TearLab Osmolarity Test at the Dry Eye Centre

We are now pleased to have the Tear Lab Osmolarity test at the Dry Eye Centre. This is a useful tool in our diagnostic armoury.  The test measures the osmolarity of the tears. Osmolarity is a measurement of the number of solid particles in a solution. Increased osmolarity means an increased number of particles. When measuring tears this means that an increase osmolarity or hyperosmolarity means there is an increase in the saltiness of the tears compared to normal tears.

Hyperosmolarity is now included in the definition of dry eye. So an elevated level is 90% predictive that the patient has Dry Eye.

The Tear Lab test is easy to perfom and allows us to determine whether or not you have dry eye. In addition it also gives an indication of the severity. 

If you want this test included in your examination, please ask at your appointment.

Isotretinoin / Roaccutane use is a potential cause of Dry Eye

Isotretinoin is a drug used for the treatment of acne. It is a retinoid, meaning it derives from vitamin A and is found in small quantities naturally in the body. Isotretinoin binds to and activates nuclear retinoic acid receptors (RAR), thereby regulating cell proliferation and differentiation. This agent also exhibits immunomodulatory and anti-inflammatory responses and inhibits ornithine decarboxylase, thereby decreasing polyamine synthesis and keratinization. Isotretinoin noticeably reduces the production of sebum and shrinks the sebaceous glands. The exact mechanism of action is unknown, however it is known that it alters DNA transcription. It is a very successful drug in the treatment of acne.

Unfortunately the meibomian glands in the eyes are sebaceous glands and they are often affected by Isotretinoin. Many studies have shown that Isotretinoin causes dry eye symptoms as well as causing dry lips.

Patients taking Isotretinoin should use eye drops to keep their eyes lubricated and perhaps include an oily drop such as Eumistil. Contact lens wearers may want to reduce or cease wear whilst on Isotretinoin.

For most patients, these symptoms disappear after stopping the drug. However we have seen several cases where the symptoms have not improved. We have found both meibomian gland dysfunction and aqueous deficiency in these patients. If symptoms of dry eye do not disappear within 3 months after stopping the medicine we would recommend a dry eye assessment.