Study: Contact lens osmolality is associated with comfort and ocular surface characteristics

As reported on the OSN Super Site, a new technique for measuring contact lens osmolality proved repeatable and independent of lens material and power, a study showed.

The article titled "Influence of Tear Film and Contact Lens Osmolality on Ocular Comfort in Contact Lens Wear" is published in the July 2009 issue of Optometry and Vision Science:

The article authors, Stahl, Naduvilath, and Stapleton, said "Although no association between tear film osmolality and ocular comfort after 6 hours of lens wear could be demonstrated, contact lens osmolality was associated with comfort and ocular surface characteristics, and may provide the link between symptoms and clinical observations."

Investigators tested the method of measuring contact lens osmolality for repeatability and assessing its independence of lens material, power and osmolality value of the lens. Fifteen subjects wore nine different lens types.

Study data showed that the method of measuring contact lens osmolality was independent of lens material, power and osmolality value of the lens. In addition, data showed no differences in contact lens osmolalities between two different days.

Comfort after 6 hours of lens wear correlated with osmolality of the worn lens (P = .006) but not with tear osmolality after lens wear. Results showed significant correlations between osmolality of worn lenses and tear film breakup time, lens water content, conjunctival indentation and ocular sensitivity.

(July 9, 2009)