Silicone droplets are highly prevalent in the vitreous of patients who undergo intravitreal injection treatment, but they appear to have little impact on symptomatology and intraocular pressure (IOP), according to research published in BMC Ophthalmology.
“Intravitreal injections with anti-[vascular endothelial growth factor (VEGF)] agents are currently used to treat multiple retinal pathologies. [Each injection is] administered with a different syringe and needle, which were not initially designed for intravitreal use, and contain small amounts of silicone oil,” researchers explain.
The investigators evaluated the percentage of patients who have silicone droplets in the vitreous after treatment with different anti-VEGF intravitreal injections and interviewed patients on their associated symptomatology.
A total of 152 eyes of 140 patients (mean age, 73.6 years; 53.3% men, 46.7% women) who had received at least 1 intravitreal injection were included in the study. The investigators classified eyes as having a “non-existent” (28.3%), “scarce” (23.0%), “moderate” (23.0%), and “abundant” (22.4%) number of bubbles. Patients had received a mean number of intravitreal injections per eye of 10.11 and had a mean follow-up duration since the beginning of intravitreal treatment of 34.7 months.
The researchers found silicone oil droplets in 71.7% of eyes and demonstrated a positive correlation between the number of intravitreal injections received and the quantity of droplets observed (ranging from 6.26 injections in those with no droplets to 11.97 injections in those with abundant droplets; P <.001). They also found that 65.8% of patients had posterior vitreous detachment (PVD), which showed a positive correlation with the number of bubbles across all groups (ranging from PVD in 47.5% of those with scarce droplets to 88.2% of those with abundant droplets; P =.003).
From patient interviews on symptomatology, the study shows that 39.5% of patients had floaters and their presence was correlated with the quantity of droplets observed (ranging from 27.9% of those with no droplets to up to 60% of those with moderate droplets; P =.026). Though not statistically significant, the mean IOP was numerically higher among patients with abundant droplets than in all other groups.
“A positive correlation was demonstrated between PVD and the number of bubbles. We believe that PVD allows the silicone droplets to move freely in the vitreous,” researchers report.
Limitations of the study included the inability to detect micro-sized droplets (size range, 0.1-10 μm) by slit-lamp observation, differing abilities of examination techniques to quantify droplets in medias with different transparencies (eg cataract or intraocular lenses carriers), and potential variation in droplet quantification across physicians.
García SB, Garrell-Salat X, Trejo-Velasco F, Aragón-Roca D, Zapata MÁ, García-Arumí J. Prevalence and implications of the presence of intraocular silicone oil droplets in patients treated with intravitreal injections of anti-VEGF. BMC Ophthalmol. 2022;22(1):319. doi:10.1186/s12886-022-02536-2