The effect of a preoperative subconjuntival injection of dexamethasone on blood-retinal barrier breakdown following scleral buckling retinal detachment surgery: a prospective randomized placebo-controlled double blind clinical trial

Evaluation of a steroid delivery system to mitigate the severity of proliferative vitreoretinopathy in a minipig model

Purpose

To investigate the efficacy of liposomal prednisolone phosphate to mitigate the severity of proliferative vitreoretinopathy (PVR) in a minipig model of PVR.

Methods

A total of 18 eyes of 9 minipigs underwent PVR induction surgically. Eyes were randomized equally into three groups: intravitreal injection of liposomal prednisolone phosphate (LPP), triamcinolone acetonide (TA), and controls. PVR severity was graded on fundoscopic examination using a modified version of the Silicon Study Classification System. Severe PVR was defined as grade 2-5 on this classification, and the proportion of eyes with retinal detachment from severe PVR, defined as retinal re-detachment, i.e., PVR grade 2-5, was compared between treatment and control groups.

Results

On day 28, five eyes (83.3%) in the control group were observed to have severe PVR. Within the LPP group, one (16.7%) eye developed retinal detachment due to severe PVR. Grade 0 PVR was observed in four (66.7%) eyes, grade 1 in one (16.7%) eye, and grade 5 in one (16.7%) eye. Within the TA group, grade 0 PVR was observed in four eyes (66.7%), grade 1 in two eyes (16.6%), and grade 5 in one (16.7%) eye. The difference in the proportion of eyes with severe PVR was significantly lower in the LPP group compared to controls at day 28 (16.7% vs 83.3%, p=0.02). There was no significant difference in the rate of severe PVR or median PVR grade between the liposomal prednisolone phosphate and triamcinolone acetonide groups.

Conclusion

Liposomal prednisolone phosphate reduces the severity of PVR in a minipig model of PVR.

Steroid Drugs as an Adjunct for Reducing the Incidence of Proliferative Vitreoretinopathy after Rhegmatogenous Retinal Detachment Surgery: A Meta-Analysis of Randomized Controlled Studies

INTRODUCTION

The efficacy and influence of steroids for reducing the incidence of proliferative vitreoretinopathy (PVR) after rhegmatogenous retinal detachment (RRD) surgery remain controversial. Systematic review and meta-analysis were conducted to explore the effect of steroids versus placebo on risk of PVR.

METHODS

We searched PubMed, Embase, Web of science, EBSCO, and Cochrane library databases through September 2020 for randomized controlled trials (RCTs), assessing the effect of steroid drugs as an adjunct for reducing the incidence of PVR after RRD surgery. This meta-analysis was performed using the random-effect model. Data were extracted by two reviewers independently; the quality of RCTs was assessed by the Cochrane risk-of-bias tool. We calculated risk ratio (RR) and the 95% confidence intervals (CIs) of all outcomes and plotted on forest plots. I2 accessed using the χ2 test was applied to quantify the degree of heterogeneity.

RESULTS

Four RCTs involving 478 patients (478 eyes) are included in the meta-analysis. There was no significant difference in the incidence of PVR recurrence between steroid groups and control groups (RR: 0.87, 95% CI: 0.70-1.08, p = 0.19). However, the incidence of recurrent PVR was lower in the steroid group (RR: 0.67, 95% CI: 0.46-0.99, p = 0.04) than in the control group when only PVR grades A and B were taken into consideration. Besides, steroids could significantly reduce the incidence of macular edema after surgery (RR: 0.64, 95% CI: 0.47-0.88, p = 0.007). The steroid group and control group had comparable outcomes of retinal reattachment rate and reoperation rate after primary surgery. Additionally, there was no significant difference of the incidence of epiretinal membrane, and the incidence of surgery required by epiretinal membrane.

CONCLUSION

This meta-analysis reveals that RRD surgery combined with steroid drugs administration could significantly reduce the recurrence in PVR grade A and B subgroup, as well as the incidence of macular edema after surgery.

