PREDICTIVE FACTORS FOR PROLIFERATIVE VITREORETINOPATHY FORMATION AFTER UNCOMPLICATED PRIMARY RETINAL DETACHMENT REPAIR

Intravitreal methotrexate as an adjuvant in vitrectomy in cases of retinal detachment with proliferative vitreoretinopathy

PURPOSE

To compare the rate of re-detachment in patients with rhegmatogenous retinal detachment and Grade-C PVR following vitreoretinal surgery, with and without serial intravitreal injections of methotrexate.

METHODS

It was a randomized control trial. Patients aged more than 18 years undergoing pars plana vitrectomy for rhegmatogenous retinal detachment with PVR grade C or more were included in the study. Patients treated with intravitreal injection of methotrexate were grouped as cases and those not injected served as controls. The cases received 3 intravitreal injections of methotrexate at monthly intervals. Patients were evaluated on Day 1, 1st month, 2nd month, 3rd month and 6th month in terms of BCVA, rate of re-attachment and grade of PVR.

RESULTS

The case group had 23 patients and the control group had 20 patients. 2 patients in the case group were lost to follow-up after the first follow-up, so they were excluded. So 21 patients in case group and 20 patients in control group were followed up. Six months after surgery, 15 'cases' had completely attached retina whereas 6 patients had partial detachment with macula on. There was no patient amongst the cases with macula-off retinal re-detachment. Out of 20 patients in the control group, 9 had a complete retinal attachment, 4 had partial detachment with macula-on and 7 had partial detachment with macula-off. There was statistically significant difference in macula off retinal detachment rates (p-value- 0.003).

CONCLUSION

Serial intravitreal methotrexate injections reduce the incidence of re-detachment in patients undergoing PPV for RRD with PVR-C. Further investigation into this promising therapeutic approach is warranted.

KEY MESSAGES

What is known Methotrexate is an anti-inflammatory agent which is safe for intravitreal use There are case series retrospective and prospective studies suggesting potential benefit of intravitreal methotrexate in preventing re-detachment due to PVR What is new First randomized control trial studying the efficacy of intravitreal methotrexate in preventing re-detachment due to PVR Our study showed statistically significant difference in macula off retinal detachment between the 2 groups at 6 months of follow up.

Proliferative Vitreoretinopathy in Retinal Detachment: Perspectives on Building a Digital Twin Model Using Nintedanib

Proliferative vitreoretinopathy (PVR) is a pathological process characterized by the formation of fibrotic membranes that contract and lead to recurrent retinal detachment. Pars plana vitrectomy (PPV) is the primary treatment, but recurrence rates remain high, as surgery does not address the underlying molecular mechanisms driving fibrosis. Despite several proposed pharmacological interventions, no approved therapies exist, partly due to challenges in conducting preclinical and in vivo studies for ethical and safety reasons. This review explores the potential of computational models and Digital Twins, which are increasingly gaining attention in medicine. These tools could enable the development of progressively complex PVR models, from basic simulations to patient-specific Digital Twins. Nintedanib, a tyrosine kinase inhibitor targeting PDGFR, VEGFR, and FGFR, is presented as a prototype for computational models to simulate its effects on fibrotic pathways in virtual patient cohorts. Although still in its early stages, the integration of computational models and Digital Twins offers promising avenues for improving PVR management through more personalized therapeutic strategies.

The Wisconsin silicone oil study (report #1): anatomical and functional outcomes of repair of retinal detachment with proliferative vitreoretinopathy

BACKGROUND

Silicone oil (SO) is a long-term tamponade for repair of complex retinal pathology but has limitations including late redetachment. This study describes our experience with SO tamponade for repair of retinal detachment with proliferative vitreoretinopathy (PVR), with attention to anatomic and functional outcomes.

METHODS

Retrospective consecutive case series of eyes with retinal detachment (RD) complicated by proliferative vitreoretinopathy (PVR) receiving SO tamponade at the University of Wisconsin between 2013 and 2019. Group 1 defined as primary SO placement; Group 2 had SO placed after failing prior retinal detachment repair.

