Subretinal AAV delivery of RNAi-therapeutics targeting VEGFA reduces choroidal neovascularization in a large animal model

Neovascular age-related macular degeneration (nAMD) is a frequent cause of vision loss among the elderly in the Western world. Current disease management with repeated injections of anti-VEGF agents accumulates the risk for adverse events and constitutes a burden for society and the individual patient. Sustained suppression of VEGF using gene therapy is an attractive alternative, which we explored using adeno-associated virus (AAV)-based delivery of novel RNA interference (RNAi) effectors in a porcine model of choroidal neovascularization (CNV). The potency of VEGFA-targeting, Ago2-dependent short hairpin RNAs placed in pri-microRNA scaffolds (miR-agshRNA) was established in vitro and in vivo in mice. Subsequently, AAV serotype 8 (AAV2.8) vectors encoding VEGFA-targeting or irrelevant miR-agshRNAs under the control of a tissue-specific promotor were delivered to the porcine retina via subretinal injection before CNV induction by laser. Notably, VEGFA-targeting miR-agshRNAs resulted in a significant and sizable reduction of CNV compared with the non-targeting control. We also demonstrated that single-stranded and self-complementary AAV2.8 vectors efficiently transduce porcine retinal pigment epithelium cells but differ in their transduction characteristics and retinal safety. Collectively, our data demonstrated a robust anti-angiogenic effect of VEGFA-targeting miR-aghsRNAs in a large translational animal model, thereby suggesting AAV-based delivery of anti-VEGFA RNAi therapeutics as a valuable tool for the management of nAMD.

Thyroid dysfunction and exudative age-related macular degeneration - A longitudinal nationwide registry-based cohort study

PURPOSE

The association between thyroid dysfunction and exudative age-related macular degeneration (AMD) is unknown.

METHODS

In this Danish longitudinal nationwide registry-based cohort study we included all Danish residents aged 50-100 between 2008 and 2018. Using the Danish national registries, we studied the association between thyroid dysfunction and exudative AMD. Thyroid dysfunction was classified as two consecutive redeemed prescriptions of thyroid hormones (hypothyroidism) or anti-thyroid medication (hyperthyroidism). Exudative AMD was classified as an ICD diagnosis of AMD and a code for anti-VEGF treatment. All patients are treated for exudative AMD in a hospital in Denmark, and we therefore have complete registration of this patient group.

RESULTS

We included 2 087 305 individuals, of which 1 072 567 (51.4%) were women; 59 318 (2.8%) had hypothyroidism, and 33 922 (1.6%) had hyperthyroidism. During a median follow-up of 11 years, 26 998 (1.3%) people developed exudative AMD. Hypothyroidism (adjusted hazard ratio [HR]: 1.17; 95% confidence interval [CI] 1.10-1.25; p < 0.001) and hyperthyroidism (HR: 1.23; 95% CI:1.13-1.34; p < 0.001) were both associated with the development of exudative AMD. The age-stratified analyses yielded similar results to the main analyses, except that the risks were exaggerated in the older part of the population.

CONCLUSION

This is the first longitudinal nationwide study showing that both hypo- and hyperthyroidism are associated with an increased risk of exudative AMD. AMD is a quantitative problem in the population and our findings could have a public health impact. Further studies are needed to study the underlying mechanisms of the association.

The vasoactive effects of bradykinin, vasoactive intestinal peptide, calcitonin gene-related peptide and neuropeptide Y depend on the perivascular tissue in porcine retinal arterioles in vitro

PURPOSE

The retina contains a number of vasoactive neuropeptides and corresponding receptors, but the role of these neuropeptides for tone regulation of retinal arterioles has not been studied in detail.

METHODS

Porcine arterioles with preserved perivascular retinal tissue were mounted in a wire myograph, and the tone was measured after the addition of increasing concentrations of bradykinin, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP) and brain natriuretic peptide (BNP). The experiments were performed during inhibition of the synthesis of nitric oxide (NO), prostaglandins and dopamine and were repeated after removal of the perivascular retinal tissue.

RESULTS

Bradykinin, VIP and CGRP induced significant concentration-dependent dilatation and NPY significant concentration-dependent contraction of the arterioles in the presence of perivascular retinal tissue (p < 0.03 for all comparisons) but not on isolated arterioles. BNP and SP had no effect on vascular tone. The NOS inhibitor L-NAME reduced bradykinin- and VIP-induced relaxation (p < 0.001 for both comparisons), whereas none of the other inhibitors influenced the vasoactive effects of the studied neuropeptides.

CONCLUSION

The effects of neuropeptides on the tone of retinal arterioles depend on the perivascular retinal tissue and may involve effects other than those mediated by nitric oxide, prostaglandins and adrenergic compounds. Investigation of the mechanisms underlying the vasoactive effect of neuropeptides may be important for understanding and treating retinal diseases where disturbances in retinal flow regulation are involved in the disease pathogenesis.

Convergence insufficiency in patients with post-concussion syndrome is accompanied by a higher symptom load: a cross-sectional study

OBJECTIVE

To estimate the prevalence of convergence insufficiency (CI) in adult patients with post-concussion syndrome and determine the impact of CI on symptom load.

METHODS

Cross-sectional study of 103 patients with neurological symptoms 2-6 months after a concussion. Symptoms were assessed with the Rivermead Post Concussion Symptoms Questionnaire (RPQ), and CI was diagnosed using near point of convergence, vergence facility, and the Convergence Insufficiency Symptom Survey. The RPQ score for patients with and without CI was compared, and sensitivity, specificity, and area under the receiver operating characteristic curve for the two visually related RPQ questions as indicators of CI were calculated.

RESULTS

The proportion of patients diagnosed with symptomatic CI was 20.4% (95% confidence interval: 13.1-29.5%). The RPQ score was significantly higher for patients with symptomatic CI both before (p = .01) and after removal of the two visually related questions in the RPQ-questionnaire (p = .03). The two visually related RPQ questions were unable to detect CI.

CONCLUSION

In patients with post-concussion syndrome, the load of nonvisual symptoms is higher in the presence of CI. A prospective interventional study on CI is required to study the relationship between CI and other post-concussion symptoms.

Risk of diabetic retinopathy according to subtype of type 2 diabetes

Type 2 diabetes is a heterogeneous disease that can be subdivided based on beta-cell function and insulin sensitivity. We aimed to investigate the presence, incidence and progression of diabetic retinopathy (DR) according to subtypes of type 2 diabetes. In a national cohort, we identified three subtypes of type 2 diabetes which included classical, hyperinsulinemic and insulinopenic type 2 diabetes based on HOMA2 measurements. From the Danish Registry of Diabetic Retinopathy (DiaBase) we extracted information on level of DR. We used several national health registries to link information on comorbidity, medications and laboratory tests. We found individuals with hyperinsulinemic type 2 diabetes were less likely to have DR at entry date compared to classical type 2 diabetes, whereas individuals with insulinopenic type 2 diabetes were more likely to have DR. In multivariable Cox regression analysis, individuals with hyperinsulinemic type 2 diabetes had a decreased risk of both incidence and progression of DR compared to classical type 2 diabetes. We did not find any clear difference in risk of incident or progression of DR in individuals with insulinopenic compared to classical type 2 diabetes. These findings indicate that subcategorization of type 2 diabetes is important in evaluating the future risk of DR.

Two-Year Results of 0.01% Atropine Eye Drops and 0.1% Loading Dose for Myopia Progression Reduction in Danish Children: A Placebo-Controlled, Randomized Clinical Trial

We investigated the two-year safety and efficacy of 0.1% loading dose and 0.01% low-dose atropine eye drops in Danish children for reduction in myopia progression in an investigator-initiated, placebo-controlled, double-masked, randomized clinical trial. Ninety-seven six- to twelve-year old myopic participants were randomized to 0.1% loading dose for six months and then 0.01% for eighteen months (loading dose group, N = 33), 0.01% for two years (0.01% group, N = 32) or placebo for two years (placebo, N = 32). Axial length (AL) and spherical equivalent refraction (SER) were primary outcomes. Secondary outcomes included adverse events and reactions, choroidal thickness, and other ocular biometrical measures. Outcomes were measured from baseline and at six-month intervals. Individual eyes nested by participant ID were analyzed with linear-mixed model analysis. Data were analyzed with intention-to-treat. Mean AL was 0.08 mm less (95% confidence interval (CI): -0.01; 0.17, p-value = 0.08) in the 0.1% loading dose and 0.10 mm less (95% CI: 0.01; 0.19, p-value = 0.02) in the 0.01% group after two years of treatment compared to placebo. Mean SER progression was 0.12 D (95% CI: -0.10; 0.33) less in the loading dose and 0.26 D (95% CI: 0.04; 0.48) less in the 0.01% groups after two years of treatment compared to placebo (p-value = 0.30 and 0.02, respectively). In total, 17 adverse events were reported in the second-year follow-up, and all were rated as mild. Adjusting for iris color did not affect treatment effect estimates. Intra-ocular pressure increased over two years comparably between all groups but remained within normal limits. Two-year treatment with 0.01% low-dose atropine eye drops is a safe and moderately efficacious intervention in Danish children for reducing myopia progression.