Evaluation of Lymphocyte-to-Monocyte Ratio and Mean Platelet Volume-to-Platelet Ratio in Rhegmatogenous Retinal Detachment

Purpose

To assess the predictive value of inflammatory blood biomarkers in rhegmatogenous retinal detachment (RRD) patients and its correlation with proliferative retinopathy (PVR) grade.

Methods

82 RRD patients and 1 : 1 age- and gender-randomly matched cataract patients as the control group were included. The clinical features and laboratory parameters of all participants were collected and recorded, and the comprehensive index of inflammatory blood and its correlation with PVR were calculated.

Results

Monocytes and monocyte-to-high-density lipoprotein ratio (MHR) were significantly lower (P=0.005, P=0.044), while mean platelet volume (MPV), lymphocyte-to-monocyte ratio (LMR), and MPV-to-platelet ratio (MPR) were significantly higher in RRD patients as compared with the control group (P=0.013, P=0.019, P=0.037). LMR and MPR might be the predictors of RRD. The receiver operating characteristics analysis showed that the values of MPV, LMR, and MPR in RRD patients were 0.612, 0.606, and 0.594, respectively. PVR grade was not associated with inflammatory blood biomarkers.

Conclusion

The increase in MPV, LMR, and MPR were associated with increased odds of RRD. LMR and MPR may be useful as inexpensive and effortless biomarkers for assessing the occurrence of RRD.

Reporting of Complications in Retinal Detachment Surgical Trials: A Systematic Review Using the CONSORT Extension for Harms

IMPORTANCE

Knowledge on the frequency and severity of complications in surgical trials for rhegmatogenous retinal detachment (RRD) is essential to determine whether surgical procedures are developed and compared adequately, taking into account not only efficacy but also harms.

OBJECTIVE

To review standards of reporting of complications in recent randomized clinical trials of RRD surgery.

EVIDENCE REVIEW

This systematic review included randomized clinical trials on RRD surgery published between January 2008 and January 2021 in Embase, MEDLINE, and Web of Science Core Collection databases. Titles, abstracts, and full-text articles retrieved were reviewed for eligibility by 2 independent authors. Eligible studies were evaluated against checklist items from the Consolidated Standards of Reporting Trials Extension for Harms criteria by 2 independent authors, and discrepancies were resolved by discussion with a third author.

FINDINGS

Fifty studies were included. The median number of checklist items fulfilled was 8 (range, 0-15), of a possible total of 18. Frequently reported items were discussions balanced with regard to efficacy and adverse events (42 studies [84%]) and inclusions of harm-associated timing of data collection (41 studies [82%]). The least frequently reported items were distinctions between expected and unexpected adverse events (1 study [2%]) and mentions of the use of a validated instrument to report adverse event severity (4 studies [8%]). Frequency of complications was commonly reported (29 studies [58%]) in contrast with complication severity (10 studies [20%]).

CONCLUSIONS AND RELEVANCE

This review suggests that severity of complications of RRD surgery has been infrequently quantified and reported in randomized clinical trials and potentially represents an important area of improvement in future RRD surgical trials.

Preoperative, Intraoperative and Postoperative Corticosteroid Use as an Adjunctive Treatment for Rhegmatogenous Retinal Detachment

The treatment for rhegmatogenous retinal detachment (RRD) is surgery, including pars plana vitrectomy (PPV) and scleral buckling (SB). Despite surgical advances, degeneration of the photoreceptors and post-operative complications, such as proliferative vitreoretinopathy (PVR), often occurs as the result of inflammation, preventing complete visual recovery or causing RRD recurrence. There is increasing evidence that in the presence of RRD, the activation of inflammatory processes occurs and the surgery itself induces an inflammatory response. This comprehensive review focuses on the use of different formulations of corticosteroids (CCS), as an adjunctive treatment to surgery, either PPV or SB, for RRD repair. The purpose was to review the efficacy and safety of CCS in improving functional and anatomical outcomes and in preventing postoperative complications. This review is organized according to the timing of CCS administration: preoperative, intraoperative, and postoperative. The evidence reviewed supported the role of the pre-operative use of CCS in the treatment of combined RRD and choroidal detachment (CD), reducing CD height. No solid consensus exists on intraoperative and postoperative use of CCS to treat and prevent postoperative complications. However, a large randomized clinical trial including more than 200 eyes suggested that oral prednisone after surgery decreases the rate of postoperative grade B PVR.

