Monitoring of Diabetic Retinopathy in relation to Bariatric Surgery: a Prospective Observational Study

Association of continuous subcutaneous insulin therapy and diabetic retinopathy in type 1 diabetes: A national cohort study

AIM

This study aimed to investigate the short-and long-term effect on diabetic retinopathy (DR) in individuals with type 1 diabetes treated with continuous subcutaneous insulin injections (CSII) compared to those using multiple daily injections (MDI).

METHODS

We conducted a register-based matched cohort study utilizing data from the Danish Registry of Diabetic Retinopathy as well as several other national Danish health registers. Our cohort consisted of all individuals with type 1 diabetes who attended the Danish screening program for DR from 2013 to 2022. We included individuals registered with CSII treatment, and compared them to individuals using MDI, matched by age, sex, and DR level. Cox regression analysis was performed to evaluate the outcomes.

RESULTS

The study included 674 individuals treated with CSII and 2006 matched MDI users. In our cohort 53.4 % were female and median age was 36 (IQR 27-47). Average follow-up risk-time was 4.8 years. There was no difference in the risk of DR worsening between the CSII group and MDI group (HR 1.05 [95%CI 0.91; 1.22], p = 0.49). However, an increased risk of focal photocoagulation was observed in the CSII group (HR 2.40 [95%CI 1.11; 5.19], p = 0.03).

CONCLUSIONS

Our findings indicate that CSII treatment does not confer a significant difference in the overall short- and long-term risk of DR worsening or ocular intervention compared to MDI treatment. These results provide insights into the DR outcomes of CSII treatment in individuals with type 1 diabetes.

Impact of Bariatric Surgery on Treatment Burden and Progression of Diabetic Retinopathy

Purpose: To assess the severity, progression, and treatment burden of diabetic retinopathy (DR) in patients after bariatric surgery compared with controls. Methods: A retrospective cohort study was performed of patients with type 2 diabetes and DR seen at the Duke Eye Center between 2014 and 2023. Clinical data included hemoglobin A1c (HbA1c), diagnostic stage of DR, diabetic macular edema (DME) or vitreous hemorrhage (VH), visual acuity (VA), and treatment burden at baseline and follow-up. Generalized estimating equation analysis was used to account for the correlation between 2 eyes of the same patient. Results: Sixteen patients who had bariatric surgery were matched by age, sex, and duration of diabetes with 60 control patients managed medically during the same time period. The HbA1c level, severity of DR, presence of DME or VH, VA, and treatment burden were not significantly different (all P > .05) at the baseline examination. On average, patients were followed for 6 years. The HbA1c level at the follow-up was significantly lower in the bariatric surgery group (6.4% vs 8.5%; P < .001). At the follow-up, the treatment burden was reduced in the bariatric surgery group compared with the control group (P = .04). There was a clear trend toward reduced progression of DR and treatment burden in the bariatric surgery group over the follow-up. Conclusions: Bariatric surgery may improve glycemic control, stabilize DR progression, and reduce the treatment burden, which may have a significant impact on quality of life for patients with DR.

Bariatric surgery in individuals with type 2 diabetes is not associated with short or long-term risk of diabetic retinopathy progression: results from a nationwide cohort study

AIMS

Bariatric surgery is used to induce weight loss and glycemic stability in type 2 diabetes (T2D). It has been a concern that this may lead to early worsening of diabetic retinopathy (DR) due to a rapid decline in HbA1c. In this study, we evaluated the risk of short and long-term DR development and need for ocular intervention in an entire nation of individuals with T2D undergoing bariatric surgery.

METHODS

The study comprised a national, register-based cohort of individuals with T2D screened for DR. Cases were matched by age, sex and DR level at the date of surgery (index date) with non-bariatric controls. We extracted information on DR levels, in- and outpatient treatments, pharmaceutical prescriptions and laboratory values. We evaluated worsening of DR (incident and progressive DR) at follow-up (6 and 36 months).

