Can dry eye delay healing?

Yes. The tear film supplies the growth factors and adhesion proteins the epithelium needs; its impoverishment slows repair.

Are preserved eye drops harmful?

Benzalkonium chloride is cumulatively toxic to the epithelium. In a patient instilling several drops a day for years, switching to unit doses is often decisive.

Should dry eye be treated before eye surgery?

Yes. An unstable surface corrupts preoperative measurements and makes recovery less comfortable.

Dry eye and corneal healing: an underrated link

Dry eye is usually presented as a matter of comfort. It is also, and this is less well known, one of the main causes of delayed corneal healing — and one of the few that can be addressed before any problem arises.

The tear film nourishes, it does not merely wet

The cornea has no blood vessels: that is the condition of its transparency. It therefore receives oxygen and nutrients by two routes only, the aqueous humour behind and the tear film in front. That film delivers growth factors, vitamin A, adhesion proteins and defence molecules.

An unstable or impoverished tear film thus deprives the epithelium of its nourishing medium. On a healthy surface this means discomfort; on an injured or operated surface, healing that drags on.

The vicious circle of inflammation

Dry eye is not simply a lack of water. Tear film hyperosmolarity activates epithelial cells, which release inflammatory cytokines and metalloproteinases — MMP-9 in particular, whose presence can now be measured with a rapid test. These enzymes disrupt the junctions between cells and weaken the barrier, which increases evaporation and therefore hyperosmolarity.

This is why established dryness is not corrected by adding tears alone: the inflammation must also be interrupted.

Preservatives, an avoidable aggravating factor

Benzalkonium chloride, present in most multidose eye drops, is a detergent: it disrupts the tight junctions of the epithelium and kills surface cells, with an effect proportional to the number of daily instillations.

A patient using three preserved drops four times a day receives twelve daily exposures. In someone treated for glaucoma for ten years, the cumulative effect is considerable — and it is one reason why such eyes heal badly. Switching to preservative-free unit doses is often the most effective measure, and the simplest.

Before surgery, treat first

Dryness left untreated before cataract or refractive surgery has two consequences: distorted preoperative measurements — keratometry is read off the tear film, and an unstable film corrupts the implant calculation — and uncomfortable recovery, with slower visual rehabilitation.

Treating the surface before operating is therefore not a comfort measure: it is a condition of the result.

When to seek care without delay. Seek care if dryness is accompanied by increasing pain, reduced vision or persistent redness: these signs go beyond simple dryness and may indicate corneal involvement.

Frequently asked questions

Can dry eye delay healing?: Yes. The tear film supplies the growth factors and adhesion proteins the epithelium needs; its impoverishment slows repair.
Are preserved eye drops harmful?: Benzalkonium chloride is cumulatively toxic to the epithelium. In a patient instilling several drops a day for years, switching to unit doses is often decisive.
Should dry eye be treated before eye surgery?: Yes. An unstable surface corrupts preoperative measurements and makes recovery less comfortable.