title: Bilateral tear film alterations in patients with unilateral quiescent herpes simplex keratitis.
abstract: OBJECTIVE
  To evaluate bilateral tear function and corneal sensitivity in patients with unilateral quiescent herpes simplex keratitis (HSK) and determine the correlation between corneal sensitivity and tear secretion in both eyes.
  
  
  METHODS
  Thirty-five patients diagnosed with unilateral quiescent HSK and 35 heathy controls were included in this study. Bilateral tear osmolarity, Schirmer's test, the tear break-up time (TBUT) and corneal sensitivity were measured in all participants.
  
  
  RESULTS
  In the HSK group, both eyes demonstrated a significant increase in tear osmolarity, and a decrease in Schirmer's test and the TBUT compared with healthy controls (All p < 0.001). The bilateral tear osmolarity and Schirmer's test were similar, but the TBUT (4.9 ± 2.1 versus 7.4 ± 2.0 second; p < 0.001) and corneal sensitivity (35.1 ± 1.9 versus 54.3 ± 0.8 mm; p < 0.001) were significantly lower in the affected eyes. The bilateral tear osmolarity, Schirmer's test and the TBUT were significantly correlated with corneal sensitivity of the affected eye (All p < 0.001). When corneal sensitivity of the unaffected eye was treated as a control variable, tear osmolarity (R = -0.626, p < 0.001), Schirmer's test (R = 0.739, p < 0.001) and the TBUT (R = 0.691, p < 0.001) of the unaffected eyes were still significantly correlated with the corneal sensitivity of the affected eyes.
  
  
  CONCLUSIONS
  Unilateral quiescent HSK causes bilateral tear impairment, which depends on the loss of corneal sensitivity in the affected eye. In the affected eye with severe corneal sensitivity loss, bilateral dry eye occurred.
authors.affiliation: Department of Ophthalmology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Ma
authors.affiliation: Department of Ophthalmology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
mesh_terms: D003315:Cornea / Q000294:innervation / Q000503:physiopathology*; D015828:Eye Infections, Viral / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016849:Keratitis, Herpetic / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011446:Prospective Studies; D012677:Sensation; D012720:Severity of Illness Index; D013666:Tears / Q000378:metabolism*
keywords: bilateral tear impairment; dry eye; tear secretion reflex; unilateral herpes simplex keratitis