Abstract
Purpose: :
To examine the association between the central corneal thickness (CCT) and the peripheral corneal thickness (PCT) beneath the upper eyelid in patients during hyperbaric oxygen (HBO) therapy. The corneal surface covered by the upper eyelid is not directly exposed to hyperoxia as is the central cornea.
Methods: :
16 nondiabetic patients (Hb-HbA1c < 6.3%) were receiving 100% oxygen at a pressure of 240 kPa in a monoplace chamber for 90 min daily, five days a week for 20 days. Corneal thickness measurements were performed with the noncontact rotating Scheimpflug camera (Pentacam, Oculus) on the first day of the HBO therapy and repeated when the patients had completed 19 days of the treatment. The Pentacam device collects true thickness data over the entire transparent cornea, including the central area. CCT measurements were based on 9 closely spaced assessments, one in the center and 8 over an optical zone of diameter 2 mm around the center. PCT measurements were based on 9 closely spaced assessments in the superior quadrant 3-5 mm from the corneal center. Changes in corneal thickness were calculated as the difference between the initial and the follow-up measurements.
Results: :
Mean CCT and PCT were 563.0 ± 20.5 µm (range 529.9 to 603.2 µm) and 692.2 ± 38.4 µm (range 615.4 to 746.8 µm) before, and 562.7 ± 20.5 µm (range 525.0 to 597.7 µm) and 681.0 ± 49.7 µm (range 565.6 to 747.0 µm) after the HBO therapy. Mean changes in CCT were -0.1 ± 1.4 % (p=0.89) (range -2.6 to 2.4 %), and PCT were -1.7 ± 3.5 % (p=0.07) (range -9.6 to 3.0 %). No corneal oedema was observed with the biomicroscope slitlamp. The intraocular pressure remained unchanged.
Conclusions: :
Corneal thickness was reduced during hyperbaric oxygen therapy. The reduction was larger in the periphery of the cornea compared to the central area, but the changes were not significantly different from baseline.
Clinical Trial: :
REK, Bergen, Norway, REK 3.2007.1422
Keywords: cornea: clinical science • oxygen • eyelid