Mr Saurabh Ghosh
Consultant Ophthalmologist
With up to a third of the UK population suffering from dry eye, correct treatment with lubricating eye drops is needed to prevent further worsening of symptoms.
Dry eye is a very common condition that can vary from mild symptoms to sight-threatening consequences. It is often underdiagnosed, as many sufferers do not seek medical attention [1].
Treatment is readily available and can be very effective, but if the wrong treatment is used, symptoms can be made worse. Great care is needed when choosing the correct dry eye drop – the right drop for the right patient.
Tears are the natural protectors of the eye; they provide lubrication and without them, we can experience discomfort and vision impairment.
Tears are produced in the tear gland found under the upper eye lid and are spread across the surface by blinking – a process similar to that of windscreen wipers on your car.
Tears have a surprisingly complex structure, any abnormalities of which could be detrimental to the effectiveness of the eye [2].
Dry eyes can feel gritty and may sting
Dry eye occurs when the gland producing tears begins to fail (often as a result of age or illness), or when the tears evaporate too quickly [3].
Sufferers often note a grittiness or stinging, which is only partially relieved upon blinking. They often find this is worse after reading or prolonged viewing of screens, because when we concentrate, we naturally blink less, which means our eyes become drier.
Dry eye can be very severe and, if not properly treated, can result in permanent eye damage. Although most people have mild to moderate symptoms, even these can have significant effects on daily life, so it is important to address symptoms from the point of onset [4].
Preservatives may worsen dry eye if frequent or long term use is necessary
Current treatment is well established and very effective, essentially replacing the lack of tears through the addition of artificial tear drops. There are several different types and treatment regimes available and most people are able to manage symptoms using eyedrops when required.
There is, however, a potential paradox with dry eye treatments in that most eye drops contain preservatives, which can sometimes make symptoms of dry-eye worse.
Most eye drops contain preservatives, which can often make symptoms of dry-eye worse.
Historically, preservatives have been necessary to prevent bacterial contamination of the solution in the bottle and, when used short-term, these preservatives have the desired effect and generally cause minimal harm.
However, preservatives have a detergent-like action, meaning they disrupt the tear film and damage the delicate cells lining the front of the eye. This cell damage results in inflammation, which further damages the tear film and the cells it should protect.
Thus, when used longer-term, and frequently, preservatives can cause further damage to the eye. Since dry eye is a life-long condition stemming from an already impaired ocular surface, a vicious cycle ensues; preservative-containing dry eye treatments worsen the symptoms, which leads to further discomfort and further use of the damaging eye drops.
New bottles prevent bacteria contaminating the solution
A new generation of bottles, that allow eye drops to be free from preservatives in a multi-dose dropper bottle, have revolutionised the treatment of dry eye.
The bottles prevent bacterial entry, and therefore contamination of the solution in the bottle. Without inclusion of potentially damaging preservatives, the dry eye products can help stabilise the tear film and protect the ocular surface.
The vicious cycle is broken, and an environment can be created that allows cells to function correctly, reducing inflammation and discomfort.
Preservative-free (PF) dry eye drops are, unsurprisingly, becoming the mainstay of dry eye treatment [5]; they can be used as frequently as required, often with contact lenses and by those with allergic eye disease.
They are now available in multi-dose dropper bottles, which are convenient, last up to two months and help to overcome the environmental burden of single-use plastic unit dose vials.
1 https://dtb.bmj.com/content/54/1/9 | 2 https://www.glaucoma-association.com/media/wysiwyg/Leaflet_PDF_Files/Dry_Eye_Download.pdf | 3 https://bestpractice.bmj.com/topics/en-gb/962 | 4 https://iovs.arvojournals.org/article.aspx?articleid=2166230 | 5 https://www.tandfonline.com/doi/abs/10.1185/030079906X132640
