Association of lipid-lowering drugs and antidiabetic drugs with age-related macular degeneration: a meta-analysis in Europeans

BACKGROUND/AIMS

To investigate the association of commonly used systemic medications with prevalent age-related macular degeneration (AMD) in the general population.

METHODS

We included 38 694 adults from 14 population-based and hospital-based studies from the European Eye Epidemiology consortium. We examined associations between the use of systemic medications and any prevalent AMD as well as any late AMD using multivariable logistic regression modelling per study and pooled results using random effects meta-analysis.

RESULTS

Between studies, mean age ranged from 61.5±7.1 to 82.6±3.8 years and prevalence ranged from 12.1% to 64.5% and from 0.5% to 35.5% for any and late AMD, respectively. In the meta-analysis of fully adjusted multivariable models, lipid-lowering drugs (LLD) and antidiabetic drugs were associated with lower prevalent any AMD (OR 0.85, 95% CI=0.79 to 0.91 and OR 0.78, 95% CI=0.66 to 0.91). We found no association with late AMD or with any other medication.

CONCLUSION

Our study indicates a potential beneficial effect of LLD and antidiabetic drug use on prevalence of AMD across multiple European cohorts. Our findings support the importance of metabolic processes in the multifactorial aetiology of AMD.

From randomised controlled trials to real-world data: Clinical evidence to guide management of diabetic macular oedema

Randomised clinical trials (RCTs) are generally considered the gold-standard for providing scientific evidence for treatments' effectiveness and safety but their findings may not always be generalisable to the broader population treated in routine clinical practice. RCTs include highly selected patient populations that fit specific inclusion and exclusion criteria. Although they may have a lower level of certainty than RCTs on the evidence hierarchy, real-world data (RWD), such as observational studies, registries and databases, provide real-world evidence (RWE) that can complement RCTs. For example, RWE may help satisfy requirements for a new indication of an already approved drug and help us better understand long-term treatment effectiveness, safety and patterns of use in clinical practice. Many countries have set up registries, observational studies and databases containing information on patients with retinal diseases, such as diabetic macular oedema (DMO). These DMO RWD have produced significant clinical evidence in the past decade that has changed the management of DMO. RWD and medico-administrative databases are a useful resource to identify low frequency safety signals. They often have long-term follow-up with a large number of patients and minimal exclusion criteria. We will discuss improvements in healthcare information exchange technologies, such as blockchain technology and FHIR (Fast Healthcare Interoperability Resources), which will connect and extend databases already available. These registries can be linked with existing or emerging retinal imaging modalities using artificial intelligence to aid diagnosis, treatment decisions and provide prognostic information. The results of RCTs and RWE are combined to provide evidence-based guidelines.

Association of Systemic Medication Use with Glaucoma and Intraocular Pressure: The European Eye Epidemiology Consortium

PURPOSE

To investigate the association of commonly used systemic medications with glaucoma and intraocular pressure (IOP) in the European population.

DESIGN

Meta-analysis of 11 population-based cohort studies of the European Eye Epidemiology Consortium.

PARTICIPANTS

The glaucoma analyses included 143 240 participants and the IOP analyses included 47 177 participants.

METHODS

We examined associations of 4 categories of systemic medications-antihypertensive medications (β-blockers, diuretics, calcium channel blockers [CCBs], α-agonists, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers), lipid-lowering medications, antidepressants, and antidiabetic medications-with glaucoma prevalence and IOP. Glaucoma ascertainment and IOP measurement method were according to individual study protocols. Results of multivariable regression analyses of each study were pooled using random effects meta-analyses. Associations with antidiabetic medications were examined in participants with diabetes only.

MAIN OUTCOME MEASURES

Glaucoma prevalence and IOP.

RESULTS

In the meta-analyses of our maximally adjusted multivariable models, use of CCBs was associated with a higher prevalence of glaucoma (odds ratio [OR], 1.23; 95% confidence interval [CI], 1.08 to 1.39). This association was stronger for monotherapy of CCBs with direct cardiac effects (OR, 1.96; 95% CI, 1.23 to 3.12). No other antihypertensive medications, lipid-lowering medications, antidepressants, or antidiabetic medications were associated with glaucoma. Use of systemic β-blockers was associated with a lower IOP (β coefficient, -0.33 mmHg; 95% CI, -0.57 to -0.08 mmHg). Monotherapy of both selective systemic β-blockers (β coefficient, -0.45 mmHg; 95% CI -0.74 to -0.16 mmHg) and nonselective systemic β-blockers (β coefficient, -0.54 mmHg; 95% CI, -0.94 to -0.15 mmHg) was associated with lower IOP. A suggestive association was found between use of high-ceiling diuretics and lower IOP (β coefficient, -0.30 mmHg; 95% CI, -0.47 to -0.14 mmHg) but not when used as monotherapy. No other antihypertensive medications, lipid-lowering medications, antidepressants, or antidiabetic medications were associated with IOP.