Preoperative Steroid Use in Rhegmatogenous Retinal Detachment Associated with Choroidal Detachment after 23-Gauge Vitrectomy

Background

Rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD) is rare and the prognosis is poor. This retrospective study evaluated the effect of preoperative steroid on the clinical outcome of patients with RRDCD receiving 23-gauge pars plana vitrectomy (PPV).

Methods

Sixty-six patients (67 eyes) with diagnosed RRDCD underwent 23-gauge PPV. The patients assigned to receive systemic or subtenon injection of preoperative steroids were considered Group A (35 eyes) and did not receive are considered Control Group B (32 eyes). Most patients in Group A received subtenon injection of glucocorticoids. The cyclodialysis angle was measured with ultrasound biomicroscopy. Preoperative, intraoperative, and postoperative data were compared.

Results

The rates of retinal reattachment in Group A after the first and second operations were 68.8% (24/35 eyes) and 91.43% (32/35 eyes), respectively, which were not significantly different from that of Group B (78.1%, 25/32 eyes; 96.6%, 31/32 eyes). The logMAR (logarithm of the minimum angle of resolution) visual acuity in Group A (1.63 ± 0.75) was similar to that of Group B (1.34 ± 0.74). Postoperative intraocular pressure and ocular hypertension in Group A (17.94 ± 9.82 mmHg and 37.1%, respectively; 13/35 eyes) were comparable to that of Group B (20.93 ± 10.21 mmHg and 56.3%; 18/32 eyes). Logistic regression analysis showed that postoperative reattachment was negatively associated with preoperative cyclodialysis angle as measured with ultrasound biomicroscopy (P=0.048) but was not significantly associated with preoperative steroid use (P=0.907).

Conclusions

Preoperative steroid use does not improve retinal reattachment and visual acuity in patients with RRDCD after 23-gauge PPV. Preoperative measurement of the cyclodialysis angle with ultrasound biomicroscopy may be useful for predicting clinical outcomes.

Inflammatory and Fibrogenic Factors in Proliferative Vitreoretinopathy Development

Purpose

Proliferative vitreoretinopathy (PVR) occurs in 5%-10% of rhegmatogenous retinal detachment cases and is the principle cause for failure of retinal reattachment surgery. Although there are a number of surgical adjunctive agents available for preventing the development of PVR, all have limited efficacy. Discovering predictive molecular biomarkers to determine the probability of PVR development after retinal reattachment surgery will allow better patient stratification for more targeted drug evaluations.

Methods

Narrative literature review.

Results

We provide a summary of the inflammatory and fibrogenic factors found in ocular fluid samples during the development of retinal detachment and PVR and discuss their possible use as molecular PVR predictive biomarkers.

Conclusions

Studies monitoring the levels of the above factors have found that few if any have predictive biomarker value, suggesting that widening the phenotype of potential factors and a combinatorial approach are required to determine predictive biomarkers for PVR.

Translational Relevance

The identification of relevant biomarkers relies on an understanding of disease signaling pathways derived from basic science research. We discuss the extent to which those molecules identified as biomarkers and predictors of PVR relate to disease pathogenesis and could function as useful disease predictors. (http://www.umin.ac.jp/ctr/ number, UMIN000005604).

Postoperative aqueous humour flare as a surrogate marker for proliferative vitreoretinopathy development

PURPOSE

As some surgical procedures have been shown to increase postoperative flare values and thus contribute to blood-ocular barrier breakdown, retinal reattachment surgery might influence the risk of developing proliferative vitreoretinopathy (PVR). Therefore, we investigated whether postoperative aqueous flare values are a surrogate marker for the development of postoperative PVR.

METHODS

We prospectively included 195 patients with primary rhegmatogenous retinal detachment (RRD) and measured aqueous laser flare preoperatively, and at 2 and 6 weeks postoperatively. Postoperative PVR was defined as reoperation for redetachment due to PVR membranes, within 6 months of initial surgery. Logistic regression and receiver operating characteristic (ROC) analysis determined whether higher postoperative flare values were associated with an increased risk of developing PVR later on.