RESULTS

Amongst 238,967 individuals with T2D, who attended diabetic eye screening, we identified 553 that underwent bariatric surgery (0.2%) and 2677 non-bariatric controls. Median age was 49 years, and 63% were female. Cases had more comorbidities, lower HbA1c as well as more frequent use of glucose-lowering and antihypertensive medication than controls at index date. In a fully adjusted logistic regression model, the risk of DR worsening for cases was not significantly different compared to controls, neither short-term (OR 0.41 [CI 95% 0.13; 1.33], p = 0.14) nor long-term (OR 0.64 [CI 95% 0.33; 1.24], p = 0.18).

CONCLUSIONS

In this nationwide study, bariatric surgery did not associate with increased risk of short- or long-term DR worsening.

A comparative study of retinal layer changes among patients with schizophrenia and healthy controls

AIM

This study aimed to evaluate the retinal nerve fibre layer changes among different group of patients with schizophrenia and compare it with healthy controls by using swept-source optical coherence tomography.

METHODOLOGY

Patients with first-episode schizophrenia (n = 21) in remission (n = 35) or with treatment-resistant schizophrenia (TRS) (n = 35) and 36 healthy controls were evaluated for retinal thickness.

RESULTS

Patients with psychotic illnesses had significantly lower sub-foveal choroidal thickness (effect size 0.84-0.86), when compared to the healthy controls. When patients with first-episode schizophrenia were compared with patients with TRS, TRS patients had significant lower sub-foveal choroidal thickness (left eye) when the various confounders (such as age, gender, duration of treatment, smoking, current medications, body mass index, waist circumference, blood pressure, fasting glucose, HbA1c, presence or absence of metabolic syndrome) were taken into account. When the patients with TRS were compared with healthy controls, initially significant differences were observed for the macular volume (left and right) and the ganglion cell thickness (right eye) but these differences disappeared after controlling for the various covariates.

CONCLUSIONS

Compared to healthy controls, patients with schizophrenia, psychotic illnesses have thinning of the retina, especially in the sub-foveal choroidal thickness.

Diabetic macular edema treatment guidelines in India: All India Ophthalmological Society Diabetic Retinopathy Task Force and Vitreoretinal Society of India consensus statement

Diabetic macular edema (DME) is a common cause of moderate visual impairment among people with diabetes. Due to the rising number of people with diabetes in India, the absolute numbers of people with DME are significant. There are several treatment options for DME, and the choice of treatment is based on the availability of retinal specialists and infrastructure for the delivery of treatment. A major challenge is the out-of-pocket expenditure incurred by patients as most treatment options are costly. Treatment also varies based on the associated ocular and systemic conditions. The All India Ophthalmology Society (AIOS) and the Vitreo-Retinal Society of India (VRSI) have developed this consensus statement of the AIOS DR task force and VRSI on practice points of DME management in India. The objective is to describe the preferred practice patterns for the management of DME considering the different presentations of DME in different clinical scenarios.

Outcomes of Diabetic Retinopathy Post-Bariatric Surgery in Patients with Type 2 Diabetes Mellitus

Bariatric surgery is an emerging therapeutic approach for obese type 2 diabetes mellitus (T2DM) patients, with proven benefits for achieving target glucose control and even remission of diabetes. However, the effect of bariatric surgery upon diabetic retinopathy is still a subject of debate as some studies show a positive effect while others raise concerns about potential early worsening effects. We performed a systematic review, on PubMed, Science Direct, and Web of Science databases regarding the onset and progression of diabetic retinopathy in obese T2DM patients who underwent weight-loss surgical procedures. A total of 6375 T2DM patients were analyzed. Most cases remained stable after bariatric surgery (89.6%). New onset of diabetic retinopathy (DR) was documented in 290 out of 5972 patients (4.8%). In cases with DR at baseline, progression was documented in 50 out of 403 (12.4%) and regression in 90 (22.3%). Preoperative careful preparation of hemoglobin A1c (HbA1c), blood pressure, and lipidemia should be provided to minimize the expectation of DR worsening. Ophthalmologic follow-up should be continued regularly in the postoperative period even in the case of diabetic remission. Further randomized trials are needed to better understand the organ-specific risk factors for progression and provide personalized counseling for T2DM patients planned for bariatric surgery.