CONCLUSIONS

We identified a potentially harmful association between use of CCBs and glaucoma prevalence. Additionally, we observed and quantified the association of lower IOP with systemic β-blocker use. Both findings potentially are important, given that patients with glaucoma frequently use systemic antihypertensive medications. Determining causality of the CCB association should be a research priority.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Impact of COVID-19 lockdown on surgical procedures for retinal detachment in France: a national database study

BACKGROUND/AIMS

The COVID-19 crisis and the decisions made regarding population lockdown may have changed patient care. We aimed to investigate the incidence rate of rhegmatogenous retinal detachment (RRD) cases during the COVID-19 lockdown period.

METHODS

In this nationwide database study, we identified hospital and clinic admissions of French residents for a first episode of RRD in France from 2017 to the lockdown period in 2020. The monthly hospital incidence rates of RRD procedures per 100 000 inhabitants before, during and after lockdown were computed for the whole country. Finally, we assessed the influence of viral incidence on the RRD incidence rate, comparing two regions with highly contrasting viral penetration.

RESULTS

From January to July, the average monthly national hospital incidence rate of RRD decreased from a mean of 2.59/100 000 inhabitants during 2017-2019 to 1.57/100 000 inhabitants in 2020. Compared with 2019, during the 8-week lockdown period in 2020, a 41.6% decrease in the number of RRD procedures was observed (p<0.001) with the weekly incidence of RRD decreasing from 0.63/100 000 inhabitants in 2019 to 0.36/100 000 inhabitants. During the 4-month post-lockdown period, no increased activity related to postponed procedures was observed. No difference was found in the rate of RRD surgery when comparing two regions with highly contrasting viral incidence.

CONCLUSION

Containment may have been responsible for a decrease in the number of surgical procedures for RRD, without any compensating post-lockdown activity in France. These results might help increase awareness of the management of RRD emergencies.

Modification of erythrocyte membrane phospholipid composition in preterm newborns with retinopathy of prematurity: The omegaROP study

N-3 polyunsaturated fatty acids (PUFAs) may prevent retinal vascular abnormalities observed in oxygen-induced retinopathy, a model of retinopathy of prematurity (ROP). In the OmegaROP prospective cohort study, we showed that preterm infants who will develop ROP accumulate the n-6 PUFA arachidonic acid (ARA) at the expense of the n-3 PUFA docosahexaenoic acid (DHA) in erythrocytes with advancing gestational age (GA). As mice lacking plasmalogens ―That are specific phospholipids considered as reservoirs of n-6 and n-3 PUFAs― Display a ROP-like phenotype, the aim of this study was to determine whether plasmalogens are responsible for the changes observed in subjects from the OmegaROP study. Accordingly, preterm infants aged less than 29 weeks GA were recruited at birth in the Neonatal Intensive Care Unit of University Hospital Dijon, France. Blood was sampled very early after birth to avoid any nutritional influence on its lipid composition. The lipid composition of erythrocytes and the structure of phospholipids including plasmalogens were determined by global lipidomics using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). LC-HRMS data confirmed our previous observations by showing a negative association between the erythrocyte content in phospholipid esterified to n-6 PUFAs and GA in infants without ROP (rho = −0.485, p = 0.013 and rho = −0.477, p = 0.015 for ethanolamine and choline total phospholipids, respectively). Phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) species with ARA, namely PtdCho16:0/20:4 (rho = −0.511, p < 0.01) and PtdEtn18:1/20:4 (rho = −0.479, p = 0.015), were the major contributors to the relationship observed. On the contrary, preterm infants developing ROP displayed negative association between PtdEtn species with n-3 PUFAs and GA (rho = −0.380, p = 0.034). They were also characterized by a positive association between GA and the ratio of ethanolamine plasmalogens (PlsEtn) with n-6 PUFA to PlsEtn with n-3 PUFAs (rho = 0.420, p = 0.029), as well as the ratio of PlsEtn with ARA to PlsEtn with DHA (rho = 0.843, p = 0.011). Altogether, these data confirm the potential accumulation of n-6 PUFAs with advancing GA in erythrocytes of infants developing ROP. These changes may be partly due to plasmalogens.

Twelve-month outcomes of ranibizumab versus aflibercept for macular oedema in branch retinal vein occlusion: data from the FRB! registry

BACKGROUND/AIMS

To compare the efficacy of ranibizumab (0.5 mg) with aflibercept (2 mg) in the treatment of cystoid macular oedema due to branch retinal vein occlusion (BRVO) over 12 months.

METHODS

A multicentre, international, database observational study recruited 322 eyes initiating therapy in real-world practice over 5 years. The main outcome measure was mean change in EDTRS letter scores of visual acuity (VA). Secondary outcomes included anatomic outcomes, percentage of eyes with VA >6/12 (70 letters), number of injections and visits, time to first inactivity, switching or non-completion.

