H. Stevie Tan

Iatrogenic retinal breaks in 25-gauge macular surgery.

PURPOSE To describe the incidence and characteristics of iatrogenic retinal breaks in 25-gauge macular surgery. DESIGN Retrospective, noncomparative, interventional case series. METHODS We included 177 consecutive operations in 171 patients who underwent 25-gauge vitrectomy for idiopathic macular pucker or idiopathic macular hole. Main outcome measures were the incidence of breaks related to the sclerotomies, the incidence of breaks occurring elsewhere, the incidence of lesions suspicious for traction, the location of identified breaks, and intraoperative induction of posterior vitreous detachment (PVD). RESULTS Retinal breaks occurred in 15.8% of operations. In 6.2%, breaks were related to the sclerotomies, and in 10.7%, breaks were found elsewhere. In 8.5% of eyes, only lesions suspicious for traction were detected. Breaks or suspicious lesions were treated with external cryocoagulation in a total of 24.3% of cases. A statistically significant relation between PVD induction and presence of breaks elsewhere was identified. No correlation with lens status, initial diagnosis, or preoperative refraction was found. Retinal detachment occurred in 1.7% of cases. CONCLUSIONS We report an incidence of retinal breaks that is higher than previously found for 20- or 25-gauge surgery. Despite the high incidence of breaks, the incidence of postoperative retinal detachment was low. A specific characteristic was the relatively high incidence of breaks elsewhere and their relation to PVD induction. Our findings underscore the importance of scrupulous full 360-degree internal search at the end of each procedure to identify and treat all breaks and suspicious lesions optimally.

A shift in the balance of vascular endothelial growth factor and connective tissue growth factor by bevacizumab causes the angiofibrotic switch in proliferative diabetic retinopathy

Introduction In proliferative diabetic retinopathy (PDR), vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF) may cause blindness by neovascularisation followed by fibrosis of the retina. It has previously been shown that a shift in the balance between levels of CTGF and VEGF in the eye is associated with this angiofibrotic switch. This study investigated whether anti-VEGF agents induce accelerated fibrosis in patients with PDR, as predicted by this model. Methods CTGF and VEGF levels were measured by ELISA in 52 vitreous samples of PDR patients, of which 24 patients had received intravitreal bevacizumab 1 week to 3 months before vitrectomy, and were correlated with the degree of vitreoretinal fibrosis as determined clinically and intra-operatively. Results CTGF correlated positively, and VEGF correlated negatively with the degree of fibrosis. The CTGF/VEGF ratio was the strongest predictor of fibrosis. Clinically, increased fibrosis was observed after intravitreal bevacizumab. Conclusions These results confirm that the CTGF/VEGF ratio is a strong predictor of vitreoretinal fibrosis in PDR, and show that intravitreal anti-VEGF treatment causes increased fibrosis in PDR patients. These findings provide strong support for the model that the balance of CTGF and VEGF determines the angiofibrotic switch, and identify CTGF as a possible therapeutic target in the clinical management of PDR.

Safety of Vitrectomy for Floaters

PURPOSE To assess the risks of vitrectomy for the removal of primary and secondary vitreous opacities. DESIGN Retrospective, nonrandomized, interventional case series. METHODS We reviewed the results of 116 consecutive cases of vitrectomy for vitreous floaters. Eighty-six cases were primary and 30 cases were secondary floaters. Main outcome measures were the incidence of iatrogenic retinal breaks and postoperative rhegmatogenous retinal detachments. RESULTS We found iatrogenic retinal breaks in 16.4% of operations. There was no statistically significant difference in risk between cases of primary and secondary floaters. Intraoperative posterior vitreous detachment induction was found to increase significantly the risk of breaks. Retinal detachment occurred in 3 cases (2.5%), all after operations for primary floaters. One case of complicated retinal detachment ended with a low visual acuity of hand movements. Cataract occurred in 50% of phakic cases. Transient postoperative hypotony was found after 5.2% of our operations, and transient postoperative high intraocular pressure was encountered in 7.8%. An intraoperative choroidal hemorrhage occurred in 1 case, which resolved spontaneously. The mean visual acuity improved from 0.20 to 0.13 logarithm of the minimal angle of resolution units. CONCLUSIONS The risk profile of vitrectomy for floaters is comparable with that of vitrectomy for other elective indications. Retinal breaks are a common finding during surgery and treatment of these breaks is crucial for the prevention of postoperative retinal detachment. Patients considering surgery for floaters should be informed specifically about the risks involved.