RESULTS

Reoperation for postoperative PVR was needed in 12 (6.2%) patients; in 18 (9.2%), reoperation was not related to PVR. The median flare value for patients who would develop PVR was significantly higher than that of patients who would not develop PVR, both at 2 weeks (p = 0.001) and 6 weeks (p < 0.001) postoperatively. Logistic regression analyses showed that a higher flare value significantly increased the odds of developing PVR, either at 2 weeks [odds ratio (OR) 1.027; 95% CI: 1.010-1.044] or 6 weeks (OR 1.076; 95% CI: 1.038-1.115).

CONCLUSION

Flare values both at 2 and 6 weeks postoperatively seem a good surrogate marker in terms of sensitivity and specificity for the development of postoperative PVR but have only a modest positive predictive value. The 2-week value would be more useful in terms of early recognition of high-risk patients and hence give the possibility to better study effects of treatment methods.

Surgical outcomes of preoperative steroid for rhegmatogenous retinal detachment with associated choroidal detachment

PurposeTo investigate the effect of preoperative steroid on anatomical and functional outcomes of vitrectomy in patients with rhegmatogenous retinal detachment with associated choroidal detachment (RRD-CD), a rare but particular type of RRD.Patients and methodsThis retrospective cohort study included RRD-CD patients at Siriraj Hospital during January 2005 to December 2014. Patients with preexisting uveitis or RRD with giant retinal tears were excluded. Preoperative, intraoperative, and postoperative data were reviewed and analyzed.ResultsA total of 76 patients (76 eyes) with RRD-CD were included: 37 patients without preoperative steroid (Group A) and 39 patients with preoperative steroid for a median of 7 days (Group B: 34 patients with oral prednisolone (0.5-1 mg/kg/day) and 5 patients with 20 or 40 mg of subtenon triamcinolone). The total retinal reattachment rate at 3 months after one operation was not different between the two groups (59 vs 51%) with adjustment for confounders. The proportion of patients with visual acuity (VA) improvement at 3 months was also not different (57 vs 54%). Survival analysis revealed that 96% of redetachment cases occurred within the first 3 months and redetachment rate was not different between the two groups for up to 3 years. However, Group B showed a significant regression (partial or complete) of CD prior to operation compared to Group A (82 vs 30%, P<0.001).ConclusionPreoperative steroid significantly improved CD before vitrectomy, but seemed not to improve the single-operation retinal reattachment rate or VA at 3 months when compared to no steroid treatment in RRD-CD patients.

Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment

BACKGROUND/AIMS

Patients with rhegmatogenous retinal detachment (RRD) who develop postoperative proliferative vitreoretinopathy (PVR) have been found to have higher preoperative laser flare values than patients with RRD who do not develop this complication. Measurement of laser flare has therefore been proposed as an objective, rapid and non-invasive method for identifying high-risk patients. The purpose of our study was to validate the use of preoperative flare values as a predictor of PVR risk in two additional patient cohorts, and to confirm the sensitivity and specificity of this method for identifying high-risk patients.

METHODS

We combined data from two independent prospective studies: centre 1 (120 patients) and centre 2 (194 patients). Preoperative aqueous humour flare was measured with a Kowa FM-500 Laser Flare Meter. PVR was defined as redetachment due to the formation of traction membranes that required reoperation within 6 months of initial surgery. Logistic regression and receiver operating characteristic analysis determined whether higher preoperative flare values were associated with an increased risk of postoperative PVR.

RESULTS

PVR redetachment developed in 21/314 patients (6.7%). Median flare values differed significantly between centres, therefore analyses were done separately. Logistic regression showed a small but statistically significant increase in odds with increasing flare only for centre 2 (OR 1.014; p=0.005). Areas under the receiver operating characteristic showed low sensitivity and specificity: centre 1, 0.634 (95% CI 0.440 to 0.829) and centre 2, 0.731 (95% CI 0.598 to 0.865).

CONCLUSIONS

Preoperative laser flare measurements are inaccurate in discriminating between those patients with RRD at high and low risk of developing PVR.