RESULTS

Generalised mixed effect models demonstrated that mean (95% CI) adjusted 12-month VA changes for ranibizumab and aflibercept were similar (+10.8 (8.2 to 13.4) vs +10.9 (8.3 to 13.5) letters, respectively, p=0.59). The mean adjusted change in central subfield thickness (CST) was greater for aflibercept than ranibizumab (-170 (-153 to -187) µm vs -147 (-130 to -164) µm, respectively, p=0.001). The overall median (Q1, Q3) of 7 (4, 8) injections and 9 (7, 11) visits was similar between treatment groups. First grading of inactivity occurred sooner with aflibercept (p=0.01). Switching was more common from ranibizumab (37 eyes, 23%) than from aflibercept (17 eyes, 11%; p=0.002).

CONCLUSION

Visual outcomes at 12 months in this direct comparison of ranibizumab and aflibercept for BRVO in real-world practice were generally good and similar for the 2 drugs, despite a greater effect of aflibercept on CST and time to first grading of inactivity.

Incidence of rhegmatogenous retinal detachment in France from 2010 to 2016: seasonal and geographical variations

AIMS

To investigate the annual and monthly hospital incidence rate of rhegmatogenous retinal detachments (RRDs) from 2010 to 2016 in France at the national and regional levels.

METHODS

In this nationwide database study, we identified hospital and clinic admissions of French residents for a first episode of RRD in France during 2010-2016 from the national administrative database. The annual and monthly hospital incidence rates of RRD per 100 000 population were calculated for the whole country and for each region.

RESULTS

The average annual national hospital incidence rate of RRD was 21.97±1.04 per 100 000 population. The annual national hospital incidence rate of RRD was the lowest in 2010 (20.91 per 100 000 population) after which it increased until 2015 (23.55 per 100 000 population). The average monthly national RRD hospital incidence rate was the highest in June (2.03±0.12 per 100 000 population) and the lowest in August (1.60±0.09). The average annual age-standardised and sex-standardised regional hospital incidence rate was the highest in Guadeloupe and Pays de la Loire (28.30±2.74 and 26.13±0.84 per 100 000 population, respectively) and the lowest in French Guiana and Martinique (15.51±3.50 and 17.29±2.12 per 100 000 population, respectively).

CONCLUSIONS

The average annual national hospital incidence rate of RRD increased from 2010 to 2015. The hospital incidence rate of RRD seemed to vary according to season and geographical location.

Accuracy of the ISNT rule and its variants for differentiating glaucomatous from normal eyes in a population-based study

AIMS

To evaluate the accuracy of the ISNT rule (I=inferior, S=superior, N=nasal, T=temporal) and its variants with neuroretinal rim width and retinal nerve fibre layer (RNFL) thickness measurements differentiating normal from glaucomatous eyes.

METHODS

The diagnosis accuracy of the ISNT rule and its variants was evaluated in a population-based study. Neuroretinal rim widths were measured on monoscopic optic disc photographs with an image-processing program. RNFL thickness measurements were obtained with spectral-domain optical coherence tomography (SD-OCT).

RESULTS

In this study including 940 normal subjects and 93 patients with glaucoma, the sensitivity of the ISNT rule with optic disc photographs was 94.1% (95% CI 90.2 to 98.1), whereas its specificity was 49.2% (46.9 to 51.6). When using the IST rule, the sensitivity decreased to 69.9% (62.1 to 77.6) with a higher specificity, 87.0% (85.3 to 88.6). All the diagnosis indicators were somewhat lower for the different rules using RNFL thickness: the sensitivity of the ISNT rule was 79.4% (72.6 to 86.2) and its specificity was 34.1% (31.9 to 36.4). With the IST rule, the sensitivity decreased to 50.0% (41.6 to 58.4) while the specificity increased to 64.9% (62.7 to 67.2).

CONCLUSIONS

The ISNT and IST rules applied to neuroretinal rim width measurement by optic disc photographs are useful and simple tools for differentiating normal from glaucomatous eyes. The translation of these rules to RNFL thickness by SD-OCT is of limited value.

Is combined cataract surgery associated with acute postoperative endophthalmitis? A nationwide study from 2005 to 2014

PURPOSE

To assess the incidence of acute postoperative endophthalmitis (POE) after cataract surgery combined with corneal, glaucoma or vitreoretinal surgical procedures from 2005 to 2014 in France.

METHODS

In this cohort study, acute POE occurring within 6 weeks after surgery was identified by means of billing codes recorded in a national database in patients operated for cataract extraction with phacoemulsification, or corneal, glaucoma or vitreoretinal surgical procedures, either combined or stand-alone.

RESULTS

From January 2005 to December 2014, up to 6 260 477 eyes underwent phacoemulsification cataract surgery as a single procedure and 115 468 eyes underwent phacoemulsification combined with corneal, glaucoma or vitreoretinal surgical procedures. The crude incidence of acute POE after stand-alone or combined cataract surgery was 0.102% and 0.149%, respectively. In multivariate Poisson analysis, combined surgery taken as a whole was at higher risk than cataract stand-alone surgery, with an adjusted incidence rate ratio (IRR) (95% CI) of 1.38 (1.11 to 1.70; p=0.0054). Glaucoma surgeries were associated with a lower acute POE incidence compared with phacoemulsification, conversely to vitreoretinal surgical procedures: IRR 0.63 (0.47 to 0.85; p<0.001) and IRR 1.78 (1.58 to 2.01; p<0.001), respectively.