Association of Gastric Bypass Surgery With Risk of Developing Diabetic Retinopathy Among Patients With Obesity and Type 2 Diabetes in Sweden: An Observational Study

Importance

Knowledge of the incidence and progression of diabetic retinopathy (DR) after gastric bypass surgery (GBP) in patients with obesity and diabetes could guide the management of these patients.

Objective

To investigate the incidence of diabetic ocular complications in patients with type 2 diabetes after GBP compared with the incidence of diabetic ocular complications in a matched cohort of patients with obesity and diabetes who have not undergone GBP.

Design, Setting, and Participants

Data from 2 nationwide registers in Sweden, the Scandinavian Obesity Surgery Registry and the National Diabetes Register, were used for this cohort study. A total of 5321 patients with diabetes from the Scandinavian Obesity Surgery Registry who had undergone GBP from January 1, 2007, to December 31, 2013, were matched with 5321 patients with diabetes from the National Diabetes Register who had not undergone GBP, based on sex, age, body mass index (BMI), and calendar time (2007-2013). Follow-up data were obtained until December 31, 2015. Statistical analysis was performed from October 5, 2018, to September 30, 2019.

Exposure

Gastric bypass surgery.

Main Outcomes and Measures

Incidence of new DR and other diabetic ocular complications.

Results

The study population consisted of 5321 patients who had undergone GBP (3223 women [60.6%]; mean [SD] age, 49.0 [9.5] years) and 5321 matched controls (3395 women [63.8%]; mean [SD] age, 47.1 [11.5] years). Mean (SD) follow-up was 4.5 (1.6) years. The mean (SD) BMI and hemoglobin A1c concentration at baseline were 42.0 (5.7) and 7.6% (1.5%), respectively, in the GBP group and 40.9 (7.3) and 7.5% (1.5%), respectively, in the control group. The mean (SD) duration of diabetes was 6.8 (6.3) years in the GBP group and 6.4 (6.4) years in the control group. The risk for new DR was reduced in the patients who underwent GBP (hazard ratio, 0.62 [95% CI, 0.49-0.78]; P < .001). The dominant risk factors for development of DR at baseline were diabetes duration, hemoglobin A1c concentration, use of insulin, glomerular filtration rate, and BMI.

Conclusions and Relevance

This nationwide matched cohort study suggests that there is a reduced risk of developing new DR associated with GBP, and no evidence of an increased risk of developing DR that threatened sight or required treatment.

Early worsening of diabetic retinopathy after simultaneous pancreas and kidney transplantation-Myth or reality?

Early worsening of diabetic retinopathy due to sudden glucose normalization is a feared complication of pancreas transplantation; however, its rate or severity has not been studied prospectively. We followed up 43 pancreas and kidney recipients for a composite endpoint comprising new need for laser therapy, newly diagnosed proliferation, macular edema, visual acuity worsening, and blindness over 12 months. Although 37% of patients met this primary endpoint, its severity was rather low. Mean central retinal thickness and proportion of patients with subclinical macular edema increased significantly, with spontaneous resolution in half of them. Visual acuity did not change. There was no significant difference in the absolute glycated hemoglobin (HbA1c) drop, age, and diabetes duration between the patients who met and those who did not meet the primary endpoint, but a higher proportion of patients with worsening had a recent history of laser treatment. Retinopathy remained stable in 62.8% of patients. In 26%, the visual acuity significantly improved. Although retinopathy worsening was documented in more than one-third of patients, its evolution was not related to the magnitude of metabolic change; rather, it corresponded to the expected natural course of retinopathy. Nonetheless, comprehensive ophthalmologic care should be a substantial component of the recipient management.

Bariatric Surgery Induces Retinal Thickening Without Affecting the Retinal Nerve Fiber Layer Independent of Diabetic Status

PURPOSE

Obese patients have neurodegeneration of the optic nerve demonstrated by decreased peripapillary nerve fiber layer. Whether bariatric surgery reverses this neurodegenerative process has not been explored. We aimed to evaluate the impact of bariatric surgery in the structure of the retina and optic nerve.

