Purpose
To evaluate ocular surface changes in eyes on long term topical ocular hypotensive therapy and correlate them to the central corneal subbasal nerve fibre density
Methods
prospective case-control study of 50 eyes of 25 patients on longterm topical ocular hypotensive therapy (> two antiglaucoma medications > 6 months) and 50 normal eyes as controls.Data recorded included demographic and treatment data, comprehensive ocular evaluation, ocular surface evaluation tests (FTBUT, Schirmer's I test, OSDI score, conjunctival and corneal staining scores), corneal sensitivity and central corneal confocal subbasal nerve fiber layer density (SBNFLD). Quantitative variables were compared between cases and control groups using 2 sample T-test, correlation between ocular surface evaluation parameters and corneal SBNFLD was assessed using Pearson correlation coefficient.
Results
Mean OSDI score, Schirmer I score, FTBUT, corneal staining and conjunctival staining score in the eyes on longterm ocular hypotensive therapy was 35.89 + 16.07, 7.63 + 2.64 mm, 9.44 + 2.76 seconds, 5.7 + 2.33 and 5.06 + 1.94 respectively. Mean OSDI score, Schirmer I, FTBUT, corneal staining and conjunctival staining score in the control eyes was 6.02 + 3.84, 12.86 + 1.93 mm, 11.80 + 1.88 seconds, 1.1 + 0.58 and 0.84 + 0.46 respectively (p< 0.001). Mean sub-basal nerve fiber number, length and density was 3.58 + 0.99, 1101.44 + 287.56 µm and 12,273.15 + 3516.04 µm/ mm2 respectively in the ocular hypotensives therapy group compared to 5.40 ± 1.70, 1963.70 ± 562.56 µm, and 12,273.15 ± 3516.04 µm/mm2 in controls (p< 0.001). Corneal sensitivity was 5.07 ± 0 .37 in the ocular hypotensive group and 4.68 ± 0.44 in the controls (p= 0.076). Corneal (R2 = 0.86)and conjunctival staining (R2= 0.71) and OSDI score (R2 = 0.67) showed statistically significant negative correlation with central corneal SBNFLD while FTBUT (R2 = 0.84), corneal sensitivity (R2 = 0.52) showed positive correlation to central corneal SBNFLD in the ocular hypotensive therapy group.
Conclusions
Ocular surface changes, dry eye disease seems to be related to the decreased sub-basal nerve fibers in eyes on chronic topical ocular hypotensive treatment.
Keywords: 479 cornea: clinical science •
484 cornea: stroma and keratocytes •
486 cornea: tears/tear film/dry eye