CONCLUSION

A higher incidence of acute POE after combined cataract surgery than after cataract surgery done as a stand-alone procedure was observed based on the French nationwide medical-administrative database. The incidence of acute POE after combined surgery was related to the type of surgery performed simultaneously with cataract extraction.

Ganglioside Profiling of the Human Retina: Comparison with Other Ocular Structures, Brain and Plasma Reveals Tissue Specificities

Gangliosides make a wide family of glycosphingolipids, highly heterogeneous in both the ceramide moiety and the oligosaccharide chain. While ubiquitously expressed in mammalian tissues, they are particularly abundant in the brain and the peripheral nervous system. Gangliosides are known to play a crucial role in the development, maintenance and functional integrity of the nervous system. However, the expression and roles of gangliosides in the retina, although often considered as a window on the brain, has been far less studied. We performed an in-depth analysis of gangliosides of the human retina, especially using powerful LC/MS methods. We compared the pattern of ganglioside classes and ceramide molecular species of this tissue with other ocular structures and with brain and plasma in elderly human individuals. About a hundred of ganglioside molecular species among 15 distinct classes were detected illustrating the huge structural diversity of these compounds. The retina exhibited a very diverse ganglioside profile and shared several common features with the brain (prominence of tetraosylgangliosides, abundance of d20:1 long chain base and 18:0 fatty acid…). However, the retina stood out with the specific expression of GD3, GT3 and AcGT3, which further presented a peculiar molecular species distribution. The unique ganglioside pattern we observed in the human retina suggests that these ganglioside species play a specific role in the structure and function of this tissue. This lipidomic study, by highlighting retina specific ganglioside species, opens up novel research directions for a better understanding of the biological role of gangliosides in the retina.

Plasmatic Ganglioside Profile and Age-Related Macular Degeneration: A Case-Control Study

PURPOSE

Gangliosides are glycosphingolipids that are particularly abundant in the nervous system, including the retina. However, their precise role in this tissue and its pathologies remain poorly understood. The objective of the present study was to characterize the ganglioside profile of human plasma and to determine whether it is affected in age-related macular degeneration (AMD).

METHODS

Eighty-three subjects were included: control subjects (n = 25), atrophic AMD patients (n = 27) and exudative AMD patients (n = 31). For each subject, gangliosides were extracted from plasma and analyzed by liquid chromatography coupled to mass spectrometry.

RESULTS

GM3 appeared to be by far the major ganglioside of human plasma, associated with GD3. No specific ganglioside class was detected in the plasma of AMD patients. Fourteen molecular species of GM3 and 9 species of GD3, accounting for the variability of the ceramide moiety of the ganglioside molecule, were identified and characterized. Analyses revealed no significant differences in the proportion of these species between control, atrophic and exudative AMD patient groups. Total GM3 levels did not differ either.

CONCLUSION

Although gangliosides are considered important for the retina's structure and function, it seems that circulating gangliosides are not associated with the retinal damage occurring during the course of AMD.

Early adaptive response of the retina to a pro-diabetogenic diet: Impairment of cone response and gene expression changes in high-fructose fed rats

The lack of plasticity of neurons to respond to dietary changes, such as high fat and high fructose diets, by modulating gene and protein expression has been associated with functional and behavioral impairments that can have detrimental consequences. The inhibition of high fat-induced rewiring of hypothalamic neurons induced obesity. Feeding rodents with high fructose is a recognized and widely used model to trigger obesity and metabolic syndrome. However the adaptive response of the retina to short term feeding with high fructose is poorly documented. We therefore aimed to characterize both the functional and gene expression changes in the neurosensory retina of Brown Norway rats fed during 3 and 8 days with a 60%-rich fructose diet (n = 16 per diet and per time point). Glucose, insulin, leptin, triacylglycerols, total cholesterol, HDL-cholesterol, LDL-cholesterol and fructosamine were quantified in plasma (n = 8 in each group). Functionality of the inner retina was studied using scotopic single flash electroretinography (n = 8 in each group) and the individual response of rod and cone photoreceptors was determined using 8.02 Hz Flicker electroretinography (n = 8 in each group). Analysis of gene expression in the neurosensory retina was performed by Affymetrix genechips, and confirmed by RT-qPCR (n = 6 in each group). Elevated glycemia (+13%), insulinemia (+83%), and leptinemia (+172%) was observed after 8 days of fructose feeding. The cone photoreceptor response was altered at day 8 in high fructose fed rats (Δ = 0.5 log unit of light stimulus intensity). Affymetrix analysis of gene expression highlighted significant modulation of the pathways of eIF2 signaling and endoplasmic reticulum stress, regulation of eIF4 and p70S6K signaling, as well as mTOR signaling and mitochondrial dysfunction. RT-qPCR analysis confirmed the down regulation of Crystallins, Npy, Nid1 and Optc genes after 3 days of fructose feeding, and up regulation of End2. Meanwhile, a trend towards an increased expression of αA- and αB-crystallin proteins was observed at day 8. Our results are consistent with early alterations of the functioning and gene expression in the retina in a pro diabetogenic environment.

