Incidence of Complete Posterior Vitreous Detachment After Trabeculectomy.

Intraocular surgery could induce vitreous degeneration and posterior vitreous detachment (PVD). Vitreomacular interface (VMI) abnormalities usually are caused by abnormal PVD, vitreoschisis and partial-thickness PVD. Furthermore, the PVD could induce the peripheral break. The incidence of peripheral break and epimacular membrane (EMM) after pneumatic retinopexy were 11.7% and 4-11%, respectively. Although multiple intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections induced PVD of 5.6%, but peripheral break was reported as only 0.67%. The most common intraocular surgery is cataract surgery. From the literature review, many methods were used to detect the PVD after phacoemulsification. The former studies used indirect ophthalmoscopy and ocular ultrasound for diagnosis of PVD. The later studies used the optical coherence tomography (OCT) for PVD detection. The OCT device had higher effectiveness in evaluation of the posterior segment, then it can detect post-phacoemulsification PVD more and early than previous studies. Ivastinovic et al demonstrated 59.2% of patients had PVD at 1 month after phacoemulsification, and increased up to 71.4% at 3 months. The incidence of rhegmatogenous retinal detachment (RRD) after phacoemulsification is gradually increased with time. The accumulative risk of RRD was increased from 0.27% at 1 year to 1.27% at 20 years after phacoemulsification.

Trabeculectomy is one of the intraocular surgery. Although the volume of intraocular fluid use during the trabeculectomy was much less than used during phacoemulsification, trabeculectomy also could induce the PVD and it's sequelae such as VMI abnormalities. Because the baseline visual acuity of glaucoma patients who were indicated for trabeculectomy usually quite poor, so the sequelae of PVD can cause more visual loss. The incidence of PVD after trabeculectomy has never been published before and nowadays no standard guideline for retinal examination or screening after surgery. Furthermore, Tsukahara et al introduced wide-field OCT-based PVD classification. The new OCT device with higher technology will be useful in PVD detection.

Wide-field OCT was performed 1-2 weeks before the trabeculectomy. The OCT was done postoperatively at 1 month, 3 months, 6 months and 12 months after surgery.

Merged 4 images of wide-field optical coherence tomography, 2 images of vertical scan and 2 images of horizontal scan.

Inclusion Criteria: Primary open angle glaucoma or primary angle closure glaucoma Age 18-65 years Could be taken the wide-field OCT images Written informed consent Exclusion Criteria: History of intraocular inflammation or infection History of ocular trauma or head trauma History of intraocular surgery such as intravitreal drug injection and cataract surgery History of vitreoretinal diseases such as diabetic retinopathy, retinal vascular occlusion and age-related macular degeneration History of laser treatment including laser capsulotomy and retinal photocoagulation High myopia; spherical equivalence >4 diopters Complete PVD was detected before the enrollment