The posterior vitreous cortex is now recognized to be a major component of epiretinal membranes [
Intravitreous triamcinolone acetonide (TA) staining has been widely used to visualize the transparent vitreous cortex and facilitates complete separation of the posterior vitreous cortex from the retina. However, even after spontaneous or surgical PVD in pars plana vitrectomy surgery, some residual cortex may be observed. This phenomenon has not been reported in ocular trauma, and risk factors for RVC are not yet known.
The purpose of this study was to determine the incidence of RVC after spontaneous or surgical PVD in patients who had undergone vitrectomy and to analyze the factors that influence the risk for RVC occurrence.
This is a cross-sectional and observational study of eyes from 72 consecutive patients who were diagnosed with ocular trauma and who underwent vitrectomy at the Eye Hospital of Wenzhou Medical College and the Affiliated Eye Hospital of Nanchang University between December 2013 and December 2015. Our study was approved by the Institutional Review Board of the Affiliated Eye Hospital of Nanchang University, designated by the Ministry of Health of China, and followed the ethical standards of the Declaration of Helsinki. The possible merits and risks of the present treatment were explained to the patients before surgery, and informed consent was obtained from all patients. The surgeon for each patient was determined randomly.
We excluded patients with (a) systemic diseases, such as diabetes and hypertension, (b) any previous retinal pathology and accepted vitrectomy surgery, (c) endophthalmitis, (d) proliferative vitreoretinopathy, (e) traumatic macular diseases, (f) injuries that had occurred more than 1 month earlier, (g) unsuccessful surgical PVD, and (h) any kind of intervention in the vitreous cavity like anti-VEGF injections during operation.
In all cases, an ophthalmic B-scan ultrasound was performed before vitrectomy. The patients were examined in a supine position on the bed with an ultrasound probe placed on the closed eyelid surface, with the minimum pressure. If necessary, gentle eye movements were maintained during the examination. In cases with vitreous opacities and obscuration, we judged whether a spontaneous PVD was present or not by ultrasound before the vitrectomy surgery. As described by McNicholas et al. and Almendárez et al. [
Patient data, such as age, sex, preoperative visual acuity, days after injury, post-injury operations, the existence of spontaneous PVD before vitrectomy, and the type of injury, which included closed globe injury and open globe injury, were collected. Preoperative visual acuity values were transformed to the logMAR scale. In cases of profound low vision or near blindness, as determined by perception of counting fingers, hand movements, light perception (LP), and no LP, visual acuity values were substituted by logMAR values of 1.7, 2.0, 2.5, and 3.0, respectively, as reported by Heimann et al. [
All patients underwent a standard 3-port 23-gauge (G) pars plana vitrectomy. If there was no spontaneous PVD, a surgical PVD was created with high vacuum levels transmitted through the vitrectomy probe or flute needle, down from the vitreous cortex to over the optic nerve, and was confirmed by the appearance of a peripapillary Weiss ring (Figure
Formation of surgical posterior vitreous detachment (PVD). (a) The attraction of the vitreous cortex with high vacuum levels transmitted through the vitrectomy probe, over the optic nerve. (b) The vitreous cortex is gently pulled up by the vitrectomy probe. (c) Suspension of triamcinolone acetonide granules in the vitreous cavity. (d) Successful surgical PVD is confirmed by the appearance of a peripapillary Weiss ring.
After surgery, two retinal specialists watched the video of the surgery and confirmed the shape and the area of the RVC. Based on the area, the RVC was divided into the following two types: focal, with an RVC area smaller than 1 disc diameter, and diffuse, with an RVC area equal to or larger than 1 disc diameter (Figure
Patterns of the residual vitreous cortex (RVC): (a) focal type; (b) diffuse type.
Continuous variables were expressed as mean ± standard deviation. We used the chi-squared test and Kruskal–Wallis test to compare clinical results in the absence and presence of RVC groups. The presence of RVC (no RVC = 0 and RVC = 1) is a dependent variable; multivariate logistic regression analysis was used to evaluate the effects of variables which were significant in the chi-squared test or Kruskal–Wallis test. The data were analyzed using the SPSS 19.0 software. Results with
The study evaluated 72 consecutive cases who underwent pars plana vitrectomy after ocular trauma, of whom 63 (87.5%) were men and 9 (12.5%) were women. Of the eyes studied, 35 (48.6%) were right eyes and 37 (51.4%) were left eyes.
RVC was observed on the macula after spontaneous or surgical PVD during TA-assisted vitrectomy in 35 (48.6%) eyes. TA staining demonstrated that the RVC patterns were of the diffuse type in 19 (54.3%) eyes and of the focal type in 16 (45.7%) eyes.