Erythrocyte phospholipid and polyunsaturated fatty acid composition in diabetic retinopathy

Background

Long chain polyunsaturated fatty acids (LCPUFAs) including docosahexaenoic acid and arachidonic acid are suspected to play a key role in the pathogenesis of diabetes. LCPUFAs are known to be preferentially concentrated in specific phospholipids termed as plasmalogens. This study was aimed to highlight potential changes in the metabolism of phospholipids, and particularly plasmalogens, and LCPUFAs at various stages of diabetic retinopathy in humans.

Methodology and Principal Findings

We performed lipidomic analyses on red blood cell membranes from controls and mainly type 2 diabetes mellitus patients with or without retinopathy. The fatty acid composition of erythrocytes was determined by gas chromatography and the phospholipid structure was determined by liquid chromatography equipped with an electrospray ionisation source and coupled with a tandem mass spectrometer (LC-ESI-MS/MS). A significant decrease in levels of docosahexaenoic acid and arachidonic acid in erythrocytes of diabetic patients with or without retinopathy was observed. The origin of this decrease was a loss of phosphatidyl-ethanolamine phospholipids esterified with these LCPUFAs. In diabetic patients without retinopathy, this change was balanced by an increase in the levels of several phosphatidyl-choline species. No influence of diabetes nor of diabetic retinopathy was observed on the concentrations of plasmalogen-type phospholipids.

Conclusions and Significance

Diabetes and diabetic retinopathy were associated with a reduction of erythrocyte LCPUFAs in phosphatidyl-ethanolamines. The increase of the amounts of phosphatidyl-choline species in erythrocytes of diabetic patients without diabetic retinopathy might be a compensatory mechanism for the loss of LC-PUFA-rich phosphatidyl-ethanolamines.

Involvement of plasmalogens in post-natal retinal vascular development

Objective

Proper development of retinal blood vessels is essential to ensure sufficient oxygen and nutrient supplies to the retina. It was shown that polyunsaturated fatty acids (PUFAs) could modulate factors involved in tissue vascularization. A congenital deficiency in ether-phospholipids, also termed “plasmalogens”, was shown to lead to abnormal ocular vascularization. Because plasmalogens are considered to be reservoirs of PUFAs, we wished to improve our understanding of the mechanisms by which plasmalogens regulate retinal vascular development and whether the release of PUFAs by calcium-independent phospholipase A2 (iPLA2) could be involved.

Methods and Results

By characterizing the cellular and molecular steps of retinal vascular development in a mouse model of plasmalogen deficiency, we demonstrated that plasmalogens modulate angiogenic processes during the early phases of retinal vascularization. They influence glial activity and primary astrocyte template formation, endothelial cell proliferation and retinal vessel outgrowth, and impact the expression of the genes involved in angiogenesis in the retina. These early defects led to a disorganized and dysfunctional retinal vascular network at adult age. By comparing these data to those obtained on a mouse model of retinal iPLA2 inhibition, we suggest that these processes may be mediated by PUFAs released from plasmalogens and further signalling through the angiopoietin/tie pathways.

Conclusions

These data suggest that plasmalogens play a crucial role in retinal vascularization processes.

Decreasing dietary linoleic acid promotes long chain omega-3 fatty acid incorporation into rat retina and modifies gene expression

Age-related macular degeneration (AMD) may be partially prevented by dietary habits privileging the consumption of ω3 long chain polyunsaturated fatty acids (ω3s) while lowering linoleic acid (LA) intake. The present study aimed to document whether following these epidemiological guidelines would enrich the neurosensory retina and RPE with ω3s and modulate gene expression in the neurosensory retina. Rat progenitors and pups were fed with diets containing low or high LA, and low or high ω3s. After scotopic single flash and 8-Hz-Flicker electroretinography, rat pups were euthanized at adulthood. The fatty acid profile of the neurosensory retina, RPE, liver, adipose tissue and plasma was analyzed using gas chromatography. Gene expression was analyzed with real-time PCR in the neurosensory retina. Diets rich in ω3s efficiently improved the incorporation of ω3s into the organs and tissues. This raising effect was magnified by lowering LA intake. Compared to a diet with high LA and low ω3s, low LA diets significantly upregulated LDL-receptor gene expression. Similar but not significant upregulation of CD36, ABCA1, ALOX5 and ALOX12 gene expression was observed in rats fed with low LA. No effect was observed on retinal function. Increasing the intake in ω3s and lowering LA improved the enrichment with ω3s of the tissues, including the neurosensory retina and RPE, and upregulated genes involved in lipid trafficking in the neurosensory retina. Those results consistently reinforced the beneficial role of ω3s in the prevention of AMD, especially when the diet contained low levels of LA, as suggested from epidemiological data.

