Table 2

Baseline characteristics in the study population with suspected infectious keratitis (2004–2014), in total and according to outcome of corneal culture by direct plating under aerobic conditions

All included patients, both culture positive and culture negative (n=355)Culture positive patients (n=165)Culture negative patients (n=190)P value
Mean age at episode onset (SD; range)50.5 (21.3; 5–98)57.1 (21.5; 7–98)44.7 (19.4; 5–91)<0.001*
Sex (Female)202 (57%)90 (55%)112 (59%)0.404†
Laterality (Right)178 (50%)73 (44%)105 (55%)0.038†
Monomicrobial growth of aerobic microbe isolated by direct plating136136
Polymicrobial growth of 2 aerobic microbes isolated by direct plating2626
Polymicrobial growth of 3 aerobic microbes isolated by direct plating22
Polymicrobial growth of 4 aerobic microbes isolated by direct plating11
Topical antibiotic treatment prior to corneal culture65 (18%)24 (14%)41 (22%)0.087†
Polymyxin B220
Combination of 213310
Combination of 3101
Contact lens wear155 (44%)57 (34%)98 (52%)0.001†
No known risk factor70 (20%)34 (21%)36 (19%)0.695†
Ocular surface disease including eyelid disorders57 (16%)34 (21%)23 (12%)0.030†
Prior ocular surgery and trauma46 (13%)23 (14%)23 (12%)0.608†
Blind/severely ill eye prior to episode8 (2%)4 (2%)4 (2%)1.000‡
Combination of 2 of above risk factors19 (5%)13 (8%)6 (3%)0.049†
Median best corrected visual acuity at first visit with keratitis episode (SE)<0.001§
25th percentile0.060.010.3
75th percentile1.00.851.0
  • Thirty-six cases were excluded from calculations on median visual acuity, since visual acuity was not measured at first visit. Of these, 16 cases were culture negative for aerobic microbes on direct plating and 20 were culture positive.

  • *t-test.

  • †Pearson’s χ2 test.

  • ‡Fisher’s exact test.

  • §Mann-Whitney U-test.

  • SE, Snellen equivalents.