Honey. Sweet, sticky, golden, delicious, anti-inflammatory, and anti-microbial honey.

In addition to being a delicious condiment for your breakfast, it turns out that honey – manuka honey in particular – can also be quite beneficial in the treatment of dry eye disease (DED).

A Quick Recap on Dry Eye
Dry eye can be an insidious condition and is now widely recognized as much more complicated than what we originally thought. Often the level of ocular discomfort experienced by a patient will not match up with what the eye doctor may observe in the examination room, which can further complicate its diagnosis and treatment. Many people, in fact, will not even realize they suffer from dry eyes, thinking that the gritty, irritated feeling in their eyes is merely part of life or just because they’ve had a long day at work. Fortunately, with an increased understanding of dry eye disease and the multitude of factors that contribute to it, dry eye treatments can progress beyond a simple squirt of saline in your eye.

There are two broad categorizations for DED:

1. Aqueous deficiency dry eye
2. Evaporative dry eye, also known as meibomian gland dysfunction

The meibomian glands are a row of little sebaceous glands that line the top and bottom eyelids, opening along the lid margin just behind the eyelashes. These glands secrete an oil known as meibum, which plays a crucial role in preventing the tear film from evaporating too quickly into the environment between eyelid blinks. When these glands become blocked, inflamed, overrun with bacteria, and are just misbehaving overall, it can lead to a poor quality and quantity of meibum, a low tear evaporation time, and subsequent evaporative dry eye. Inflammation and damage to the surface of the eye from dryness result in soreness and irritation of the eye, red eyes, and general unhappiness.

The Magical, Medicinal Properties of Manuka Honey
Manuka honey has been long known to exhibit medicinal benefits (It’s been used as a dressing for wounds and burns.) In modern day medicine we may no longer reach for the honey jar to treat scrapes and grazes, but think about the last time someone suggested honey lemon tea for a sore throat. In ophthalmology, honey has been investigated for various uses, including the reduction
of post-operative swelling of the cornea and also as a pre-operative preventative treatment to reduce the risk of infection during the course of eye surgery.

Not only is honey handy for the aforementioned situations plus as a nourishing hair mask, researchers from the Queensland University of Technology in Australia were also able to validate the claim that honey made from the mystical-sounding Leptospermum scoparium species of plant has the ability to improve various measures of dry eye, both symptomatically and clinically. During this clinical trial, participants across both treatment and control groups were required to use traditional evaporative dry eye treatment in the form of a warm compress to the eyes followed by gentle massage of the eyelids, and were also permitted to use preservative-free lubricant eye drops as needed during the study. The treatment groups were provided with two variations of the manuka honey dry eye product – one in a preservative-free gel form with a higher concentration of honey, and the other in a preserved liquid drop form with a lower honey concentration.

By the end of the trial period, all the groups reported an improvement in their dry eye symptoms, an increased tear evaporation time, and reduced inflammation and redness of the eye, lending some credibility to the value of the time-tested, good ol’ hot compress and lid massage. However, while the control group demonstrated a significant improvement to the quality of the meibum secretions, only the two treatment groups found the ease of expression of this meibum from the glands was improved. The amount of staphylococcus epidermidis bacteria found on the eyelids was also reduced with the use of the honey products and as the skin’s natural bacterial load plays a role in affecting the composition of meibum, this was good news for meibomian gland dysfunction. Participants using the honey products also found they were less dependent on the lubricant eye drops throughout the day, as did the control group but to a smaller, statistically insignificant degree.

Though not yet FDA-approved in the US, in other countries such as the UK and Australia, properly formulated manuka honey dry eye products already inhabit an important niche in the dry eye therapy hive:

• It is available in a non-preserved gel with an extended shelf-life. Preservatives in many eye drops can often contribute to irritation of the ocular surface, particularly if used frequently. Though non-preserved tear lubricants are widely available, these are produced only in single-use vials, contributing to wastage and cost. Manuka honey remains naturally sterile for longer even after the tube is unsealed.
• It does not induce damage to the ocular surface (known as cytotoxicity) despite frequent and long-term use.
• It is available at a relatively low cost and does not require a doctor’s prescription. Intensive dry eye therapies such as IPL treatment can rack up bills into the hundreds (or even thousands) or dollars over the years; fancy dry eye drops such as cyclosporin or autologous serum can be tricky to get and require a script.
• It is au naturale but still offers valuable broad spectrum antibacterial and anti-inflammatory action in the war against dry eye.

If you suffer from dry eyes, this news may have you all abuzz. But before you reach for the closest jar of top-notch Australian and New Zealand Leptospermum scoparium manuka honey in the grocery store, be aware that the honey you slather on the toast is of a different grade from the honey you slather on your eye. It may sound like the elusive unicorn of dry eye treatments but use only regulatory-approved ophthalmic preparations of manuka honey for the treatment of meibomian gland dysfunction and evaporative dry eye.

References
Randomised controlled trial of topical antibacterial Manuka (Leptospermum species) honey for evaporative dry eye due to meibomian gland dysfunction. https://onlinelibrary.wiley.com/doi/full/10.1111/cxo.12524
Honey prophylaxis reduces the risk of endophthalmitis during perioperative period of eye surgery. https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.3606
Standardized antibacterial Manuka honey in the management of persistent post-operative corneal oedema: a case series. https://onlinelibrary.wiley.com/doi/full/10.1111/cxo.12295