際乾眼定義與分類（蒸發／水液／混合）。教育架構；不是個人診斷標籤。
- Jones L, Downie LE, Korb D, et al. TFOS DEWS II Management and Therapy Report. Ocul Surf. 2017;15(3):575-628. PMID 28736343分階處理共識。潤滑減輕症狀，不是根治；階梯不是購物清單。
This is general medical information, not a diagnosis, and cannot replace an in-person consultation with a registered ophthalmologist, refraction, or a dilated fundus exam. It is not advice to use any medicine or undergo any procedure. Medicines (including off-label use), laser or surgery must be decided by a registered doctor after examination, according to indications and Hong Kong registration. Figures from the literature are published averages, not any clinic’s results. This site does not book, prescribe or refer. Do not change treatment on your own.