Factors influencing the natural history of diabetic retinopathy

Incidence and Progression of Diabetic Retinopathy After Cataract Surgery: A Systematic Review and Meta-Analysis

PURPOSE

The impact of cataract surgery on diabetic retinopathy (DR) in patients with diabetes mellitus (DM) remains uncertain. This study aimed to investigate the incidence and progression of DR in patients with DM who underwent cataract surgery.

DESIGN

Meta-analysis.

METHODS

A systematic search of PubMed, Cochrane CENTRAL, and Embase databases was conducted from inception to April 2024. Randomized controlled trials or observational cohort studies involving adult patients with DM who underwent cataract surgery were included. Studies reporting data on the incidence or progression of postoperative DR were considered. Effect sizes were determined using risk ratios (RRs) with 95% confidence intervals (CIs), and meta-analysis was performed using a random-effects model. Subgroup analysis and meta-regression were conducted on perioperative demographic factors such as types of cataract surgery, DM durations, preoperative glycated hemoglobin A1c levels, and postoperative follow-up durations.

RESULTS

Data from 15 studies, involving 7,287 patients were analyzed. Postoperative DR incidence was elevated compared to the control group (RR, 1.38; 95% CI: 1.16-1.63; P < .001), although not significantly different in paired studies (RR, 0.85; 95% CI: 0.39-1.83; P = .671). DR progression was significantly higher after cataract surgery (RR, 1.46; 95% CI: 1.28-1.66; P < .001), irrespective of cataract surgery type and study design. Our analysis also revealed a significant increase in DR progression to sight-threatening DR, which includes clinically significant macular edema and proliferative diabetic retinopathy, following cataract surgery (RR, 1.84; 95% CI: 1.21-2.81; P = .005). Additionally, various risk factors such as preoperative HbA1c level, duration of postoperative follow-up, duration of diabetic diagnosis, age, and use of insulin therapy were investigated, However, none of these parameters significantly influenced the incidence or progression of postoperative DR.

CONCLUSIONS

Further research is needed to fully understand the incidence of DR after cataract surgery. However, our study provides moderate evidence supporting the progression of DR following such surgical interventions. Therefore, it is imperative to closely monitor DR progression within one year following cataract surgery in patients with DM.

Associations between lipid abnormalities and diabetic retinopathy across a large United States national database

BACKGROUND/OBJECTIVES

While dyslipidaemia has been suggested as a potential risk factor for diabetic retinopathy (DR), previous studies have reported conflicting findings. This study aimed to better characterize the relationship between abnormal serum levels of various lipid markers and the risk of the development and progression of DR.

SUBJECTS/METHODS

This retrospective cohort study utilized a United States national database of electronic medical records. Adults with a history of type 2 diabetes mellitus without type 1 diabetes mellitus were divided into cohorts based on the presence of abnormal serum levels of various lipid markers. Propensity score matching was performed to match cohorts with abnormal lipid levels to those with normal lipid levels on covariates. The cohorts were then compared to evaluate the hazard ratios (HR) of receiving a new DR diagnosis, pars plana vitrectomy, panretinal photocoagulation, vitreous haemorrhage, proliferative diabetic retinopathy, diabetic macular oedema (DMO), and traction retinal detachment.

RESULTS

The database contained 1,126,231 eligible patients (mean age: 60.8 [14.2] years; 46.0% female). Among patients without prior DR, low HDL (HR = 0.94, CI = 0.90-0.98), total cholesterol (HR = 0.88, CI = 0.85-0.91), and high triglyceride (HR = 0.91, CI = 0.86-0.97) levels were associated with a decreased risk of receiving a DR diagnosis. Among patients with preexisting DR, high LDL levels was associated with an increased risk of DMO (HR = 1.42, CI = 1.15-1.75), whereas low HDL levels was associated with a marginally decreased risk (HR = 0.92, CI = 0.85-0.99).

