Evaluation of the frequency of ophthalmic solution application: washout effects of topical saline application on tear components.
To determine and compare the effects of single and frequent topical applications of saline solution on tear protein concentration in clinically normal subjects....
Even a single application of saline solution resulted in significant changes in major tear protein and sialic acid concentration in the tears of normal subjects. Differences in the recovery of tear protein concentration may be related to the process of protein production and secretion. A balance between normal tear function and the therapeutic effects of ophthalmic solutions should be considered when deciding the frequency of application, particularly in patients with dry eye.
The first thing I thought of reading this was... wish I could see the exact same study using, say, Refresh Plus PF or some other typical non viscous CMC drop. Obviously, saline is NOT a lubricant and should not be thought of or used as such... yet... I've known so many people who overused artificial tears (say every 10 minutes or so) and never had any doctor suggest it might not be good for them, though one would think the 'washout' effect described here ought presumably to apply to those too I would think?
I confess I am a proponent of occasional use of saline drops by dry eye patients – but for specific reasons and ONLY within reasonable limits.
1) As an alternative eyewash. Better to use saline (0.9% sodium chloride) than a BAK-preserved commercial eyewash product (as they virtually all are).
2) As an occasional drop for the soothing effect. There are a lot of dry eye patients who report that all polymer artificial tears make their eyes feel worse… temporarily wet, for sure, but less comfortable. Some of them have developed sensitivities to certain ingredients. Many of those who can afford it are on serum tears instead. Most pursue alternatives to keeping comfortable such as moisture chamber glasses, cold compresses or what have you. But now and then they just need some way to feel nice and wet without introducing irritating stuff. There's nothing more soothing when your eyes feeling like they're burning holes in your head than a stream of chilled saline. But not as a habit, please!!!!
3) As a buffer for more irritating drops. A handy trick for rendering a highly irritating Rx drop (Restasis a commonly cited one…) is to put in a teeny drop of saline 10-15 minutes earlier.
Curr Eye Res. 2013 Jul;38(7):722-8. doi: 10.3109/02713683.2013.777967. Epub 2013 Mar 22.
Shigeyasu C, Hirano S, Akune Y, Mochizuki H, Yamada M.
National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center , Meguro-ku, Tokyo , Japan.