Hypotony after 25-gauge vitrectomy.

PURPOSE To describe the incidence of hypotony after 25-gauge vitrectomy and to identify preoperative and intraoperative factors that influence the occurrence of hypotony. DESIGN Retrospective, nonrandomized, interventional case series. METHODS We reviewed 122 consecutive cases of 25-gauge vitrectomy for all surgical indications. The primary outcome measure was intraocular pressure (IOP) at postoperative day 1, measured with Goldmann tonometry. Secondary outcome measures were clinical signs of hypotony and other complications. RESULTS Hypotony, defined as an IOP of 5 mm Hg or less, was found in 13.1% of cases on postoperative day 1. Clinical signs of hypotony were encountered in 7 eyes (5.7%). The risk of hypotony was significantly lower in cases with air or gas tamponade (3.3%) than in cases without tamponade (22.4%). Hypotony was encountered more often in reoperations (29.9%) than in primary operations (9.2%; statistically significant difference). In cases in which intravitreal triamcinolone was used, the risk of hypotony was significantly higher (35.3%) than in cases without triamcinolone (10.3%). Phakic eyes had significantly less chance of hypotony (6.7%) than pseudophakic eyes (15.6%) and eyes undergoing combined phacoemulsification and vitrectomy (25.0%). At postoperative day 7, all cases of hypotony recovered spontaneously. None of our cases developed endophthalmitis. CONCLUSION Our results show that a transient hypotony occurs commonly after 25-gauge vitrectomy. Hypotony was significantly influenced by tamponade, reoperation, intraoperative lens status, and use of intravitreal triamcinolone. Although all cases of hypotony recovered spontaneously without permanent damage, the high frequency of hypotony does impose potential risks. Increased vigilance with focus on perioperative antisepsis and low tolerance of sclerotomy leakage are important for the prevention of endophthalmitis. Strategies aimed at lowering the risk of hypotony are needed to improve the safety of this promising technique.

Primary Retinectomy in Proliferative Vitreoretinopathy

PURPOSE To describe the functional and anatomic results of retinectomy without scleral buckling for anterior proliferative vitreoretinopathy in eyes that did not undergo previous buckling surgery. DESIGN Retrospective, nonrandomized, interventional case series. METHODS We reviewed the results of 123 consecutive cases of retinectomy for rhegmatogenous retinal detachment complicated by anterior proliferative vitreoretinopathy. The primary outcome measure was anatomic success, defined as complete retinal reattachment. Secondary outcome measures were final anatomic success, final visual acuity outcome, number of operations required for retinal reattachment, baseline extent of proliferative vitreoretinopathy, ocular pressure at final follow-up, extent of retinectomy, and occurrence of complications. RESULTS The anatomic success rate was 77.2%. Final attachment rate was 95.9%, reached after 1 rhegmatogenous retinal detachment reoperation in 21 cases and after 2 rhegmatogenous retinal detachment reoperations in 4 cases. We had a low rate of postoperative hypotony (4.1%). Visual acuity was significantly improved from 2.10 to 1.44 logarithm of the minimal angle of resolution units (P < .001). Improvement was related significantly to retinectomy extent and primary anatomic success. CONCLUSIONS Our results show that primary retinectomy without scleral buckling has good anatomic and functional results.

