Ophthalmic surgeons are aware that there are a number of circumstances in which several undesirable retinal iatrogenic injuries might occur, sometimes with serious consequences. This is why surgeons should take every precaution at each surgical step to avoid any possible retinal iatrogenic damage.

Aim To study the solubility of perfluorohexyloctane (F6H8) in silicone oil (polydimethylsiloxane (PDMS) 1000) and to measure the viscosity and the specific gravity of the mixture obtained (heavy silicone oil or HSO tamponade) to define the ideal ratio of these components. Methods The solubility diagram of the mixture was obtained with the turbidimetric method, indicating the miscibility of F6H8 and silicone oil 1000 at all the useful temperatures. The viscosity was measured in steady shear conditions by using a controlled stress rheometer (Haake RS150) and a double cone/plate (DC 60/4) system, both at 25 and 371C for different volume per cent compositions of the mixture. The specific gravity was measured at 371C using a digital densimeter. Results A mixture of F6H8 30 v% and PDMS 70 v% was found to be transparent and stable at all the useful temperatures. By combining these proportions of the two substances, a resultant density of 1.06 g/cm 3 was obtained. The viscosity of the 30% F6H8 mixture was 203 mPa.s at 251C and 163 mPa.s at 371C respectively. Conclusions The ideal F6H8 and silicone oil mixture can be obtained combining 30% of F6H8 with 70% of silicone oil 1000. This mixture seems to have rheological properties useful for its use as an alternative intraocular heavy tamponade.

In our sample of healthy eyes, no significant correlation was found between TSNIT Avg and OD area. In spite of a shorter distance between OD and measurement ellipse margins, larger discs did not necessarily show a thicker RNFL. Probably the large inter-subject variability for RNFL thickness, and then for axonal count, was a predominant factor over OD area.

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Purpose: To study the solubility of perfluorohexyloctane (F6H8) in silicone oil (PDMS 1000 – polydimethylsiloxane 1000) and to measure the viscosity and the specific gravity of this mixture. Methods: The solubility diagram of the mixture was obtained with the turbidimetric method, indicating the miscibility of F6H8 and silicone oil 1000 at all the useful temperatures. The viscosity was measured in steady shear conditions by using a controlled stress rheometer (Haake RS150) and a double cone/plate (DC 60/4) system, both at 25 and 37°C for different volume percent compositions of the mixture. The specific gravity was measured at 37° using a digital densimeter. Results: A mixture of F6H8 v30% and PDMS 70 v% was found to be transparent and stable at all the useful temperatures. By combining these proportions of the two substances a resultant density of 1.06 g.cm‐3 was obtained. The viscosity of the 30% F6H8 mixture was 203 mPas at 25°C and 163 mPas at 37°C respectively. Conclusions: The ideal F6H8 and silicon oil mixture can be obtained combining 30% of F6H8 with 70% of silicon oil 1000.