Pars Plana Vitrectomy and Removal of the Internal Limiting Membrane in Diabetic Macular Edema Unresponsive to Grid Laser Photocoagulation

The association between different hypoglycemic regimens and postoperative diabetic macular edema after vitrectomy in the Japanese patients with proliferative diabetic retinopathy

PURPOSE

To study the association between different hypoglycemic regimens and postoperative diabetic macular edema (DME).

METHODS

A secondary analysis based on a retrospective cohort study.

RESULTS

In this secondary analysis, 124 eyes from patients with proliferative diabetic retinopathy (PDR) who underwent pars plana vitrectomy (PPV) between January 2008 and September 2012 were included. We found that compared with oral hypoglycemic medication, oral hypoglycemic medication plus insulin treatment revealed an insignificant relationship with postoperative DME (odds ratio [OR]=0.8, 95% confidence interval [CI]: 0.12-5.21, P=0.8167), only insulin treatment revealed a significant association with postoperative DME (OR=0.10, 95% CI: 0.01-0.84, P=0.0337) after adjusted age, sex. After adjusted age, sex, diabetes mellitus (DM) duration, glycosylated hemoglobin (HbA1c), the results did not have obvious changes (OR=0.61, 95% CI: 0.09-4.26, P=0.6187; OR=0.07, 95% CI: 0.01-0.65, P=0.0197). Furthermore, after adjusted age, sex, DM duration, HbA1c, hypertension, intraoperative retinal photocoagulation, vitreous hemorrhage, macular detachment, fibrovascular membrane, intraocular lens implantation and microincision vitrectomy surgery, the results were consistent (OR=0.66, 95% CI: 0.05-9.49, P=0.7621; OR=0.06, 95% CI: 0.00-0.81, P=0.0342). The same trend was observed in these adjusted models as well (p for trend was 0.0254, 0.0141, and 0.0311, respectively).

CONCLUSION

In conclusion, our results of the secondary analysis should be interpreted as a significant association between insulin treatment and reduced risks of postoperative DME in Japanese PDR patients with PPV surgery, compared with oral medications. Well glycemic control with longstanding insulin therapy may be beneficial to reduce the risks of postoperative DME in PDR patients. Our investigation calls for large-scale and long-term prospective clinical studies for a full evaluation of the exact role of insulin in the progression of postoperative DME.

Revisiting pars plana vitrectomy in the primary treatment of diabetic macular edema in the era of pharmacological treatment

Diabetic macular edema (DME) is the most common cause of moderate visual loss in diabetic patients. The current treatment of choice for center-involved DME is anti-vascular endothelial growth factor (VEGF) treatment. Most patients that undergo pharmacological inhibition with anti-VEGF agents need multiple monitoring visits that include optical coherence tomography imaging and multiple injections. Despite this intensive treatment, up to 60% of eyes will have persistent DME after six consecutive monthly injections of an anti-VEGF. Its sustainability over the long term has been questioned. Pars plana vitrectomy (PPV) by increasing the vitreous cavity oxygenation, relieving vitreomacular traction, and removing cytokines from the vitreous cavity may cause long-term resolution of DME without the aforementioned concerns in selected cases. Eyes with vitreomacular traction clearly benefit from PPV as the primary treatment. The role of PPV for eyes with DME without tractional elements is less clear and needs to be explored further.

PARS PLANA VITRECTOMY FOR DIABETIC MACULAR EDEMA: A Systematic Review, Meta-Analysis, and Synthesis of Safety Literature

PURPOSE

To assess the risk and benefit of pars plana vitrectomy for diabetic macular edema.

METHODS

The authors conducted a systematic literature review using PubMed, EMBASE, Web of Science, and Cochrane Central Database of Controlled Trials until September 2014. The population was patients with diabetic macular edema, intervention vitrectomy, comparator macular laser or observation, and efficacy outcome visual acuity and central retinal thickness. Safety outcomes were intraoperative and postoperative surgical complications. The efficacy meta-analysis included only randomized controlled trials. The safety analysis included prospective, retrospective, controlled, and uncontrolled studies.