CONCLUSIONS

Elevated levels of markers of dyslipidaemia are inversely associated with the risk of receiving a DR diagnosis, but this relationship is blunted after the onset of DR.

Is primary open-angle glaucoma a risk factor for diabetic retinopathy?

PURPOSE

To compare the prevalences of diabetic retinopathy in diabetes mellitus patients, with and without primary open-angle glaucoma, with a view to determine if glaucoma is a risk factor for the development of diabetic retinopathy.

METHODS

Cross-sectional, comparative study consisting of 86 diabetic patients with glaucoma matched with 86 diabetic patients without glaucoma. The two groups were matched by age, sex and duration of diabetes mellitus. Demographic data were obtained via patient medical records and self-administered questionnaires. Participants underwent a standardized examination protocol including blood pressure measurement and ocular examination. Main outcome measure was the presence of diabetic retinopathy.

RESULTS

Two hundred and ninety-two eyes (144 glaucomatous eyes and 148 non-glaucomatous eyes) of 172 participants with diabetes mellitus were assessed. The prevalence of diabetic retinopathy among 86 participants with glaucoma comorbidity was 23.6%, while the prevalence among 86 non-glaucomatous participants was 33.8% (p = 0.06). After the regression analysis, controlling for systemic and ocular risk factors for diabetic retinopathy, the odds of developing diabetic retinopathy were significantly higher in the glaucomatous eyes compared with eyes without glaucoma (OR: 2.75; p = 0.03; 95% CI: 1.10-6.87).

CONCLUSION

This study demonstrated that glaucomatous diabetic eyes were almost three times more likely to develop diabetic retinopathy compared to non-glaucomatous diabetic eyes. Prospective studies may be required to establish a risk-cause relationship. Ocular perfusion pressure control should be considered in patients with diabetes mellitus and glaucoma.

Differences in Risk Factors for Diabetic Retinopathy in Type 1 and Type 2 Diabetes Mellitus Patients in North-East Poland

Background and objective: Nowadays, diabetes is one of the main causes of blindness in the world. Identification and differentiation of risk factors for diabetic retinopathy depending on the type of diabetes gives us the opportunity to fight and prevent this complication. Aim of the research: To assess differences in the risk factors for diabetic retinopathy in type 1 and type 2 diabetes mellitus patients in Warmia and Mazury Region, Poland. Materials and Methods: Risk factors for diabetic retinopathy (DR) were assessed on the basis of an original questionnaire, which included: personal data, clinical history of diabetes and eye disease. Elements of clinical examination: blood pressure, BMI, waist circumference. Indicators of diabetes metabolic control: mean glycemia, glycated hemoglobin (HbA1c), total cholesterol and triglycerides, creatinine, glomerular filtration rate (GFR), albumin-creatinine ratio in urine. Results: The study group included 315 (26%) patients with DM1 and 894 (74%) patients with DM2. Risk factors were estimated on the basis of logistic regression and verified with Student's t-test. Statistically significant dependencies were found in both groups between the occurrence of diabetic retinopathy and diabetes duration, HbA1c, triglyceride concentrations, indicators of kidney function and cigarette smoking status. In the DM2 group, the development of DR was significantly influenced by the implemented models of diabetic treatment. Conclusions: In the whole study group, the risk of DR was associated with the duration of diabetes, HbA1c, triglyceride concentrations and smoking. In DM1 patients, the risk of DR was associated with diabetic kidney disease in the G1A1/A2 stage of chronic kidney disease, and in DM2 patients with the G2 stage of chronic kidney disease. An important risk factor for DR in DM2 patients was associated with late introduction of insulin therapy.

SYSTEMIC RISK FACTORS IN BILATERAL PROLIFERATIVE DIABETIC RETINOPATHY REQUIRING VITRECTOMY

PURPOSE

The visual outcome after vitrectomy for proliferative diabetic retinopathy (PDR) is often poor. Bilateral vitrectomy has been especially associated with a poor visual prognosis in patients with PDR. The authors investigated the systemic risk factors for PDR requiring bilateral vitrectomy compared with unilateral vitrectomy.