RESULTS

Inclusion criteria of SO placement for repair of RD with PVR was met for 117 eyes. The final reattachment rate was 84% for all eyes, with no difference between Groups 1 and 2. Vision improvement was 2.1 lines for Group 1 (p = 0.06 from baseline) and 4.6 lines for Group 2 (p < 0.0001). The mean number of silicone oil placements was 1.4. Less improvement in vision was noted with repeat SO placement, though overall functional vision of 5/200 or better was achieved in 63.2% of patients.

CONCLUSIONS

SO tamponade allows long-term anatomical stabilisation and substantial vision recovery in eyes with retinal detachment complicated by PVR. Rates of anatomic and functional success have improved significantly when compared to prior studies using oil tamponade for repair of PVR.

Risk factors for proliferative vitreoretinopathy after retinal detachment surgery: A systematic review and meta-analysis

BACKGROUND

To comprehensively investigate risk factors for proliferative vitreoretinopathy (PVR) after retinal detachment (RD) surgery.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were systematically searched until May 22, 2023. Risk factors included demographic and disease-related risk factors. Odds ratios (ORs) and weighted mean differences (WMDs) were used as the effect sizes, and shown with 95% confidence intervals (CIs). Sensitivity analysis was conducted. The protocol was registered with PROSPERO (CRD42022378652).

RESULTS

Twenty-two studies of 13,875 subjects were included in this systematic review and meta-analysis. Increased age was associated with a higher risk of postoperative PVR (pooled WMD = 3.98, 95%CI: 0.21, 7.75, P = 0.038). Smokers had a higher risk of postoperative PVR than non-smokers (pooled OR = 5.07, 95%CI: 2.21-11.61, P<0.001). Presence of preoperative PVR was associated with a greater risk of postoperative PVR (pooled OR = 22.28, 95%CI: 2.54, 195.31, P = 0.005). Presence of vitreous hemorrhage was associated with a greater risk of postoperative PVR (pooled OR = 4.12, 95%CI: 1.62, 10.50, P = 0.003). Individuals with aphakia or pseudophakia had an increased risk of postoperative PVR in contrast to those without (pooled OR = 1.41, 95%CI: 1.02, 1.95, P = 0.040). The risk of postoperative PVR was higher among patients with macula off versus those with macula on (pooled OR = 1.85, 95%CI: 1.24, 2.74, P = 0.002). Extent of RD in patients with postoperative PVR was larger than that in patients without (pooled WMD = 0.31, 95%CI: 0.02, 0.59, P = 0.036). Patients with postoperative PVR had longer duration of RD symptoms than those without (pooled WMD = 10.36, 95%CI: 2.29, 18.43, P = 0.012).

CONCLUSION

Age, smoking, preoperative PVR, vitreous hemorrhage, aphakia or pseudophakia, macula off, extent of RD, and duration of RD symptoms were risk factors for postoperative PVR in patients undergoing RD surgery, which may help better identify high-risk patients, and provide timely interventions.

Proliferative Vitreoretinopathy: A Reappraisal

Proliferative vitreoretinopathy (PVR) remains the main cause of failure after retinal detachment (RD) surgery. Despite the development of modern technologies and sophisticated techniques for the management of RD, the growth of fibrocellular membranes within the vitreous cavity and on both sides of the retinal surface, as well as intraretinal fibrosis, can compromise surgical outcomes. Since 1983, when the term PVR was coined by the Retina Society, a lot of knowledge has been obtained about the physiopathology and risk factors of PVR, but, despite the proposal of a lot of therapeutic challenges, surgical skills seem to be the only effective way to manage PVR complications.