No consequences of dietary n-3 polyunsaturated fatty acid deficiency on the severity of scopolamine-induced dry eye

PURPOSE

Epidemiological studies suggest that dietary n-3 polyunsaturated fatty acids (PUFAs) may protect against dry eye. This study aimed to evaluate whether a dietary deficiency in n-3 PUFAs may increase the severity of the pathology in a scopolamine-induced model of dry eye in the rat.

METHODS

Lewis rats of three consecutive generations were bred under a balanced diet or a diet deprived of n-3 PUFAs. Dry eye was experimentally induced by continuous scopolamine delivery in female animals from the third generation of both groups. After 10 days of treatment, the clinical signs of ocular dryness were evaluated in vivo using fluorescein staining. MHC II and the rat mucin rMuc5AC were immunostained on ocular sphere cryosections. The transcript levels of the pro-inflammatory cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were quantified in the exorbital lacrimal glands (LG) and in the conjunctiva using reverse transcription followed by polymerase chain reaction. Lipids were extracted from the exorbital LG for fatty acid analysis of the phospholipids using gas chromatography.

RESULTS

When compared to control animals, the scopolamine treatment induced an increase in the cornea fluorescein staining score (from 0.5 ± 0.0 to 2.5 ± 1.0 arbitrary units (AU) for the balanced diet and from 1.2 ± 0.8 to 2.6 ± 0.5 AU for the n-3 PUFA-deficient diet); a decrease in rMuc5AC immunostaining in the conjunctival epithelium (-34% for the balanced diet and -23% for the n-3 PUFA-deficient diet); an increase in the LG transcript levels of TNF-α for the balanced diet and of TNF-α and IFN-γ for the deficient diet; an increase in the conjunctival transcript levels of IL-1β and IL-6 for the deficient diet; an increase in arachidonic acid (AA) and in the ∆5-desaturase index (ratio of AA to dihomo-gamma-linolenic acid) in the exorbital LG for both diets. When compared to the balanced diet, the n-3 PUFA-deficient diet induced an increase in the LG transcript levels of IL-6 for the control animals and of TNF-α for the control and dry eye animals as well as an increase in the conjunctival transcript levels of IL-6 for the dry eye animals. There was no significant diet difference in fluorescein staining, rMuc5AC, and MHC II immunostaining scores.

CONCLUSIONS

Our data suggest that an n-3 PUFA deficiency does not increase the severity of dry eye in a rat model of dry eye.

Nutrition for the eye: different susceptibility of the retina and the lacrimal gland to dietary omega-6 and omega-3 polyunsaturated fatty acid incorporation

The purpose of this study was to compare the susceptibility of the retina and the exorbital lacrimal gland to dietary supplies of long-chain omega-3 (omega3) and omega-6 (omega6) polyunsaturated fatty acids (LC-PUFAs). Male Wistar rats were fed a 5% lipid diet containing: (1) 10% eicosapentaenoic acid (EPA) and 7% docosahexaenoic acid (DHA), or (2) 10% gamma-linolenic acid (GLA), or (3) 10% EPA, 7% DHA and 10% GLA or (4) a balanced diet deprived of EPA, DHA and GLA for 3 months. Lipids were extracted from plasma phospholipids, retina and exorbital lacrimal gland, and fatty acid composition was determined by gas chromatography. Dietary supplementation with EPA and DHA increased omega3 PUFA levels in plasma phospholipids as well as in the retina and the exorbital lacrimal gland. By contrast, GLA supplementation favored omega6 PUFA incorporation, and particularly the incorporation of the end-chain omega6 product, docosapentaenoic acid (DPA), into all tissues. Supplementation with EPA, DHA and GLA increased the levels of DHA, EPA and dihomo-GLA (dGLA), whereas arachidonic acid (AA) was unchanged and DPA decreased in the retina and the lacrimal gland. The ability of both tissues to incorporate PUFAs from blood was evaluated. The results showed that the retina was more selective than the lacrimal gland for EPA. In spite of the different susceptibility of the retina and the lacrimal gland to dietary PUFAs, these results suggest that the concomitant use of dietary omega3 and omega6 PUFAs may be useful in modulating inflammation in both tissues.

A dietary combination of omega-3 and omega-6 polyunsaturated fatty acids is more efficient than single supplementations in the prevention of retinal damage induced by elevation of intraocular pressure in rats

BACKGROUND

To evaluate the effect of a dietary combination of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) compared to single PUFA supplementations on the outcome of a substantial elevation of intraocular pressure (IOP) in rats.

METHODS

Sprague Dawley rats were fed for 6 months with either a control diet, a diet enriched with omega-3 PUFAs (eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA), a diet enriched with omega-6 PUFAs (gamma-linolenic acid, GLA) or a diet enriched with both omega-3 and omega-6 PUFAs (EPA + DHA and GLA). After 3 months of feeding, elevation of IOP was induced by photocoagulation of the episcleral veins, limbus and trabecular meshwork using a 532-nm laser. IOP and scotopic electroretinograms (ERGs) were monitored after the induction of IOP elevation until the end of the nutritional supplementation. Retinal morphometry and GFAP immunohistochemistry were performed 3 months after laser photocoagulation. Retinal ganglion cells (RGCs) were quantified using retrograde labelling.