METHODS

Multicentric observational study. Obese patients scheduled for bariatric surgery were consecutively recruited and included in the study and evaluated before and 6-12 months after the intervention. The retinal structure was evaluated as retinal thickness in the different retinal layers in the foveal, perifoveal, and parafoveal regions using optical coherence tomography. Choroidal thickness and optic nerve retinal nerve fiber layer thickness were also evaluated.

RESULTS

Eighty eyes from 40 participants were included. Globally, we found a significant thickening of the retina after bariatric surgery (foveal: 273.5 (21.5) μm vs 280.0 (28.8) μm, p < 0.001; parafoveal 332.4 ± 17.8 μm vs 336.6 ± 15.9 μm, p = 0.003; perifoveal: 293.4 ± 13.8 μm vs 295.7 ± 14.9 μm; p = 0.001), whereas no significant differences were found for the ganglion cell layer, choroid, or peripapillary nerve fiber layer thickness. The retinal thickening was confined to inner retinal layers and was independent of the diabetic status of the patients. After multivariate adjustment, HbA1c variation, preoperative C-peptide, preoperative hypertension, preoperative OSA, and preoperative LDL and TG levels seem to be clinical predictors of retinal thickening.

CONCLUSIONS

We found a significant thickening of the retina after bariatric surgery that was independent of the diabetic status. The thickening was confined to inner retinal layers and may represent and improve perfusion. The peripapillary nerve fiber layer remained unchanged after the surgery.

Metabolic and cardiovascular outcomes of bariatric surgery

PURPOSE OF REVIEW

Bariatric surgery is an effective therapy for morbid obesity that also improves weight-related metabolic parameters and reduces morbidity and mortality. The purpose of this review is to consolidate our current understanding of metabolic, macrovascular and microvascular benefits of bariatric surgery and to provide an update.

RECENT FINDINGS

Early resolution of insulin resistance and type 2 diabetes mellitus (T2DM) varies by type of bariatric surgery and appears to be mediated by changes in secretion of gut hormones, metabolism of bile acids, expression of glucose transporters and the gut microbiome. Dyslipidaemia, atherosclerosis, microvascular complications of obesity and diabetes, systemic and tissue-level inflammation show evidence of regression and hypertension improves significantly after bariatric surgery.

SUMMARY

Bariatric surgery leads to improvements in obesity-related metabolic comorbidities such as dyslipidaemia, HDL functionality, hypertension, T2DM, insulin resistance and inflammation. It slows the atherosclerotic process and reduces cardiovascular and all-cause mortality. Recent data have demonstrated regression of the microvascular complications of obesity and diabetes including the regeneration of small nerve fibres. The magnitude of change in short-term metabolic effects depends on the surgical procedure whilst longer term effects are related to the amount of sustained excess weight loss.

The Effect of Metabolic Surgery on the Complications of Diabetes: What Are the Unanswered Questions?

It is now established that metabolic surgery (also known as bariatric surgery or obesity surgery) is an effective treatment for type 2 diabetes. Data from several randomized controlled trials have shown that surgery, when used as an adjunct to best medical therapy, is superior to medical therapy alone in achieving glycaemic and metabolic treatment targets in diabetes care. This has resulting in metabolic surgery being recommended as a treatment option for obesity-associated type 2 diabetes in national and international diabetes care guidelines. While the superior glycaemic effect of surgery is clear, the effect of surgery on the complications of diabetes is not fully understood. There are observational and epidemiological data that indicate a preventative effect in cohorts who do not have complications at baseline, as well as a positive effect on those with established diabetic kidney disease. However, there is a dearth of randomized controlled studies that specifically examine the effect of surgery on the complications of diabetes. Therefore, we should remain cautious in some cases, especially in those with retinopathy or neuropathy, as there is potential for deterioration of disease post-operatively. Further study is needed on this important topic. A lot is known, but there remain several unanswered questions. This article summarizes what we know about the effect of metabolic surgery on the complications of diabetes, poses some unanswered questions, and suggests how we could answer them.