Inter-grader reliability in the Danish screening programme for diabetic retinopathy

PURPOSE

The Danish Registry of Diabetic Retinopathy includes information from >200 000 patients who attends diabetic retinopathy (DR) screening in Denmark. Screening of patients with uncomplicated type 2 diabetes is often performed by practicing ophthalmologists, while patients with type 1 and complicated type 2 diabetes attends screening at hospitals. We performed a clinical reliability study of retinal images from Danish screening facilities to explore the inter-grader agreement between the primary screening ophthalmologist and a blinded, certified grader.

METHODS

Invitations to participate were sent to screening facilities across Denmark. The primary grader uploaded fundus photographs with information on estimated level of DR (International Clinical Diabetic Retinopathy scale as 0 [no DR], 1-3 [mild, moderate or severe nonproliferative DR {NPDR}], or 4 [proliferative DR {PDR}]), region of screening, image style, and screening facility. Images were then regraded by a blinded, certified, secondary grader. Weighted kappa analysis was performed to evaluate agreement.

RESULTS

Fundus photographs from 230 patients (458 eyes) were received from practicing ophthalmologists (52.6%) and hospital-based grading centres (47.4%) from all Danish regions. Reported levels of DR by the primary graders were 66.8%, 12.2%, 13.1%, 1.3% and 5.5% for DR levels 0-4. The overall agreement between primary and secondary graders was 93% (κ = 0.83). Based on screening facility agreement was 96% (κ = 0.89) and 90% (κ = 0.76) for practicing ophthalmologists and hospital-based graders.

CONCLUSION

In this nationwide study, we observed a high overall inter-grader agreement and based on this, it is reasonable to assume that reported DR gradings in the screening programme in Denmark, accurately reflect the truth.

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.

Safety and efficacy of 0.01% and 0.1% low-dose atropine eye drop regimens for reduction of myopia progression in Danish children: a randomized clinical trial examining one-year effect and safety

BACKGROUND

To investigate the efficacy and safety of 0.1% and 0.01% low-dose atropine eye drops in reducing myopia progression in Danish children.

METHODS

Investigator-initiated, placebo-controlled, double-masked, randomized clinical trial. Ninety-seven six- to twelve-year old myopic participants were randomized to 0.1% loading dose for six months followed by 0.01% for six months (loading dose group, Number (N) = 33), 0.01% for twelve months (0.01% group, N = 32) or vehicle for twelve months (placebo, N = 32). Primary outcomes were axial length and spherical equivalent refraction. Secondary outcomes included adverse events and reactions, choroidal thickness and ocular biometry. Outcomes were measured at baseline and three-month intervals. Data was analyzed with linear-mixed model analysis according to intention-to-treat.

RESULTS

Mean axial elongation was 0.10 mm less (95% confidence interval (CI): 0.17; 0.02, adjusted-p = 0.06) in the 0.1% loading dose and 0.07 mm less (95% CI: 0.15; 0.00, adjusted-p = 0.16) in the 0.01% group at twelve months compared to placebo. Mean spherical equivalent refraction progression was 0.24 D (95% CI: 0.05; 0.42) less in the loading dose and 0.19 D (95% CI: 0.00; 0.38) less in the 0.01% groups at twelve months, compared to placebo (adjusted-p = 0.06 and 0.14, respectively). A total of 108 adverse events were reported during the initial six-month loading dose period, primarily in the loading dose group, and 14 were reported in the six months following dose switching, all deemed mild except two serious adverse events, unrelated to the intervention.

CONCLUSIONS

Low-dose atropine eye drops are safe over twelve months in otherwise healthy children. There may be a modest but clinically relevant reduction in myopia progression in Danish children after twelve months treatment, but the effect was statistically non-significant after multiple comparisons adjustment. After dose-switching at six months the loading dose group approached the 0.01% group, potentially indicating an early "rebound-effect".

TRIAL REGISTRATION

this study was registered in the European Clinical Trials Database (EudraCT, number: 2018-001286-16) 05/11/2018 and first posted at www.

CLINICALTRIALS

gov (NCT03911271) 11/04/2019, prior to initiation.

Increased Oxygen Saturation in Retinal Venules During Isometric Exercise Is Accompanied With Increased Peripheral Blood Flow in Normal Persons

Purpose

A recent study has shown that an increase in the arterial blood pressure of approximately 10 mm Hg in healthy persons can increase the oxygen saturation in venules from the retinal periphery but not from the macular area. The purpose of the present study was to investigate whether a higher increase in blood pressure has further effects on oxygen saturations and whether this is accompanied with changes in retinal blood flow.

Methods

In 30 healthy persons, oxygen saturation, diameter, and blood flow were measured in arterioles to and venules from the retinal periphery and the macular area. The experiments were performed before and during an experimental increase in arterial blood pressure of (mean ± SD) 18.3 ± 6.2 mm Hg.

Results

A higher number of venules than arterioles branching from the temporal vascular arcades to the macular area was balanced by a smaller diameter of the venules. Isometric exercise induced significant contraction of both peripheral and macular arterioles (P < 0.01 for both comparisons) and significant increase in oxygen saturation in both peripheral and macular venules (P < 0.001 for both comparisons). This was accompanied with a significant increase in the blood flow in the peripheral arterioles and venules (P = 0.4 for both comparisons), but not in their macular counterparts (P > 0.06 for both comparisons).

Conclusions

Increased systemic blood pressure leading to arterial contraction and increased venous oxygen saturation in the retina in normal persons can increase peripheral blood flow without significant effects on macular blood flow. This may contribute to explaining regional differences in the response pattern of retinal vascular disease.

Longitudinal bidirectional associations between diabetic retinopathy and diagnosed depression: Results from a Danish nationwide registry-based cohort study

OBJECTIVE

Diabetic retinopathy (DR) is a feared complication and a leading course of visual impairment, but the connection between DR and depression including the direction has never been studied in a nationwide cohort. We aimed to assess, whether the associations between DR and diagnosed depression are bidirectional.

METHODS

We performed a national register-based cohort study of individuals with type 2 diabetes, who attended diabetic eye screening between January 2013 and June 2022. Level of DR was extracted from the Danish Registry of Diabetic Retinopathy. The severity of DR was assessed according to the International Clinical Diabetic Retinopathy severity scale. Diagnosed depression was ascertained by physician diagnostic codes of unipolar depression (F32), recurrent depression (F33) or dysthymia (F34.1) from the Danish National Patient Register. We estimated presence of diagnosed depression according to DR level at index date and risk of diagnosed depression during follow-up using multivariable logistic and Cox regression, respectively. Secondly, we assessed whether diagnosed depression at index date could predict incident DR.

RESULTS

We included 240,893 individuals with type 2 diabetes with baseline rates of diagnosed depression ranging from 5.2 to 6.0 % for DR level 1-4. At index date, individuals with type 2 diabetes and DR were less likely to have a history of diagnosed depression (multivariable adjusted OR, 0.77 [95 % CI 0.73-0.82]). In 226,523 individuals with type 2 diabetes followed for 1,159,755 person-years, 1.7 % developed at least one episode of diagnosed depression. In a model adjusted for age and sex, individuals with DR at index date had an increased risk of incident diagnosed depression compared to those without DR (HR 1.25 [95 % CI 1.16-1.36]). Adjusting for marital status, use of glucose-, lipid- and blood pressure lowering medication, HbA1c, diabetic neuropathy and Charlson comorbidity index waived the above risk (multivariable adjusted HR 1.02 [95 % CI 0.93-1.12]). Furthermore a previous history of diagnosed depression was not associated with increased risk of incident DR (multivariable adjusted HR 0.89 [95 % CI 0.77-1.03]).

CONCLUSION

In this nationwide cohort study, individuals with DR at first screening were 23 % less likely to have a history of depression, but our data did not support a bidirectional association between DR and depression. Selection bias may have occurred as diagnosed depression is a known barrier for attending DR-screening.

Five-Year Incidence of Proliferative Diabetic Retinopathy and Associated Risk Factors in a Nationwide Cohort of 201 945 Danish Patients with Diabetes

Purpose

To evaluate the proliferative diabetic retinopathy (PDR) progression rates and identify the demographic and clinical characteristics of patients who later developed PDR compared with patients who did not progress to that state.

Design

A national 5-year register-based cohort study including 201 945 patients with diabetes.

Subjects

Patients with diabetes who had attended the Danish national screening program (2013-2018) for diabetic retinopathy (DR).

Methods

We used the first screening episode as the index date and included both eyes of patients with and without subsequent progression of PDR. Data were linked with various national health registries to investigate relevant clinical and demographic parameters. The International Clinical Retinopathy Disease Scale was used to classify DR, with no DR as level 0, mild DR as level 1, moderate DR as level 2, severe DR as level 3, and PDR as level 4.

Main Outcome Measures

Hazard ratios (HRs) for incident PDR for all relevant demographic and clinical parameters and 1-, 3-, and 5-year incidence rates of PDR according to baseline DR level.

Results

Progression to PDR within 5 years was identified in 2384 eyes of 1780 patients. Proliferative diabetic retinopathy progression rates from baseline DR level 3 at 1, 3 and 5 years were 3.6%, 10.9%, and 14.7%, respectively. The median number of visits was 3 (interquartile range, 1-4). Progression to PDR was predicted in a multivariable model by duration of diabetes (HR, 4.66 per 10 years; 95% confidence interval [CI], 4.05-5.37), type 1 diabetes (HR, 9.61; 95% CI, 8.01-11.53), a Charlson Comorbidity Index score of > 0 (score 1: HR, 4.62; 95% CI, 4.14-5.15; score 2: HR, 2.28; 95% CI, 1.90-2.74; score ≥ 3: HR, 4.28; 95% CI, 3.54-5.17), use of insulin (HR, 5.33; 95% CI, 4.49-6.33), and use of antihypertensive medications (HR, 2.23; 95% CI, 1.90-2.61).

