[Survey of silicone oil for ocular diseases in Japan]

To survey the use of silicone oil in clinical ophthalmology in Japan.

Questionnaires were sent to 1,240 hospitals registered as being ophthalmology residency training institutions with the Japanese Ophthalmological Society as of September 2007. Responses were collected via the Internet and results totaled. The use of silicone oil at each institution for the 2006 one-year period was assessed, included queries regarding type of silicone oil, indication for use, results and complications. Hospitals were divided into non-specialty institutions, intermediate-specialty institutions and specialty institutions based on number of vitrectomy procedures performed in the one-year period, and trends were analyzed based on these divisions.

Responses were received from 272 institutions (21.9% response rate). Of a total of 36,104 vitrectomy procedures, silicone oil was used in 2,170 cases (6.0%). The diagnosis was proliferative vitreoretinopathy in the majority of cases, followed by proliferative diabetic retinopathy and rhegmatogenous retinal detachment. The majority of institutions replied that the indication for use was complicated case. The type of silicone oil used was ophthalmic formulation in 120 institutions (54.1%) and industrial formulation in 73 institutions (32.9%). Specialty institutions had a higher rate of use of the industrial formulation. The average volume used at one time was 6.4 ml. The majority of institutions responded that silicone oil removal was performed at 3 months after the initial vitrectomy. Silicone oil was not removed in 530 cases in which continued tamponade was judged to be appropriate; this comprised 53.3% of cases at non-specialty institutions. The overall evaluation for silicone oil use was good; silicone oil was rated as being indispensable in 72 cases (31.2%) and effective in 130 cases (56.3%). Responses stating a high need for silicone oil were most frequent for proliferative vitreoretinopathy and proliferative diabetic retinopathy. Complications related to silicone oil use were glaucoma in 125 cases (5.6%), intraocular pressure elevation in 411 cases (18.4%), hypotony in 28 cases (1.3%), endophthalmitis in 5 cases (0.22%), retinal detachment in 13 cases (0.58%), corneal opacification in 105 cases (4.7%), inadvertant subretinal infusion in 31 cases (1.4%) and silicone oil emulsification in 82 cases (3.7%). It was the opinion of many institutions that, in cases where silicone oil could not be used, the number of necessary surgical procedures increased, with lower rates of cure and greater burden on the patient.

Silicone oil was utilized in approximately 1 in every 17 vitrectomy procedures performed in 2006 by the Japanese institutions surveyed. Complications were observed, however overall the indications were appropriate and the use of silicone oil was judged to be necessary by nearly 90% of institutions surveyed.