Evidence-based Danish guidelines for screening of diabetic retinopathy

PURPOSE

Diabetic retinopathy (DR) is among the leading causes of visual loss in the working-age population. It is generally accepted that screening of DR is cost-effective and can detect DR before it becomes sight-threatening to allow timely treatment.

METHODS

A group of retinal specialists was formed by the Danish Ophthalmological Society with the aim to formulate contemporary evidence-based guidelines for screening of DR in order to implement these in the Danish screening system.

RESULTS

We hereby present evidence for DR-screening regarding (1) classification of DR, (2) examination techniques, (3) screening intervals and (4) automated screening. It is our recommendation that the International Clinical Retinopathy Disease Severity Scale should be used to classify DR. As a minimum, mydriatic two-field disc- and macular-centred images are required. In the case of suspected clinically significant diabetic macular oedema, supplementary optical coherence tomography can increase the diagnostic accuracy. There is solid evidence to support a flexible, individualized screening regimen. In particular, it is possible to prolong screening intervals to 24-48 months for patients with no or mild nonproliferative diabetic retinopathy (NPDR), but it is also possible to use extended intervals of 12-24 months for patients with moderate NPDR given that these are well-regulated regarding glycaemic control (HbA1c ≤ 53 mmol/mol) and blood pressure (≤130/80 mmHg). Automated screening of DR is encouraging but is not ready for implementation at present.

CONCLUSION

Danish evidenced-based guidelines for screening of DR support high-quality imaging and allow flexible, individualized screening intervals with a potential for extension to patients with low risk of DR progression.

Gastric bypass surgery does not increase the risk for sight-threatening diabetic retinopathy

PURPOSE

To study the occurrence and level of diabetic retinopathy (DRP) before and after planned bariatric surgery and to investigate potential risk factors for deterioration of DRP.

METHODS

The Scandinavian Obesity Surgery Registry (SOReg) was used to identify diabetic patients who underwent gastric bypass (GBP) surgery at three centres in Sweden during 2008-2010. Information regarding DRP screening was obtained from ophthalmological patient charts. Patients who had DRP screening before and after GBP surgery were included in the study.

RESULTS

The survey included 117 patients. Mean age was 50 (SD 10) years, body mass index (BMI) 43 (SD 8) kg/m² and HbA1c 64 (SD 18) mmol/mol before surgery. One year post-GBP, BMI was reduced to 31 (SD 6) kg/m² . HbA1c was 43 (SD 10) mmol/mol, and in 66% (77/117) treatment for diabetes had been discontinued. Occurrence of DRP before GBP was as follows: no DRP 62%, mild 26%, moderate 10%, severe 0% and proliferative DRP 2%. No significant changes in occurrence of DRP after surgery were observed. Twelve patients (16%) developed mild DRP. In seven patients with pre-existing DRP, deterioration was observed and two of these patients required treatment for sight-threatening DRP. No association between preoperative BMI, HbA1c or reduction in HbA1c and worsening of DRP was found.

CONCLUSION

In a majority of patients, no deterioration of DRP following GBP was observed. Screening for DRP before planned surgery is recommended for all diabetic patients about to undergo bariatric surgery to identify any pre-existing DRP.

The IGF-Axis and Diabetic Retinopathy Before and After Gastric Bypass Surgery

BACKGROUND

Laparoscopic gastric bypass (LGB) abruptly causes remission of type 2 diabetes (T2D). Such dramatic metabolic changes have previously been found to cause worsening of diabetic retinopathy (DR) and circulating insulin-like growth factor I (IGF-I) has been suggested as a causal mediator. We aimed to evaluate baseline imbalances in the circulating IGF-system and changes after LGB in patients with T2D.

METHODS

Prospective ocular examinations and measurement of the IGF-axis before and 3 and 12 months after LGB. IGF-bioactivity was measured by cell-based IGF-I receptor (IGF-IR) kinase activation assay (bioactive IGF). Total IGF-I, IGF-II and IGF binding protein (IGFBP) 1 and 3 were determined by immunoassays.