Conclusions

In a 5-year longitudinal study of an entire screening nation, we found increased risk of PDR with increasing baseline DR levels, longer duration of diabetes, type 1 diabetes, systemic comorbidity, use of insulin, and blood pressure-lowering medications. Most interestingly, we found lower risk of progression from DR level 3 to PDR compared with that in previous studies.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Differential effects of purines and prostaglandins on hypoxia induced dilatation of porcine retinal vessels at different branching level ex vivo

The metabolic pathways leading from hypoxia to retinal vasodilatation can involve effects of both purines and prostaglandins, but the effects of these compounds at different vascular branching levels are unknown. The purpose of the present study was to investigate differential effects of purines and prostaglandins in hypoxia-induced dilatation of retinal arterioles, precapillary arterioles and capillaries ex vivo. Porcine hemiretinas were mounted in a tissue chamber while monitoring temperature, pH, and oxygen tension. The effect of hypoxia on the diameter of larger arterioles, precapillary arterioles and capillaries was studied in the presence of the ecto-nucleotidase inhibitor AOPCP, the nonselective P2 purinoreceptor antagonist PPADS, the A2B adenosine receptor antagonist MRS 1754, the A3 adenosine receptor antagonist MRS 1523, the EP1 receptor antagonist SC-19220, the EP2 receptor antagonist PF-04418948, the EP3 receptor antagonist L-798,106, the EP4 receptor antagonist L-161-982, the prostaglandin synthesis inhibitor ibuprofen, and ibuprofen combined with AOPCP or ATP. Hypoxia-induced dilatation in arterioles was reduced by the A2B adenosine receptor antagonist (p < 0.01) and increased by the EP2 and the EP3 receptor antagonists (p < 0.01 for both comparisons). In precapillary arterioles the dilatation was reduced by the EP2 receptor antagonist (p < 0.04) and increased by the EP1 receptor antagonist (p < 0.03), whereas in capillaries the dilatation was increased by both the A3 adenosine receptor antagonist (p < 0.01), by ibuprofen in combination with the unspecific ecto-nucleotidase inhibitor AOPCP (p = 0.04) and by the prostaglandin EP3 receptor antagonist. Hypoxia-induced dilatation of retinal vessels is influenced by adenosine A2B and A3 receptors, and by the prostaglandin EP1, EP2 and EP3 receptors. The effects mediated by these receptors differ at different branching levels of the resistance vessels.

Porcine models of choroidal neovascularization: A systematic review

Animal models of choroidal neovascularization (CNV) are extensively used in translational studies of CNV formation and to evaluate angiostatic treatment strategies. However, the current paucity of large animal models compared with rodent models constitutes a knowledge gap regarding the clinical translation of findings. Ocular anatomical and physiological similarities to humans suggest the pig as a relevant model animal. Thus, a systematic survey of porcine CNV models was performed to identify pertinent model parameters and suggest avenues for model standardization and optimization. A systematic search was performed in PubMed and EMBASE on November 28, 2022 for porcine models of CNV. Following inclusion by two investigators, data from the articles were extracted according to a predefined protocol. A total of 14 articles, representing 19 independent porcine CNV models were included. The included models were almost equally divided between laser-induced (53%) and surgically-induced (47%) models. Different specified breeds of domestic pigs (71%) were most commonly used in the studies. All studies used normal animals. Female pigs were reported used in 43% of the studies, while 43% did not report on sex of the animals. Younger pigs were typically used. The surgical models reported consistent CNV induction following mechanical Bruch's membrane rupture. The laser models used variants of the infrared diode laser (40%) or the frequency-doubled Nd:YAG laser (50%). Both lasers enabled successful CNV induction with reported induction rates ranging from 60 to 100%. Collateral damage to the neuroretina was reported for the infrared diode laser. CNV evaluation varied across studies with fluorescein angiography (50%) as the most used in vivo method and retinal sections (71%) as the most used ex vivo method. In interventional studies, quantification of lesions was in general performed between 7 and 14 days. The field of porcine CNV models is relatively small and heterogeneous and almost equally divided between surgically-induced and laser-induced models. Both methods have allowed successful modeling of CNV formation with induction rates comparable to those of non-human primates. However, the field would benefit from standardization of model parameters and reporting. This includes laser parameters and validation of CNV formation as well as methods of CNV evaluation and statistical analysis.

Visual Function and Inner Retinal Structure in Relation to Birth Factors in Autosomal Dominant Optic Atrophy

Purpose

The extreme variation in expressivity of autosomal dominant optic atrophy (ADOA) is unexplained. It is present from early childhood, why there is reason to search for pre- and perinatal risk factors for poor vision in ADOA. The process of ganglion cell pruning in the fetus is of interest because mitochondria are involved in apoptosis. We hypothesized that suboptimal mitochondrial function makes the developing retina and optic nerve vulnerable to fetal stress in ADOA. We have examined visual function and inner retinal layer structure in relation to birth parameters in ADOA.

Methods

The study included 142 participants with OPA1 ADOA, 62 unaffected first-degree relatives, and 90 unrelated control subjects. Outcome measures included best-corrected visual acuity, microperimetric sensitivity, nerve fiber layer (NFL) volume, and ganglion cell layer (GCL) volume. Descriptive parameters included birth weight, maternal age at birth, birth complications, and gestational age. Analysis was made using mixed modeling.

Results

The analysis showed a significant positive association between microperimetric sensitivity and longer gestational age in ADOA (0.5 dB/week, P = 0.017). Interaction analysis showed a significant different association between microperimetric sensitivity and gestational age between participants with ADOA and the control groups (P = 0.007) and a significant difference in association between NFL volume and birth weight (P = 0.04) and gestational age (P = 0.02) between variant types.

Conclusions

The study suggests that gestational age and birth weight may affect the expressivity of ADOA. The results support that prospectively collected pre- and perinatal data should be included in future studies of the natural history of ADOA.

Diabetic retinopathy is a predictor of chronic respiratory failure: A nationwide register-based cohort study

Purpose

Diabetic retinopathy (DR) is a hypoxic retinal disease, but so far, the association with systemic hypoxia is poorly understood. Hence, the aim of this study was to evaluate cross-sectional and longitudinal associations between DR and chronic respiratory failure (CRF) in a national cohort.

Design

Cross-sectional and 5-year longitudinal register-based cohort study.

Methods

Between 2013 and 2018, we included patients with diabetes from the Danish Registry of Diabetic Retinopathy, who were each age and sex matched with five controls without diabetes. At index date, the prevalence of CRF was compared between cases and controls, and the longitudinal relationship between DR and CRF was assessed in a five-year follow-up.

Results

At baseline, we identified 1,980 and 9,990 patients with CRF among 205,970 cases and 1,003,170 controls. The prevalence of CRF was higher among cases than controls (OR 1.75, 95% CI 1.65-1.86), but no difference between cases with and without DR was found.During follow-up, we identified 1,726 and 5,177 events of CRF among cases and controls, respectively. The incidence of CRF was higher among both cases with and without DR compared to controls (DR level 0: HR 1.24, 95% CI 1.16-1.33, DR level 1-4: HR 1.86, 95% CI 1.63-2.12), and higher among cases with DR compared to cases without DR (HR 1.54, 95% CI 1.38-1.72).

Conclusion

In this study based on nationwide data, we found an increased risk of present and incident CRF in patients with diabetes with or without DR, and we identified DR as a predictor of future CRF.

Sortilin Inhibition Protects Neurons From Degeneration in the Diabetic Retina

Purpose

To investigate the level and localization of the multifunctional receptor sortilin in the diabetic retina, as well as the effect of sortilin inhibition on retinal neurodegeneration in experimental diabetes.

Methods

The localization of sortilin and colocalization with the p75 neurotrophin receptor (p75NTR) and Müller cell (MC) markers were determined using immunofluorescence on retinal sections from human patients with diabetes and streptozotocin-induced diabetic C57BL/6J male mice. In the diabetic mice, levels were further quantified using Western blot and quantitative PCR. Therapeutic studies were performed on diabetic mice using intravitreally injected anti-sortilin antibodies. Neuroprotection was evaluated in vivo by optical coherence tomography and by quantification of retinal ganglion cells (RGCs) in flat mounts.

Results

Increased levels of sortilin were observed in human and murine diabetic retinas compared with nondiabetic control retinas. Sortilin was highly localized to retinal MCs, and, notably, colocalization with p75NTR was only seen in diabetic retinas. A remarkable protective effect of sortilin inhibition on inner retinal cells was observed in diabetic mice. At eight weeks after diabetes induction, inner retinal thickness was reduced by 9.7% (-12.7%, -6.6%; P < 0.0001; n = 11-12) in the PBS-injected control group compared with the anti-sortilin injected group. Similarly, the count of RGCs was reduced by 20.5% (-30.8%, -10.2%; P = 0.0009) in the PBS-injected control group compared with the anti-sortilin-injected group.