TNF-α and NF-κB signaling play a critical role in cigarette smoke-induced epithelial-mesenchymal transition of retinal pigment epithelial cells in proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is characterized by the growth and contraction of cellular membranes within the vitreous cavity and on both surfaces of the retina, resulting in recurrent retinal detachments and poor visual outcomes. Proinflammatory cytokines like tumor necrosis factor alpha (TNFα) have been associated with PVR and the epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells. Cigarette smoke is the only known modifiable risk factor for PVR, but the mechanisms are unclear. The purpose of this study was to examine the impact of cigarette smoke on the proinflammatory TNFα/NF-κB/Snail pathway in RPE cells to better understand the mechanisms through which cigarette smoke increases the risk of PVR. Human ARPE-19 cells were exposed to cigarette smoke extract (CSE), for 4 to 24-hours and TNFα, Snail, IL-6, IL-8, and α-SMA levels were analyzed by qPCR and/or Western blot. The severity of PVR formation was assessed in a murine model of PVR after intravitreal injection of ARPE-19 cells pre-treated with CSE or not. Fundus imaging, OCT imaging, and histologic analysis 4 weeks after injection were used to examine PVR severity. ARPE-19 cells exposed to CSE expressed higher levels of TNFα, SNAIL, IL6 and IL8 mRNA as well as SNAIL, Vimentin and α-SMA protein. Inhibition of TNFα and NF-κB pathways blocked the effect of CSE. In vivo, intravitreal injection of ARPE-19 cells treated with CSE resulted in more severe PVR compared to mice injected with untreated RPE cells. These studies suggest that the TNFα pathway is involved in the mechanism whereby cigarette smoke increases PVR. Further investigation into the role of TNFα/NF-κB/Snail in driving PVR and pharmacological targeting of these pathways in disease are warranted.

Intravitreal Tissue Plasminogen Activator Injection for the Treatment of Proliferative Vitreoretinopathy in a Rabbit Model

INTRODUCTION

The purpose of this study was to evaluate the effect of intravitreal injection of tissue plasminogen activator (tPA) on proliferative vitreoretinopathy (PVR).

METHODS

PVR was induced in a rabbit model by intraocular injection of dispase (0.05 U/0.1 mL). Progression of PVR was followed by indirect ophthalmic examination. Following 6 weeks, 5 animals received intravitreal injection of 25 µg/0.1 mL tPA and four were injected with balanced salt solution (BSS). Animals were euthanized at 48 h following tPA/BSS injection, and eyes were enucleated for histological evaluation and staining with α-smooth muscle actin (αSMA) and Sirius Red.

RESULTS

Following tPA injection, one eye had a reduction in PVR from grade 2 to 1 and three eyes remained stable. Following BSS, PVR grade was unchanged in three eyes. In one eye in each group, the severity of PVR could not be assessed due to limited view. Staining with αSMA showed reduced presence of fibroblasts in eyes injected with tPA compared with those injected with BSS. Collagen type I and III, demonstrated by Sirius Red staining, was reduced in the tPA group in comparison with controls.

CONCLUSION

Our results suggest that intravitreally injected tPA may show an inhibitory effect on PVR progression. Further exploration in clinical trials is desired.

Outcomes of Eyes Undergoing Multiple Surgical Interventions after Failure of Primary Rhegmatogenous Retinal Detachment Repair

PURPOSE

To assess outcomes among eyes undergoing surgery for recurrent rhegmatogenous retinal detachment (RRD) and investigate variables that correlate with visual and anatomic outcomes.

DESIGN

Retrospective, consecutive case series.

PARTICIPANTS

Eyes in which initial RRD repair failed that underwent ≥2 surgeries for RRD repair between January 1, 2016, and December 31, 2020.

METHODS

A retrospective analysis of eyes that underwent ≥2 RRD repairs. Eyes with etiologies of retinal detachment other than RRD, previous vitreoretinal surgery, and proliferative diabetic retinopathy were excluded. One-way analysis of variance with Tukey honestly significant difference testing and multivariate regression analyses were used to assess statistical significance.

MAIN OUTCOME MEASURES

Anatomic success rate and habitual best recorded visual acuity (VA) at postoperative time intervals and at final follow-up.

RESULTS

The single-operation success rate (SOSR) among eyes that underwent primary RRD repair over a 5-year period was 92.4% (2021 of 2187 eyes). The remaining 166 eyes (164 patients) in which primary RRD repair failed were included in this study. Although the anatomic success rates after the second and third RRD repairs were lower than the SOSR (71.7% and 68.1%, respectively), the final anatomic success rates did not significantly differ between eyes that underwent ≥2 RRD repairs (range, 90.6%-100%) (P > 0.05), and final anatomic success was achieved in 95.8% of the eyes. The average VA at both postoperative time intervals and final follow-up decreased with an increased total number of RRD repairs. Eyes that received silicone oil endotamponade during the second RRD repair were 20.3% (P = 0.03) and 38.4% (P = 0.04) less likely to require a third RRD repair compared with eyes that received octafluoropropane and sulfur hexafluoride gases, respectively. Eyes that developed a third RRD due to proliferative vitreoretinopathy (PVR) (n = 43) were 110% more likely to require a fourth RRD repair than eyes that developed a third RRD due to a new tear or failure to reattach (n = 4) (P = 0.04).

