title: The influence of rigid gas permeable lens wear on the concentrations of dinucleotides in tears and the effect on dry eye signs and symptoms in keratoconus.
abstract: OBJECTIVE
  To evaluate the signs and symptoms of dry eye and dinucleotide secretion in tears of keratoconus patients (KC) and the potential effect of rigid gas permeable (RGP) contact lens wear.
  
  
  METHODS
  Twenty-three KC patients and forty control subjects were enrolled in this study. Signs of dry eye including tear volume, tear stability and corneal staining along with symptoms were assessed using the McMonnies questionnaire. Tears were collected using Schirmer strips, and dinucleotide concentrations in collected tears measured using high pressure liquid chromatography. Values obtained in KC and controls were compared. The effect of contact lens wear in KC was also assessed.
  
  
  RESULTS
  KC eyes showed a significantly lower tear volume compared to controls, shorter tear break up time (TBUT), higher corneal staining and higher McMonnies dry eye questionnaire scores (p<0.05). When compared with non-wearers, KC contact lens wearers showed significantly higher symptoms, lower Schirmer and TBUT values (p<0.05). Concentration of Ap4A (0.695±0.304μM vs. 0.185±0.178μM) and Ap5A (0.132±0.128μM vs. 0.045±0.036μM) were higher in KC compared to controls (p<0.001) and only Ap4A was statistically higher in RGP wearers compared to non-wearers (0.794±0.478μM vs. 0.417±0.313μM) (p<0.05).
  
  
  CONCLUSIONS
  Signs and symptoms of dry eye as well as concentrations of Ap4A and Ap5A were markedly increased in KC patients compared to controls. Moreover, Ap4A and symptoms of dry eye were statistically higher in RGP wearers compared to non-wearers. This seems to indicate that factors such as RGP contact lens wear might exacerbate the clinical condition of dry eye.
authors.affiliation: Department of Optics II (Optometry and Vision), Faculty of Optic and Optometry, Universidad Complutense de Madrid, Madrid, Spain; Department of Biochemistry and Molecular Biology IV, Faculty of Optic and Optometry, Universidad Complutense de Madrid, Madrid, Spain. Electronic address: jgcarrac@ucm.es.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Carracedo
authors.affiliation: Clinical & Experimental Optometry Research Lab, Center of Physics (Optometry), School of Sciences, University of Minho, Braga, Portugal.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: González-Méijome
authors.affiliation: Department of Biochemistry and Molecular Biology IV, Faculty of Optic and Optometry, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Martín-Gil
authors.affiliation: Department of Optics II (Optometry and Vision), Faculty of Optic and Optometry, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Carballo
authors.affiliation: Department of Biochemistry and Molecular Biology IV, Faculty of Optic and Optometry, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Pintor
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D003261:Contact Lenses / Q000009:adverse effects*; D015226:Dinucleoside Phosphates / Q000032:analysis*; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D005260:Female; D005740:Gases / Q000737:chemistry; D006801:Humans; D007640:Keratoconus / Q000150:complications / Q000378:metabolism / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010539:Permeability; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D063189:Symptom Assessment; D013666:Tears / Q000737:chemistry*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D015226:Dinucleoside Phosphates; D005740:Gases; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C020733:diadenosine tetraphosphate
keywords: Dry eye; GP lenses; Keratoconus; Nucleotides