Conclusions

Sortilin is upregulated in the diabetic retina, and sortilin inhibition effectively protects against neuronal loss. Thus sortilin emerges as a novel pharmacological target in diabetic retinal neurodegeneration-an important early event in the pathogenesis of diabetic retinopathy.

Effects of semaglutide and empagliflozin on oxygenation, vascular autoregulation, and central thickness of the retina in people with type 2 diabetes: A prespecified secondary analysis of a randomised clinical trial

AIMS

Semaglutide and empagliflozin have shown cardiovascular protection. In SUSTAIN-6, semaglutide was associated with an increased risk of diabetic retinopathy. We investigated whether changes in retinal oxygenation, retinal vascular autoregulation, and central retinal thickness are altered by semaglutide, empagliflozin or the combination.

METHODS

This study was a prespecified, secondary outcome from a randomised, 32 weeks partly placebo-controlled, partly open-label, clinical trial on the effects of semaglutide and empagliflozin on arterial stiffness and kidney oxygenation. A total of 120 participants with type 2 diabetes, established or high risk of cardiovascular disease and age ≥50 years were randomised into four parallel groups (semaglutide, empagliflozin, the combination or tablet placebo, n = 30 for each group). We primarily hypothesized that semaglutide would increase venular oxygenation.

RESULTS

We found no changes in retinal arteriolar, venular or venular-arteriolar oxygenation nor in retinal vessel diameter regardless of treatment group. Semaglutide increased central retinal thickness compared to placebo with ~1 % (3.8 μm 95 % CI [0.9;6.7], p = 0.009) with no changes in the empagliflozin or combination group.

CONCLUSION

Neither semaglutide, empagliflozin nor the combination alters markers of retinal function. The effect of semaglutide on central retinal thickness was small, but the clinical significance is uncertain.

Presence and development of diabetic retinopathy in 153 238 patients with type 2 diabetes in the Danish Registry of Diabetic Retinopathy

PURPOSE

The purpose of the study was to evaluate the prevalence and incidence of diabetic retinopathy (DR) along with associated markers in patients with type 2 diabetes in the Danish DR-screening programme.

METHODS

We included all persons with type 2 diabetes in the Danish Registry of Diabetic Retinopathy, who had attended at least one episode of DR screening in 2013-2018. DR was classified as levels 0-4 indicating increasing severity. Data were linked with various national health registries to retrieve information on diabetes duration, marital status, comorbidity and systemic medication.

RESULTS

Among 153 238 persons with type 2 diabetes, median age and duration of diabetes were 66.9 and 5.3 years and 56.4% were males. Prevalence and 5-year incidences of DR, 2-step-or-more progression of DR and progression to proliferative DR (PDR) were 8.8%, 3.8%, 0.7% and 0.2%, respectively. In multivariable models, leading markers of incident DR and progression to PDR were duration of diabetes (HR 1.98, 95% CI 1.87-2.09; HR 2.89, 95% CI 2.34-3.58 per 10 years of duration) and use of insulin (HR 1.88, 95% CI 1.76-2.01; HR 2.40, 95% CI 1.84-3.13), while the use of cholesterol-lowering medicine was a protecting marker (HR 0.87, 95% CI 0.81-0.93; HR 0.70, 95% CI 0.52-0.93). From 2013 to 2015, 3-year incidence rates of PDR decreased from 1.22 to 0.45 events per 1000 person-years.

CONCLUSION

Nationally, among Danish individuals with type 2 diabetes attending DR screening, we identified duration of diabetes and use of insulin as the most important predictor for the development of DR, while cholesterol-lowering medicine was a protective factor.

Low Levels of Vitamin C during Pregnancy; a Risk Marker of Progression of Diabetic Retinopathy in Type 1 Diabetic Women?

Pregnancy is a risk factor for the development or aggravation of diabetic retinopathy. Here, we suggest a relationship between plasma vitamin C (vitC) status during pregnancy and into postpartum in type 1 diabetes and the possible progression of diabetic retinopathy based on data of 29 women. VitC was measured in first, second, and third trimesters and three months postpartum. The women had visual acuity testing and fundus photography performed at least twice during pregnancy and onto four months after birth. An overall retinopathy grade was assigned on a scale from 0 (no retinopathy) to four according to the International Clinical Diabetic Retinopathy scale. At baseline in 1st trimester, 12 women had no retinopathy; seventeen women had retinopathy in grade 1–3. The retinopathy grade increased in nine women; remained unchanged in 17 women, and improved in three women. No women had or developed proliferative retinopathy (grade 4). The level of vitC in 1st trimester predicted the possible progression of retinopathy—the lower the vitC, the more probable the progression (p = 0.03; OR 1.6 (95% CI:1.06–3.2); n = 29 (multiple logistic regression))—while the combined levels of 1st and 2nd trimesters and the mean vitC level of the whole pregnancy did not. The diabetes duration, retinopathy grade per se in 1st trimester, 24-h blood pressure measurements, kidney function, urinary protein, HbA1c, or lipid profile were not independent predictors of progression of retinopathy during pregnancy. Retrospectively, the women who experienced progression of their retinopathy during and into postpartum had significantly lower vitC levels in 1st trimester (p = 0.02; n = 9/20), combined level of vitC in 1st and 2nd trimester (p = 0.032; n = 7/18), and mean vitC level of the whole pregnancy (p = 0.036; n = 7/9), respectively. In conclusion, our results suggest that low vitC status in pregnancy could be associated with progression of diabetic retinopathy.

Myopia Control with Low-Dose Atropine in European Children: Six-Month Results from a Randomized, Double-Masked, Placebo-Controlled, Multicenter Study

The effect and safety of low-dose atropine in myopia control have not been studied in randomized, placebo-controlled trials outside Asia. We investigated the efficacy and safety of 0.1% atropine loading dose and 0.01% atropine compared with a placebo in a European population. Investigator-initiated, randomized, double-masked, placebo-controlled, equal-allocation, multicenter study comparing 0.1% atropine loading dose (six months) followed by 0.01% atropine (18 months), 0.01% atropine (24 months), and placebo (24 months). Participants were monitored for a 12-months washout period. Outcome measures were axial length (AL), cycloplegic spherical equivalent (SE), photopic and mesopic pupil size, accommodation amplitude, visual acuity, intraocular pressure (IOP), and adverse reactions and events. We randomized 97 participants (mean [standard deviation] age, 9.4 [1.7] years; 55 girls (57%) and 42 boys (43%)). After six months, AL was 0.13 mm shorter (95% confidence interval [CI], -0.18 to -0.07 [adjusted p < 0.001]) with 0.1% atropine loading dose and 0.06 mm shorter (95% CI, -0.11 to -0.01 [adjusted p = 0.06]) with 0.01% atropine than in the placebo group. We observed similar dose-dependent changes in SE, pupil size, accommodation amplitude, and adverse reactions. No significant differences in visual acuity or IOP were found between groups, and no serious adverse reactions were reported. We found a dose-dependent effect of low-dose atropine in European children without adverse reactions requiring photochromatic or progressive spectacles. Our results are comparable to those observed in East Asia, indicating that results on myopia control with low-dose atropine are generalizable across populations with different racial backgrounds.

Visual acuity and causes of central visual loss in the adult Danish population 2020-2022. Results from the FORSYN study

PURPOSE

Knowledge of visual health in the population is necessary for designing and implementing measures to handle visual handicap. The purpose of the FORSYN (Forekomst af synshandicap og synshjaelpemidler i Danmark) project was to study visual health in the Danish population 2020-2022 after implementation of the recent advances in the management of choroidal and retinal vascular disease. The present study reports visual acuity and causes of central visual loss from this study.

METHODS

A population-representative sample of 10 350 citizens living within 40 kilometres from Aarhus University Hospital were invited to answer a questionnaire about quality of life related to vision, measurement of visual acuity and a non-mydriatic examination of the eyes. The data were corrected for selection bias on the basis of demographic and socioeconomic factors so that the results could be projected to represent the adult Danish population.

RESULTS

Population-adjusted visual acuity in ETDRS letters (mean ± SD) differed significantly (p < 0.0001) among the worse eye (84.1 ± 0.25), the better eye (88.4 ± 0.11) and binocularly (89.2 ± 0.15). Social blindness affected 0.22% (95% CI: 0.14%-0.33%) of the population and was in none of the studied persons due to exudative age-related macular degeneration (AMD) or diabetic retinopathy. The most frequent causes of visual loss were atrophic AMD, neuro-ophthalmic disorders and other chorioretinal diseases.

CONCLUSIONS

Recent advances in the therapy of chorioretinal vascular diseases have been paralleled with a reduction in central vision loss secondary to exudative AMD and diabetic retinopathy in Denmark. The demographic development can be expected to increase the demand for treatments of vision-threatening diseases that mainly affect older persons.

The effect of serifs and stroke contrast on low vision reading

PURPOSE

Patients with low vision are generally recommended to use the same fonts as individuals with normal vision. However, we are yet to fully understand whether stroke width and serifs (small ornamentations at stroke endings) can increase readability. This study's purpose was to characterize the interaction between two factors (end-of-stroke and stroke width) in a well-defined and homogenous group of patients with low vision.

METHODS

Font legibility was assessed by measuring word identification performance of 19 patients with low vision (autosomal dominant optic atrophy [ADOA] with a best-corrected average visual acuity 20/110) and a two-interval, forced-choice task was implemented. Word stimuli were presented with four different fonts designed to isolate the stylistic features of serif and stroke width.

