Objective To compare the outcomes of 23G and 20G vitrectomy in treatment of proliferative diabetic retinopathy (PDR). Methods This was a prospective randomized study. One hundred twenty six patients (142 eyes) suffering from PDR with symptoms requiring vitrectomy were randomly divided into 20G vitrectomy group (66 patients, 74 eyes) and 23G vitrectomy group (60patients,68eyes). Visual acuity, intraocular pressures,indirect ophthalmoscopy, B-scan ultrasound, tear film break up time (BUT), Schirmer Ⅰ test (S Ⅰ T), astigmatic power and the astigmatic axial at 6 mm area of anterior and posterior corneal surface were observed and measured before surgery. The follow-up period was 15.0 and 12.5 months separately in 20G and 23G groups. Intraoperative complications, operation time, postoperative visual acuity, intraocular pressure, postoperative complications, reoperation, and postoperative ocular conditions including changes of astigmatic power and the astigmatic axial measurements were analyzed. Results At last follow-up, there was 49 eyes (66.2%) and 47 eyes (69.1%) with visual acuity ge;0.05 in 20G and 23G groups. Comparing visual acuity ge;0.05, there was no statistical difference between the groups (chi;2=0.14, P＞0.05). The eyes suffering from iatrogenic injuries were 18 (24.3%) and seven (10.3%). There was obvious difference in iatrogenic injury between the two groups (chi;2=4.81, P＜0.05). The mean surgical times were (69.0plusmn;8.2) and (51.0plusmn;6.3) minutes in 20G and 23G group, which was significantly different (t=3.65, P＜0.05). The postoperative third day, hypotony was detected in three (4.1%) and 11 eyes (14.7%) in 20G and 23G group, which was a significantly different (chi;2=5.85, P＜0.05). Postoperatively high intraocular pressures were not significantly different between the two groups (chi;2=2.54,P＞0.05). There were 24 (32.4%) and 14 eyes (20.6%) in 20G and 23G group. There were significant differences in BUT, SⅠT, astigmatic power and the astigmatic axial measurements compared with those preoperatively at the first month after operation (t=3.35, 4.12, -3.12, -3.22; P＜0.05), but no significant differences in them at the third and sixth month after operation (third month: t=0.45, 0.98, -2.12, -1.02; P＞0.05, and the sixth month: t=0.95, 1.48, -1.02, -2.11; P＞0.05). In 23G group, there were no significant differences in BUT, SⅠT, astigmatic power and the astigmatic axial measurements compared with those preoperatively at the first, third and sixth month after operation (first month: t=1.21, 1.46, -2.32, -1.61; P＞0.05, third month: t=1.45, 2.21, -2.19, -1.89; P＞0.05, and sixth month: t=1.92, 1.25, -1.76, -2.35; P＞0.05). Conclusion 23G vitrectomy is a safe and effective treatment for PDR with shorter surgery time, fewer surgical complications and postoperative ocular surface changes.
Objective To investigate the effect of N-methyl-N-nitrosourea (MNU) on expressions of interphotoreceptor retinoid-binding protein (IRBP) and recoverin in rat retinal. Methods Thirty female SpragueDawley (SD) rats were randomly divided into five groups, including normal control group, and MNU treatment one day, three days, seven days and 10 days groups, each group had six rats. Rats in MNU-treatment groups received a single intraperitoneal injection of 40 mg /kg MNU, while rats in the normal control group received intraperitoneal injection of saline 5 ml/kg. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence were used to detect the retinal expression of IRBP and recoverin. Results RT-PCR results indicated that retinal IRBP levels decreased after MNU injection compared with normal control (P＜0.01)，while recoverin levels increased (one day: P＞0.05; three days: P＜0.05; seven days: P＜0.5; 10 days：P＜0.05). Immunofluorescence assays demonstrated that normally IRBP protein is mainly in the inner and outer segments of photoreceptors. After MNU treatment, IRBP protein was detected in all retinal layers but much faint. Recoverin was expressed in the inner nuclear layer, inner plexiform layer and ganglion cell layer, and its expression was increased after MNU injection. Conclusion MNU suppresses IRBP expression and promotes recoverin expression in rat retina.