No / We consider and compare the various different kinds of flow that may take place in the anterior chamber of a human eye. The physical mechanisms re- sponsible for causing such flows may be classified as follows: (i) buoyancy-driven flow arising from the temperature difference between the anterior surface of the cornea and the iris, (ii) flow generated by the aqueous production of the ciliary body, (iii) flow generated by the interaction between buoyancy and gravity while sleeping while sleeping in a face-up position, (iv) flow generated by phakodenesis (lens tremor), (v) flow generated by Rapid Eye Movement (REM) during sleep. Each flow is studied using a traditional fluid mechanics/asymptotic analysis ap- proach. We also assess the veracity of a hypothesis that was recently advanced [see Maurice, D.M., 1998. The Von Sallman Lecture 1996: An ophthalmological explanation of REM sleep. Exp. Eye. Res. 66, 139¿145, for details] to suggest that, contrary to previous opinion, the purpose of REM during sleep is to ensure corneal respiration in the absence of the buoyant mixing that routinely takes place due to (i) above during waking conditions.

Purpose: Previous clinical studies have suggested a positive effect of low-frequency pulsed electromagnetic fields (PEMF) on wound healing and inflammation in the eye. We tried to test the value of PEMF treatment in a hyphema animal model with well-defined conditions. Methods: After injection of citrated autologous blood for the production of hyphema, 16 rabbit eyes were treated with 10 or 20 mT for 60 min on 4 days within the postoperative week. Two control groups with hyphema alone (n = 8) and PEMF irradiation without hyphema (n = 4) were also included. The rate of resorption was recorded daily. Histopathologic evaluation was performed. Results: The incidence of endothelial cell damage and fibrotic clots was markedly reduced in the 10-mT group while the resorption time of 8 days was identical with the control group. In the 20-mT group, the complication rate and the resorption time was increased versus the control group. Conclusions: The use of PEMF treatment is of some, however, limited value as it did not reduce the resorption time of hyphema but displayed a dose-dependent, beneficial influence on some serious side effects. Future clinical studies with low-dose PEMF irradiation are justified and should determine the optimal dosage and suitable indications of PEMFs as an adjunctive treatment in ocular inflammation or trauma. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Purpose: Previous clinical studies have suggested a positive effect of low-frequency pulsed electromagnetic fields (PEMF) on wound healing and inflammation in the eye. We tried to test the value of PEMF treatment in a hyphema animal model with well-defined conditions. Methods: After injection of citrated autologous blood for the production of hyphema, 16 rabbit eyes were treated with 10 or 20 mT for 60 min on 4 days within the postoperative week. Two control groups with hyphema alone (n = 8) and PEMF irradiation without hyphema (n = 4) were also included. The rate of resorption was recorded daily. Histopathologic evaluation was performed. Results: The incidence of endothelial cell damage and fibrotic clots was markedly reduced in the 10-mT group while the resorption time of 8 days was identical with the control group. In the 20-mT group, the complication rate and the resorption time was increased versus the control group. Conclusions: The use of PEMF treatment is of some, however, limited value as it did not reduce the resorption time of hyphema but displayed a dose-dependent, beneficial influence on some serious side effects. Future clinical studies with low-dose PEMF irradiation are justified and should determine the optimal dosage and suitable indications of PEMFs as an adjunctive treatment in ocular inflammation or trauma. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.