RESULTS

Font-size threshold and sensitivity data revealed that using a single measure (i.e., font-size threshold) is insufficient for detecting significant effects but triangulation is possible when combined with signal detection theory. Specifically, low stroke contrast (smaller variation in stroke width) yielded significantly lower thresholds and higher sensitivity when a font contained serifs (331 points; d' = 1.47) relative to no serifs (345 points; d' = 1.15), E(μ_{sans, low} - μ_{serif, low}) = -14 points, 95 % Cr. I. = [-24, -5], P(δ > 0) = 0.99 and E(μ_{serif, low} - μ_{sans, low}) = 0.32, 95 % Cr. I. = [0.16, 0.49], P(δ > 0) = 0.99.

CONCLUSION

In people with low visual acuity caused by ADOA, the combination of serifs and a uniform stroke width resulted in better text legibility than other combinations of uniform/variable stroke widths and presence/absence of serifs.

Bidirectional 5-year risks of diabetic retinopathy, glaucoma and/or ocular hypertension: Results from a national screening programme

PURPOSE

We aimed to investigate if diabetic retinopathy (DR), glaucoma and/or ocular hypertension (OHT) are prospectively linked, as previous studies have proposed cross-sectional associations, but longitudinal data from larger cohorts are lacking.

METHODS

We performed a bidirectional 5 years prospective, registry-based cohort study. We extracted data from national registers, including the Danish Registry of Diabetic Retinopathy, the Danish Civil Registration System, the Danish National Patient Register and the Danish National Prescription Registry. DR level was defined by the highest level of the two eyes. Glaucoma and/or OHT was defined by diagnostic codes (H40*) or at least three redeemed prescriptions of glaucoma medication (S01E*) within 1 year. We included 205 970 persons with diabetes and 1 003 170 age- and gender-matched non-diabetes controls. Exposures were level-specific DR (i) and glaucoma and/or OHT (ii), and outcomes were hazard ratios (HRs) for 5 years incident glaucoma and/or OHT (i) and DR (ii).

RESULTS

Persons with diabetes were more likely to develop glaucoma and/or OHT (multivariable adjusted HR 1.11, 95% CI 1.06-1.15), but this did not depend on the level of DR. In persons with diabetes, those with glaucoma and/or OHT were more likely to develop DR (multivariable adjusted HR 1.12, 95% CI 1.03-1.23) within 5 years.

CONCLUSION

In a national cohort, diabetes associated with a little higher risk of upcoming glaucoma and/or OHT, and, inversely, the presence of the latter predicted a higher risk of incident DR. Nevertheless, our data do not seem to justify including glaucoma evaluation in the national Danish DR-screening programme.

Vasomotion in Retinal Arterioles Is Modified by Exercise and Flicker Stimulation

PURPOSE

Vasomotion is spontaneous oscillations in the diameter of resistance vessels with derived effects on blood flow, and it has been proposed that disturbances in vasomotion may be involved in retinal vascular disease. The purpose of this study was to investigate whether retinal vasomotion shows regional variation and is modified by activated autoregulation.

METHODS

Video recordings of the diameter of retinal arterioles previously obtained from 55 normal persons were subjected to Fourier analysis to characterize the frequencies and propagation of spontaneous diameter changes in retinal arterioles. The analyses were performed on peripapillary temporal retinal arterioles, on arteriolar branches toward the macular area and the retinal periphery, and were performed during rest, during an increase in the arterial blood pressure induced by isometric exercise, and during increased retinal metabolism induced by flickering light.

RESULTS

There was no propagation of diameter changes along the studied vascular segments. Isometric exercise constricted the arterioles significantly by (mean ± SD) 1.76% ± 3.56% (P = 0.02) and increased the power of diameter oscillations at very low frequencies (0.1-1.4 c/min). Flicker stimulation dilated the arterioles significantly by (mean ± SD) 5.10% ± 2.91% (P < 0.0001) and reduced the power of diameter oscillations at all but the very low frequencies (P < 0.006 for all comparisons). Flicker-induced dilation and changes in hydraulic conductance were lower in peripheral than in macular arterioles.

CONCLUSIONS

Retinal vasomotion in normal persons increases during increased arterial blood pressure and decreases during flicker stimulation. The findings may act as a basis for the study of vasomotion in retinal vascular disease.

Vision-related quality of life and visual ability in patients with autosomal dominant optic atrophy

PURPOSE

The purpose of the study was to evaluate vision-related quality of life and visual ability in patients with OPA1 autosomal dominant optic atrophy (ADOA).

METHODS

This cross-sectional, observational study included 145 participants with a mutation in the OPA1 gene associated with ADOA, 63 mutation-free first-degree relatives and 92 healthy subjects unrelated to the families. Participants underwent a clinical eye examination, and adult participants completed the National Eye Institute Visual Function Questionnaire (NEI-VFQ-39), while children completed the Cardiff Visual Ability Questionnaire for Children (CVAQC).

RESULTS

In adults with ADOA, both mean visual acuity (VA) and mean contrast sensitivity (CS) were significantly inferior to both first-degree relatives and unrelated controls (p < 0.001). In children with ADOA, mean VA was significantly lower compared with first-degree relatives (p = 0.0052), whereas CS was not (0.127). Adults with ADOA scored lower than both comparator groups on composite score (p < 0.001), general health subscale (p = 0.0075) and all vision-related subscales (p < 0.001) except the ocular pain subscale (p = 0.2). In children with ADOA, the median CVAQC logit score was significantly lower compared with first-degree relatives (p = 0.037). The science lessons subscale was significantly lower for children with ADOA compared with first-degree relatives (p = 0.046), as well as the language lessons subscale (p = 0.038). For adults, composite score and subscale scores were significantly associated with both VA, CS and fixation status.

CONCLUSION

OPA1 mutation is associated with lower quality of life and visual ability in patients with ADOA compared with both first-degree relatives and unrelated controls. VA, CS and fixation status affect quality of life in patients with ADOA.

Attendance in a national screening program for diabetic retinopathy: a population-based study of 205,970 patients

AIMS

A nationwide diabetic retinopathy (DR) screening program has been established in Denmark since 2013. We aimed to perform an evaluation of adherence to DR screenings and to examine whether non-adherence was correlated to DR progression.

METHODS

The population consisted of a register-based cohort, who participated in the screening program from 2013 to 2018. We analyzed age, gender, marital status, DR level (International Clinical DR severity scale, none, mild-, moderate-, severe non-proliferative DR (NPDR) and proliferative DR (PDR)), comorbidities and socioeconomic factors. The attendance pattern of patients was grouped as either timely (no delays > 33%), delayed (delays > 33%) or one-time attendance (unexplained).

RESULTS

We included 205,970 patients with 591,136 screenings. Rates of timely, delayed and one-time attendance were 53.0%, 35.5% and 11.5%, respectively. DR level at baseline was associated with delays (mild-, moderate-, severe NPDR and PDR) and one-time attendance (moderate-, severe NPDR and PDR) with relative risk ratios (RRR) of 1.68, 2.27, 3.14, 2.44 and 1.18, 2.07, 1.26, respectively (P < 0.05). Delays at previous screenings were associated with progression to severe NPDR or PDR (hazard ratio (HR) 2.27, 6.25 and 12.84 for 1, 2 and 3+ delays, respectively). Any given delay doubled the risk of progression (HR 2.28).

CONCLUSIONS

In a national cohort of 205,970 patients, almost half of the patients attended DR screening later than scheduled or dropped out after first screening episode. This was, in particular, true for patients with any levels of DR at baseline. DR progression in patients with delayed attendance, increased with the number of missed appointments.

Similarities and differences in systemic risk factors for retinal artery occlusion and retinal vein occlusion: A nationwide case-control study

BACKGROUND

To investigate the relationship between risk factors for retinal artery occlusion (RAO) and retinal vein occlusion (RVO) and thereby identify similarities and differences between the two types of retinal vascular occlusions.

METHODS

In this case-control study, 5708 patients with RAO were included and matched with three patients with RVO each. The patients with RVO were matched on sex and age at index date. All patients, personal information, diagnoses, and prescriptions were obtained from the Danish nationwide registries. Adjusted conditional logistic regression was used to investigate the association of RAO and RVO with the included risk factors.

RESULTS

RAO was stronger associated with arterial hypertension, heart failure, ischemic heart disease, peripheral artery disease, and stroke than RVO, with effect measures ranging from 1.10 to 2.21. RVO was associated with cataract and glaucoma with effect measures of 0.80 (95% CI 0.73-0.87) and 0.65 (95% CI 0.56-0.76), respectively.

CONCLUSION

Differences in the level of associations with the included risk factors suggests differences in the pathophysiologies of the two diseases. The main pathophysiology associated with RAO was atherosclerosis, whereas the main pathophysiology associated with RVO was changes in the pressure gradients of the eyes.

A review of risk factors for retinal vein occlusions

INTRODUCTION

Risk factors for retinal vein occlusion have been extensively studied, with varying population sizes. Smaller populations result in less certain measures of associations. The present review included studies with a relevant population size to identify clinically relevant risk factors for retinal vein occlusion. Understanding the risk factors of retinal vein occlusion is important for the management of these patients.