Cannabinoid 2 receptor is a novel anti-inflammatory target in experimental proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) can develop after ocular trauma or inflammation and is a common complication of surgery to correct retinal detachment. Currently, there are no pharmacological treatments for PVR. Cannabinoids acting at cannabinoid 2 receptor (CB2R) can decrease inflammation and fibrosis. The objective of this study was to examine the anti-inflammatory actions of CB2R as a candidate novel therapeutic target in experimental PVR. PVR was induced by intravitreal injection of dispase in wild-type (WT) and CB2R genetic knockout (CB2R^-/-) mice. Ocular pathology was studied at 24 h or one week after dispase injection. CB2R modulation was examined in WT mice, using the CB2R agonist, HU308, and the CB2R antagonist, AM630. Histopathological scoring and quantification of microglia was used to evaluate tissue pathology. Quantitative PCR and multiplex assays were used to assess changes in proinflammatory cytokines. Intravital microscopy (IVM) was used to visualize and quantify leukocyte-endothelial adhesion to the iridial microcirculation. Activation of CB2R with HU308 in WT mice with PVR decreased mean histopathological scores, the number of microglia, and leukocyte adhesion compared to vehicle-treated animals. Conversely, an increase in histopathological scores and activated microglia was observed in PVR animals after treatment with AM630. CB2R^-/- mice with PVR exhibited exacerbated ocular histopathology, increased microglia numbers, and elevated protein levels of cytokines as compared to WT mice. In conclusion, our results indicate that intervention at early stage PVR with CB2R agonists reduces ocular inflammation and disease severity. CB2R may represent a therapeutic target to prevent PVR progression and vision loss. This article is part of the Special Issue entitled 'Lipid Sensing G Protein-Coupled Receptors in the CNS'.

Proliferative vitreoretinopathy: A new concept of disease pathogenesis and practical consequences

During the last four decades, proliferative vitreoretinopathy (PVR) has defied the efforts of many researchers to prevent its occurrence or development. Thus, PVR is still the major complication following retinal detachment (RD) surgery and a bottle-neck for advances in cell therapy that require intraocular surgery. In this review we tried to combine basic and clinical knowledge, as an example of translational research, providing new and practical information for clinicians. PVR was defined as the proliferation of cells after RD. This idea was used for classifying PVR and also for designing experimental models used for testing many drugs, none of which were successful in humans. We summarize current information regarding the pathogenic events that follow any RD because this information may be the key for understanding and treating the earliest stages of PVR. A major focus is made on the intraretinal changes derived mainly from retinal glial cell reactivity. These responses can lead to intraretinal PVR, an entity that has not been clearly recognized. Inflammation is one of the major components of PVR, and we describe new genetic biomarkers that have the potential to predict its development. New treatment approaches are analyzed, especially those directed towards neuroprotection, which can also be useful for preventing visual loss after any RD. We also summarize the results of different surgical techniques and clinical information that is oriented toward the identification of high risk patients. Finally, we provide some recommendations for future classification of PVR and for designing comparable protocols for testing new drugs or techniques.

Subconjunctival injection of XG-102, a JNK inhibitor peptide, in patients with intraocular inflammation: a safety and tolerability study

PURPOSE

We aimed to investigate the safety, tolerability, and systemic diffusion of a single escalating dose of XG-102 (a 31-D-amino-acid peptide inhibiting JNK pathway activation), administered subconjunctivally in the treatment of post-surgery or post-trauma intraocular inflammation.

METHODS

This is a dose-escalating, tolerance Phase Ib study. Twenty patients with post-surgery or post-traumatic intraocular inflammation were assigned to 1 of the 4 dose escalating (45, 90, 450, or 900 μg XG-102) groups of 5 patients each. Patients were evaluated at 24, 48 h, 8, and 28 days following the administration of XG-102, including laboratory tests, standard eye examinations, vital signs, and occurrence of adverse events. A single plasma quantification of XG-102 was performed 30 min after administration, according to previous pharmacokinetics studies performed on volunteers.

