title: Evaluation of point-of-care test for elevated tear matrix metalloproteinase 9 in post-LASIK dry eyes.
abstract: To evaluate the performance of a point-of-care test for detection of matrix metalloproteinase 9 (MMP-9) levels in post-laser-assisted in situ keratomileusis (LASIK) dry eyes.
  
  
  
  A comparative study between patients with mild to moderate post-LASIK dry eyes and age-matched normal subjects was conducted. Ocular surface disease index (OSDI), tear break-up time (TBUT), and tear film MMP-9 and total protein levels were compared between the two groups. A point-of-care test device (RPS InflammaDry, Sarasota, Florida, USA) was utilised to confirm elevated MMP-9 levels in tear film.
  
  
  
  Fourteen post-LASIK dry eyes and 34 normal eyes were included. There was no significant difference in age and gender between both groups (p>0.175). The OSDI was significantly higher (25.5±7.7 vs 7.4±2.5; p<0.001) and TBUT levels were significantly lower (5.4±0.9 vs 13.5±2.3; p<0.001) in patients with dry eye compared with normal subjects. The tear film MMP-9 levels were 52.7±32.5 ng/mL in dry eyes and 4.1±2.1 ng/mL in normal eyes (p<0.001). MMP-9 levels were >40 ng/mL in 7/14 (50.0%) post-LASIK dry eyes. The InflammaDry was positive in 8/14 (57.1%) post-LASIK eyes. All positive cases had tear film MMP-9 levels ≥38.03 ng/mL. Agreement between InflammaDry and MMP-9 was excellent with Cohen κ value of 0.857 in post-LASIK dry eyes.
  
  
  
  Only half of post-LASIK dry eyes were found to have significant inflammation associated with elevated MMP-9. The OSDI is useful to non-specifically identify patients with symptomatic dry eye while the InflammaDry determined which patients with dry eye were associated with significant inflammation that may guide therapeutic management decisions.
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong Hong Kong Eye Hospital, Kowloon, Hong Kong.
authors.forename: Tommy C Y
authors.identifier: 0000-0003-4228-9482
authors.initials: TC
authors.lastname: Chan
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Cong
authors.initials: C
authors.lastname: Ye
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Kwok Ping
authors.initials: KP
authors.lastname: Chan
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Kai On
authors.initials: KO
authors.lastname: Chu
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong Hong Kong Eye Hospital, Kowloon, Hong Kong Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Vishal
authors.initials: V
authors.lastname: Jhanji
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D003315:Cornea / Q000378:metabolism / Q000473:pathology*; D015352:Dry Eye Syndromes / Q000209:etiology / Q000378:metabolism / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D019095:Point-of-Care Systems; D011183:Postoperative Complications; D011446:Prospective Studies; D013666:Tears / Q000201:enzymology*
chemical_list: D015415:Biomarkers; D020780:Matrix Metalloproteinase 9
keywords: Tears