AREAS COVERED

A comprehensive literature review was conducted through a systematic literature search in PubMed and Embase. Additional studies were selected from cross references in the assessed studies. Weighted effect measures were calculated for all included risk factors.Risk factors associated with retinal vein occlusion included cardiovascular diseases, eye diseases, systemic diseases, medical interventions, and sociodemographic factors.

EXPERT OPINION

This review provided an extensive overview of a wide variety of risk factors increasing the risk of developing retinal vein occlusion. The severity of the identified risk factors indicated that these patients have been in contact with the health care system before their retinal vein occlusion event. Therefore, the clinical course for patients with retinal vein occlusion may benefit from a multidisciplinary collaboration between ophthalmologists and especially cardiologists.

Animal Models of Choroidal Neovascularization: A Systematic Review

Purpose

Animal models of choroidal neovascularization (CNV) are extensively used to characterize the pathophysiology of chorioretinal diseases with CNV formation and to evaluate novel treatment strategies. This systematic review aims to give a detailed overview of contemporary animal models of CNV.

Methods

A systematic search was performed in PubMed and EMBASE from November 20, 2015, to November 20, 2020, for mammalian animal models of CNV. Following inclusion by two investigators, data from the articles were extracted according to a predefined protocol.

Results

A total of 380 full articles, representing 409 independent animal models, were included. Mice were by far the most utilized animal (76%) followed by rats and non-human primates. The median age of rodents was 8 weeks but with a wide range. Male animals were used in 44% of the studies, but 32% did not report the sex. CNV was laser induced in 89% of the studies, but only 44% of these reported sufficiently on standard laser parameters. Surprisingly, 28% of the studies did not report a sample size for quantitative CNV evaluation. Less than half of the studies performed quantitative in vivo evaluation, and 73% evaluated CNV quantitatively ex vivo. Both in vivo and ex vivo evaluations were conducted primarily at day 7 and/or day 14.

Conclusions

The laser-induced mouse model is the predominant model for experimental CNV. The widespread use of young, healthy male animals may complicate clinical translation, and inadequate reporting challenges reproducibility. Definition and implementation of standardized methodologic and reporting guidelines are attractive.

Similarities and differences in systemic risk factors for retinal artery occlusion and stroke: A nationwide case-control study

BACKGROUND

Retinal artery occlusion (RAO) has been considered a stroke equivalent. This study compares risk factor profiles for thromboembolism among patients with RAO and stroke, respectively.

METHODS

This case-control study is based on 5683 RAO patients entered in the Danish National Patient Register between 1^st of January 2000 and 31^st of December 2018. Cases were matched on sex, year of birth, and age at event with 28,415 stroke patients. The Danish nationwide registries were used to collect information about age, sex, previous diagnoses, and drug prescriptions. Adjusted conditional logistic regression models were used to investigate the association between hypothesised risk factors and the patient outcome.

RESULTS

For atrial fibrillation, a substantially stronger association to stroke was found, with an odds ratio (OR) of 0.52 (95% CI: 0.47-0.58) when comparing RAO patients with stroke patients. RAO was stronger associated with arterial hypertension, peripheral artery disease, retinal vein occlusion, cataract, and glaucoma with OR's ranging from 1.21-11.70. The identified effect measures reached equivalence or was close to equivalence for diabetes, heart failure, ischemic heart disease, and renal disease.

CONCLUSION

The differences in risk factor profiles between RAO and stroke suggests differences in the pathophysiology of the two diseases. These variations in pathophysiologies between the two diseases may indicate that different interventions are needed to ensure the optimal long-term prognosis for the patients.

Nationwide Incidence of Thyroid Eye Disease and Cumulative Incidence of Strabismus and Surgical Interventions in Denmark

Importance

Thyroid eye disease (TED) is a serious condition that can cause proptosis and strabismus and, in rare cases, lead to blindness. Incidence data for TED and strabismus and surgical interventions after TED are sparce.

Objective

To investigate the nationwide incidence of TED, strabismus, and surgical interventions associated with TED.

Design, Setting, and Participants

A Danish nationwide registry-based cohort study between 2000, which marks the beginning of uniform coding for the decompression surgery nationwide, and 2018. The cohort consisted of a mean 4.3 million people aged 18 to 100 years with no prior TED diagnosis each year. Total observation time was 8.22 × 107 person-years (women, 4.18 × 107 person-years; men, 4.04 × 107 person-years).

Main Outcome Measures

The annual numeric and age-standardized incidence of hospital-treated TED and cumulative incidence of strabismus, strabismus surgery, and orbital decompression surgery in patients with TED. The incidence was stratified by sex, thyroid diagnosis, and age.

Results

A total of 4106 incident diagnoses of TED were identified during 19 years among 3344 women (81.4%) and 762 men (18.6%). The mean numeric annual nationwide incidence rate of TED was 5.0 per 100 000 person-years overall, 8.0 per 100 000 person-years in women, and 1.9 per 100 000 person-years in men, resulting in a 4:1 ratio of women to men with TED. The age-standardized incidence was similar. The mean (SD) age at onset was 51.3 (14.5) years. At the time of TED diagnosis, 611 patients (14.9%) were euthyroid, 477 (11.6%) were hypothyroid, and 3018 (73.5%) were hyperthyroid. In patients with TED who were euthyroid, the 4-year cumulative incidence was 41% for antithyroid medication and 13% for L-thyroxine. In patients with TED, the 4-year cumulative incidence for strabismus was 10%. The 4-year cumulative incidence of surgical interventions after TED was 8% for strabismus surgery and 5% for orbital decompression. At 4 years, strabismus surgery was more common in men (13.3%; 95% CI, 10.75-15.86) than in women (7.2%; 95% CI, 6.24-8.08), and the absolute difference was 6.1% (95% CI, 3.42-8.14; P < .001).

Conclusions and Relevance

This study in Denmark provides nationwide empirical incidence of TED and strabismus and surgical interventions after TED that required inpatient or outpatient hospital treatment, and might be used for patient information and health care planning.

The risk for developing vision-threatening retinopathy after cataract surgery in diabetic patients depends on the postoperative follow-up time

PURPOSE

To identify parameters that can predict the postoperative risk for progression of retinopathy to a vision-threatening stage after cataract surgery. This may optimize the timing of surgery and the postoperative follow-up strategy in diabetic patients.

METHODS

Multi-state survival analysis with death as competing risk was used to investigate how year of onset and age of onset of diabetes, gender, body mass index, HbA1c and blood pressure had affected the risk for developing diabetic macular oedema (DME) and proliferative diabetic retinopathy (PDR) among 2540 right eyes from 2797 diabetic patients operated for cataract on one or both eyes during 25 years until July 1. 2019.

RESULTS

Cataract surgery had been performed in 98.8% of patients reaching 90 years of age. The risk for developing both DME and PDR was increased by cataract surgery. The risk was highest during the first postoperative years and increased by pre-operative variability in HbA1c. The risk after more than 20 years postoperatively increased by increased cumulative HbA1c pre-operatively. The other studied risk factors contributed differently to the development of the two complications.

CONCLUSIONS

Decision models for the timing of cataract surgery in diabetic patients should consider that the risk for developing vision-threatening retinopathy depends on follow-up time. Differences in the risk profiles for developing DME and PDR after cataract surgery support that the two complications should be regarded as separate late complications.

Lack of predictive value of retinal oxygen saturation for visual outcome after angiostatic treatment of branch retinal vein occlusion

PURPOSE

Previous studies have shown that the retinal oxygen saturation in central retinal vein occlusion treated with anti-VEGF compound has no predictive value for visual outcome after 12 months. It is of interest to evaluate whether this conclusion is similar for patients with branch retinal vein occlusion among whom only some patients are treated.

METHODS

Retinal oxygen saturation, visual acuity and central retinal thickness were studied at the time of referral and after six and 12 months in 111 patients successively referred to the Department of Ophthalmology, Aarhus University Hospital, with a venous occlusion affecting branches peripheral from the central retinal venule. The predictive value of the oxygen saturation at referral was investigated in treated and untreated patients.

RESULTS

Seventy-three patients with visual acuity between 35 and 70 ETDRS letters at referral were treated with intravitreal injection of anti-VEGF compound. Over 12 months, the venous oxygen saturation improved in parallel with central retinal thickness and visual acuity but had no predictive value for visual outcome. In 12 untreated patients with visual acuity >70 ETDRS letters, younger age and high oxygen saturation at the time of referral were positive predictors for the visual outcome after 12 months.

CONCLUSION

Oxygen saturation, visual acuity and central retinal thickness improve in parallel during treatment of branch retinal vein occlusion with intravitreal anti-VEGF medication. Retinal oximetry at referral cannot predict visual acuity after 12 months in treated patients but may perhaps become a tool for predicting the visual prognosis in a subgroup of patients where treatment is omitted because of a too high visual acuity at the time of diagnosis of the disease.