RESULTS

A total of 17 non-serious adverse events, considered unrelated to the study treatment, were reported for 10 patients. The adverse event incidence was not related to the drug dose. All patients experienced a decrease in intraocular inflammation as of 24 h post-administration and this decrease was sustained up to 28 days thereafter. No patient required local injection or systemic administration of corticoids following the administration of XG-102. XG-102 was undetectable in the first 3 dose groups. In the fourth-dose group (900 μg) the XG-102 plasma levels were above the limit of detection for 3 patients and above the limit of quantification for 1 patient.

CONCLUSIONS

In this first clinical trial using XG-102, administered as a single subconjunctival injection as adjunct therapy, in patients with recent post-surgery or post-trauma intraocular inflammation is safe and well tolerated. Further studies are required to evaluate its efficacy.

A study of the dexamethasone sodium phosphate release properties from a periocular capsular drug delivery system

The aim of this study was to investigate whether a periocular capsular drug delivery system (DDS) can release dexamethasone sodium phosphate (DEXP) in vitro and in vivo to the posterior segment of rabbit's eye. In vitro, the periocular capsular DDS containing 2 mg/ml or 5 mg/ml DEXP was immersed in modified Franz diffusion cell. Four-hundred microliters of liquid was aspirated at 0.5, 1, 2, 4, 8, 24 and 48 h for determination. In vivo, the DEXP-filled periocular capsular DDS was implanted into the sub-Tenon's sac of the New Zealand rabbit. DEXP concentration at the serum aqueous humor, cornea, iris, lens, ciliary body, vitreous, retina, choroids and sclera was quantified at 1, 3, 7, 14, 28 and 56 d after implantation. The DEXP concentration was determined by ultra-performance liquid chromatography-tandem mass spectrometry. In vitro, the periocular capsular DDS released the DEXP in time-dependent manner from 1/2 to 48 h. In vivo, the concentrations of the DEXP at the retina, choroids, ciliary body and iris were 123.11 (91.23, 732.61) ng/g, 362.46 ± 330.46 ng/g, 71.64 (71.35, 180.21) ng/g and 192.50 ± 42.66 ng/g, respectively, at 56 d after implantation. Minimal DEXP was found in the aqueous, serum and vitreous. Our results demonstrated that DEXP could be sustained released from the periocular capsular DDS, which indicated that the periocular capsular DDS might be a potential candidate of transscleral drug delivery for the management of posterior segment diseases.

Effects of recombinant adenovirus-mediated hypoxia-inducible factor-1alpha gene on proliferation and differentiation of endogenous neural stem cells in rats following intracerebral hemorrhage

OBJECTIVE

To investigate the effects of adenovirus (Ad)-mediated hypoxia-inducible factor-1alpha (HIF-1α) gene on proliferation and differentiation of endogenous neural stem cells (NSCs) in rats following intracerebral hemorrhage (ICH) and the underlying mechanisms.

METHODS

A total of 120 specific pathogen-free, adult, male Sprague-Dawley rats were included in this study. After establishment of ICH models in rats, PBS, Ad, or Ad-HIF-1α was administered via the ischemic ventricle. On the 1st, 7th, 14th, 21st and 28th d after ICH, rat neurological deficits were scored, doublecortin (DCX) expression in the subventricular zone cells was detected by immunohistochemical staining, and 5-bromo-2'-deoxyuridine (BrdU)-, BrdU/DCX-, and BrdU/glial fibrillary acidic protein-positive cells in the subventricular zone were counted using immumofluorescence method among PBS, Ad, and Ad-HIF-1α groups.

RESULTS

On the 7th, 14th, 21st and 28th d after ICH, neurological deficit scores in the Ad-HIF-1α group were significantly lower than in the PBS and Ad groups (P<0.05). In the Ad-HIF-1α group, DCX expression was significantly increased on the 7th d, peaked on the 14th d, and then gradually decreased. In the Ad-HIF-1α group, BrdU-positive cells were significantly increased over time course, and significant difference in BrdU-positive cell counts was observed when compared with the PBS and Ad groups at each time point (P<0.01 or 0.05). On the 7th, 14th, 21st and 28th d after ICH, the number of DCX-, BrdU-, BrdU/DCX-, and BrdU/DCX-positive cells in the Ad-HIF-1α group was significantly greater than in the PBS and Ad groups (P<0.05).