RESULTS

At baseline, 18 of 36 patients presented with DR. These patients had higher levels of bioactive IGF (p = 0.03) than patients without DR and this association was strengthened in multivariate analysis (p = 0.006). Three patients had worsening of DR, unrelated to other markers. In univariate analysis, bioactive IGF increased at 3 months (p = 0.05) but this change became insignificant in multivariate analysis (p = 0.11). IGFBP-1 increased whereas IGFBP-3 and total IGF-II decreased at the two postoperative visits (p ≤ 0.001). Total IGF-I showed no significant changes. HbA1c, glucose, HOMA-IR and lipids improved after surgery. Two patients did not complete the 12-month visit.

CONCLUSIONS

In obese T2D patients, bioactive IGF is a potential biomarker for DR and levels tended to increase 3 months after bariatric surgery. IGFBP-1 increased while IGFBP-3 and total IGF-II decreased postoperatively, but these changes were unassociated with the development of DR. Markers of the metabolic syndrome improved.

Early worsening of diabetic retinopathy after rapid improvement of blood glucose control in patients with diabetes

AIM

To review the frequency, importance of and risk factors for "early worsening of diabetic retinopathy" (EWDR) after rapid improvement of blood glucose in patients with diabetes.

METHODS

This was a systematic review of key references (PubMed 1980-2016) and the current international recommendations for the above-mentioned topics.

RESULTS

EWDR has been described during intensive treatment (IT) in patients with uncontrolled type 1 or 2 diabetes, and after pancreas transplantation or bariatric surgery. EWDR arises in 10-20% of patients within 3-6 months after abrupt improvement of glucose control, and in nearly two times that proportion in patients with advanced baseline diabetic retinopathy (DR). While EWDR is often transient and predominantly driven by the development of cotton-wool spots and intraretinal microvascular abnormalities in patients with no or minimal DR, it can lead to irreversible retinal damage in patients with advanced DR before IT. Its identified risk factors include higher baseline levels and larger magnitudes of reduction of HbA_1c, longer diabetes durations and previous severity of DR.

CONCLUSION

Intensive diabetes treatment inducing a rapid fall in glucose should prompt vigilance and caution, particularly in patients with long-term and uncontrolled diabetes and DR prior to IT. Careful retinal examination should be performed in all patients before initiating IT; however, in patients with severe non-proliferative or proliferative DR, panretinal photocoagulation therapy should be performed promptly. During the year following IT, quarterly eye monitoring is required in patients at high risk of EWDR (long-term uncontrolled diabetes, previous advanced DR), whereas follow-up every 6 months can be applied in patients with short-term diabetes and no/minimal DR before IT. To date, there is no evidence that controlling the speed or magnitude of HbA_1c decreases will reduce the risk of EWDR in patients with diabetes.

Does bariatric surgery prevent progression of diabetic retinopathy?

PurposeTo assess the changes in diabetic retinopathy (DR) in type 2 diabetes (T2DM) patients post bariatric surgery and report on the risk factors that may be associated with it.Patients and methodsRetrospective observational study of T2DM patients who underwent bariatric surgery in a UK specialist bariatric unit between 2009 and 2015. Preoperative and postoperative weight, HbA1c, and annual DR screening results were collected from medical records. Patients with preoperative retinal screening and at least one postoperative retinal screening were eligible for analysis. Multivariate analysis was used to explore significant clinical predictors on postoperative worsening in DR.ResultsA total of 102 patients were eligible for analysis and were followed up for 4 years. Preoperatively, 68% of patients had no DR compared to 30% with background retinopathy, 1% pre-proliferative retinopathy, and 1% proliferative retinopathy. In the first postoperative visit, 19% of patients developed new DR compared to 70% stable and 11% improved. These proportions remained similar for each postoperative visit over time. Young age, male gender, high preoperative HbA1c, and presence of preoperative retinopathy were the significant predictors of worsening postoperatively.ConclusionBariatric surgery does not prevent progression of DR. Young male patients with pre-existing DR and poor preoperative glycaemic control are most at risk of progression. All diabetic patients should attend regular DR screening post bariatric surgery to allow early detection of potentially sight-threatening changes, particularly among those with identifiable risk factors. Future prospective studies with prolonged follow-up are required to clarify the duration of risk.