Early simultaneous fundus autofluorescence and optical coherence tomography features after pars plana vitrectomy for primary rhegmatogenous retinal detachment

Purpose: To describe fundus autofluorescence and optical coherence tomography (OCT) features of the macula after pars plana vitrectomy for rhegmatogenous retinal detachment. Methods: Thirty-three eyes of 33 consecutive patients with repaired rhegmatogenous retinal detachment with or without the involvement of the macula were prospectively investigated with simultaneous fundus autofluorescence and OCT imaging using the Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany) within a few weeks after the operation. Results: Fundus autofluorescence imaging of the macula showed lines of increased and decreased autofluorescence in 19 cases (57.6%). On OCT, these lines corresponded to the following abnormalities: outer retinal folds, inner retinal folds, and skip reflectivity abnormalities of the photoreceptor inner segment/outer segment band. Other OCT findings, not related to abnormal lines on fundus autofluorescence, consisted of disruption of photoreceptor inner segment/outer segment band and collection of intraretinal or subretinal fluid. The presence of outer retinal folds significantly related to metamorphopsia but did not relate to poor postoperative visual acuity. Conclusion: Partial-thickness retinal folds occur commonly after vitrectomy for rhegmatogenous retinal detachment repair and may represent an important anatomical substrate for postoperative metamorphopsia. Fundus autofluorescence and OCT are both sensitive techniques for the detection of these abnormalities.

Enhanced internal search for iatrogenic retinal breaks in 20-gauge macular surgery

Purpose To evaluate the incidence and characteristics of iatrogenic retinal breaks in 20-gauge macular surgery with an intensified search strategy. Design Retrospective, non-comparative interventional case series. Participants 218 consecutive operations in 209 patients who underwent 20-gauge vitrectomy vitrectomy for idiopathic macular pucker or idiopathic macular hole. Methods Retrospective review of patient records undergoing 20-gauge vitrectomy with intensified peripheral search for retinal defects. Main outcome measures Incidence of breaks related to the sclerotomies, the incidence of breaks occurring elsewhere, the incidence of lesions suspicious for traction, the location of identified breaks and intraoperative induction of posterior vitreous detachment. Results Retinal breaks occurred in 24.3% of operations. In 17.4% breaks were related to the sclerotomies and in 9.6% of breaks were found elsewhere. In 6.4% of eyes, only lesions suspicious for traction were detected. Retinal detachment occurred in 1.8% of cases. The occurrence of breaks was significantly related to induction of PVD. Conclusions With intensified intraoperative search, a much higher incidence of retinal breaks was found than previously reported in the literature. Despite the high incidence of breaks, the incidence of postoperative rhegmatogenous retinal detachment was low. These findings support the rationale that intensive intraoperative search for iatrogenic breaks is crucial for the prevention of postoperative retinal detachments in macular surgery.

Evolution of outer retinal folds occurring after vitrectomy for retinal detachment repair.

PURPOSE To assess the evolution of outer retinal folds (ORFs) occurring after repair of rhegmatogenous retinal detachment (RRD) using spectral domain-optical coherence tomography (sd-OCT) and fundus autofluorescence (FAF), and to discuss their pathogenesis. METHODS Twenty patients were operated on with 25-gauge pars plana vitrectomy and 20% sulfur hexafluoride gas injection for primary macula-off RRD repair and were followed prospectively. Sd-OCT and FAF images were recorded at 1, 3 and 6 months postoperatively. RESULTS ORFs appeared on sd-OCT as hyperreflective lesions consisting of folded inner segment/outer segment of photoreceptors band and external limiting membrane band. Corresponding lines of increased or decreased autofluorescence were observed on FAF. Over the follow-up, the thick hypoautofluorescent lines progressively evolved to thick hyperautofluorescent lines and to thin hyperautofluorescent lines and eventually disappeared. Concomitantly, OCT scans revealed that the corresponding hyperreflective lesions decreased in number, height, and size. In six cases FAF assessment at month 6 was precluded by cataract development. CONCLUSIONS ORFS tend to resolve spontaneously within a few months from operation leaving no or subtle abnormalities at the level of the outer retinal layers. OCT is superior to FAF to follow the evolution of orfs in phakic eyes. The following factors might be involved in ORFS pathogenesis: structural changes occurring in the detached retina, residual pockets of subretinal fluid after retinal reattachment, intravitreal gas, unintentional retinal translocation, and intraoperative or perioperative hypotony.

