title: Objective optical assessment of tear-film quality dynamics in normal and mildly symptomatic dry eyes.
abstract: OBJECTIVE
  To evaluate and compare the tear-film dynamics in normal eyes and in eyes with mild dry-eye symptoms using a new noninvasive optical method based on a double-pass instrument.
  
  
  METHODS
  Hospital Universitario Virgen de la Arrixaca, Murcia, Spain.
  
  
  METHODS
  Evaluation of diagnostic test or technology.
  
  
  METHODS
  Dynamic recording of double-pass retinal images during unforced tear-film breakup was performed in eyes with mild dry-eye symptoms (study group) and in an asymptomatic control group. Series of consecutive retinal images were recorded every 0.5 seconds while the patient avoided blinking. Measurements were performed under low-light conditions to naturally increase pupil diameter and maximize the method's sensitivity. Additional clinical tests were performed for comparison and included tear breakup time (TBUT), Schirmer I tests, and a normalized questionnaire (McMonnies). From the retinal images, a quality metric, the intensity distribution index, was calculated. An objective TBUT value was estimated in each eye when the intensity distribution index surpassed a defined threshold value compared with the initial baseline.
  
  
  RESULTS
  The study group comprised 20 eyes and the control group, 18 eyes. Symptomatic dry eyes had a typical exponential increase in the intensity distribution index with time. The objective TBUT values in the study group were comparable to the clinical TBUT estimates.
  
  
  CONCLUSIONS
  The new objective optical method to evaluate the quality and stability of the tear film was sensitive in detecting mild symptoms of dry eye and differentiating from normal cases. The procedure may allow early detection and follow-up of patients' tear film-related complaints.
authors.affiliation: Laboratorio de Óptica, Universidad de Murcia, Murcia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Benito
authors.forename: Guillermo M
authors.initials: GM
authors.lastname: Pérez
authors.forename: Sandra
authors.initials: S
authors.lastname: Mirabet
authors.forename: Meritxell
authors.initials: M
authors.lastname: Vilaseca
authors.forename: Jaume
authors.initials: J
authors.lastname: Pujol
authors.forename: José M
authors.initials: JM
authors.lastname: Marín
authors.forename: Pablo
authors.initials: P
authors.lastname: Artal
mesh_terms: D000328:Adult; D003941:Diagnostic Techniques, Ophthalmological; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011680:Pupil; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D013666:Tears / Q000378:metabolism*