Based on the presence or absence of RVC, we divided all cases into two groups. Table
Clinical characteristics of ocular trauma patients with absence and presence of RVC.
Absence of RVC | Presence of RVC |
|
||
---|---|---|---|---|
Number of eyes | 37 (51.4%) | 35 (48.6%) | ||
Diffuse type | Focal type | |||
19 (54.3%) | 16 (45.7%) | |||
Age (years) | 46.05 (±10.14) | 37.71 (±10.67) | 0.007 | |
Sex (M/F) | 32/5 | 31/4 | 0.909 |
|
Preoperative visual acuity (logMAR) | 1.81 (±0.58) | 1.57 (±0.62) | 0.042 | |
Days after injury | 12.16 (±8.16) | 6.66 (±4.33) | 0.002 | |
Operative times after injury | 0.43 (±0.56) | 0.49 (±0.51) | 0.452 |
|
Spontaneous PVD | 11 (29.7%) | 3 (8.6%) | 0.024 | |
Injury type | 0.004 | |||
Closed globe | 14 (37.8%) | 3 (8.6%) | ||
Open globe | 23 (62.2%) | 32 (91.4%) |
RVC = residual vitreous cortex; PVD = posterior vitreous detachment. Data displayed are either mean values with SDs for continuous variables or number and percentage for categorical variables in the absence and presence of RVC groups. Unmarked
Table
Multivariate logistic regression analysis of factors independently contributing to presence of RVC.
Variables | OR (95% CI) |
|
|
---|---|---|---|
Dependent | Independent | ||
Presence of RVC | Age (years) | 0.933 (0.878–0.991) | 0.025 |
Preoperative visual acuity (logMAR) | 0.341 (0.104–1.120) | 0.076 | |
Days after injury | 0.862 (0.767–0.969) | 0.013 | |
Spontaneous PVD | 0.742 (0.142–3.873) | 0.723 | |
Injury type | 4.288 (0.942–19.519) | 0.060 |
RVC = residual vitreous cortex; PVD = posterior vitreous detachment; OR = odds ratio.
In this study, we have investigated the frequency and patterns of RVC at the fovea after PVD during vitrectomy for ocular trauma and the risk factors associated therewith.
The phenomenon of an RVC adhering to the retina after PVD is commonly observed with TA staining of the vitreous cortex [
We propose that the occurrence of RVC at the fovea may be due to the following: First, the staining may be related to vitreoschisis [
Sonoda et al. found that the diffuse type (88.9%) of RVC was more common compared to the focal type (11.1%) in diabetic patients after PVD for vitreopathy [
It has been confirmed that eyes with RVC have a higher rate of epiretinal membranes after vitrectomy compared to eyes without RVC [
To address this, we used multivariate logistic regression analysis to evaluate the effects of age, preoperative visual acuity, days after injury, the existence of spontaneous PVD before vitrectomy, and the type of injury on the occurrence of RVC in traumatic eyes. Age and days after injury had a significant influence on the occurrence of RVC. Although patients with RVC on the macula were less common among cases with spontaneous PVD, those that had worse preoperative visual acuity, and those with closed globe injury, no statistically significant association was detected between preoperative visual acuity, the existence of spontaneous PVD, and injury type.
There are three known mechanisms by which age protects against RVC. First, age is closely related to vitreous liquefaction because age-related free radicals cause hyaluronan depolymerization, which leads to the destruction of the gel structure [
In addition, the increasing number of days between the injury and vitrectomy showed a significant protective effect against RVC, which may be because of vitreous changes. After an eye injury, the intraocular structures change, and the blood-retinal barrier is broken. The blood components and cell mediation lead to vitreous shrinkage, causing PVD [
The major limitations of this study include (a) a small sample size and (b) judgement of spontaneous PVD and RVC without objective standards. However, this study revealed that RVC frequently remains on the macula after PVD. The impact of various factors on the occurrence of RVC in traumatic eyes has also not been described previously. We believe these findings may be valuable for surgeons performing vitrectomy and can facilitate understanding of the pathological mechanism underlying vitreoretinopathy, allowing for a better clinical prognosis.
In conclusion, in ocular trauma, the presence of premacular RVC is very common, even after spontaneous or surgical PVD during vitrectomy. We show that older age and more days after injury are significant protective factors for RVC at the fovea. Further objective studies are needed to evaluate the difference in these influential factors, using larger sample sizes.
The datasets obtained and/or analyzed during the current study are available from the corresponding author on reasonable request (email:
None of the authors has conflicts of interest with this submission.
This study was supported by the Science and Technology Research Project of Jiangxi Education Department of China (no. 170164).