RESULTS

A significant rise in IOP was observed in the laser-treated eyes. PUFA supplementation did not influence the time course of IOP in the laser-treated eyes. Three months after laser photocoagulation, the activation of glial cells observed in the laser-treated eyes was significantly lower in animals fed with the EPA + DHA + GLA diet when compared to those fed the control diet, while single supplementations with either EPA + DHA or GLA were not effective. The same protective effect of the EPA + DHA + GLA combination was observed on retinal structures in the laser-treated eyes. However, PUFA supplementation did not influence either ERG b-wave amplitude or the RGC loss in the laser-treated eyes.

CONCLUSIONS

This study demonstrates that a 6-month supplementation with a combination of omega-3 and omega-6 PUFAs is more effective than single supplementations, since the EPA + DHA + GLA dietary combination prevented retinal cell structure and decreased glial cell activation induced by the elevation of IOP in rats.

Dietary n-3 and n-6 PUFA enhance DHA incorporation in retinal phospholipids without affecting PGE(1) and PGE (2) levels

The purpose of this study was to determine whether dietary n-3 and n-6 PUFA may affect retinal PUFA composition and PGE(1) and PGE(2) production. Male Wistar rats were fed for 3 months with diets containing: (1) 10% eicosapentaenoic acid (EPA) and 7% docosahexaenoic acid (DHA), or (2) 10% gamma-linolenic acid (GLA), or (3) 10% EPA, 7% DHA and 10% GLA, or (4) a balanced diet deprived of EPA, DHA, and GLA. The fatty acid composition of retinal phospholipids was determined by gas chromatography. Prostaglandin production was measured by enzyme immunoassay. When compared to rats fed the control diet, the retinal levels of DHA were increased in rats fed both diets enriched with n-3 PUFA (EPA + DHA and EPA + DHA + GLA diets) and decreased in those supplemented with n-6 PUFA only (GLA diet). The diet enriched with both n-6 and n-3 PUFA resulted in the greatest increase in retinal DHA. The levels of PGE(1) and PGE(2) were significantly increased in retinal homogenates of rats fed with the GLA-rich diet when compared with those of animals fed the control diet. These higher PGE(1) and PGE(2) levels were not observed in animals fed with EPA + DHA + GLA. In summary, GLA added to EPA + DHA resulted in the highest retinal DHA content but without increasing retinal PGE(2) as seen in animals supplemented with GLA only.

The learning curve for primary vitrectomy without scleral buckling for pseudophakic retinal detachment

BACKGROUND

To assess the functional and anatomical outcome of primary vitrectomy without scleral buckling for rhegmatogenous retinal detachment (RRD) in pseudophakic patients and to present the learning curve for this surgery in less experienced surgeons.

METHODS

We reviewed the charts of pseudophakic patients treated with primary vitrectomy without scleral buckling for a rhegmatogenous retinal detachment with PVR<C in two academic centres by four surgeons (two more experienced and two less experienced surgeons) for 1 year. The primary endpoint was the reattachment rate with a single procedure by less experienced and more experienced surgeons. Then, to assess the learning curve of this treatment, we compared the results obtained in consecutive pseudophakic patients by less experienced surgeons at the beginning and after a 2-year training period.

RESULTS

First, 133 patient charts with a minimum follow-up of 6 months were included. Retinal reattachment was achieved with a single surgery in 75.2% for all surgeons. This rate was 80.9% for more experienced surgeons compared to 70% for less experienced surgeons (p = 0.37). In another series of 239 patients operated on by less experienced surgeons, the success rate obtained at the beginning of the training period for less experienced surgeons significantly increased after 2 years (from 66.7% to 80%, p < 0.049).

CONCLUSION

Primary vitrectomy without scleral buckling is an effective procedure to treat pseudophakic retinal detachment. Less experienced surgeons need sufficient time to achieve acceptable success rates, reflecting the learning curve for this procedure.

Lipid and fatty acid profile of the retina, retinal pigment epithelium/choroid, and the lacrimal gland, and associations with adipose tissue fatty acids in human subjects