METHODS

The authors retrospectively reviewed 86 consecutive patients with Type 2 diabetes mellitus with PDR who underwent vitrectomy. These patients were divided into 2 groups: bilateral vitrectomy within 1 year (n = 25) and unilateral vitrectomy (n = 61). The authors compared the systemic risk factors: age, sex, duration of diabetes, hemoglobin A1c, body mass index, estimated glomerular filtration rate, uric albumin, hypertension, dyslipidemia, history of ischemic heart disease, arteriosclerosis obliterans, and smoking.

RESULTS

There were significantly more cases with severe renal dysfunction in the bilateral vitrectomy group compared with the unilateral one (estimated glomerular filtration rate <30 mL/minute/1.73 m; bilateral cases = 5/25; unilateral cases = 2/61; P = 0.02).

CONCLUSION

The authors found that severe renal dysfunction may be a risk factor in PDR requiring bilateral vitrectomy, indicating that careful attention needs to be paid to prevent the progression of diabetic retinopathy to severe PDR in the other eye if patients have severe unilateral PDR and severe renal dysfunction.

Nonmydriatic fundus camera for diabetic retinopathy screening in a safety net hospital: effectiveness, prevalence, and risk factors

PURPOSE

To evaluate diabetic retinopathy (DR) prevalence and risk factors, and the effectiveness of nonmydriatic fundus camera as a screening tool for the detection of DR, in a safety net hospital.

METHODS

This was a retrospective, population-based, cross-sectional study. Diabetic patients, referred by their primary care physicians to a DR community screening program, were included. A Topcon TRC NW-6S camera was used to obtain 45-degree digital color fundus images. Images were interpreted by retina specialists using a quality rating system. Patients with retinal findings or unreadable photographs were referred for a complete examination. Outcome measures were attendance rates, photograph quality, DR prevalence, and associated risk factors.

RESULTS

A total of 948 diabetic patients were sent for camera screening, with an attendance rate of 65.6%, which increased during the study period. The mean age was 55.8 ± 11.6 years, the majority (56.9%) were Hispanic, and 43.5% were uninsured. Overall photograph quality rating was relatively high, with 81.7% graded as good or fair. Thirty photographs (2.9%) were unreadable. The prevalence of newly diagnosed DR was 11.1%. Independent DR-associated risk factors included Hispanic race (odds ratio [OR] = 2.29), lack of health insurance (OR = 2.49), longer duration of diabetes (OR = 1.07), higher HbA1c levels (OR = 1.19), presence of diabetic complications (OR = 2.93), and lack of previous eye examination (OR = 13.22).

CONCLUSIONS

Nonmydriatic fundus camera is an effective and feasible screening tool for the early detection of DR in a safety net institution. It should be considered in areas with limited access to health care to improve quality of care and potentially reduce vision loss rates.

Anti-vascular endothelial growth factor therapy for diabetic macular edema

Diabetes mellitus is a serious health problem that affects over 350 million individuals worldwide. Diabetic retinopathy (DR), which is the most common microvascular complication of diabetes, is the leading cause of new cases of blindness in working-aged adults. Diabetic macular edema (DME) is an advanced, vision-limiting complication of DR that affects nearly 30% of patients who have had diabetes for at least 20 years and is responsible for much of the vision loss due to DR. The historic standard of care for DME has been macular laser photocoagulation, which has been shown to stabilize vision and reduce the rate of further vision loss by 50%; however, macular laser leads to significant vision recovery in only 15% of treated patients. Mechanisms contributing to the microvascular damage in DR and DME include the direct toxic effects of hyperglycemia, sustained alterations in cell signaling pathways, and chronic microvascular inflammation with leukocyte-mediated injury. Chronic retinal microvascular damage results in elevation of intraocular levels of vascular endothelial growth factor A (VEGF), a potent, diffusible, endothelial-specific mitogen that mediates many important physiologic processes, including but not limited to the development and permeability of the vasculature. The identification of VEGF as an important pathophysiologic mediator of DME suggested that anti-VEGF therapy delivered to the eye might lead to improved visual outcomes in this disease. To date, four different inhibitors of VEGF, each administered by intraocular injection, have been tested in prospective, randomized phase II or phase III clinical trials in patients with DME. The results from these trials demonstrate that treatment with anti-VEGF agents results in substantially improved visual and anatomic outcomes compared with laser photocoagulation, and avoid the ocular side effects associated with laser treatment. Thus, anti-VEGF therapy has become the preferred treatment option for the management of DME in many patients.

