Investigations on the human pre-ocular tear film

• Main Author: Johnson, Michael Edward
• Published: Cardiff University 2007
• Subjects: 612.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548833

Information regarding the performance of tests used to assess the tear film is currently incomplete. This hinders the interpretation of their results, and so obstructs the management of patients with disorders of the tear film. This work determined the repeatability and identified confounding variables of methods that assess tear breakup time and tear meniscus height. It was found that the reproducibility of both these tests were poor when considered over the range of values encountered in clinical practice; however, the situation was improved for lower values. Furthermore, results indicated that the volume of Fluorescein solution instilled prior to the assessment of tear break-up time and the delay after a blink when assessing tear meniscus height should be standardized. Additionally, a new instrument to grade the severity of symptoms of ocular surface irritation was developed and psychometrically tested. This has advantages over its predecessors because it derives measures on a linear interval scale and more satisfactorily accounts for missing data. It is envisaged that this instrument will be used in future clinical trials, and will improve the power of inferences made from their data. Finally, the effectiveness of eyedrops containing Sodium hyaluronate in the treatment of moderate dry eye was investigated. A pharmacokinetic analysis established that their beneficial effects on the tear film last several hours, and a follow-up study found that they reduce symptoms and improve ocular surface health when used for a month