CONCLUSIONS

In this series, the rates of anatomic success appeared consistent after each surgery when multiple reoperations were required for RRD. The VA decreased with an increased total number of RRD repairs, and the endotamponade choice might have affected the risk of additional reoperations. Proliferative vitreoretinopathy was a significant prognostic factor for RRD recurrence.

Managing PVR in the Era of Small Gauge Surgery

Proliferative vitreoretinopathy (PVR) is the leading cause of failed rhegmatogenous retinal detachment (RRD) surgery. Based upon the presence of clinical features and due to associated underlying risk factors, it is classified into various grades based upon its severity and extent of involvement. Despite excellent skills, flawless techniques, and high-end technology applied in the management of RRD, PVR still occurs in 5–10% of cases. Due to the advancements in wide angle viewing systems, advance vitrectomy machines and fluidics, early identification, use of long-term heavy silicon oil tamponades, high-speed cutters, small-gauge vitrectomies, use of perfluorocarbon liquid (PFCL), and small-gauge forceps and scissors, the success rate in the management of PVR has increased leading to improved anatomical outcomes. However, functional outcomes do not correlate well with improved anatomical outcomes. Various complications occur after RRD repair that are responsible for re-retinal detachment and recurrence of PVR. This article highlights causes, risk factors, classification, grading, diagnosis, and approach to management of PVR and post-PVR surgery complications.

SURGICAL FAILURES AFTER PRIMARY SCLERAL BUCKLING FOR RHEGMATOGENOUS RETINAL DETACHMENT: Comparison of Eyes With and Without Proliferative Vitreoretinopathy

PURPOSE

To compare proliferative vitreoretinopathy (PVR)-related surgical failure and non-PVR-associated failure after scleral buckling for primary rhegmatogenous retinal detachment.

METHODS

In this single-center, retrospective, consecutive case series, eyes with surgical failure after scleral buckling for primary rhegmatogenous retinal detachment were identified. Eyes with surgical failure were categorized as PVR-associated and non-PVR-associated failure, and these groups were compared.

RESULTS

Of the 530 scleral buckling procedures performed, 69 were surgical failures (13%), of which 27 of the 530 (5%) were due to PVR and 42 of the 530 (8%) were from non-PVR causes. Patients with PVR-associated failure were more likely to be smokers (P < 0.001), have a delayed presentation after symptoms (P = 0.011), have preoperative vitreous hemorrhage (P = 0.004), and have preoperative PVR (P = 0.002). Multivariate logistic regression models showed that the odds of PVR-associated failure were greater in eyes with preoperative vitreous hemorrhage (odds ratio, 8.2; P = 0.048), preoperative PVR (odds ratio, 22.7; P = 0.023), and among previous smokers (odds ratio, 28.8; P < 0.001). Thirty-two of 69 patients (46%) required one additional surgical intervention, and 37 of the 69 patients (53%) required two or more additional interventions to achieve final reattachment.

CONCLUSION

Proliferative vitreoretinopathy-related surgical failure after primary scleral buckling was 5%. Risk factors for PVR-associated failure parallel those commonly referenced for pars plan vitrectomy, including smoking history, preoperative vitreous hemorrhage, and preoperative PVR.

Clinical Outcomes of Rhegmatogenous Retinal Detachment Treated With Pneumatic Retinopexy

IMPORTANCE

Pneumatic retinopexy (PR) is the only clinic-based method of rhegmatogenous retinal detachment (RRD) repair. Registry-acquired clinical practice setting outcomes data with this procedure have not yet been reported.

OBJECTIVE

To describe the clinical outcomes associated with RRD treated primarily with PR.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, data from patients 19 years and older with noncomplex RRD treated at academic and private ophthalmology practices participating in the American Academy of Ophthalmology IRIS Registry (Intelligent Research in Sight) were analyzed. Data were collected from January 1, 2013, to December 31, 2019, and data were analyzed from January to December 2020.

