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Mario Romano, Vito Romano, Riccardo Vinciguerra, Jose Vallejo-garcia, Ciro Costagliola, Paolo Vinciguerra; Thermodynamics of vitreoretinal surgery in human eyes and implication of changes in rheology of endotampoandes. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2145.
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© ARVO (1962-2015); The Authors (2016-present)
To report the fluctuations in temperature occurring inside the human eye during vitreoretinal surgery and to investigate the effect of such fluctuations in temperature on intraocular tamponades.
Intraocular temperature was recorded in continuous during the entire vitrectomy in 16 eyes of 16 patients with idiopathic or diabetic epiretinal membrane. Temperature was monitored through a custom made thermoprobe. Time points of particular interest during the vitrectomy for statistical analysis were: a) baseline (inflow off - outflow off), b) beginning of the vitrectomy, c) end of vitrectomy (inflow on - outflow on), d) during the epiretinal procedures (inflow on - outflow off), e) under air infusion, e) under oil, e) under endolaser treatment. The effect of the recorded temperature variations in vivo was investigated in vitro on rheology of intraocular tamponades. We calculated the changes in the kinematic shear viscosity of 1000cS and 5000 cS silicon oil (SO) at the different temperatures using a Ubbelhode viscometer. Interactions between different kinds of PFCL [perfluoro-n-octane (PFO) or perfluorodecaline (PFD)] and HSO (either alkane or ether) were also studied in vitro by incubating fluids for 7 days at 36°C and removed at different temperatures.
The mean temperature in the AC and on the nasal retinal side was 23.8 (SD 1.6) °C and 32.7 (SD 1.2) °C respectively. The mean vitreous temperature at baseline, before opening the infusion, was 34.2 (SD 1.1) °C. The mean temperature at the beginning and end of the vitrectomy was 27.1°C (SD 1.1) and 24.4 (SD 1.0) °C respectively. The fluctuations in temperature were statistically different between the time points during the vitrectomy (P<0.001). Kinematic viscosity of SO shows a decrease of 188 cSt for the 1000 cS and of 866 cSt for the 5000 cS SO increasing the temperature from 22 to 32 C°. In vitro, interactions between PFCL-HSO led to the formation of hyper-viscous solutions with significative decrease in aspiration time at 36°C versus 22°C in group (P = 0.003).
Vitreoretinal surgery induces significative fluctuation in temperature in human eye. The rheology properties of intraocular tamponades is affected by such variations. Keeping the temperature stable around 30°C we could reduce shear SO viscosity and we could also dissolve the sticky oil formation induced by the interaction between PFCL-HSO.
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