Causes of blindness among adult Jordanians: a hospital-based study

PURPOSE

To assess the causes of blindness among adults aged 20 years and over who attended two big general ophthalmic clinics in Jordan.

PATIENTS AND METHODS

This hospital-based study was undertaken at Jordan University Hospital in Amman (the capital of Jordan) and Princess Basma Teaching Hospital which is affiliated with Jordan University of Science and Technology in Irbid, the third largest city in the country. A total of 2732 patients seen consecutively over 26 months were examined and the ophthalmic findings were recorded. Using standard Snellen charts, subjects were placed in one of three categories according to their best corrected visual acuity: (1) unilateral blindness: less than 6/60 in the worst eye, 6/60 or more in the better eye; (2) moderate bilateral blindness: less than 6/60 in the worst eye, less than 6/60 to 3/60 or more the better eye; and (3) severe bilateral blindness: less than 3/60 in both eyes.

RESULTS

Of the totalpatients seen, 373 were blind according to the selection criteria. Among 248 patients with unilateral blindness, diabetic retinopathy, cataract and trauma were the leading causes. Among the 81 patients with moderate bilateral blindness, diabetic retinopathy and cataract were the leading causes. Diabetic retinopathy and glaucoma were the leading causes in patients with severe bilateral blindness.

CONCLUSIONS

These data could be used in planning blindness prevention and treatment programs while awaiting a national survey on the prevalence and causes of blindness in Jordan.

Matrix metalloproteinases in human diabetic and nondiabetic vitreous

PURPOSE

To compare matrix metalloproteinase (MMP) activities in human vitreous samples from patients with diabetic retinopathy (DR) and other vitreoretinal diseases, and to investigate the factors influencing the MMP activities in human DR vitreous samples.

METHODS

Thirty-one diabetic and 17 nondiabetic vitreous samples (from nine patients with macular holes and eight patients with epiretinal membranes) were examined. Samples collected at the time of pars plana vitrectomy were subjected to substrate zymography to conduct a quantitative analysis of MMP activity. Immunoblotting against antihuman MMP-1, 2, and 9 was performed to identify MMP in vitreous samples. The effects of posterior vitreous detachment (PVD), vitreous hemorrhage, proliferative membrane, traction detachment, and cystoid macular edema on MMP activities were investigated.

RESULTS

All vitreous samples from both DR and non-DR patients showed a single band at the position of 72 kD, corresponding to MMP-2. Another band at 99 kD, corresponding to MMP-9, was detected significantly more often in DR samples than in non-DR samples: 45.2% and 0%, respectively (P = 0.0007). The number of samples showing a band from MMP-9 was significantly higher in partial PVD samples than in complete PVD samples: 66.7% and 15.4%, respectively (P = 0.001).

CONCLUSION

The results indicated that MMP-9 may be involved in DR and that partial PVD may be related to the MMP-9 activity in DR.

