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Stephen M. Grenon, Caroline A. Blackie, Donald R. Korb, Scott Liddle, Joshua Grenon; A Comparison Of Predicted Theoretical And Empirical Heating Of The Inner Eyelid Surface And The Cornea During Treatment For Meibomian Gland Dysfunction Using The Lipiflow. Invest. Ophthalmol. Vis. Sci. 2012;53(14):604.
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To compare the theoretical heat transfer and predicted temperature rise of the inner eyelid and corneal surfaces with the measured temperature rise on human and excised porcine eyes.
The TearScience LipiFlow treatment temperature was simulated using finite element analysis (FEA) based on a published heat transfer model utilizing the actual geometry and material characteristics associated with the LipiFlow. The simulation data was then compared to measured corneal and inner eyelid surface temperatures obtained during LipiFlow treatments. Subjects (n = 5) were recruited and consented for the study. A small thermocouple placed between the LipiFlow heater and the inner eyelid surface recorded the temperature during the 12-minute treatment. The temperature of the corneal surface was recorded at baseline and immediately following treatment using an IR thermal video camera. Since the corneal temperature could not be measured during the treatment without the potential of injuring the patient, freshly excised porcine eyes (n=30) were implanted with a needle thermocouple placed 1 mm under the corneal surface. The porcine eye was then installed in an aluminum block which was submerged in a circulating water bath regulated to body temperature (37 degrees C) and simulated eyelids were installed over the excised eye. A treatment was performed using the LipiFlow. The corneal temperature was recorded and compared to the finite element analysis.
FEA predicted inner lid surface temperature: 42.4 degrees C; mean inner lid temperature thermocouple measurements: 42.8 +/- 0.6 degrees C; FEA predicted corneal temperature: 38.7 degrees C; mean human IR corneal temperature measurements: 38.1 +/- 0.4 degrees C; mean porcine corneal temperature measurements: 38.7 +/- 1.1 degrees C.
Combining the 3D model of the LipiFlow with published thermal model of the human eye and using Element Analysis (FEA) one can predict the temperature exposure of the LipiFlow treatment to the ocular surfaces. The model was within 0.4 degrees C of the measured data. The corneal temperature was within 0.6 degrees C of the post treatment human data and equal to the in-treatment ex vivo porcine data to a resolution of 0.1 degrees C.
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