RESULTS

Five studies were eligible for the efficacy meta-analysis (n = 127 eyes) and 40 for the safety analysis (n = 1,562 eyes). Combining follow-up intervals from 6 to 12 months, the meta-analysis found a nonsignificant 2 letter visual acuity difference favoring vitrectomy, and a significant 102 μm greater reduction in central retinal thickness favoring vitrectomy, but a post hoc subgroup analysis found that a 6-month central retinal thickness benefit reversed by 12 months. The most frequent complications were retinal break (7.1%), elevated intraocular pressure (5.2%), epiretinal membrane (3.3%), and vitreous hemorrhage (2.4%). Cataract developed in 68.6% of 121 phakic eyes.

CONCLUSION

Vitrectomy produces structural and functional improvements in select eyes with diabetic macular edema, but the visual gains are not significantly better than with laser or observation. No major safety concerns were identified.

EFFECT OF INTERNAL LIMITING MEMBRANE PEELING ON LONG-TERM VISUAL OUTCOMES FOR DIABETIC MACULAR EDEMA

PURPOSE

To evaluate the effect of internal limiting membrane (ILM) peeling on the long-term visual outcomes in eyes with diffuse, nontractional diabetic macular edema.

METHODS

One hundred and sixteen eyes of 58 patients with the same degree of diabetic macular edema in both eyes underwent pars plana vitrectomy with the creation of a posterior vitreous detachment in both eyes. Internal limiting membrane peeling was performed in one randomly selected eye (ILM-off group), and ILM peeling was not performed (ILM-on group) in the fellow eye. The postoperative follow-up period ranged from 12 months to 161 months (average, 80.4 months).

RESULTS

In the ILM-off group, the mean best-corrected visual acuity in logMAR units (Snellen equivalent) increased from 0.55 ± 0.31 (20/71) before surgery to 0.35 ± 0.35 (20/45) at 1 year (P < 0.0001) and 0.46 ± 0.43 (20/59) at the final visit (P = 0.058). In the ILM-on group, the mean best-corrected visual acuity increased from 0.55 ± 0.41 (20/71) before surgery to 0.43 ± 0.38 (20/54) at 1 year (P = 0.010) and 0.44 ± 0.45 (20/56) at the final visit (P = 0.043). The differences in the best-corrected visual acuity between the two groups were not significant at any time point.

CONCLUSION

Pars plana vitrectomy with or without ILM peeling improves the long-term visual acuity of nontractional diabetic macular edema. Internal limiting membrane peeling does not affect the postoperative best-corrected visual acuity significantly.

The correlation between visual acuity outcomes and optical coherence tomography parameters following surgery for diabetic epiretinal membrane and taut posterior hyaloid

Purpose

To evaluate the relationship between visual outcomes and the determinants detected by spectral domain optical coherence tomography (OCT) in eyes with epiretinal membrane (ERM) and/or taut posterior hyaloid (TPH) that underwent pars plana vitrectomy (PPV).

Materials and methods

A total of 30 participants with diabetic ERM and TPH were included in the study. All study participants underwent PPV. Preoperative and postoperative best corrected visual acuity (BCVA), peripapillary retinal nerve fiber layer (RNFL), macular RNFL, ganglion cell layer, inner plexiform layer, and ganglion cell complex thicknesses were measured in each participant. Linear regression analyses were performed to determine the association between the OCT parameters and the visual acuity measured at the time of the OCT measurement.

Results

The postoperative BCVA logarithm of the minimum angle of resolution (logMAR) values were statistically higher than the preoperative values in the ERM group and TPH group (P=0.001 and P<0.001, respectively). The postoperative BCVA logMAR value was negatively correlated with average RNFL, inferior RNFL thicknesses, and image quality (P=0.002, P=0.004, and P=0.006, respectively). The preoperative and postoperative BCVA logMAR value difference was not correlated with age and all of the OCT parameters measured (P>0.05).

Conclusion

This study shows that achievement of better peripapillary RNFL thickness results in better visual outcome after PPV and ERM/TPH removal.

