Ocular surface disease (OSD) and dry eye disease (DED) are very common problems in the elderly, and they both considerably decrease vision-related quality of life.1,2 For those OSD patients who are chronically treated with preserved topical glaucoma medication, and in particular, drops preserved with benzalkonium chloride (BAK), ocular surface problems are particularly severe.
The condition can be characterised with the term glaucoma-therapy related ocular surface disease. It has been well established that BAK (and possibly, to a less extent, other preservatives or components used in intraocular pressure-lowering drops) damage the ocular surface.
For BAK, the mechanisms comprise a dose-dependent toxic effect, induction of apoptosis and, due to its detergent activity, destruction of the tear film lipid layer, which increases tear film evaporation. Thus, long-term use of preservatives applied in topical glaucoma medication frequently induces OSD in those who have normal ocular surface when the treatment is initiated, and significantly worsens OSD in eyes with OSD or DED, even after a short treatment period.1,2,3
Preservative-free (PF) topical medication has been widely available in the developed world for many years. For example, PF timolol, topical carbonic anhydrase inhibitors, protaglandin analogues, timolol/carboanhydrase inhibitors and prostaglandin/timolol fixed combinations are widely used.
However, numerous patients are still treated with preserved eye drops or eye drop versions, even if they exhibit typical symptoms (tearing, itching, frequent blinking, eye irritation and pain) and signs (red eye, blepharitis) of OSD. Many ophthalmologists think that detecting OSD is time-consuming and difficult, but this is a misconception.