title: Ocular demodicosis as a risk factor of pterygium recurrence.
abstract: OBJECTIVE
  To evaluate ocular demodicosis as a potential risk factor in pterygium recurrence.
  
  
  METHODS
  Cross-sectional study to correlate clinical findings with laboratory data.
  
  
  METHODS
  We retrospectively reviewed 94 patients (43 with primary and 51 with recurrent pterygia), among whom 68 patients received surgical correction, and prospectively enrolled another 23 pterygium patients and 14 nonpterygium controls for measuring the tear level of interleukin (IL)-17.
  
  
  METHODS
  All patients had microscopically confirmed ocular demodicosis. Statistical correlations were analyzed among age, sex, aqueous tear deficiency, dry eye, ocular demodicosis, follow-up period, surgical outcome, and tear levels of IL-17 measured by enzyme-linked immunosorbent assay.
  
  
  METHODS
  Correlation between ocular demodicosis or IL-17 levels and pterygium recurrence.
  
  
  RESULTS
  Among 94 patients, ocular demodicosis was more prevalent in patients with recurrent pterygium than those with primary pterygium (P = 0.015). During follow-up of 16.5 ± 11.5 months, 68 postsurgical patients developed 7 corneal recurrences, which constituted 7.4% of primary and 12.2% of recurrent pterygium (P = 0.820). They also developed 8 conjunctival recurrences. Kaplan-Meier survival analysis showed combined (P = 0.000), corneal (P = 0.044), and conjunctival (P = 0.002) recurrence was significantly higher among patients with demodicosis than those without. Conjunctival recurrence occurred within 6 months in eyes without demodicosis but extended beyond 6 months in eyes with demodicosis. In 34 postsurgical patients with demodicosis, the mite count of 14 patients with recurrence was significantly higher than that of 20 without (P = 0.005). The IL-17 level was significantly higher in patients with either pterygium or demodicosis than controls (P = 0.049 and 0.040, respectively), and the IL-17 level was further elevated in patients with both pterygium and demodicosis (all P<0.05).
  
  
  CONCLUSIONS
  Ocular demodicosis is a risk factor for pterygium recurrence, especially for conjunctival recurrence, presumably by perpetuating chronic inflammation mediated by T-helper (Th)17 lymphocytes.
authors.affiliation: Ocular Surface Center, Miami, Florida 33173, USA.
authors.forename: Yukan
authors.initials: Y
authors.lastname: Huang
authors.forename: Hua
authors.initials: H
authors.lastname: He
authors.forename: Hosam
authors.initials: H
authors.lastname: Sheha
authors.forename: Scheffer C G
authors.initials: SC
authors.lastname: Tseng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D015822:Eye Infections, Parasitic / Q000150:complications* / Q000175:diagnosis / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020381:Interleukin-17 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008924:Mite Infestations / Q000150:complications* / Q000175:diagnosis / Q000378:metabolism; D013508:Ophthalmologic Surgical Procedures; D011446:Prospective Studies; D011625:Pterygium / Q000175:diagnosis / Q000209:etiology* / Q000378:metabolism; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D013666:Tears / Q000378:metabolism
chemical_list: D005136:Eye Proteins; D020381:Interleukin-17; C042434:tear proteins