Introduction: Silicone oil (SO) is widely used as a long-term intraocular tamponade following pars plana vitrectomy (PPV) for complex retinal conditions. However, its emulsification is associated with serious complications, including intraocular inflammation and glaucoma. While various factors influencing this process have been explored, the role of time in SO emulsification remains unclear. This study investigates the movement time effect on SO emulsification using a physiologically realistic model, with a focus on changes in droplet size distribution and emulsion density. Methods: A 3D-printed, anatomically accurate model of the human vitreous chamber was filled with SO and an albumin-containing aqueous phase, maintained at 35 degrees C. Experiments were conducted with varying albumin concentrations and saccadic eye movements of different amplitudes. Emulsions were sampled and analyzed after 6 h, 12 h, 24 h, and 6 days. Results: Emulsification was observed under all conditions. Over time, the number of smaller droplets increased, and emulsion density rose sharply within the first 12 h, followed by a slower progression. Higher albumin levels and larger saccadic amplitudes promoted more extensive emulsification. Conclusion: These findings identify the early postoperative period, particularly the first 12 h, as critical for SO emulsification.Vitrectomy is a surgical procedure performed to treat pathological states of the retina, consisting in the removal of the vitreous body and its substitution with tamponade fluids. High-viscosity silicone oils (SO) are widely used as vitreous substitutes, despite their tendency to emulsify with the aqueous phase produced in the eye, leading to several post-surgical complications. It is, therefore, of great interest to investigate which factors affect the generation and characteristics of the emulsion in order to allow ophthalmologists to intervene to prevent or reduce the occurrence of this phenomenon. The study of water/SO interfacial properties in the presence of key serum proteins in the physiological concentration range is relevant for getting information on the components that mainly affect the formation of stable emulsions. On the other side, the emulsion appearance is strictly correlated to the energy imposed for mixing the two immiscible phases. In order to experimentally investigate the influence of surfactants, eye rotation, and movement duration, experiments are carried out in a model of the vitreous chamber, which replicates the geometry of an ocular cavity subjected to rotations, simulating the physiological conditions. It has been demonstrated that the emulsion formation is affected not only by the intensity of eye rotations but also by the geometry of the vitreous chamber and the duration of the experiment. The characterization of the formed emulsions is, therefore, performed by optical microscopy, in particular concerning the drop number and their size distribution.
Time Effect on Silicone Oil Emulsion Formed in a Model of the Eye Vitreous Chamber
Romano, Mario;
2026-01-01
Abstract
Introduction: Silicone oil (SO) is widely used as a long-term intraocular tamponade following pars plana vitrectomy (PPV) for complex retinal conditions. However, its emulsification is associated with serious complications, including intraocular inflammation and glaucoma. While various factors influencing this process have been explored, the role of time in SO emulsification remains unclear. This study investigates the movement time effect on SO emulsification using a physiologically realistic model, with a focus on changes in droplet size distribution and emulsion density. Methods: A 3D-printed, anatomically accurate model of the human vitreous chamber was filled with SO and an albumin-containing aqueous phase, maintained at 35 degrees C. Experiments were conducted with varying albumin concentrations and saccadic eye movements of different amplitudes. Emulsions were sampled and analyzed after 6 h, 12 h, 24 h, and 6 days. Results: Emulsification was observed under all conditions. Over time, the number of smaller droplets increased, and emulsion density rose sharply within the first 12 h, followed by a slower progression. Higher albumin levels and larger saccadic amplitudes promoted more extensive emulsification. Conclusion: These findings identify the early postoperative period, particularly the first 12 h, as critical for SO emulsification.Vitrectomy is a surgical procedure performed to treat pathological states of the retina, consisting in the removal of the vitreous body and its substitution with tamponade fluids. High-viscosity silicone oils (SO) are widely used as vitreous substitutes, despite their tendency to emulsify with the aqueous phase produced in the eye, leading to several post-surgical complications. It is, therefore, of great interest to investigate which factors affect the generation and characteristics of the emulsion in order to allow ophthalmologists to intervene to prevent or reduce the occurrence of this phenomenon. The study of water/SO interfacial properties in the presence of key serum proteins in the physiological concentration range is relevant for getting information on the components that mainly affect the formation of stable emulsions. On the other side, the emulsion appearance is strictly correlated to the energy imposed for mixing the two immiscible phases. In order to experimentally investigate the influence of surfactants, eye rotation, and movement duration, experiments are carried out in a model of the vitreous chamber, which replicates the geometry of an ocular cavity subjected to rotations, simulating the physiological conditions. It has been demonstrated that the emulsion formation is affected not only by the intensity of eye rotations but also by the geometry of the vitreous chamber and the duration of the experiment. The characterization of the formed emulsions is, therefore, performed by optical microscopy, in particular concerning the drop number and their size distribution.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