EXPOSURES

Data from the IRIS Registry were queried for eyes that underwent PR for noncomplex RRD and had at least 3 months of follow-up. Cases were identified by a combination of diagnosis code for RRD and a Current Procedural Terminology code for PR.

MAIN OUTCOMES AND MEASURES

The number of eyes that achieved single-operation success (SOS), defined as retinal reattachment without a subsequent retinal detachment surgery or repeated PR.

RESULTS

Of 9553 included patients, 5827 (61.0%) were male, and the mean (SD) age was 62 (10) years. A total of 9659 eyes were identified. SOS was achieved in 6613 eyes (68.5%). Best-corrected visual acuity significantly differed 9 to 12 months after treatment between the SOS group, with a mean of 0.24 logMAR (95% CI, 0.23-0.25; approximate Snellen equivalent, 20/35), and the single-operation failure group, with a mean of 0.43 logMAR (95% CI, 0.40-0.46; approximate Snellen equivalent, 20/54). Among all patients, the mean time to maximal visual recovery was 268 days (95% CI, 260-276). Endophthalmitis was observed in 3 eyes (0.03%). SOS was associated with female sex (odds ratio, 1.51; 95% CI, 1.38-1.65), while current smoking status was associated single-operation failure (odds ratio, 0.78; 95% CI, 0.68-0.91).

CONCLUSIONS AND RELEVANCE

In this registry-based study, which encompasses a large number of eyes drawn from multiple, heterogenous electronic health record systems, SOS was achieved in 68.5% of eyes with noncomplex RRD treated by primary PR. It is unknown how these outcomes would have compared with other methods of RRD repair in this cohort.

Infectious necrotizing scleritis and proliferative vitreoretinopathy after scleral buckling in a patient with atopic dermatitis

Purpose

To report a case of necrotizing scleritis and proliferative vitreoretinopathy due to an acute infection following scleral buckling for the management of rhegmatogenous retinal detachment in a patient with untreated atopic dermatitis.

Observations

A 40-year-old man with untreated atopic dermatitis presented with rhegmatogenous retinal detachment in his right eye. He underwent uncomplicated scleral buckling surgery with an encircling silicon sponge band, then noticed severe hyperemia and purulent discharge in the eye at 3 weeks after surgery. The silicon sponge was exposed and had migrated anteriorly. The patient was then diagnosed with post-scleral-buckling infection and underwent scleral buckle removal. Marked scleral thinning due to necrotizing scleritis was evident beneath the scleral buckle. Eye discharge culture findings were positive for Staphylococcus aureus. After removal of the scleral buckle, the patient's necrotizing scleritis improved, but he developed proliferative vitreoretinopathy. The patient then underwent pars plana vitrectomy, which resulted in reattachment of his retina.

Conclusions and Importance

Although postoperative infection within 1 month after scleral buckling is rare, surgeons should note that patients with atopic dermatitis are at high risk of postoperative infection after scleral buckling, leading to the development of sight-threatening complications such as necrotizing scleritis, which could lead to incomplete retinal attachment and proliferative vitreoretinopathy.

Molecular Targets for Proliferative Vitreoretinopathy

While innovations in the surgical management of retinal detachment (RD) with proliferative vitreoretinopathy (PVR) have significantly improved anatomic and visual outcomes over the years, recurrent RD due to PVR remains the major limitation to success. There are currently no medical therapies proven to be effective against PVR in humans. Increased understanding of the pathophysiology and risk factors for PVR have helped guide investigations for molecular targets. Drugs that counteract inflammation, proliferation, and growth factors are the leading candidates for treatment of PVR. This review discusses the ongoing search for pharmacologic therapies, with an emphasis on the results of recent clinical investigations.

Predictive modeling of proliferative vitreoretinopathy using automated machine learning by ophthalmologists without coding experience