Accumulation of lipids within Bruch's membrane (BrM) and between BrM and retinal pigment epithelium (RPE) accounts for one of the biological changes associated with normal aging and may contribute to the development of age-related maculopathies. The origin of these lipids is still being actively investigated. The relative contribution of plasma lipids and lipids coming from the neural retina remains a matter of controversy. Low-density lipoproteins (LDLs) have been reported to significantly participate in the retina's lipid supply, after active remodeling within RPE. Meanwhile, RPE expresses the enzymatic machinery for synthesizing lipoprotein-like particles. The objective of this study was to establish associations between the fatty acid profile of the ocular structures and adipose tissue as a surrogate for the subjects' past dietary intake. Lipids and fatty acids were analyzed from the neural retina, retinal pigment epithelium (RPE)/choroid, the lacrimal gland, and adipose tissue, collected from 27 human donors (19 women, eight men) aged 59-95 years. DHA concentrations in the neural retina were positively associated with the concentrations in cholesteryl esters (CEs) from RPE/choroid and negatively associated with DHA concentrations in phospholipids (PLs) from RPE/choroid. DHA in orbital fat was positively associated with DHA in the lacrimal gland. No significant association was observed in the other ocular structures. Linoleic acid in orbital fat was positively associated with linoleic acid in the lacrimal gland, followed by the neural retina and CEs from RPE/choroid; it was slightly correlated with PLs from RPE/choroid. Other fatty acids that originate exclusively from the diet such as trans fatty acids were detected in orbital fat, the lacrimal gland, PLs, and CEs from RPE/choroid. DHA in the neural retina was poorly associated with its dietary intake, contrary to other fatty acids such as linoleic acid. Within this context, CEs may be important carriers of fatty acids entering the retina. Although epidemiological studies have reported the benefit of DHA in the prevention of age-related macular degeneration, the leading cause of blindness in Western countries, the relevance of supplementing patients with DHA is questioned.

Time course of ocular surface and lacrimal gland changes in a new scopolamine-induced dry eye model

BACKGROUND

The aim of this study was to set up an animal model of dry eye showing disturbance in several components of the lacrimal functional unit, and to describe the time course of the appearance of clinical signs and inflammatory markers.

METHODS

Dry eye was induced in 6-week-old female Lewis rats by a systemic and continuous delivery of scopolamine via osmotic pumps implanted subcutaneously. We first determined the appropriate dose of scopolamine (6, 12.5, or 25 mg/day) for 28 days. In a second set of experiments, we determined markers after 1, 2, 3, 7, 10, 17, or 28 days of a 12.5-mg/day dose. Clinical signs of corneal dryness were evaluated in vivo using fluorescein staining. MHC II expression and mucin Muc5AC production were detected on the conjunctival epithelium using immunostaining. The level of IL-1beta, IL-6, TNF-alpha, and IFN-gamma mRNA was evaluated by real-time polymerase chain reaction in conjunctiva and exorbital lacrimal gland (LG). Lipids were extracted from the exorbital LG for fatty acid analysis.

RESULTS

Daily scopolamine doses of 12.5 mg and 25 mg applied for a 28-day period induced keratitis, a decrease in Muc5AC immunostaining density in the conjunctival epithelium, and modifications in the fatty acid composition of the exorbital LG. Animals treated with a 12.5-mg/day dose of scopolamine exhibited an increase in corneal fluorescein staining after 2, 10, and 28 days. All animals exhibited unilateral or bilateral keratitis after 17 days. In the conjunctival epithelium, a significant decrease in Muc5AC immunostaining density was observed at early and late time points, and MHC II expression tended to be increased after 1, 7, 10, and 28 days, without reaching statistical significance. The levels of TNF-alpha, IL-1beta and IL-6 mRNA were increased with scopolamine treatment in both conjunctiva and exorbital LG. Arachidonic acid and the Delta5 desaturase index were significantly increased in the exorbital LG of dry eye animals at each time point.

CONCLUSIONS

This systemic and continuous scopolamine-induced model of dry eye in the rat may represent a helpful tool to investigate moderate dry eye, and makes a contribution in the field of dry eye study.

Plasmalogens in the retina: In situ hybridization of dihydroxyacetone phosphate acyltransferase (DHAP-AT) – the first enzyme involved in their biosynthesis – and comparative study of retinal and retinal pigment epithelial lipid composition

Plasmalogens (Pls) are phospholipids containing a vinyl-ether bond in the sn-1 position of the glycerol backbone. The physiological role of Pls is still enigmatic, especially within the eye where their deficiency leads to developmental abnormalities. In order to learn more about the functions of Pls in the posterior eye, we evaluated retinal Pl content as well as the expression of the first enzyme involved in Pls biosynthesis, dihydroxyacetone phosphate acyltransferase (DHAP-AT) in the retina. In situ hybridization of DHAP-AT mRNA was performed on rat eye sections. The Pl contents of calf retina and retinal pigment epithelium (RPE) samples were determined by high-performance liquid chromatography, thin-layer chromatography, and gas chromatography. DHAP-AT was highly expressed in the inner segment of photoreceptors and in the RPE, suggesting two distinct sites for Pl biosynthesis. Plasmenyl-ethanolamine was the prominent class of Pls in both neural retina and RPE (28-29% of the total phospho-ethanolamine-glycerides). According to the nature of the alkenyl residue linked to the sn-1 position of Pls, the most striking finding was the greater proportion of octadecanal-aldehyde in the sn-1 position of plasmenyl-ethanolamine of the neural retina compared to all the other classes of Pls in the neural retina and the RPE. These findings might be relevant to the biological functions of Pls against oxidative stress and in the formation of lipid rafts.