Bariatric surgery and diabetic retinopathy: a systematic review and meta-analysis of controlled clinical studies

BACKGROUND

Uncontrolled studies have indicated appearance or progression of diabetic retinopathy in obese diabetic patients after bariatric surgery. The aim of this systematic review and meta-analysis was to compare the rate of appearance, as well as progression or regression of diabetic retinopathy in studies comparing medical and surgical treatment of obese type 2 diabetes.

METHODS AND FINDINGS

Intervention effect (new cases of retinopathy, and cases with any change of diabetic retinopathy score) was expressed as odds ratio (OR), with 95% confidence intervals (CIs); change of diabetic retinopathy score was expressed as standardized mean difference (SMD), with 95% CIs. Meta-analyses were performed by a random-effects model according to DerSimonian and Laird. Heterogeneity was assessed through Q and I2 statistics for each comparison, and potential sources of heterogeneity were discussed where appropriate. Appropriate methodology [preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement] was used. Seven studies were analyzed, and incident cases of retinopathy were fewer with bariatric surgery than with medical treatment; change of retinopathy score (three studies) was not different, while only two studies were available on numbers of patients showing progression or regression of retinopathy. Heterogeneity was not significant, and publication bias was not present.

CONCLUSIONS

Bariatric surgery seems to prevent new cases of diabetic retinopathy, but available studies are not sufficient to support progression or regression of retinopathy. Further studies are needed to draw firm conclusions on the effect of bariatric surgery on diabetic retinopathy.

The Effect of Bariatric Surgery on Diabetic Retinopathy: Good, Bad, or Both?

Bariatric surgery, initially intended as a weight-loss procedure, is superior to standard lifestyle intervention and pharmacological therapy for type 2 diabetes in obese individuals. Intensive medical management of hyperglycemia is associated with improved microvascular outcomes. Whether or not the reduction in hyperglycemia observed after bariatric surgery translates to improved microvascular outcomes is yet to be determined. There is substantial heterogeneity in the data relating to the impact of bariatric surgery on diabetic retinopathy (DR), the most common microvascular complication of diabetes. This review aims to collate the recent data on retinal outcomes after bariatric surgery. This comprehensive evaluation revealed that the majority of DR cases remain stable after surgery. However, risk of progression of pre-existing DR and the development of new DR is not eliminated by surgery. Instances of regression of DR are also noted. Potential risk factors for deterioration include severity of DR at the time of surgery and the magnitude of glycated hemoglobin reduction. Concerns also exist over the detrimental effects of postprandial hypoglycemia after surgery. In vivo studies evaluating the chronology of DR development and the impact of bariatric surgery could provide clarity on the situation. For now, however, the effect of bariatric surgery on DR remains inconclusive.

Retinal characteristics during 1 year of insulin pump therapy in type 1 diabetes: a prospective, controlled, observational study

PURPOSE

To investigate changes in retinal metabolism, function, structure and morphology in relation to initiation of insulin pump therapy (continuous subcutaneous insulin infusion, CSII).

METHODS

Visual acuity, retinopathy level, dark adaptation kinetics, retinal and subfoveal choroidal thickness, macular perfusion velocities, retinal vessel diameters and blood oxygen saturations were measured at baseline and after 1, 4, 16, 32 and 52 weeks in 31 patients with type 1 diabetes who started CSII and 20 patients who continued multiple daily insulin injections (MDI).