CONCLUSIONS

HIF-1α gene can promote the proliferation, migration and differentiation of endogenous neural stem cells after ICH, thereby contributing to neurofunctional recovery after ICH.

Proliferative vitreoretinopathy after eye injuries: an overexpression of growth factors and cytokines leading to a retinal keloid

Eye injury is a significant disabling worldwide health problem. Proliferative Vitreoretinopathy (PVR) is a common complication that develops in up to 40–60% of patients with an open-globe injury. Our knowledge about the pathogenesis of PVR has improved in the last decades. It seems that the introduction of immune cells into the vitreous, like in penetrating ocular trauma, triggers the production of growth factors and cytokines that come in contact with intra-retinal cells, like Müller cells and RPE cells. Growth factors and cytokines drive the cellular responses leading to PVR's development. Knowledge of the pathobiological and pathophysiological mechanisms involved in posttraumatic PVR is increasing the possibilities of management, and it is hoped that in the future our treatment strategies will evolve, in particular adopting a multidrug approach, and become even more effective in vision recovery. This paper reviews the current literature and clinical trial data on the pathogenesis of PVR and its correlation with ocular trauma and describes the biochemical/molecular events that will be fundamental for the development of novel treatment strategies. This literature review included PubMed articles published from 1979 through 2013. Only studies written in English were included.

Pathophysiology of proliferative vitreoretinopathy in retinal detachment

Because proliferative vitreoretinopathy cannot be effectively treated, its prevention is indispensable for the success of surgery for retinal detachment. The elaboration of preventive and therapeutic strategies depends upon the identification of patients who are genetically predisposed to develop the disease, as well as upon an understanding of the biological process involved and the role of local factors, such as the status of the uveovascular barrier. Detachment of the retina or vitreous activates glia to release cytokines and ATP, which not only protect the neuroretina but also promote inflammation, retinal ischemia, cell proliferation, and tissue remodeling. The vitreal microenvironment favors cellular de-differentiation and proliferation of cells with nonspecific nutritional requirements. This may render a pharmacological inhibition of their growth difficult without causing damage to the pharmacologically vulnerable neuroretina. Moreover, reattachment of the retina relies upon the local induction of a controlled wound-healing response involving macrophages and proliferating glia. Hence, the functional outcome of proliferative vitreoretinopathy will be determined by the equilibrium established between protective and destructive repair mechanisms, which will be influenced by the location and the degree of damage to the photoreceptor cells that is induced by peri-retinal gliosis.

Rhegmatogenous Retinal Detachment with a High Risk of Proliferative Vitreoretinopathy Treated with Episcleral Surgery and an Intravitreal Dexamethasone 0.7-mg Implant

Purpose

To report a case of rhegmatogenous retinal detachment with a high risk of proliferative vitreoretinopathy (PVR) effectively treated with episcleral surgery and an intravitreal dexamethasone 0.7-mg implant.

Methods

A 35-year-old Caucasian man with a macula-off rhegmatogenous subtotal retinal detachment that had persisted for 1 month in his myopic left eye presented several risk factors that could have led to the development of PVR after retinal detachment surgery. His best corrected visual acuity was hand motion. He received an intravitreal dexamethasone 0.7-mg implant (Ozurdex^®) after episcleral surgery to prevent this complication.

Results

At least 9 months after surgery, no sign of PVR or pucker has developed in the treated eye. Visual acuity improved to 0.2, the retina was attached and no complications were observed.

Conclusion

Intravitreal dexamethasone 0.7-mg implant (Ozurdex) could be considered as off-label treatment following episcleral surgery to prevent PVR.

Time course of changes in aqueous flare intensity after vitrectomy for rhegmatogenous retinal detachment

PURPOSE

To investigate the time course of changes in aqueous flare intensity after vitrectomy for rhegmatogenous retinal detachment (RD) and to determine the clinical factors related to an increase in aqueous flare.

METHODS

The present study included 22 unilateral patients with RD undergoing primary 20-gauge vitrectomy. Aqueous flare intensity was measured preoperatively and at 1 week, 2 weeks, 1 month, and 3, 6, and 12 months postoperatively using the laser flare meter.

