Studies confirm tear osmolarity is central to OSD

In 1978 Jeff Gilbard, MD, a pioneer in ocular surface disease (OSD), proposed that hypersmolarity of the tear film plays an important role in inducing the disease seen in the cornea and conjunctiva.¹ In 1979, Dr. Gilbard demonstrated that there was a significant positive correlation between tear film osmolarity and Rose Bengal staining.²

In rabbit models, he showed that decreases in corneal epithelial glycogen and in conjunctival goblet cell density, and morphological abnormalities of the conjunctiva correlated with increases in tear film osmolarity and duration of disease (1988).³ Dr. Gilbard also showed that closure of the meibomian gland orifices increased tear film osmolarity in the presence of normal lacrimal gland function and caused dry eye-type ocular surface abnormalities (1989).⁴

This work contributed to the International Dry Eye WorkShop in 2007, identifying tear hyperosmolarity as an important factor in the pathogenesis of DES including it as a part of the definition of dry eye.⁵

Dr. Mastrota is center director of Omni Eye Surgery in New York City and associate optometric editor of Optometry Times.Now, 35 years later, what do tear osmolarity studies show? Searching the literature, here’s what we find:

• Tear film osmolarity is increased in patients with diabetes mellitus compared with healthy controls. Tear film osmolarity also correlates with the duration of the disease.⁶

• Tear hyperosmolarity and abnormal tear film function are associated with pterygium. Pterygium excision improved tear osmolarity and tear film function. Tear osmolarity, however, deteriorated again with the recurrence of pterygium.⁷

• Exposure to air pollution reduces tear film stability and negatively influences tear film osmolarity.⁸

• There are significant relationships between tear osmolarity and lid characteristics, including lid sensitivity.⁹

• Patients complaining of epiphora in the absence of other ocular surface pathology have significantly lower tear osmolarity.¹⁰

• Tear osmolarity is increased in patients treated for glaucoma or ocular hypertension, particularly in patients using multiple preserved eye drops.¹¹

• The cytotoxic effects of BAK on conjunctival epithelial cells in vitro are increased in hyperosmotic conditions, with characteristic cell death processes such as apoptosis.¹²

• Orally administered ethanol is secreted into the tears. Ethanol in tears induced tear hyperosmolarity and shortened tear break-up time.¹³

• Tear osmolarity is higher in eyes of patients with pseudoexfoliation when compared with normal subjects.¹⁴

• A significant increase of osmolarity was found in patients with severe conjunctivochalasis.¹⁵

• Tear osmolarity is increased with dehydration and tracked alterations in plasma osmolarity.¹⁶

These studies evaluate how tear osmolarity is impacted by a variety of conditions in vivo, in vitro, and in animal models. It appears tear osmolarity is an integral factor in the complex condition of ocular surface disease.ODT

References

Gilbard JP, Farris RL, Santamaria J 2nd.Arch. Osmolarity of tear microvolumes in keratoconjunctivitis sicca. Arch Ophthalmol. 1978 Apr;96(4):677-681.

Gilbard JP, Farris RL. Tear osmolarity and ocular surface disease in keratoconjunctivitis sicca. Arch Ophthalmol. 1979 Sep;97(9):1642-1646.

Gilbard JP, Rossi SR, Gray KL, Hanninen LA, Kenyon KR. Tear film osmolarity and ocular surface disease in two rabbit models for keratoconjunctivitis sicca. Invest Ophthalmol Vis Sci. 1988 Mar;29(3):374-378.

Gilbard JP, Rossi SR, Heyda KG. Tear film and ocular surface changes after closure of the meibomian gland orifices in the rabbit. Ophthalmology. 1989 Aug;96(8):1180-1186.

Lemp MA, Baudouin C, Baum J, et al. The definition and classification of dry eye disease: Report of the definition and classification subcommittee of the International Dry Eye WorkShop (2007). Ocular Surface. 2007;5(2):75–92.

Sağdık HM, Tetikoğlu M, Uçar F, Uğurbaş SC, Ugurbas SH. Tear Film Osmolarity in Patients with Diabetes Mellitus. Ophthalmic Res. 2013 Feb 22;50(1):1-5.

Türkyılmaz K, Oner V, Sevim MŞ, Kurt A, Sekeryapan B, Durmuş M. Effect of pterygium surgery on tear osmolarity. J Ophthalmol. 2013;2013:863498.

Torricelli AA, Novaes P, Matsuda M, Braga A, Saldiva PH, Alves MR, Monteiro ML. Correlation between signs and symptoms of ocular surface dysfunction and tear osmolarity with ambient levels of air pollution in a large metropolitan area. Cornea. 2013 Apr;32(4):e11-5. doi: 10.1097/ICO.0b013e31825e845d.

Golebiowski B, Chim K, So J, Jalbert I. Lid margins: sensitivity, staining, meibomian gland dysfunction, and symptoms. Optom Vis Sci. 2012 Oct;89(10):1443-1449.

Saleh GM, Hussain B, Woodruff SA, Sharma A, Litwin AS. Tear film osmolarity in epiphora. Ophthal Plast Reconstr Surg. 2012 Sep-Oct;28(5):338-340. doi: 10.1097/IOP.0b013e31825e6960.

Labbé A, Terry O, Brasnu E, Van Went C, Baudouin C. Tear film osmolarity in patients treated for glaucoma or ocular hypertension. Cornea. 2012 Sep;31(9):994-999. doi: 10.1097/ICO.0b013e31823f8cb6.

Clouzeau C, Godefroy D, Riancho L, Rostène W, Baudouin C, Brignole-Baudouin F. Hyperosmolarity potentiates toxic effects of benzalkonium chloride on conjunctival epithelial cells in vitro. Mol Vis. 2012;18:851-863. Epub 2012 Apr 6.

Kim JH, Kim JH, Nam WH, Yi K, Choi DG, Hyon JY, Wee WR, Shin YJ. Oral alcohol administration disturbs tear film and ocular surface. Ophthalmology. 2012 May;119(5):965-971.

Öncel BA, Pinarci E, Akova YA. Tear osmolarity in unilateral pseudoexfoliation syndrome. Clin Exp Optom. 2012 Sep;95(5):506-509. doi: 10.1111/j.1444-0938.2011.00683.

Fodor E, Kosina-Hagyó K, Bausz M, Németh J. Increased tear osmolarity in patients with severe cases of conjunctivochalasis. Curr Eye Res. 2012 Jan;37(1):80-84.

Fortes MB, Diment BC, Di Felice U, Gunn AE, Kendall JL, Esmaeelpour M, Walsh NP. Tear fluid osmolarity as a potential marker of hydration status. Med Sci Sports Exerc. 2011 Aug;43(8):1590-1597. doi: 10.1249/MSS. 0b013e31820e7cb6.