Platelet expression of tumour necrosis factor-alpha (TNF-alpha), TNF receptors and intercellular adhesion molecule-1 (ICAM-1) in patients with proliferative diabetic retinopathy

Microvascular complications of insulin-dependent diabetes mellitus (IDDM) have been strongly associated with platelet abnormalities, whilst TNF-alpha has been implicated in the pathogenesis of this condition. However, at present it is not clear whether human circulating platelets express TNF-alpha or TNF receptors (TNF-R) or whether impaired expression of these molecules and of the TNF-reactive adhesion molecule ICAM-1 may be associated with platelet abnormalities in patients with IDDM. On this basis we investigated the platelet expression of these molecules in patients with IDDM complicated or uncomplicated by proliferative diabetic retinopathy (PDR) and in healthy subjects. We observed that the proportion of platelets staining for TNF-alpha was significantly higher in IDDM patients with active PDR than in patients without microvascular complications (P = 0.0078), quiescent PDR (P = 0.003) or healthy subjects (P = 0.0013). Patients with active PDR also showed a higher proportion of platelets expressing TNF-RI (P = 0. 0052) and TNF-RII (P = 0.015) than healthy controls or patients with quiescent PDR (P = 0.009 and 0.0006, respectively). In addition, the percentage of ICAM-1+ platelets was significantly higher in patients with active PDR than in patients with quiescent PDR (P = 0.0065) or normal subjects (P = 0.013). There was a direct correlation between platelet expression of TNF-alpha and that of TNF-R in PDR patients, indicating that platelet staining for TNF-alpha may be due to binding of this cytokine to its receptors. The results suggest that increased platelet expression of TNF-alpha, TNF-R and ICAM-1 in IDDM patients may constitute important markers of thrombocyte abnormalities during the development of microvascular complications of diabetes mellitus.

Modifying factors related to asymmetric diabetic retinopathy

PURPOSE

To identify the modifying factors related to the development of proliferative diabetic retinopathy (PDR).

METHODS

Thirty-eight eyes of 19 non-insulin-dependent diabetes mellitus (NIDDM) patients with maintained asymmetric PDR were retrospectively reviewed.

RESULTS

Five patients with ipsilateral carotid stenoses > or = 90% had PDR. Four patients with high myopia over 6 dioptres and 4 patients with optic atrophy and at least a quadrant defect in the visual field had non-proliferative diabetic retinopathy. Of 6 patients with unilateral asteroid hyalosis, 5 had no posterior vitreous detachment (PVD) and PDR.

CONCLUSION

Two factors reached statistical significance as factors modifying PDR: carotid occlusive disease and PVD. Optic atrophy and high myopia showed trends of being a protective influence.

Evidence for control of tumour necrosis factor-alpha (TNF-alpha) activity by TNF receptors in patients with proliferative diabetic retinopathy

TNF-alpha has been implicated in the pathogenesis of insulin- dependent diabetes mellitus (IDDM). At present there are no studies linking serum levels of soluble TNF receptors (sTNF-R) to the development of diabetic microvascular complications such as proliferative diabetic retinopathy (PDR), or to the production of TNF-alpha in these patients. We investigated serum levels of sTNF receptors (sTNF-RI and sTNF-RII) in IDDM patients with or without PDR, and related these to the in vitro production of TNF-alpha upon activation of whole blood and isolated mononuclear cells (MNC). We observed higher serum levels of sTNF-RI in IDDM patients with active (range 945-6630 pg/ml; P = 0.029) or quiescent PDR (range 1675-4970 pg/ml; P = 0.00092) than in individuals with IDDM without retinopathy (range 657-2617 pg/ml) or healthy controls (range 710-1819 pg/ml; P = 0.0092 and 0.0023, respectively). Increased serum levels of sTNF-RII were also seen in IDDM patients with active PDR (range 1749-5218 pg/ml; P = 0.034) or quiescent PDR (range 1494-5249 pg/ml; P = 0.0084) when compared with disease controls (range 1259-4210 pg/ml) or healthy subjects (range 1237-4283 pg/ml). Whole blood production of biologically active TNF-alpha was lower in PDR patients than in disease (P = 0.04) and healthy controls (P < 0.005), contrasting with a higher production of TNF-alpha by lipopolysaccharide (LPS)-activated MNC from PDR patients (P = 0.013). Inhibition of TNF-alpha by TNF-R in plasma supernatants of activated blood from PDR patients was demonstrated by increase of TNF-alpha activity in the presence of anti-TNF-RI and anti-TNF-RII antibodies. These observations suggest that abnormalities in TNF-alpha production and control may operate during the development of microvascular complications of diabetes mellitus.