Pars plana vitrectomy versus three intravitreal injections of bevacizumab for nontractional diabetic macular edema. A prospective, randomized comparative study

BACKGROUND

The aim of this study was to compare the effectiveness of pars plana vitrectomy (PPV) and removal of the internal limiting membrane (ILM) with three, monthly, intravitreal bevacizumab (IVB) injections for refractory diabetic macular edema.

MATERIALS AND METHODS

This was a prospective, randomized, comparative, interventional study. Forty-four patients were enrolled and randomized in two groups. Twenty-two eyes enrolled in Group I received three IVB injections at monthly interval. Twenty-two eyes were enrolled in Group II which underwent PPV with ILM removal. The primary outcomes measured were: (1) Best corrected logMAR visual acuity (BCVA) using Snellen's visual acuity chart. (2) Central macular thickness (CMT) on optical coherence tomography. The secondary outcome measures were: Complication rates like (1) progression of lens opacities, (2) high intraocular pressure needing further treatment/procedure, (3) development of vitreous hemorrhage related to the procedure employed, (4) retinal detachment and (5) severe inflammation/endophthalmitis.

RESULTS

In Group I (IVB): 3 (13.6%) eyes showed no change in BCVA; 3 (13.6%) eyes reported decrease in BCVA and 16 (72.8%) eyes showed improvement in BCVA; (P = 0.0181). In Group II (PPV): 4 (18.2%) eyes showed no change in BCVA; 5 (22.7%) eyes showed decrease and 13 (59.1%) eyes showed improvement in BCVA (P = 0.0281). Mean decrease in CMT in IVB group was 108.45 μ, whereas mean decrease in CMT in PPV group was 161.36 μ. No major complications were seen in either group.

CONCLUSION

Posttreatment decrease in CMT was more in PPV group and vision improvement more in IVB group. However, no statistically significant difference between the two methods was found.

Management paradigms for diabetic macular edema

PURPOSE

To provide evidence-based recommendations for diabetic macular edema (DME) management based on updated information from publications on DME treatment modalities.

DESIGN

Perspective.

METHODS

A literature search for "diabetic macular edema" or "diabetic maculopathy" was performed using the PubMed, Cochrane Library, and ClinicalTrials.gov databases to identify studies from January 1, 1985 to July 31, 2013. Meta-analyses, systematic reviews, and randomized controlled trials with at least 1 year of follow-up published in the past 5 years were preferred sources.

RESULTS

Although laser photocoagulation has been the standard treatment for DME for nearly 3 decades, there is increasing evidence that superior outcomes can be achieved with anti-vascular endothelial growth factor (anti-VEGF) therapy. Data providing the most robust evidence from large phase II and phase III clinical trials for ranibizumab demonstrated visual improvement and favorable safety profile for up to 3 years. Average best-corrected visual acuity change from baseline ranged from 6.1-10.6 Early Treatment Diabetic Retinopathy Study (ETDRS) letters for ranibizumab, compared to 1.4-5.9 ETDRS letters with laser. The proportion of patients gaining ≥ 10 or ≥ 15 letters with ranibizumab was at least 2 times higher than that of patients treated with laser. Patients were also more likely to experience visual loss with laser than with ranibizumab treatment. Ranibizumab was generally well tolerated in all studies. Studies for bevacizumab, aflibercept, and pegaptanib in DME were limited but also in favor of anti-VEGF therapy over laser.

CONCLUSIONS

Anti-VEGF therapy is superior to laser photocoagulation for treatment of moderate to severe visual impairment caused by DME.

Surgical management of diabetic retinopathy

Surgery for late complications of proliferative diabetic retinopathy remains the cornerstone of management even in patients who have received optimal laser photocoagulation and medical therapy. With improvisation in the surgical techniques and development of micro-incision surgical techniques for vitrectomy, the indications for surgical intervention are expanding to include diabetic macular edema with a greater number of patients undergoing early intervention. This review describes the current indications, surgical techniques, adjunctive anti-vascular endothelial growth factor therapy, surgical outcomes, and postoperative complications of pars plana vitrectomy for proliferative diabetic retinopathy and macular edema.