Air versus gas tamponade in retinal detachment surgery

Objective To compare the outcome of air tamponade with gas tamponade in primary vitrectomy for the treatment of rhegmatogenous retinal detachment (RRD). Methods We examined the records of 524 cases of 523 patients that underwent primary vitrectomy for RRD with air or sulphur hexafluoride 20% gas tamponade and a follow-up of at least 3 months, excluding cases with inferior retinal breaks. Results 318 cases were treated with gas and 128 cases with air. Overall, vitrectomy led to an attached retina after a single operation in 85.1% of cases. Eyes treated with air had an 81.0% chance of primary success and those treated with gas had an 86.9% success rate (p=0.083, NS, χ2 test). Involvement of lower retinal quadrants in the retinal detachment was revealed as a significant confounding factor. After correction for this confounder using a multivariate logistic regression model, air versus gas tamponade became a statistically significant determinant for success rate (OR 1.97; p=0.012). In a sub-analysis, eyes with a retinal detachment that involved the inferior quadrants had significantly lower primary success rates when using air tamponade (69.6%), compared to gas tamponade (84.7%; p=0.009, χ2 test). Conclusions Gas tamponade is superior to air tamponade in retinal detachment cases with involvement of the lower quadrants. These results suggest that air tamponade should only be used in retinal detachments that are restricted to the superior quadrants. Further prospective study is needed to confirm these findings, and to address functional outcome.

Vitreous TIMP-1 levels associate with neovascularization and TGF-β2 levels but not with fibrosis in the clinical course of proliferative diabetic retinopathy

In proliferative diabetic retinopathy (PDR), vascular endothelial growth factor (VEGF) and CCN2 (connective tissue growth factor; CTGF) cause blindness by neovascularization and subsequent fibrosis. This angio-fibrotic switch is associated with a shift in the balance between vitreous levels of CCN2 and VEGF in the eye. Here, we investigated the possible involvement of other important mediators of fibrosis, tissue inhibitor of metalloproteinases (TIMP)-1 and transforming growth factor (TGF)-β2, and of the matrix metalloproteinases (MMP)-2 and MMP-9, in the natural course of PDR. TIMP-1, activated TGF-β2, CCN2 and VEGF levels were measured by ELISA in 78 vitreous samples of patients with PDR (n = 28), diabetic patients without PDR (n = 24), and patients with the diabetes-unrelated retinal conditions macular hole (n = 10) or macular pucker (n = 16), and were related to MMP-2 and MMP-9 activity on zymograms and to clinical data, including degree of intra-ocular neovascularization and fibrosis. TIMP-1, CCN2 and VEGF levels, but not activated TGF-β2 levels, were significantly increased in the vitreous of diabetic patients, with the highest levels in PDR patients. CCN2 and the CCN2/VEGF ratio were the strongest predictors of degree of fibrosis. In diabetic patients with or without PDR, activated TGF-β2 levels correlated with TIMP-1 levels, whereas in PDR patients, TIMP-1 levels, MMP-2 and proMMP-9 were associated with degree of neovascularization, like VEGF levels, but not with fibrosis. We confirm here our previous findings that retinal fibrosis in PDR patients is significantly correlated with vitreous CCN2 levels and the CCN2/VEGF ratio. In contrast, TIMP-1, MMP-2 and MMP-9 appear to have a role in the angiogenic phase rather than in the fibrotic phase of PDR.