So far in this series of interactive exercises aimed at the management of dry eye, we have focused on two patients with, primarily, evaporative dry eye, the second made more severe by an ongoing meibomian gland dysfunction. In the latter, the management of the lid problem was essential to a long-term solution to the symptoms and so underlines the typical need for a multi-option approach to management. As we all know, dry eye management is not about offering a single lubricant drop and hoping things improve.

One area we have yet to cover in this series is the best management of dry eye with a clear systemic involvement. I presented last year (Optician 12.06.19) a case study to illustrate such a presentation, in this case a quite obvious systemic association requiring management. I used this case here to show how a dry eye problem sometimes requires some knowledge of systemic influences, as well as some understanding of the differences between lubricants.

Different Drops

A few years ago, we published an article by Professor Christine Purslow (Optician 13.11.15) which looked at what is in a drop and suggested ‘All dry eye drops are not created equal’. A version of this feature is available online and acts as useful source material for this exercise along with some previously published cases of dry eye management.

Some key points to consider from this paper include the following:

The best products need to achieve as much as possible: to influence both the tonicity and stability of the tear film, and protect the ocular surface from the potential desiccation in between blinks.

Here are five simple principles to follow in order to guide patients towards the most effective products, breaking the vicious circle from as many angles as possible:

1. Avoid preservatives wherever possible

The absence of the preservative, particularly if it is benzalkonium chloride, becomes more crucial than the active ingredient at this posology. The negative effects of this type of preservative on the ocular surface are widely accepted. Even other vanishing preservatives may not completely dissipate in a dry eye with low tear volume. If a patient is also taking other preserved topical

medication for glaucoma, then it is even more important to use preservative-free formulations for dry eye.

2. Choose a sufficiently hypotonic drop

This will help to address the increased osmolarity of the tears in a dry eye – the fundamental driver for inflammation. This may be particularly beneficial if the patient complains of stinging and burning sensations.

3. Choose products that mimic tear film behaviour

Look for products that contain ingredients that mimic the tear film’s viscoelastic behaviour in relation to shear forces (non-Newtonian behaviour). The natural choice is hyaluronic acid (HA) as a viscosity agent (or its sodium salt version). It is an excellent lubricant natural lubricant in the human body, with a sponge-like structure of polysaccharide chains that act to retain water and retard evaporation when placed on an aqueous solution. Hydrated hyaluronic acid can contain up to 1,000-fold more water than its own weight, resulting in enhanced hydration of the corneal surface. Many clinical studies demonstrate superiority over the more traditional cellulose derivatives and PVA, etc. A plant-derived alternative is hydroxypropyl-guar (HP-Guar), an ingredient that behaves like a gelling agent upon contact with the tears. This confers similar properties to the tear film in its behaviour. Both of these clever ingredients also demonstrate muco-adhesive properties, tending to coat the ocular surface well by interacting with the mucin layer. The more traditional ingredients such as cellulose derivatives, PEG, PVA might be found in addition to hyaluronic acid or HP-Guar – here they may act as adjuncts with the aim of improving residence time.

4. Look for ingredients that protect the ocular surface

Molecules (such as trehalose) protect corneal epithelial cells from death by drying, and confers resistance to high osmolarity by protecting proteins and membranes from denaturation. Other osmo-protectants include solutes such as L-carnitine and erythritol, alone or in combination.

5. Consider patient use

Finally, make sure you consider how the patient will use the product. Look for bottles that patients will find easy to squeeze, or come in unit doses – the pressure required to dispense eye drops varies enormously between products. Eye drops are seldom easy to apply – make sure your patient knows how before they leave the practice.


Interactive exercise

  • There is no one single answer for your discussion, but what is needed is a reflection of your discussion (which must be for a minimum of 10 minutes please) that is sufficient evidence of the various points having been covered.
  • Read the source material below
  • Complete six multiple choice questions to confirm you have grasped the main concepts
  • Read the case scenario about which you are to confer with a registered colleague (for at least 10 minutes please)
  • Confirm with us the name and GOC registration number of the colleague with whom you have discussed the case and also write some short notes on the outcome of your discussion
  • At the end of the month’s active period we will confirm that your discussion outcome meets the requirement for an inter
  • Look out for a published discussion based on all responses in a future issue of Optician.

Before proceeding to the case study and interactive exercise, read these resources: