Written by Dr Jonathon Ng, Ophthalmologist and surgeon, Perth Eye Hospital
Dry eye is a common problem in the community with many causes for its development. Symptoms often develop once there are enough of the multiple factors that worsen dry eye. People with glaucoma are at higher risk of dry eye because some glaucoma treatments can worsen the ocular surface and the tendency to dry eye. It is important that when dry eye occurs in someone with glaucoma, that all factors contributing to the development of dry eye are addressed as this may be enough to improve symptoms without needing to change glaucoma treatment.
Symptoms of dry eye include eyes that feel irritable or even like there is something in the eye. Itchiness is another symptom often wrongly blamed on allergy. These symptoms occur because dryness irritates and stimulates nerves on the surface of the eye. Dryness of the surface tissues of the eye can also make them redder with more obvious blood vessels on the white of the eye. The vision can also be blurred because dryness causes surface irregularities and disrupts focussing. Sometimes people with dry eye can also have a watery eye because of a reflex increase in tear production in response to dryness.
Treating dry eye involves ensuring adequate tear volume, maximising the health and function of the tears, optimising tear flow, and where possible removing or at least minimising any factors that may be worsening the tendency to dry eye.
The best way to ensure optimal tear health and function is by controlling any blepharitis through ongoing, regular lid cleaning. Blepharitis is a common condition which results in blockage of the Meibomian glands in the eyelids and can be worsened by the prostaglandin analogue class of glaucoma drops. These glands are important because they produce oils that reduce tear evaporation. Regular lid cleaning comprising of a hot compress, lid massage and eyelid margin cleaning helps keeps the Meibomian glands healthy and working. Other treatments that can supplement lid cleaning include dietary omega-3 fatty acids and oral doxycycline.
Artificial tear drops
Artificial tear drops act to moisturise the ocular surface and supplement natural tear production. Whilst generally safe to use, the main precaution is to restrict excessive use of preparations with preservatives as preservatives can cause ocular surface toxicity and worsen dry eye symptoms. To reduce drainage of tears from the eyes, punctal plugs to block the tear ducts can be beneficial in reducing the frequency of lubricating drops required to keep the eye comfortable.
Eyelid position correction
The surface of the eye can also become dry because tears are not evenly distributed across the ocular surface. This can occur because of lumps on the surface of the eye such as pingueculums or pterygia. In order for tears to be spread evenly over the surface it is important that the eyelids are in good contact with surface. Eyelids which are floppy, lax or turned out (ectropion) can also worsen the tendency to dry eye. Whilst artificial tear drops can help, sometimes surgical correction of the eyelid position may be required.
Glaucoma treatment adjustment
If symptoms of dry eye continue to cause problems despite addressing the other causes of dry eye described previously, then changes to glaucoma treatment may be necessary. Eyedrop treatments that are preservative free or when more than one medication is required then preparations that combine two medications in one bottle, can help reduce the tendency for dry eye. If suitable, laser trabeculoplasty can reduce or eliminate the need for glaucoma eye drops. Ultimately surgery may be necessary if symptoms are severe enough and worsened by glaucoma drops but this is not without risk.
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