RESULTS

Before vitrectomy, aqueous flare intensity was significantly higher in eyes with RD than in contralateral normal eyes. Vitrectomy increased aqueous flare intensity, and the peak was observed at the first postoperative week. Aqueous flare intensity decreased to a stable level at 3 months postoperatively but remained significantly higher than that of contralateral and preoperative eyes throughout the observation period. Clinical factors that were found to be significantly correlated with an increase in aqueous flare intensity included 1) before the surgical procedure: extent of RD and intraocular pressure, and 2) 3 months postoperatively: size of retinal breaks, number of laser photocoagulation spots, operation time, and performance of combined cataract surgery. Multiple regression analysis revealed that aqueous flare intensity at 3 months postoperatively had significant correlation with the size of retinal breaks (P < 0.005) and the number of laser photocoagulation spots (P < 0.05).

CONCLUSION

Aqueous flare intensity after vitrectomy for RD decreased to a stable level at 3 months postoperatively but remained significantly higher than the normal level. The size of retinal breaks and the degree of surgical invasion were associated with the increase in aqueous flare.

Proliferative vitreoretinopathy: current and emerging treatments

Proliferative vitreoretinopathy is a disease process that follows the proliferation of ectopic cell sheets in the vitreous and/or periretinal area, causing periretinal membrane formation and traction, in patients with rhegmatogenous retinal detachments. Currently, vitreous surgery is the standard treatment; however, the results aren't satisfactory given the vision loss that ensues and that redetachment is relatively common. It is becoming clearer that there exists an interplay between various cytokines/growth factors, matrix proteins, and the different cell types that drive the undesirable formation of periretinal membranes. This fundamental understanding is aiding in identifying different adjunct agents that can block the cellular events intrinsic to proliferative vitreoretinopathy. In this review, we describe the current understanding on the pathogenesis and discuss how the fundamental understanding of the biochemical/molecular events is instrumental in developing the novel treatment strategies that are also highlighted.

Interleukin and growth factor levels in subretinal fluid in rhegmatogenous retinal detachment: a case-control study

Background

Rhegmatogenous retinal detachment (RRD) is a major cause of visual loss in developed countries. Proliferative vitreoretinopathy (PVR), an eye-sight threatening complication of RRD surgery, resembles a wound-healing process with inflammation, scar tissue formation, and membrane contraction. This study was performed to determine the possible involvement of a wide range of cytokines in the future development of PVR, and to identify predictors of PVR and visual outcome.

Methodology

A multiplex immunoassay was used for the simultaneous detection of 29 different cytokines in subretinal fluid samples from patients with primary RRD. Of 306 samples that were collected and stored in our BioBank between 2001 and 2008, 21 samples from patients who developed postoperative PVR were compared with 54 age-, sex-, and storage-time–matched RRD control patients who had an uncomplicated postoperative course during the overall follow-up period.

Findings

Levels of IL-1α, IL-2, IL-3, IL-6, VEGF, and ICAM-1 were significantly higher (P<0.05) in patients who developed postoperative PVR after reattachment surgery than in patients with an uncomplicated postoperative course, whereas levels of IL-1β, IL-4, IL-5, IL-7, IL-9, IL-10, IL-11, IL-12p70, IL-13, IL-15, IL-17, IL-18, IL-21, IL-22, IL-23, IL-25, IL-33, TNF-α, IFN-γ, IGF-1, bFGF, HGF, and NGF were not (P>0.05). Multivariate logistic regression analysis revealed that IL-3 (P = 0.001), IL-6 (P = 0.047), ICAM-1 (P = 0.010), and preoperative visual acuity (P = 0.026) were independent predictors of postoperative PVR. Linear regression analysis showed that ICAM-1 (P = 0.005) and preoperative logMAR visual acuity (P = 0.001) were predictive of final visual outcome after primary RRD repair.

Conclusions/Significance

Our findings indicate that after RRD onset an exaggerated response of certain cytokines may predispose to PVR. Sampling at a time close to the onset of primary RRD may thus provide clues as to which biological events may initiate the development of PVR and, most importantly, may provide a means for therapeutic control.