title: Short-term Effect of Scleral Lens on the Dry Eye Biomarkers in Keratoconus.
abstract: OBJECTIVE
  To evaluate the most important signs of dry eye, such as osmolarity, inflammation, and diadenosine tetraphosphate (Ap(4)A) concentration before and after wearing scleral lenses for 8 h in keratoconus patients.
  
  
  METHODS
  A pilot, experimental, short-term study involved 26 keratoconus patients (average age, 36.95 ± 8.95 years). They voluntarily enrolled in the study at the Optometry Clinic of the Faculty of Optics and Optometry in the University Complutense of Madrid. They were divided into two groups: patients with intrastromal corneal ring, the ICRS group, and patients without ICRS, the keratoconus (KC) group. Ocular Surface Disease Index questionnaire, the Schirmer test without anesthesia, tear break-up time, matrix metalloproteinase 9 (MMP-9) concentration, osmolarity, and Ap4A concentration were evaluated before and after wearing a scleral lens for 8 h.
  
  
  RESULTS
  The patients wore the scleral lenses from 6 to 9 h, with a mean of 7.59 ± 0.73 h. The mean scleral lens sag for all patients was 4310 ± 166.31 μm, ranging from 4200 μm to 4800 μm. No significant changes in the Schirmer test and tear break-up time were found for either group. Ocular Surface Disease Index scores were statistically lower after wearing scleral lenses for both groups (p < 0.05). A significantly lower osmolarity and a significant rise of MMP-9 concentration after wearing scleral lenses were found in both groups (p < 0.05). Diadenosine tetraphosphate concentration was lower after wearing the scleral lens in the KC group (p < 0.05) but no significant difference was found for the ICRS group (p > 0.05).
  
  
  CONCLUSIONS
  Short-term scleral lens wearing improves the symptomatology and some signs of dry eye, such as osmolarity and Ap4A concentration. The increase of MMP-9 concentration could be caused by tear film stagnation and use of preserved saline.
authors.affiliation: *PhD †OD ‡Msc Department of Optics II (Optometry and Vision), Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain (GC, MSB, WG, JCA); and Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain (AM-G, JP).
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Carracedo
authors.forename: Maria Serramito
authors.initials: MS
authors.lastname: Blanco
authors.forename: Alba
authors.initials: A
authors.lastname: Martin-Gil
authors.forename: Wang
authors.initials: W
authors.lastname: Zicheng
authors.forename: Jesús Carballo
authors.initials: JC
authors.lastname: Alvarez
authors.forename: Jesús
authors.initials: J
authors.lastname: Pintor
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D003261:Contact Lenses; D003319:Corneal Stroma / Q000601:surgery; D015226:Dinucleoside Phosphates / Q000378:metabolism; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000378:metabolism / Q000628:therapy*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008875:Middle Aged; D009994:Osmolar Concentration; D019736:Prostheses and Implants; D017755:Prosthesis Fitting; D019919:Prosthesis Implantation; D012590:Sclera; D011795:Surveys and Questionnaires; D013666:Tears / Q000737:chemistry / Q000502:physiology*
chemical_list: D015415:Biomarkers; D015226:Dinucleoside Phosphates; C020733:diadenosine tetraphosphate; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9