The risk for developing vision threatening diabetic retinopathy is influenced by heredity to diabetes

Purpose: Clustering of vision threatening diabetic retinopathy within specific families can be the result of similarities in life style but may also be due to a common genetic background. An evaluation of the role of heredity for the development of diabetic retinopathy may help adjusting control intervals in screening programmes to each patient's individual risk profile.Methods: Survival analysis was used to study whether family history of diabetes among men and women with type 1 or type 2 diabetes together with the degree of heredity could be added as risk factors to improve the prediction of the risk for developing proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME). The study was conducted on data from 12,281 patients followed in the Aarhus area, Denmark, from January 1. 2003 to July 1. 2019.Results: The risk for developing PDR was significantly reduced 2-11 years after known onset of diabetes in the presence of female family members with type 1 diabetes, and the risk for developing DME significantly increased 4-24 years after onset of diabetes in the presence of family members with type 2 diabetes of any sex. These hereditary factors were independent of other studied risk factors such as previous cataract surgery, age of onset of diabetes, metabolic regulation and blood pressure.Conclusions: The presence of family members with diabetes affects the risk for developing vision threatening diabetic retinopathy and affects the risk for developing PDR and DME differently. This evidence may help individualizing the control intervals in screening programmes for diabetic retinopathy.

Clinical risk factors for retinal artery occlusions: a nationwide case-control study

PURPOSE

This study seeks to examine potential risk factors for the development of retinal artery occlusions (RAO).

METHODS

We used data obtained from Danish nationwide registries to evaluate potential risk factors for RAO present up to 5 years prior to the RAO diagnosis. The study included 5312 patients diagnosed with RAO registered in the Danish National Patient Register and 26,560 controls assessed from the general population matched on sex and age at index date. Adjusted conditional logistic regression was used to estimate the odds ratio of included risk factors for RAO diagnosis. We conducted supplementary analyses stratified on sex and age, and on RAO subtype. In addition, interaction analyses were performed between strata in the stratified analyses.

RESULTS

Risk factors associated with the development of RAO included diabetes, arterial hypertension, ischemic heart disease, peripheral artery disease, stroke, renal disease, cataract, and glaucoma, with ORs ranging from 1.33 to 4.94. Atrial fibrillation and sleep apnea yielded effect measures close to equivalence. The presence of a risk factor was generally associated with higher odds of RAO among the population ≤ 55 of age. Arterial hypertension was stronger associated with RAO in male patients than in female patients. The association with arterial hypertension was stronger for CRAO than for BRAO subtype.

CONCLUSION

The investigated risk factors suggest that atherosclerosis and conditions changing the intraocular pressure are involved in the pathophysiology of RAO.

Diabetic Retinopathy Predicts Risk of Alzheimer’s Disease: A Danish Registry-Based Nationwide Cohort Study

Background:

Retinal neurodegeneration is evident in early diabetic retinopathy (DR) which may be associated with other neurodegenerative diseases like Alzheimer's disease (AD).

Objective:

To investigate diabetes and DR as a risk marker of present and incident AD.

Methods:

A register-based cohort study was performed. We included 134,327 persons with diabetes above 60 years of age, who had attended DR screening, and 651,936 age- and gender-matched persons without diabetes.

Results:

At baseline, the prevalence of AD was 0.7% and 1.3% among patients with and without diabetes, respectively. In a multivariable regression model, patients with diabetes were less likely to have AD at baseline (adjusted OR 0.63, 95% CI 0.59–0.68). During follow-up, incident AD was registered for 1473 (0.35%) and 6,899 (0.34%) persons with and without diabetes, respectively. Compared to persons without diabetes, persons with diabetes and no DR had a lower risk to develop AD (adjusted HR 0.87, 95% CI 0.81–0.93), while persons with diabetes and DR had higher risk of AD (adjusted HR 1.24, 95% CI 1.08–1.43). When persons with diabetes and no DR were used as references, a higher risk of incident AD was observed in persons with DR (adjusted HR 1.34, 95% CI 1.18–1.53).

Conclusion:

Individuals with diabetes without DR were less likely to develop AD compared to persons without diabetes. However, individuals with DR had a 34% higher risk of incident AD, which raise the question whether screening for cognitive impairment should be done among individuals with DR.

Retinal oximetry does not predict 12-month visual outcome after anti-VEGF treatment for central retinal vein occlusion: A multicentre study

PURPOSE

Central retinal vein occlusion (CRVO) entails retinal hypoxia that often causes visual impairment. It has been shown that oxygen saturation in larger retinal vessels correlates with the visual acuity at the time of diagnosis of CRVO but has no predictive value for the visual outcome in patients treated with anti-VEGF medication after 3 months. However, assessing the predictive value of retinal oxygen saturation after 12 months is essential because this is when the main restitution after CRVO occurs.

METHODS

Retinal oximetry was performed in 117 patients referred with CRVO to three European centres. The correlation between oxygen saturation and visual acuity at baseline and the predictive value of oxygen saturation in larger retinal vessels for the 12-month visual outcome after treatment with anti-VEGF medication were studied.

RESULTS

In the affected eye, the oxygen saturation was significantly higher in the arterioles, significantly lower in the venules, and the arterio-venous (A-V) significantly higher than in the unaffected eye (p < 0.001 for all comparisons). Correlations between best-corrected visual acuity (BCVA) and oxygen saturations were moderate and negative for arterioles (p < 0.001), positive for venules (p = 0.03) and negative for the A-V difference (p = 0.001). Best-corrected visual acuity (BCVA), but not oxygen saturation or the other explanatory variables at baseline, contributed significantly to predicting BCVA after 12 months.

CONCLUSION

Retinal vessel oxygen saturation is affected in CRVO, and saturation correlates with BCVA. However, retinal oximetry cannot replace measures of visual function as a predictor of visual outcome after 12 months of anti-VEGF treatment for CRVO.

Increasing metabolic variability increases the risk for vitrectomy in proliferative diabetic retinopathy

PURPOSE

Proliferative diabetic retinopathy (PDR) can be treated by retinal photocoagulation, but in some cases, the treatment is initiated too late or is insufficient so that the disease advances to a stage requiring vitrectomy. There is a need to identify risk factors that can predict if patients with PDR will develop complications in need for vitrectomy.

METHODS

Survival analysis with death as competing risk was used to study systemic risk factors for PDR progression to a complication in need for vitrectomy in right eyes of all 1288 diabetic patients from the Aarhus area, Denmark, who had developed proliferative retinopathy in the right eye during the 25 years period from 1 July 1994 until 1 July 2019.

RESULTS

The overall cumulative incidence of reaching a vitrectomy end point in the right eye was 24.1% (n = 311). In 9.3% (n = 120) of the patients where vitrectomy had been performed together with the first photocoagulation, the age of onset of diabetes was significantly higher (p < 0.0001), the diabetes duration longer (p < 0.035) and BMI higher (p < 0.01) than in the patients who had been vitrectomized later than the first photocoagulation. The risk for vitrectomy was significantly increased by high variability of HbA1c before the development of PDR (p < 0.0001), but not by other parameters known to increase the risk for developing PDR.

CONCLUSION

Increasing variability of HbA1c before the development of PDR increases the risk for progression to a complication in need of vitrectomy. The need for vitrectomy is unaffected by other risk factors known to increase the risk for developing PDR.

ATP induced calcium signaling activity in perivascular cells differ at different vascular branch levels in the porcine retina

BACKGROUND

The purine adenosine triphosphate (ATP) plays a significant role in retinal blood flow regulation and recent evidence suggests that the vasoactive effect of the compound differs in vessels at different branching level. However, the cellular basis for the regulation of retinal blood flow mediated by ATP has only been scarcely studied.

METHODS

Perfused porcine hemiretinas (n = 60) were loaded with the calcium-sensitive fluorophore Oregon Green ex vivo. Spontaneous oscillations in fluorescence were studied in perivascular cells at five different vascular branching levels ranging from the main arteriole to the capillaries, before and after the addition of intra- and extravascular ATP alone or in the presence of a P2-purinergic receptor antagonist.

RESULTS

Intravascular ATP induced an overall significant (p < 0.01) constriction of (mean ± SD) -9.79 ± 13.40% and extravascular ATP an overall significant (p < 0.01) dilatation of (mean ± SD) 19.62 ± 13.47%. Spontaneous oscillations of fluorescence in perivascular cells were significantly more intense around third order arterioles than around vessels at both lower and higher branching levels (p < 0.05 for all comparisons). ATP increased intracellular fluorescence in perivascular cells of first and second order arterioles after extravascular application, and the increase correlated with the accompanying vasodilatation (p < 0.03). Blocking of P2-receptors reduced oscillating fluorescence in pre-capillary arterioles secondary to intravascular ATP (p = 0.03).

CONCLUSIONS

Spontaneous oscillations of calcium-sensitive fluorescence in perivascular retinal cells differ at different vascular branching levels. Extravascular ATP increases fluorescence in cells around the larger retinal arterioles exposed to the retinal surface. Future studies should investigate calcium signaling activity in perivascular retinal cells during interventions that simulate retinal pathology such as hypoxia.

Subretinal Saline Protects the Neuroretina From Thermic Damage During Laser Induction of Experimental Choroidal Neovascularization in Pigs

Purpose

The purpose of this study was to develop a porcine model for photocoagulation induced choroidal neovascularization (CNV) with high success rate and minimal thermic damage to the neuroretina.

Methods

Experimental CNV was induced by laser photocoagulation in both eyes of 16 domestic pigs. In the left eyes, photocoagulation was preceded by subretinal injection of saline to protect the neuroretina from thermic damage, whereas the right eyes were treated with photocoagulation only. The development of the CNV after 3, 7, 14, 28, and 42 days was evaluated by optical coherence tomography (OCT) scanning, fluorescein angiography, and OCT angiography, and by histology after enucleation.

