The following abstract is from a study in which the authors reviewed the published literature (including recent studies) pertaining to dry eye in glaucoma and ocular hypertension patients. The coincidence of dry eye and glaucoma is stunningly high (up to 60%). Add that to the well established fact of BAK toxicity and it just amazes me that every week, I can talk to yet another dry eye patient with glaucoma whose doctor never made any attempt to get them a BAK-free glaucoma drug. Come on, guys, surely we can do better than this!

Ocular surface disease in patients with ocular hypertension and glaucoma.

Purpose:
To review the prevalence, diagnosis, causes, and treatment of ocular surface disease (OSD) in patients with ocular hypertension or primary open-angle glaucoma.

Methods:
A review of the literature pertaining to OSD and glaucoma.

Results:
Recent studies indicate that OSD demonstrates an overall prevalence in glaucoma of 42% (range 20-59%) and is severe in 36% (range 14-66%). Further, the prevalence appears to increase with the greater the number of glaucoma drugs prescribed. Symptoms and signs are non-specific to the anterior surface of the eye and are thought to result from allergic, toxic, or pro-inflammatory conditions. However, the specific causes remain incompletely described, but may result from the benzalkonium chloride (BAK) preservative or occasionally the ocular hypotensive active molecule itself. Additionally, anterior segment ocular diseases might be causative, such as allergy, blepharitis, dry eye, and eyelid anatomical abnormalities. Treatment may consist of using preservative-free or non-BAK preserved glaucoma medications. Also, although unproven specifically in glaucoma patients, treatment of associated diseases of the anterior surface might reduce signs and symptoms.

Conclusions:
OSD is common in treated glaucoma patients causing symptoms and signs that may impact on a patient's quality of life. Treatment is directed towards any underlying disease process and the use of preservative-free or non-BAK-preserved glaucoma preparations.
Curr Eye Res. 2011 May;36(5):391-8.
Stewart WC, Stewart JA, Nelson LA.
Source
PRN Pharmaceutical Research Network, LLC, Charleston, South Carolina, USA.