Correlation of tear clearance rate and fluorophotometric assessment of tear turnover.

Abstract

Participants and methods SUBJECTSThe study group comprised 34 healthy individuals (mean age 58-4 (SD 14-7) years, ranging from 22 to 84 years). Tear turnover was determined in 55 eyes of the subjects. They were examined by slit-lamp microscope without fluorescein to ensure there were no corneal epithelial lesions. Subjects who wore contact lenses, had ocular abnormalities, or systemic diseases related to tear secretion were excluded. Informed consent was obtained from all subjects before the study. INSTRUMENTATIONFluorophotometric measurements were carried out with an FM-500 laser flare meter (Kowa Company Ltd, Japan), consisting of a slit-lamp and a photometric microscope. Light from the fluorescein solution passes through green barrier filters to a photomultiplier whose output can be read on a computerised display. The instrument was adjusted to scan linearly at a 300 angle between the optical axis of the eye and the excitation beam, and at a 600 angle between the optical axis of the eye and the photometric microscope. The tear film meniscus was measured at the centre of the lower lid margin. MEASUREMENT PROCEDUREAutofluorescence of the tear film meniscus was obtained from each eye before fluorophotometry. A 1 ,ul drop of 0 005% sodium fluorescein (50 ,ug/ml) was then instilled into the upper lateral part of the bulbar conjunctiva without touching the eye. The subject was asked to blink with no squeezing so as to homogenise the fluorescein over the tear film. The eye was scanned in a dark room by fluorophotometer every minute for 5 minutes, and subsequently every 1-5 minutes for 12 minutes. The Schirmer test with anaesthesia and the tear clearance rate were administered 1 hour after the fluorophotometric measurement. A 10 ,lI drop of 0-5% fluorescein and 0.40/o oxybuprocaine hydrochloride was instilled into the 1042 on 12 May 2018 by guest. Protected by copyright.

Schirmer test performed with open and closed eyes: variations in normal individuals

“…ST V may have higher values in the first minutes and diminish gradually during the tests (22)(23)(24) . ST V can also be a parameter for tear volume in humans, but further research should be carried out.…”

Central Connections of the Lacrimal Functional Unit

“…This sequence was followed by a period of 10 minutes of spontaneous blinking prior to any experimental procedure. This is in keeping with the approach of Xu and Tsubota 36 who performed the anaesthetic Schirmer test at an interval of five minutes after drop instillation and without prior removal of tear fluid from the conjunctival sac.…”

Delayed tear clearance in contact lens associated papillary conjunctivitis

“…13,14 It is suggested that there is a strong association of delayed tear clearance with intrinsically and extrinsically generated ocular surface inflammation, and that delayed tear clearance constitutes the basis for creating a vicious cycle to perpetuate the underlying insults derived from these inflammatory stimuli. 15 A delay in tear clearance might theoretically increase the immunoglobulin and/or leukotriene concentrations in the tear film and further increase the incidence of lens protein deposition and associated inflammation.…”