Techniques, rationale, and outcomes of internal limiting membrane peeling

BACKGROUND

The internal limiting membrane represents the structural interface between the retina and the vitreous and has been postulated to serve several essential functions. Recently, internal limiting membrane peeling has been used in the treatment of a variety of retinal disorders. We review the history, techniques, rationale, and outcomes of internal limiting membrane peeling.

METHODS

A review of the literature.

RESULTS

Internal limiting membrane peeling has been used to successfully treat a variety of retinal disorders including macular hole, epiretinal membrane, diabetic macular edema, retinal vein occlusion, and others.

CONCLUSION

Internal limiting membrane peeling may serve as an important component in the armamentarium of retinal surgery.

Taut internal limiting membrane causing diffuse diabetic macular edema after vitrectomy: clinicopathological correlation

AIMS

To describe 2 cases of diffuse diabetic macular edema (DME) after diabetic vitrectomy caused by a taut internal limiting membrane (ILM), with clinicopathological correlation.

METHODS

Interventional case series with immunohistochemical analysis.

RESULTS

Two patients were referred for unresponsive diffuse DME after pars plana vitrectomy with removal of the posterior hyaloid. Clinically, a taut ILM was noted over the fovea, and its removal resulted in rapid and long-term resolution of the edema, confirmed by optical coherence tomography with visual acuity improvement. Histopathology with immunostaining revealed a segment of ILM with an inner monolayer of cytokeratin-positive (retinal pigment epithelial cells) and/or glial fibrillary acidic protein-positive cells with smooth muscle actin immunoreactivity.

CONCLUSIONS

A taut ILM can cause diffuse DME after vitrectomy, and its removal can restore the normal foveal contour and improve visual acuity. Tangential tractional forces from contractile cells propagated across the fovea via the ILM appear to be the etiology.

Quantitative assessment of photoreceptor layer in eyes with resolved edema after pars plana vitrectomy with internal limiting membrane removal for diabetic macular edema

BACKGROUND/AIMS

To evaluate the correlation between visual acuity (VA) and photoreceptor integrity in eyes with resolved diabetic macular edema (DME) after pars plana vitrectomy (PPV).

METHODS

Eleven eyes with resolved macular edema following PPV with internal limiting membrane removal for DME were included in this retrospective study. The integrity of the external limiting membrane (ELM) and inner and outer segments (IS/OS) of the photoreceptor junction was evaluated by spectral domain optical coherence tomography. The main outcome measures were percentage of disrupted ELM and IS/OS lines, and correlation between VA and photoreceptor integrity.

RESULTS

The mean time after PPV was 78 ± 17 months. The mean lengths of the disrupted ELM and IS/OS lines were 223 ± 167 μm (63%) and 189 ± 175 μm (54%) in the foveola, and 900 ± 522 μm (60%) and 835 ± 582 μm (55%) in the fovea, respectively. Intact ELM and IS/OS lines were positively correlated with VA in both the fovea (p = 0.09 and p = 0.02, respectively) and foveola (p = 0.004 and p = 0.03, respectively). Linear regression analysis showed a statistically significant association of intact ELM and IS/OS lines with VA in the fovea. Disrupted ELM and IS/OS lines had a strong correlation with each other in both the fovea (r = -0.71, p = 0.013) and foveola (r = 0.81, p = 0.02).

CONCLUSIONS

The integrity of the ELM and IS/OS lines was positively correlated with VA in eyes with resolved DME after PPV.

Prediction of postoperative visual outcome after pars plana vitrectomy based on preoperative multifocal electroretinography in eyes with diabetic macular edema

BACKGROUND

To evaluate the role of preoperative optical coherence tomography (OCT), multifocal electroretinography (mfERG), and fluorescein angiography (FA) as prognostic factors for vision after pars plana vitrectomy (PPV) in diabetic macular edema (DME).

