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Evaluation of point-of-care test for elevated tear matrix metalloproteinase 9 in post-LASIK dry eyes
  1. Tommy C Y Chan1,2,
  2. Cong Ye1,
  3. Kwok Ping Chan1,
  4. Kai On Chu1,
  5. Vishal Jhanji1,2,3
  1. 1Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong
  2. 2Hong Kong Eye Hospital, Kowloon, Hong Kong
  3. 3Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia
  1. Correspondence to Dr Vishal Jhanji, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong; vishaljhanji{at}


Aim 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.

Methods 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.

Results 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.

Conclusions 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.

  • Tears

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