Diabetic eye disease: a natural history study

In previous studies on diabetic retinopathy it has not been possible to relate risk factors to reduced vision because of the influence of vision-preserving treatment. Demographic data, cardiovascular risk factors and ocular features from the diabetic population of the Seychelles are described. Diabetic retinopathy in this population had not been modified by laser treatment. The population described consists of entirely type 2, maturity onset diabetics. Using a multivariate logistic regression model, the risk factors were deduced for three outcome variables: (1) reduced vision, defined as 6/36 or worse in both eyes; (2) the presence of diabetic retinopathy; and (3) the presence of maculopathy, preproliferative and proliferative retinopathy, grouped as severe retinopathy. Insulin treatment was associated with all outcome variables, duration from diagnosis of diabetes with retinopathy of all forms, and increasing age with reduced vision and severe retinopathy. Hypertensive diabetic patients were twice as likely to have reduced vision as compared with non-hypertensive diabetic individuals.

Causes of blindness in Irbid, Jordan

To determine the most common causes of blindness and the age of onset of these conditions among Jordanians of Irbid, a study of all registered members in two societies for the care of the blind was carried out. Of all registered members, 185 individuals were blind according to the World Health Organization definition and satisfied our inclusion criteria. It was found that genetically determined causes made up 41% of the total causes. In 57% of the subjects, blindness occurred in the first two decades of life. The specific leading causes of blindness, in the order of their frequencies, were tapetoretinal degenerations as different variants of retinitis pigmentosa (17.6%), glaucomas (16%), diabetic retinopathy (13%), post-infection corneal scarring (11.5%), congenital cataract (8.8%) and uveitis (8%). The results reflect the satisfactory achievements in primary health care levels and the challenge to make specialized tertiary health care more accessible.

Detection of diabetic retinopathy by scanning laser ophthalmoscopy

A scanning laser ophthalmoscope (SLO) was used to examine the fundi of 54 diabetic patients through undilated pupils and the results compared by an experienced ophthalmologist with clinical examination through dilated pupils to assess the effectiveness of the SLO in detecting diabetic retinopathy. Whilst the SLO was not as good at detecting cotton wool spots and subtle intraretinal microvascular abnormalities, it did not miss any active new vessel formation and all eyes needing treatment would have been referred.

Gyrate atrophy of the choroid and retina with hyperornithinaemia, cystinuria and lysinuria

The case of a 45-year-old woman with gyrate atrophy of the choroid and retina is documented. Additional features in this case, to the authors' knowledge not previously described in gyrate atrophy, are massive cystinuria, massive lysinuria, axial hypermetropia and diabetes. Gyrate atrophy is a rare autosomal recessive degenerative disease of the choroid and retina and is accompanied by defective ornithine metabolism. Simell and Takki demonstrated the association with hyperornithinaemia in 1973. The main metabolic features are those of hyperornithinaemia and ornithuria caused by a deficiency of the mitochondrial matrix enzyme, ornithine aminotransferase (OAT). The responsible human gene has been localised to chromosome 10. Despite the generalised deficiency of OAT, the literature indicates significant pathological involvement of the eye only. Ophthalmological features of the disease are myopia (up to 10-20 dioptres), night blindness, constricted visual fields and complicated cataracts. The clinical picture has been detailed previously by various authors. The case of a 45-year-old woman with gyrate atrophy and hyperornithinaemia is documented here. She has been followed up for 12 years and fully investigated. Additional features in this case, to our knowledge not previously described in gyrate atrophy, are massive cystinuria, massive lysinuria, axial hypermetropia and diabetes.