Results

From day 7 after the photocoagulation, OCT showed subretinal density in all lesions of 14 alive animals, and either fluorescein or OCT angiography confirmed CNV formation in 11 of 14 of the eyes that had received photocoagulation alone and those in which photocoagulation had been preceded by subretinal injection of saline. In all cases pretreated with subretinal saline, the neuroretina was protected from immediate thermic damage. The formation of CNVs were confirmed by histology. For both groups, the largest lesions were observed within 14 days after photocoagulation.

Conclusions

Injection of subretinal saline can protect the retina from thermic damage induced by retinal photocoagulation without reducing the success rate in producing experimental CNV. The effect of interventional studies aimed at reducing photocoagulation induced experimental CNV in pigs can be evaluated within 2 weeks after photocoagulation.

Translational Relevance

This model provides a fundament to develop and evaluate novel treatment methods for neovascular retinal diseases.

Retinal oxygen saturation changes progressively over time in diabetic retinopathy

PURPOSE

According to cross-sectional studies, oxygen saturation is elevated in retinal vessels in diabetic patients. We evaluated how retinal oxygenation (metabolic marker), vessel diameters and retinopathy grade (structural markers) change over time in diabetic patients.

DESIGN

Prospective cohort study following screening in a hospital setting.

METHODS

Retinal oximetry images were acquired in 214 patients with the Oxymap T1 oximeter. Imaging was repeated after a median of 3.0 years (range 0.76-6.8 years). Oxygen saturation and vessel diameters were measured in the right eye. Semiquantitative grading of retinopathy according to international guidelines and red lesion count were performed on fundus photographs.

RESULTS

Retinopathy grade according to the international semiquantitative grading system was unchanged. Arteriolar saturation increased by 0.75±0.15 percentage points per year of follow-up (p<0.0001). Venular saturation increased by 1.74±0.26 percentage points per year (p<0.0001) and arteriovenous difference decreased by 0.99±0.20 percentage points per year (p<0.0001). Arteriolar diameters decreased by 2.7±8.5μm (p<0.0001) between visits and venular diameters decreased by 2.4±9.1μm (p = 0.0002). Median increase in red lesion count between visits was 2 lesions (range -128 to 212 lesions, p<0.0001). The change in red lesion count and change in diameters did not correlate with the length of follow-up (p>0.44).

CONCLUSIONS

Oxygen saturation in larger retinal vessels can increase and arteriovenous difference can decrease over time in diabetic patients without any observable changes in retinopathy grade. The results suggest that changes in retinal oxygen saturation may precede progression of diabetic retinopathy or that oxygen saturation is more sensitive to disease progression than retinopathy grade.

Differential Effects of Intra- and Extravascular ATP on the Diameter of Porcine Vessels at Different Branching Levels Ex Vivo

Purpose

Adenosine triphosphate (ATP) is involved in the diameter regulation of retinal vessels. The compound has been shown to induce both constriction and dilatation, but the detailed mechanisms underlying these effects and the site of action of the compound are not known in detail. Therefore, the purpose of the present study was to investigate whether the vasoactive effects of ATP on retinal vessels depend on intra- and extravascular application, and to study whether the effects differ at different vascular branching levels.

Methods

Diameter changes in arterioles, pre-capillary arterioles, and capillaries were studied in perfused porcine hemiretinas (n = 48) ex vivo after intra- and extravascular application of the nondegradable ATP analogue ATP-γ-S or ATP in the presence or not of antagonists to the CD73/ecto-5′-nucleotidase (AOPCP), the P2-purinergic receptor (PPADS), the A3-adenosine receptor (MRS1523), and the synthesis of cyclooxygenase products (ibuprofen).

Results

Intravascular ATP-induced constriction and extravascular ATP-induced dilatation of retinal arterioles, pre-capillary arterioles and capillaries, and dilatation was inhibited by ibuprofen. Both constriction and dilatation of arterioles were inhibited by antagonizing ATP degradation. Furthermore, constriction at all three branching levels was antagonized by blocking the A3 purinoceptor, whereas constriction in arterioles and pre-capillary arterioles was antagonized by blocking the P2 purinoceptor.

Conclusions

ATP affects the diameter of retinal arterioles, pre-capillary arterioles, and capillaries through different pathways, and the effects depend on whether the compound is administered intravascularly or extravascularly. This may form the basis for selective interventions on retinal vascular disease with differential involvement of vessels at different branching levels.

Vergence Exercises for Six Weeks Induce Faster Recovery of Convergence Insufficiency Than Accommodation Exercises in School Children

Purpose

Convergence insufficiency (CI) is characterized by abnormal vergence eye movement frequently accompanied by abnormal accommodation and subjective symptoms, such as headache, blurred vision, and diplopia. CI is treated with vergence and accommodation exercises that are integrated so that the relative contributions of vergence and accommodation exercises to the outcome are concealed. The purpose of the present study was to determine the individual contributions of vergence and accommodation exercises for the treatment of CI in school children.

Methods

In a prospective crossover study 44 children aged 9 to 13 years with CI were randomized to perform either vergence exercises followed by accommodation exercises each for 6 weeks or the 2 treatment regimes in the reverse order. The outcome measures were recovery from CI and the parameters vergence facility, positive fusional vergence, near point of convergence, monocular amplitude, and facility of accommodation.

Results

After the first 6-week period, full recovery from CI was significantly more frequent in the group commencing vergence exercises than in the group commencing monocular accommodation exercises (p = 0.01), whereas there was no significant difference between these proportions after the second 6-week period (p = 0.45). Vergence facility and positive fusional vergence improved significantly more after the period with vergence exercises than after the accommodation exercises, whereas there was no significant difference between the effects of the two types of exercises on the other studied parameters.

Conclusions

Vergence treatment induces a faster recovery of CI than accommodation treatment in school children. This may be used to improve compliance and success rate of the treatment.

Reduced Oxygen Extraction in the Retinal Periphery When the Arterial Blood Pressure Is Increased by Isometric Exercise in Normal Persons

Purpose

Recent evidence suggests that the smaller retinal vessels are significantly involved in the regulation of retinal blood flow and that this regulation may differ among the macular area and the retinal periphery. An alternative to studying blood flow regulation in smaller retinal vessels that are difficult to resolve is to assess the metabolic consequences of changes in the microcirculation using oximetry.

Methods

In 20 normal persons aged (mean ± SD, range) 30.1 ± 3.8 (24–37) years, the oxygen saturation and diameter of retinal arterioles and venules to the macular area and the retinal periphery were studied before and during an increase in the arterial blood pressure induced by isometric exercise.

Results

The isometric exercise increased the mean arterial blood pressure by (mean ± SEM) 10.0 ± 1.1 mm Hg but induced no significant changes in the diameter of the arterioles (P = 0.83). The isometric exercise had no significant effect on the oxygen saturation in the arterioles supplying the macular area and the retinal periphery (P > 0.42 for both comparisons). However, there was a significant increase in the oxygen saturation in venules draining the retinal periphery to reduce the oxygen extraction from (mean ± SEM) 36.0% ± 2.3% to 30.6% ± 2.1% (P = 0.002) but no significant change in the preexisting low oxygen extraction in the macular area that changed from (mean ± SEM) 18.2% ± 3.0% to 16.2% ± 1.9% (P = 0.37).

Conclusions

Minor changes in the arterial blood pressure can induce changes in retinal rheology with significant regional variation. The finding may help explain regional variations in manifestations of retinal vascular disease such as hyperpermeability in the macular area and capillary occlusion in the retinal periphery.

Inverse Cross-sectional and Longitudinal Relationships between Diabetic Retinopathy and Obstructive Sleep Apnea in Type 2 Diabetes

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Systemic risk factors contribute differently to the development of proliferative diabetic retinopathy and clinically significant macular oedema

AIMS/HYPOTHESIS

The purpose of screening for diabetic retinopathy is to detect either of the two sight-threatening complications: proliferative diabetic retinopathy (PDR) or clinically significant diabetic macular oedema (DME). The aim of the study was to evaluate whether systemic risk factors affect the risk of developing these two complications differently.

METHODS

Survival analysis with death as a competing risk was used to describe the effect of sex, age and time of onset of diabetes, systolic (SBP) and diastolic (DBP) BPs, and the weighted exposure and CV of HbA_1c for the development of PDR and DME from all 2773 patients treated for diabetic retinopathy in a defined population from the Aarhus area, Denmark, between 1 July 1994 and 1 July 2019.

RESULTS

Increasing HbA_1c above normal increased the risk of developing both PDR and DME (p < 0.04), and values below normal increased the risk of developing PDR (p < 0.013). Increasing DBP increased the risk of developing both PDR and DME (p < 0.0001), whereas increasing SBP increased the risk of developing DME (p < 0.0001), but not PDR (p > 0.08). The risk of developing PDR increased with decreasing age of onset of diabetes (p < 0.0001), whereas the risk of developing DME was maximal for a known onset of diabetes at about 30 years of age and decreased significantly for both lower and higher ages of onset (p < 0.0001). The risk of developing both PDR and DME was lower in women than in men (p < 0.004) and was reduced with lower variability of repeated HbA_1c measurements (p < 0.0001).

CONCLUSIONS/INTERPRETATION

Systemic risk factors such as metabolic regulation, arterial BP and the age of onset of diabetes contribute differently to the development of PDR and DME. The overall risk of developing treatment-requiring diabetic retinopathy should be calculated from the risks of reaching each of the two complications separately.