This study identified the patients who had underwent vitrectomy and with balanced saline vitreous tamponade at the end of vitrectomy from December 1, 2014 to August 1, 2009 because of diabetes-related complications in our hospital. There were 47 patients who incurred post-vitrectomy vitreous hemorrhage (VH) and rebleeding lasting for one month without significant absorption. Data collected included baseline
demographics, best-corrected visual acuity, indication for the air-fluid exchange, complication, outcome, and duration of follow-up. When these patients were retrospectively reviewed (Table 1), the VH was classified as either early postoperative (VH fewer than 4 weeks post-surgery but not present on postoperative day 1), delayed postoperative (VH 4 weeks or more post-surgery), or severe persistent (present since postoperative day 1 and nonclearing for more than 4 weeks) . Before the surgical procedure was given, ultrasound scan was used to verify the severity of vitreous hemorrhage and the status of the retina, to make sure there was no retinal detachment. The single-needle vitreous cavity gas-liquid exchange procedure was performed in a treatment room by the same surgeon. Written consent was obtained from all 47 patients before the procedure. Patients were excluded if they have less than 6 months of follow-up. All the study procedures adhered to the recommendations of the Declaration of Helsinki.
Topical anesthesia was administered, then the conjunctiva and conjunctival sac were fully rinsed with 5% povidone-iodine. The patient was in a seated position. A 10 ml syringe with a 0.22-micron pore size filter was used to inhale 8 ml of sterile air, see Figure 1. Then a 30-gauge needle was fitted to the 10ml syringe without the filter, the eye was opened using a speculum and the patient was told to look forward at a fixed target with their other eye. The syringe was inserted into the vitreous at the 6 o’ clock position, 3.5 or 4 mm from the limbus according to the lens status. Before proceeding it was confirmed that the needle tip was inserted into the vitreous cavity under direct visualization. While using the left hand to fix the syringe and the right hand to control the needle’s direction, the vitreous cavity was slowly injected with 0.5ml of gas to increase the intraocular pressure, 0.5ml of vitreous fluid was then gently removed from the eye. It was observed that the liquid containing blood from the vitreous cavity accumulated in the lower part of the syringe, entering through the needle; the residual 7.5ml of gas stayed in the upper part of the syringe. Once the intraocular pressure had stabilized 0.5 ml of gas was injected into the vitreous cavity and 0.5ml of intraocular fluid was elicited. The needle was then slowly withdrawn a little, so that the needle tip was kept always below the gas-liquid interface in the vitreous. This procedure was repeated until about 4-5 ml vitreous fluid was exchanged into the syringe. As the final step 0.5ml of gas was injected into the vitreous to maintain a slightly higher intraocular pressure than normal, then the needle withdrawn. During the operative procedure the intraocular pressure was assessed with finger tension.
At the end of the procedure, all patients were given a subconjunctival injection of dexamethasone 2.5mg in the temporal conjunctiva while in a seated position. They were also given a topical administration of antibiotic eye ointment four times a day for 1 week. Post treatment the patient was told to keep a prone position until the air was absorbed to help situate the air in the correct location. After the exchange procedure, additional treatments were given when needed. All cases were followed up for at least 6 months after the last procedure.
The decimal visual acuity was converted to a logarithmic scale for the minimum angle of resolution (LogMAR) used in the statistical analysis. Hand motion visual acuity was converted to 2.28 LogMAR according to a previous investigation . IBM SPSS Statistics 21, (IBM Inc., Armonk, NY, USA), were used for statistical analysis with the level of statistical significance set at p < 0.05.