Issue 1.2 : Dry Eyes

Guest Editorial – Dry Eyes

We have come a long way in our awareness of a disease entity called the “Dry Eyes” since the author first started practice in the early eighties. At that time, knowledge of the condition was abysmally low – in fact it was not recognised as a disease till the DEWS meeting of 2006-7! In those days there were a subset of patients with irritable eyes with ‘vague’ symptoms with no apparent cause – they were more of a nuisance value to be given minimum chair time in busy OPDs. They would be dismissed with either a mild topical antiseptic like sulphacetamide eye drops or some local astringent containing or vasoconstrictor eye drops like naphazoline. Hydroxypropylmethyl cellulose drops were also available and would be often tried, to be put on a prn or as per need basis.

In the mid eighties, a combination of PVA and PVP (Polyvinyl alcohol and polyvinylpyrrolidone became available in our region from a multinational initially and later from a host of local manufacturers. This was followed by CMC (carboxymethyl cellulose) along with topical cyclosporine, recognising that sub clinical inflammation was at the root cause of dry eyes. The role of increased osmolarity was recognised, though eye drops manufactured with hypo osmolar artificial tears did not succeed, making ways for sodium hyaluronate drops with “optimum” viscosity and osmolarity. The latest kids on the block are the PG and PEG tears (propylene glycol and polyethylene glycol). In some countries in the SAARC region, rebamipide, a mucomimmetic is an additional weapon in the armamentarium.

The nomenclature, too, has briefly changed. From being called dry eyes, it was referred to as ‘Dysfunctional Tear Syndrome’ or DTS. However, this did not catch on and the disease –it was recognised as a disease only by the Dry Eyes Workshop of 2006-07(DEWS1)—is now again referred to as Dry Eyes. The DEWS 1 also incorporated the elements of ocular inflammation and hyper-osmolarity in the definition. 10 years later, the DEWSII of 2017 added the concept of neuropathic pain and improved upon the algorithm of treatment first proposed by DEWS 1. It however, made the important point that there is no topical therapy vastly superior to another and that all the lubricants have a role in different patients.

In the last decade a few important developments have taken place which deserve special mention in any article on Dry Eyes.
I will list them out below.

  1. The importance of toxic effects of preservatives in all ocular topical medications especially those used for long term like anti- glaucoma medications and lubricants has been recognised. Previously all eye drops contained preservatives – thimerosal, phenyl mercuric nitrate, chlorbutanol and the most notorious, bezalkonium chloride. Preservatives were deemed essential to prolong the shelf life and prevent contamination once the bottle was opened. However, it was found that these preservatives were in many cases epitheliotoxic to the ocular surface. Besides they altered the normal micro biome (or the normal bacterial flora residing on our ocular surface), leading to further harm. Companies countered this by introducing ‘disappearing’ preservatives such as Sodium Oxychloride or SOC, polyquad and hydrogen peroxide, all of which disappeared on exposure to light or air. Some came out with novel bottles containing silver which is a strong antiseptic. The inherent toxicity of preservatives is dependant upon their frequency of use and concentration, which was thereby reduced especially for bezalkonium chloride. Single use containers also made their appearance, but have not really caught on due to their cost.
  2. Newer diagnostic machines flooded the marketplace since the last 3-5 years. These include the Lipiview and similar machines from Europe which allowed Meibography, non-invasive break up time measurements, interferometry, tear meniscus height measurement, Demodex diagnosis etc. Tear-film Osmolarity could be measured by a single machine from Tear labs and MMP-9, an inflammatory marker found in tears, could be measured with a strip changing colour like blood sugar test using a glucometer.
  3. Meibomian Gland Dysfunction, Squamous blepharitis and Demodex infestations were recognised as being important to treat along with the dry eye. Various treatments, ranging from the expensive Lipiflow, to inexpensive eye masks containing microbeads which could be heated in a microwave to provide heat to the eyelids, to various medicated lid wipes are now available to treat these conditions.
  4. The DREAM study established that Omega 3 fatty acids made from fish oil were not superior to placebo for treating Dry Eyes. However, many dry eye experts still continue to use the drug made differently as they find it does benefit patients. It was also found that those who had Vitamin D deficiency did benefit by D3 supplements especially for pain relief, so it may be worthwhile doing a D3 level test in patients with Dry Eye and ocular pain.
  5. Lastly, treatment of the ocular surface especially Dry Eyes was found to make a difference between a happy patient and a not-so-happy patient after successful cataract or refractive surgery such as PRK, Lasik and SMILE. Many surgeons started adding lubricants to their routine post cataract and refractive surgery regimes while others reserved the lubricants to be used when necessary or if patient exhibited dry eye symptoms or signs.

To conclude, we live in exciting times. New drugs, which are layer specific are around the corner. Newer diagnostic and treatment modalities are available and I am sure their usage will only increase in the region. A greater awareness of the need to respect the ocular surface and to treat any insult to it as early as possible is creeping into the minds of general ophthalmologists, which I am sure will benefit all our patients in the long run.

Dr. Quresh B. Maskati,
President SAARC Pediatric Ophthalmology & Strabismus Association
President, Cornea Society of India
Recipient of Life Time Achievement Award from ISCKRS (Indian Society for Cornea and keratorefractive Surgery), 2019

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