To compare the efficacy and safety of low-intensity illumination 3D heads-up system-assisted pars plana vitrectomy (PPV) and traditional microscope eyepiece system-assisted PPV for proliferative diabetic retinopathy (PDR).

A randomized controlled study was conducted.Forty patients (40 eyes) who were diagnosed as PDR and met the PPV standard were included in Xuzhou First People's Hospital from June to December 2022.The patients were randomly divided into 3D group and eyepiece group using a random number table method, with 20 eyes in each group.The eyes in 3D group underwent 3D heads-up system-assisted PPV, and the eyes in eyepiece group received traditional microscope eyepiece system-assisted PPV.The intravitreal injection of 0.5 mg(0.05 ml) ranibizumab was performed 6 or 7 days prior to three-channel 25G PPV for all the eyes.The brightness of endoilluminator was adjusted to minimum level during the surgical procedure, and the brightness of the optical fiber and chandelier in 3D group was set to 20%, while that in eyepiece group was 32% and 46%, respectively, and was further matched to the actual requirements of the surgery.The light intensity of optical fiber and chandelier was measured at 5 mm and 10 mm with a digital photometer.Best corrected visual acuity (BCVA) was measured before surgery and 7 days, 1 month and 3 months after surgery.Electroretinogram (ERG) was recorded by the Retiscan before surgery and 1 month after surgery to evaluate retinal function.Intraocular pressure and postoperative complications in both groups were compared.This study adhered to the Declaration of Helsinki and was approved by the Ethics Committee of The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University (No.xyy11[2022]027). Written informed consent was obtained from each subject prior to entering the cohort.

The BCVA was 2.21±1.13, 1.99±1.07, 1.26±0.86 and 0.98±0.65 in 3D group, and 1.89±0.95, 1.94±0.79, 1.42±0.80 and 1.31±0.79 in eyepiece group at before surgery and 7 days, 1 month, and 3 months after surgery, respectively.There was no significantly intergroup difference in BCVA (F_group=0.022, P=0.884). The BCVA was significantly different at various time points before and after surgery (F_time=18.765, P<0.001). The BCVA was significantly improved at 1 and 3 months after surgery in 3D group and at 3 months after surgery in eyepiece group in comparison with before surgery, showing statistically significant differences (all at P<0.05). There were significant differences in the latency of dark-adapted 3.0 a-wave before and after surgery between two groups (H_time=3.983, P=0.046), and the latency of dark-adapted 3.0 a-wave was shorter after surgery than before surgery in both groups (all at P<0.05). The light intensities of optical fiber and chandelier at 5 mm and 10 mm during surgery were lower in 3D group than in eyepiece group, and the differences were statistically significant (all at P<0.001). There was no significant difference in intraocular pressure between the two groups at different time points (F_group=0.980, P=0.328; F_time=2.706, P=0.062). There was no significant difference in the number of postoperative vitreous hemorrhage between the two groups (χ²=0.960, P=0.327).

Low-intensity illumination 3D heads-up system-assisted PPV has the same outcome as traditional microscope eyepiece system-assisted PPV for PDR.However, compared with the traditional microscope eyepiece system, the light intensity on the retina from low-intensity illumination 3D heads-up system is lower on the retina during surgery and therefore produce less light damage to retinal function of patients.

Diabetic retinopathy; Vitrectomy; Retina; Light damage; 3D heads-up system