We aimed to assess the feasibility of machine learning (ML) algorithm design to predict proliferative vitreoretinopathy (PVR) by ophthalmologists without coding experience using automated ML (AutoML). The study was a retrospective cohort study of 506 eyes who underwent pars plana vitrectomy for rhegmatogenous retinal detachment (RRD) by a single surgeon at a tertiary-care hospital between 2012 and 2019. Two ophthalmologists without coding experience used an interactive application in MATLAB to build and evaluate ML algorithms for the prediction of postoperative PVR using clinical data from the electronic health records. The clinical features associated with postoperative PVR were determined by univariate feature selection. The area under the curve (AUC) for predicting postoperative PVR was better for models that included pre-existing PVR as an input. The quadratic support vector machine (SVM) model built using all selected clinical features had an AUC of 0.90, a sensitivity of 63.0%, and a specificity of 97.8%. An optimized Naïve Bayes algorithm that did not include pre-existing PVR as an input feature had an AUC of 0.81, a sensitivity of 54.3%, and a specificity of 92.4%. In conclusion, the development of ML models for the prediction of PVR by ophthalmologists without coding experience is feasible. Input from a data scientist might still be needed to tackle class imbalance-a common challenge in ML classification using real-world clinical data.

Proliferative Vitreoretinopathy After Combat Ocular Trauma in Operation Iraqi Freedom and Operation Enduring Freedom: 2001-2011

BACKGROUND AND OBJECTIVE

To determine the risk factors associated with developing proliferative vitreoretinopathy (PVR) from combat ocular injuries in U.S. service members.

PATIENTS AND METHODS

Retrospective review of associated risk factors and outcomes of PVR within the Walter Reed Ocular Trauma Database. Ocular injuries in U.S. service members wounded during Operation Enduring Freedom and Operation Iraqi Freedom from 2001 to 2011 were assessed, and of these all cases of PVR were studied. Principal outcome measures were the risk factors associated with PVR development and rate of final visual acuity (VA) less than 20/200.

RESULTS

Eight hundred ninety eyes of 651 U.S. service members were evaluated. A total of 76 eyes (8.5%) of 66 patients developed PVR. Five patients had bilateral PVR. Nineteen patients had bilateral eye injuries. Sixty-one eyes (80.2%) had a final VA less than 20/200. PVR was found to be a significant risk factor for a poor final VA (P < .001). Retinal detachment (RD) was found in 52 eyes (68.4%) of patients. In patients with a RD, intraocular foreign bodies (IOFBs) (P < .001), unsuccessful repair (P = .002), and macular hemorrhage (P = .04) were significant risk factors for the development of PVR. Time to initial retina surgery was not found to be a risk factor for PVR development (P = .5). Time to initial retina surgery was available in 41 patients and the time to surgery on average was 22.56 days (range: 3 to 87 days).

CONCLUSIONS

PVR occurs frequently in combat trauma and is a significant cause of poor final VA. In patients with PVR and RD, injuries caused by an IOFB, macular hemorrhage, or unsuccessful repair were significant risk factors for the development of PVR. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:556-563.].

Cytokine profiles of phakic and pseudophakic eyes with primary retinal detachment

PURPOSE

To compare the cytokine profiles of phakic (p) and pseudophakic (ps) eyes with primary rhegmatogenous retinal detachment (RD) to eyes with macular holes (MH) and to identify differences in the specific cytokine profiles.

METHODS

Aqueous humour (AH) and vitreous fluid (VF) were obtained from patients with primary RD without proliferative vitreoretinopathy undergoing vitrectomy. AH and VF of patients with macular holes (MH) served as controls. Forty-three different cytokines were quantified using multiplex cytokine analysis. Intergroup and intragroup comparisons were performed. To control for multiple comparisons, Holm's correction was applied.

RESULTS

VF and AH samples of 71 eyes with RD (pRD N = 38; psRD N = 33) and 26 eyes with MH were included. Cytokine levels in psRD and pRD were similar (none with >10-fold difference). The levels of 39 of 43 cytokines in the VF were significantly higher in eyes with RD than in those with MH (>10-fold: CXLC5, CCL26, CCL1, IL-6, CXCL11, CCL7, CCL13, MIG/CXCL9, CCL19 and TGF-β1). In the AH, 23 of 43 cytokines were significantly higher compared to MH (>10-fold: CXCL5, IL-4, IL-6, IL-8/CXCL8 and CCL7).

CONCLUSION

A complex, but nonspecific cytokine environmental response seems to initiate immunological and profibrotic processes following RD. Relevant differences in the cytokine profiles of eyes with pRD and psRD were not identified, whereas cytokine differences between AH and VF in RD could be explained by upregulation in the vitreous, a higher turn around in the anterior chamber, or differences in inflammatory cascades in both compartments.