METHODS

Thirty-five eyes of 34 patients who underwent PPV were retrospectively reviewed. Best-corrected visual acuity (VA) was measured at baseline, and at 3, 6, and 9 months after surgery. Patients were categorized into two groups according to the final VA. Group 1 consisted of eyes with 0.2 or more logMAR lines of visual recovery, the rest of the eyes being placed in group 2. Preoperative FA findings, central macular thickness and mfERG responses at the central macula were evaluated to determine their effect on visual outcome.

RESULTS

Eighteen eyes showed improved VA after PPV, and were classified into group 1. Seventeen eyes were placed in group 2. The presence of macular ischemia did not affect the postoperative visual outcome between the groups, although a trend was noted toward macular ischemia with delayed implicit time. P1 implicit time at the central seven hexagons (eccentricity of 0-5 degrees ) was the only statistically significant factor predicting unfavorable visual outcome. There was significantly delayed implicit time in group 2 patients compared with those of group 1. MfERG responses at other retinal eccentricities and central macular thickness did not show significant association with visual prognosis.

CONCLUSIONS

Preoperative mfERG parameters, especially the implicit time, can be useful indicators for predicting functional visual prognosis after PPV in DME.

Pars plana vitrectomy with internal limiting membrane peeling for diabetic macular edema

PURPOSE

To evaluate anatomic and visual acuity (VA) results of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling for diffuse diabetic macular edema (DME), and to review the literature on the topic.

METHODS

Retrospective noncomparative case series of patients who underwent PPV with ILM peeling for diffuse DME between January 1, 2000, and December 1, 2005, performed by three surgeons at Bascom Palmer Eye Institute. Main outcome measures included pre- and postoperative optical coherence tomography (OCT) and visual acuity. Mean follow-up period was 8 months (range, 43 days-2 years).

RESULTS

Twenty-four eyes of 23 patients meeting the criteria were evaluated. Duration of DME ranged from 1 to 93 months. Mean preoperative logMAR vision was 0.782 (range, 0.30-1.82). Mean logMAR visual acuity at final follow-up was 0.771 (range, 0.10-2.00). At last follow-up, 25% of eyes had > or =2 line increase in VA from baseline, 54% of eyes had no improvement in VA, and 21% of eyes had > or =2 line decrease in VA. Of 9 eyes with pre- and postoperative OCT, there was an overall reduction in central macular thickness of 141 microm at postoperative month 3 and 120 microm at last follow-up. Postoperative complications included progression of cataract in 6 (60%) of 10 phakic eyes, postoperative intraocular pressure > or =30 mmHg in 6 (24%) eyes, and postoperative vitreous hemorrhage in 2 (8%) eyes.

CONCLUSIONS

Pars plana vitrectomy with ILM peeling was associated with a reduction in DME when measured by OCT in the majority of eyes, but visual acuity outcomes showed minimal improvement compared to baseline. These results suggest the efficacy of PPV with ILM peeling for eyes with DME has not been well established and should be reserved for therapy with selected cases.

Overview of epidemiologic studies of diabetic retinopathy

Diabetic retinopathy has been an important cause of blindness in young and middle age adults in the United States. Epidemiologic studies have quantitated the risk and have described potentially causal factors associated with many ocular complications of diabetes and other facets of this disease. A review of recent advances in diagnosis, treatment, temporal trends, and health care for diabetic retinopathy was conducted. Since the early 1980's, there have been studies of the variability of diabetic retinopathy in populations around the world and subpopulations in the United States which have demonstrated the high prevalences and incidences of this condition. Observational studies and clinical trials have documented the importance of glycemic and blood pressure control in the development and progression of this disease. There are some differences in the importance of confounders in different populations. Epidemiologic data have helped understand the importance of health care and health education in prevention and treatment of this condition. Observational studies have documented the importance of this disease on quality of life. Although there have been advances in understanding the distribution, causes, and severity of diabetic retinopathy, this is ever changing and requires continued monitoring. This is important because the increasing burden of diabetes will place a greater burden on the population and the medical care systems that will be caring for them.