RESULTS

One year of CSII reduced haemoglobin A1c (HbA1c ) by 1.6% (17.8 mmol/mol) compared with 0.3% (3.1 mmol/mol) in the MDI group (p < 0.0001). Central retinal thickness increased by 1.5% in the CSII group (within-group p = 0.0098; between-group p = 0.063) without producing macular oedema. No detectable change was found in any other primary outcome measure. The proportion of patients with retinopathy worsening did not differ between groups. At baseline, longer disease duration was associated with higher retinal artery oxygen saturation (p = 0.014) and lower macular venous perfusion velocity (p = 0.045).

CONCLUSION

One year of CSII led to an HbA1c reduction relative to continued MDI and a small increase in retinal thickness but not to early retinopathy worsening or to changes in retinal vascular, structural or functional characteristics. Longer duration of type 1 diabetes appears to be associated with lower macular venous perfusion velocity and higher retinal artery oxygen saturation. The latter could potentially reflect cumulative glycaemia.

Long-term Microvascular Disease Outcomes in Patients With Type 2 Diabetes After Bariatric Surgery: Evidence for the Legacy Effect of Surgery

OBJECTIVE

To identify and quantify any legacy effect of bariatric surgery on risk of incident microvascular disease in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted a retrospective observational cohort study (n = 4,683; 40% racial/ethnic minority) of patients with type 2 diabetes who underwent bariatric surgery from 2001 through 2011. The primary outcome measure was incident microvascular disease defined as a composite indicator of the first occurrence of retinopathy, neuropathy, and/or nephropathy. The Cox proportional hazards framework was used to investigate the associations between type 2 diabetes remission/relapse status and time to microvascular disease.

RESULTS

Covariate-adjusted analyses showed that patients who experienced type 2 diabetes remission had 29% lower risk of incident microvascular disease compared with patients who never remitted (hazard ratio [HR] 0.71 [95% CI 0.60, 0.85]). Among patients who experienced a relapse after remission, the length of time spent in remission was inversely related to the risk of incident microvascular disease; for every additional year of time spent in remission prior to relapse, the risk of microvascular disease was reduced by 19% (HR 0.81 [95% CI 0.67, 0.99]) compared with patients who never remitted.

CONCLUSIONS

Our results indicate that remission of type 2 diabetes after bariatric surgery confers benefits for risk of incident microvascular disease even if patients eventually experience a relapse of their type 2 diabetes. This provides support for a legacy effect of bariatric surgery, where even a transient period of surgically induced type 2 diabetes remission is associated with lower long-term microvascular disease risk.

Optical Coherence Tomography Parameters in Morbidly Obese Patients Who Underwent Laparoscopic Sleeve Gastrectomy

Purpose. To investigate changes in optical coherence tomography parameters in morbidly obese patients who had undergone laparoscopic sleeve gastrectomy (LSG). Methods. A total of 41 eyes of 41 morbidly obese patients (BMI ≥ 40) who had undergone LSG were included in study. The topographic optic disc parameters, central macular thickness (CMT), total macular volume (TMV), and retinal ganglion cell layer (RGCL) were measured by spectral-domain optical coherence tomography (SD-OCT). Subfoveal choroidal thickness (SFCT) was measured by enhanced deep imaging-optical coherence tomography (EDI-OCT). Results. The mean CMT was 237.4 ± 24.5 μm, 239.3 ± 24.1 μm, and 240.4 ± 24.5 μm preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). The mean TMV was 9.88 ± 0.52 mm³, 9.96 ± 0.56 mm³, and 9.99 ± 0.56 mm³ preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). The mean RGCL was 81.2 ± 6.5 μm, 82.7 ± 6.6 μm, and 82.9 ± 6.5 μm preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). The mean SFCT was 309.8 ± 71.8 μm, 331.0 ± 81.4 μm, and 352.7 ± 81.4 μm preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). No statistically significant differences were found between the preoperative values and 3- and 6-month postoperative values in rim area (p = 0.34), disc area (p = 0.64), vertical cup/disc ratio (p = 0.39), cup volume (p = 0.08), or retinal nerve fiber layer (p = 0.90). Conclusions. Morbidly obese patients who undergo LSG experience a statistically significant increase in CMT, TMV, SFCT, and RGCL at 3 months and 6 months after surgery.