The effect of contact lens wear on dynamic ocular surface temperature.
OBJECTIVE
To determine the dynamic emitted temperature changes of the anterior eye during and immediately after wearing different materials and modalities of soft contact lenses.


METHODS
A dynamic, non-contact infrared camera (Thermo-Tracer TH7102MX, NEC San-ei) was used to record the ocular surface temperature (OST) in 48 subjects (mean age 21.7 +/- 1.9 years) wearing: lotrafilcon-A contact lenses on a daily wear (LDW; n=8) or continuous wear (LCW; n=8) basis; balafilcon-A contact lenses on a daily wear (BDW; n=8) or continuous wear (BCW; n=8) basis; etafilcon-A contact lenses on a daily disposable regimen (EDW; n=8); and no lenses (controls; n=8). OST was measured continuously five times, for 8s after a blink, following a minimum of 2h wear and immediately following lens removal. Absolute temperature, changes in temperature post-blink and the dynamics of temperature changes were calculated.


RESULTS
OST immediately following contact lens wear was significantly greater compared to non-lens wearers (37.1 +/- 1.7 degrees C versus 35.0 +/- 1.1 degrees C; p < 0.005), predominantly in the LCW group (38.6 +/- 1.0 degrees C; p < 0.0001). Lens surface temperature was highly correlated (r=0.97) to, but lower than OST (by -0.62 +/- 0.3 degrees C). There was no difference with modality of wear (DW 37.5 +/- 1.6 degrees C versus CW 37.8+/-1.9 degrees C; p=0.63), but significant differences were found between etafilcon A and silicone hydrogel lens materials (35.3 +/- 1.1 degrees C versus 37.5 +/- 1.5 degrees C; p < 0.0005). Ocular surface cooling following a blink was not significantly affected by contact lens wear with (p=0.07) or without (p=0.47) lenses in situ.


CONCLUSIONS
Ocular surface temperature is greater with hydrogel and greater still with silicone hydrogel contact lenses in situ, regardless of modality of wear. The effect is likely to be due to the thermal transmission properties of a contact lens.
Purslow
Christine
C
Neurosciences Research Institute, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B47ET, UK. c.purslow@aston.ac.uk
Wolffsohn
James S
JS
Santodomingo-Rubido
Jacinto
J
D001767:Blinking; D001831:Body Temperature; D003261:Contact Lenses; D003262:Contact Lenses, Extended-Wear; D004209:Disposable Equipment; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007259:Infrared Rays; D008689:Methacrylates; D009799:Ocular Physiological Phenomena; D010781:Photography; D012828:Silicones; D013997:Time Factors
D008689:Methacrylates; D012828:Silicones; C114176:etafilcon; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate