Ageing changes in the eye

Effect of aging and lifestyle on photoreceptors and retinal pigment epithelium: cross-sectional study in a healthy Danish population

Photoreceptors and their supporting retinal pigment epithelium constitute the key functional parts of the retina. Here, a study was undertaken to show how aging and lifestyle factors affect the photoreceptor layer and the retinal pigment epithelium and Bruch's membrane complex (RPE-BM) in vivo in a healthy Danish population using spectral-domain optical coherence tomography. This was a cross-sectional study of healthy humans aged ≥50 years. All participants were interviewed for medical history and lifestyle factors. Maculae of all participants were scanned using spectral-domain optical coherence tomography. The thickness of the photoreceptor layer and the RPE-BM was measured on one eye from each participant. In 150 eyes of 150 participants, it was found that aging was associated with a decrease in the thickness of the photoreceptor layer (-0.143 μm/year, P = 0.031) and an increase in the thickness of the RPE-BM layer (0.100 μm/year, P = 0.029) at the foveal minimum. Regarding lifestyle factors, alcohol intake or BMI were not associated with any significant trend, but physical inactivity and smoking had effects on the photoreceptor layer (decreased thickness) and the RPE-BM layer (increased thickness) indicating an accelerated aging process of the macula. Taken together, aging affects photoreceptors and the RPE-BM, and these aging trends are accelerated in smokers and the physically inactive.

Molecular Age-Related Changes in the Anterior Segment of the Eye

Purpose

To examine the current knowledge about the age-related processes in the anterior segment of the eye at a biological, clinical, and molecular level.

Methods

We reviewed the available published literature that addresses the aging process of the anterior segment of the eye and its associated molecular and physiological events. We performed a search on PubMed, CINAHL, and Embase using the MeSH terms “eye,” “anterior segment,” and “age.” We generated searches to account for synonyms of these keywords and MESH headings as follows: (1) “Eye” AND “ageing process” OR “anterior segment ageing” and (2) “Anterior segment” AND “ageing process” OR “anterior segment” AND “molecular changes” AND “age.” Results. Among the principal causes of age-dependent alterations in the anterior segment of the eye, we found the mutation of the TGF-β gene and loss of autophagy in addition to oxidative stress, which contributes to the pathogenesis of degenerative diseases.

Conclusions

In this review, we summarize the current knowledge regarding some of the molecular mechanisms related to aging in the anterior segment of the eye. We also introduce and propose potential roles of autophagy, an important mechanism responsible for maintaining homeostasis and proteostasis under stress conditions in the anterior segment during aging.

Molecular and physiological manifestations and measurement of aging in humans

Biological aging is associated with a reduction in the reparative and regenerative potential in tissues and organs. This reduction manifests as a decreased physiological reserve in response to stress (termed homeostenosis) and a time-dependent failure of complex molecular mechanisms that cumulatively create disorder. Aging inevitably occurs with time in all organisms and emerges on a molecular, cellular, organ, and organismal level with genetic, epigenetic, and environmental modulators. Individuals with the same chronological age exhibit differential trajectories of age-related decline, and it follows that we should assess biological age distinctly from chronological age. In this review, we outline mechanisms of aging with attention to well-described molecular and cellular hallmarks and discuss physiological changes of aging at the organ-system level. We suggest methods to measure aging with attention to both molecular biology (e.g., telomere length and epigenetic marks) and physiological function (e.g., lung function and echocardiographic measurements). Finally, we propose a framework to integrate these molecular and physiological data into a composite score that measures biological aging in humans. Understanding the molecular and physiological phenomena that drive the complex and multifactorial processes underlying the variable pace of biological aging in humans will inform how researchers assess and investigate health and disease over the life course. This composite biological age score could be of use to researchers seeking to characterize normal, accelerated, and exceptionally successful aging as well as to assess the effect of interventions aimed at modulating human aging.

The Effect of Age on Dexamethasone Intravitreal Implant (Ozurdex®) Response in Macular Edema Secondary to Branch Retinal Vein Occlusion

PURPOSE

To investigate the effect of age on dexamethasone intravitreal implant (Ozurdex®) response in macular edema secondary to branch retinal vein occlusion (BRVO).

METHODS

Seventy-three eyes of 73 patients with macular edema secondary to BRVO were recruited in the study. The patients in the study were divided into the following four groups according to their ages: group 1 (<60 years), group 2 (60-69 years), group 3 (70-79 years), and group 4 (≥80 years). Single-dose Ozurdex injection was applied to all patients. The effectiveness of Ozurdex treatment on macular edema is evaluated via optical coherence tomography (OCT) according to the age groups.

RESULTS

Two months after Ozurdex injection, mean reduction of central retinal thickness in groups 1, 2, 3, and 4 were -466.4 ± 149.6, -379.7 ± 238.7, -280.1 ± 233.0, and -180.5 ± 81.4 µm, respectively. This reduction of central retinal thickness decreased with aging (p = 0.001). Also, ages of patients were negatively correlated with the mean reduction of central retinal thickness for the whole study group (r = -0.439, p < 0.001).

CONCLUSION

Our study revealed that the effectiveness of Ozurdex treatment decreases with aging.

Monocular and Binocular Contributions to Oculomotor Plasticity

Most eye movements in the real-world redirect the foveae to objects at a new depth and thus require the co-ordination of monocular saccade amplitudes and binocular vergence eye movements. Additionally to maintain the accuracy of these oculomotor control processes across the lifespan, ongoing calibration is required to compensate for errors in foveal landing positions. Such oculomotor plasticity has generally been studied under conditions in which both eyes receive a common error signal, which cannot resolve the long-standing debate regarding whether both eyes are innervated by a common cortical signal or by a separate signal for each eye. Here we examine oculomotor plasticity when error signals are independently manipulated in each eye, which can occur naturally owing to aging changes in each eye’s orbit and extra-ocular muscles, or in oculomotor dysfunctions. We find that both rapid saccades and slow vergence eye movements are continuously recalibrated independently of one another and corrections can occur in opposite directions in each eye. Whereas existing models assume a single cortical representation of space employed for the control of both eyes, our findings provide evidence for independent monoculomotor and binoculomotor plasticities and dissociable spatial mapping for each eye.

The effects of VEGF-A-inhibitors aflibercept and ranibizumab on the ciliary body and iris of monkeys

PURPOSE

To investigate the effects of intravitreal ranibizumab (Lucentis®) and aflibercept (Eylea®) on the ciliary body and the iris of 12 cynomolgus monkeys with regard to the fenestrations of their blood vessels.

MATERIALS AND METHODS

Structural changes in the ciliary body and in the iris were investigated with light, fluorescent, and transmission electron microscopy (TEM). The latter was used to specifically quantify fenestrations of the endothelium of blood vessels after treatment with aflibercept and ranibizumab. Each of the two ciliary bodies treated with aflibercept and the two treated with ranibizumab and their controls were examined after 1 and 7 days respectively. Ophthalmological investigations including funduscopy and intraocular pressure measurements were also applied.

RESULTS

Ophthalmological investigations did not reveal any changes within the groups. Both drugs reduced the VEGF concentration in the ciliary body pigmented epithelium. The structure of the ciliary body was not influenced, while the posterior pigmented epithelium of the iris showed vacuoles after aflibercept treatment. Ranibizumab was mainly concentrated on the surface layer of the ciliary epithelium, in the blood vessel walls and the lumen of some of the blood vessels, and in the cells of the epithelium of the ciliary body. Aflibercept was more concentrated in the stroma and not in the cells of the epithelium, but as with ranibizumab, also in the blood vessel walls and some of their lumina, and again on the surface layer of the epithelium. Both aflibercept-and ranibizumab-treated eyes showed a decreased number of fenestrations of the capillaries in the ciliary body compared to the untreated controls. On day 1 and day 7, aflibercept had fewer fenestrations than the ranibizumab samples of the same day.

CONCLUSIONS

Both aflibercept and ranibizumab were found to reach the blood vessel walls of the ciliary body, and effectively reduced their fenestrations. Aflibercept might eliminate VEGF to a greater extent, possibly due to a higher elimination of fenestrations in a shorter time. Moreover, the vacuoles found in the iris need further research, in order to evaluate whether they carry a possible pathological potential.

Effect of NCAM on aged-related deterioration in vision

The neural cell adhesion molecule (NCAM) is involved in developmental processes and age-associated cognitive decline; however, little is known concerning the effects of NCAM in the visual system during aging. Using anatomical, electrophysiological, and behavioral assays, we analyzed age-related changes in visual function of NCAM deficient (-/-) and wild-type mice. Anatomical analyses indicated that aging NCAM -/- mice had fewer retinal ganglion cells, thinner retinas, and fewer photoreceptor cell layers than age-matched controls. Electroretinogram testing of retinal function in young adult NCAM -/- mice showed a 2-fold increase in a- and b-wave amplitude compared with wild-type mice, but the retinal activity dropped dramatically to control levels when the animals reached 10 months. In behavioral tasks, NCAM -/- mice had no visual pattern discrimination ability and showed premature loss of vision as they aged. Together, these findings demonstrate that NCAM plays significant roles in the adult visual system in establishing normal retinal anatomy, physiology and function, and in maintaining vision during aging.

The effectiveness of a simultaneous medial spindle procedure for involutional punctal ectropion with lid laxity in patients who require endonasal dacryocystorhinostomy instead of external dacryocystorhinostomy to prevent pump failure

PURPOSE

The aim of this study was to determine the effectiveness of a concurrent medial spindle procedure (MS) to address involutional punctal ectropion and the proportion of combined surgery in patients who need endonasal dacryocystorhinostomy (DCR) instead of external dacryocystorhinostomy to prevent pump failure.

METHODS

We conducted a retrospective, interventional study on endonasal DCR and MS procedures performed between March 2004 and January 2009 by a single surgeon (S.H.B.). Patient age, sex, the results of a medial distraction test, the surgical procedure, follow-up duration, and cause of failed surgery were recorded. The indication for the medial spindle procedure was punctal eversion on slit lamp biomicroscopic examination with classifications of grades 2 and 3 on the medial distraction test.

RESULTS

Endonasal DCRs were performed on 169 eyes in 121 patients, and DCR and MS (D + M) were performed on 23 eyes in 17 patients. The proportion of combined surgery to total DCR was 13.6%. Our primary success rate was 86.9% in the combined surgery group and 87.2% in the DCR group (P = 0.39).

CONCLUSIONS

The MS for correction of punctal ectropion concurrently performed with endonasal DCR will be an effective tool to manage epiphora caused by complex situations, such as nasolacrimal duct obstruction and involutional punctal ectropion. We recommend careful examination of the punctum, which is invisible in normal conditions, under slit lamp biomicroscopy before endonasal DCR.

Oculopharyngeal muscular dystrophy as a paradigm for muscle aging

Symptoms in late-onset neuromuscular disorders initiate only from midlife onward and progress with age. These disorders are primarily determined by identified hereditable mutations, but their late-onset symptom manifestation is not fully understood. Here, we review recent research developments on the late-onset autosomal dominant oculopharyngeal muscular dystrophy (OPMD). OPMD is caused by an expansion mutation in the gene encoding for poly-adenylate RNA binding protein1 (PABPN1). The molecular pathogenesis for the disease is still poorly understood. Despite a ubiquitous expression of PABPN1, symptoms in OPMD are limited to skeletal muscles. We discuss recent studies showing that PABPN1 levels in skeletal muscles are lower compared with other tissues, and specifically in skeletal muscles, PABPN1 expression declines from midlife onward. In OPMD, aggregation of expanded PABPN1 causes an additional decline in the level of the functional protein, which is associated with severe muscle weakness in OPMD. Reduced PABNPN1 expression in muscle cell culture causes myogenic defects, suggesting that PABPN1 loss-of-function causes muscle weakness in OPMD and in the elderly. Molecular signatures of OPMD muscles are similar to those of normal muscle aging, although expression trends progress faster in OPMD. We discuss a working hypothesis that aging-associated factors trigger late-onset symptoms in OPMD, and contribute to accelerated muscle weakness in OPMD. We focus on the pharyngeal and eyelid muscles, which are often affected in OPMD patients. We suggest that muscle weakness in OPMD is a paradigm for muscle aging.

Chronic physical activity preserves efficiency of proprioception in postural control in older women

The purpose of this study was to compare the effects of proprioceptive disruption on postural control for participants of different ages according to their physical and/or sport activity levels. Two groups of young and old participants who practiced chronic physical and/or sport activities (young active [n = 17; average age 20.5 +/- 1.1 yr] and old active [n = 17; average age 74.0 +/- 3.8 yr]) and two groups of young and old participants who did not practice physical and/or sport activities (young sedentary [n = 17; average age 20.0 +/- 1.3 yr] and old sedentary [n = 17; average age 74.7 +/- 6.3 yr]) participated in the study. They were compared in a bipedal quiet stance reference condition and a bilateral Achilles tendon vibration condition. Center of foot pressure displacements and frequency analysis were compared between the groups. The results indicated that when proprioceptive information was disrupted, the postural control disturbance was more important for the old sedentary group than for the other groups. There were no differences between the old active group and the young sedentary group. Postural control was less altered for the young active group than for the other groups. Aging decreases the efficiency of postural control regardless of the assessment conditions. Physical and sport activities may compensate for the disturbing effects of proprioceptive perturbation through a better use of sensory information whatever the age of the participants.

Aging related changes of retina and optic nerve of Uromastyx aegyptia and Falco tinnunculus

Aging is a biological phenomenon that involves gradual degradation of the structure and function of the retina and optic nerve. To our knowledge, little is known about the aging-related ocular cell loss in avian (Falco tinnunculus) and reptilian species (Uromastyx aegyptia). A selected 90 animals of pup, middle, and old age U. aegyptia (reptilian) and F. tinnunculus (avian) were used. The retinae and optic nerves were investigated by light and transmission electron microscopy (TEM) and assessments of neurotransmitters, antioxidant enzymes (catalase, superoxide dismustase and glutathione s transferase), caspase-3 and -7, malonadialdhyde, and DNA fragmentation. Light and TEM observations of the senile specimens revealed apparent deterioration of retinal cell layers, especially the pigmented epithelium and photoreceptor outer segments. Their inclusions of melanin were replaced by lipofuscins. Also, vacuolar degeneration and demyelination of the optic nerve axons were detected. Concomitantly, there was a marked increase of oxidative stress involved reduction of neurotransmitters and antioxidant enzymes and an increase of lipid peroxidation, caspase-3 and -7, subG0/G1 apoptosis, and P53. We conclude that aging showed an inverse relationship with the neurotransmitters and antioxidant enzymes and a linear relationship of caspases, malondialdhyde, DNA apoptosis, and P53 markers of cell death. These markers reflected the retinal cytological alterations and lipofuscin accumulation within inner segments.

The effectiveness of simultaneous medial spindle and/or lateral tarsal strip procedure in East Asian patients who need endonasal dacryocystorhinostomy

BACKGROUNDS

To evaluate the effectiveness of simultaneous medial spindle procedure (MS) and/or lateral tarsal strip procedure (TS) with an endonasal dacryocystorhinostomy (DCR) for treatment of involutional medial punctal ectropion, horizontal eyelid laxity, and nasolacrimal duct obstruction.

METHODS

We conducted a retrospective, interventional study of DCR performed from March 2009 to July 2011 by a single surgeon (Baek SH). Patient age, sex, results of medial and lateral distraction test, surgical procedure, time of tube removal, duration of follow-up, functional and anatomical success rate, and causes of failed surgeries were recorded. Lateral lower eyelid laxity was evaluated by a medial distraction test, and medial lid laxity was evaluated by a lateral distraction test.

RESULTS

A total of 241 eyes in 175 patients were included in this study. The proportion of combined surgeries to total DCR was 24.5% (59 of 241 eyes). DCR and MS (D + M) were performed on 23 eyes in 17 patients (9.5%) and DCR and TS (D + T) on 29 eyes in 17 patients (12.0%). Concurrent DCR, MS and TS (D + M + T) were performed on seven eyes in four patients (2.9%). Mean age was significantly higher in the combined surgery groups (63.8 ± 10.0 years) than in the DCR group (56.2 ± 10.6 years; p = 0.01, by Mann-Whitney U test). The anatomical success rates were 84.2% in D, 86.9% in D + M, 89.5% in D + T, and 85.7% in D + M + T (p = 0.61 by Kruskal-Wallis test). Functional success rates were 82.4% in D, 86.9% in D + M, 86.2% in D + T, and 85.7% in D + M + T (p = 0.91 by Kruskal-Wallis test).

CONCLUSIONS

MS and TS performed concurrently with a DCR may be an effective tool to deal with epiphora due to complex clinical situations such as nasolacrimal duct obstruction, lid laxity, and involutional medial ectropion. It is recommended to examine punctum and lid laxity carefully using slit-lamp biomicroscopy and lid distraction test in patients with epiphora, especially in elderly patients.

Analysis of fine structure and biochemical changes of retina during aging of Wistar albino rats

BACKGROUND

Aging is a biological phenomenon that involves an increase of oxidative stress associated with gradual degradation of the structure and function of the retina. Gender differences and subsequent deterioration of retinal cell layers is an interesting topic, especially because there is no published work concerning it.

METHODS

One hundred and twenty male and female Wistar albino rats ages 1, 6, 18, 30 and 42 months (n = 20 equal for male and female) were used. At the time interval, retinae were investigated by light and transmission electron microscopy, assessments of neurotransmitters, anti-oxidant enzymes (catalase, superoxide dismustase and glutathione S transferase), caspase-3 and -7, malonadialdhyde, and DNA fragmentation.

RESULTS

Light and transmission electron microscopy observations of the older specimens (30 and 42 months) revealed apparent deterioration of retinal cell layers, especially ganglion and nerve fibres, nuclear, pigmented epithelium and stacked membranes of the photoreceptor's outer segments. Males were highly susceptible to aging processes. Retinal DNA fragmentation was remarked parallel with increase of apoptic markers caspase 3 and 7. Concomitantly, there was a marked reduction of neurotransmitters and anti-oxidant enzymes, and an increase of lipid peroxidation.

CONCLUSIONS

Aging contributed to an increase of oxidative stress resulting from damage of mitochondria in retinal cells, a decrease of the anti-oxidant enzyme system and an increase of markers of retinal cell death.

Looking for similarities in movement between and within homes using cluster analysis

In this article we examine data from eight purpose-built aware homes over a six-month period, looking at presence in rooms to try to determine patterns among the older residents. We look for homes that have similar movement patterns using cluster analysis. We also examine how movement over days clusters within individual homes. Our analysis shows that different homes have distinct movement patterns but within individual homes residents have strong movement routines.

HTRA1 in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of severe visual impairment and irreversible blindness in most developed countries, affecting more than 50 million of elderly people worldwide. Current treatments, such as intravitreal injection of antiangiogenic agents, mitigate the effect of advanced AMD but cannot completely cure the disease. Comprehensive understanding of the AMD pathological mechanisms is important for the development of new therapies. Previously, we identified a single-nucleotide polymorphism (rs11200638) in the promoter region of the high temperature requirement factor A1 (HTRA1) gene on chromosome 10q26 to be associated with exudative AMD. In further biological studies, we have provided evidence that HTRA1 could be a potential disease-causing gene within the 10q26 locus. In this review, we summarize the pathology of AMD and the molecular function of the HtrA1 protein. Also evaluated are the genetic effects of HTRA1 polymorphism on AMD in different populations and interactions with other AMD-associated genes, especially with the complement factor H (CFH) gene, which was identified for nonexudative AMD. The biological roles of HtrA1 are exhaustively examined on its contribution to the multifactorial pathogenic mechanism of AMD. Although HtrA1 should play a part in AMD pathogenesis, a host of other genetic and environmental factors, known and unknown, is involved and warrants intensive future research.

Lipids, lipoproteins, and age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly. While excellent treatment has emerged for neovascular disease, treatment for early AMD is lacking due to an incomplete understanding of the early molecular events. A prominent age-related change is the accumulation of neutral lipid in normal Bruch's membrane (BrM) throughout adulthood and also disease-related BrM accumulations called basal deposits and drusen. AMD lesion formation has thus been conceptualized as sharing mechanisms with atherosclerotic plaque formation, where low-density lipoprotein (LDL) retention within the arterial wall initiates a cascade of pathologic events. However, we do not yet understand how lipoproteins contribute to AMD. This paper explores how systemic and local production of lipoproteins might contribute to the pathogenesis of AMD.

Lens aging: effects of crystallins

The primary function of the eye lens is to focus light on the retina. The major proteins in the lens--alpha, beta, and gamma-crystallins--are constantly subjected to age-related changes such as oxidation, deamidation, truncation, glycation, and methylation. Such age-related modifications are cumulative and affect crystallin structure and function. With time, the modified crystallins aggregate, causing the lens to increasingly scatter light on the retina instead of focusing light on it and causing the lens to lose its transparency gradually and become opaque. Age-related lens opacity, or cataract, is the major cause of blindness worldwide. We review deamidation, and glycation that occur in the lenses during aging keeping in mind the structural and functional changes that these modifications bring about in the proteins. In addition, we review proteolysis and discuss recent observations on how crystallin fragments generated in vivo, through their anti-chaperone activity may cause crystallin aggregation in aging lenses. We also review hyperbaric oxygen treatment induced guinea pig and 'humanized' ascorbate transporting mouse models as suitable options for studies on age-related changes in lens proteins.

Age-related macular degeneration and the aging eye

Age-related macular degeneration (AMD) is an ocular disease that causes damage to the retinal macula, mostly in the elderly. Normal aging processes can lead to structural and blood flow changes that can predispose patients to AMD, although advanced age does not inevitably cause AMD. In this review, we describe changes that occur in the macular structure, such as the retinal pigment epithelium and Bruch's membrane, with advancing age and in AMD. The role of genetics in AMD and age-related changes in ocular blood flow that may play a role in the pathogenesis of AMD are also discussed. Understanding the pathophysiology of AMD development can help guide future research to further comprehend this disease and to develop better treatments to prevent its irreversible central vision loss in the elderly.

Heavy isotopes to avert ageing?

Oxidative modifications of cellular components by free radicals are thought to be the cause of ageing and age-associated diseases. Extensive prior research has aimed to lessen such damage by counteracting the free-radical oxidizers with antioxidants, but there have been no attempts to protect the oxidizer-targeted biomolecules by making them more stable against oxidation. A recent paper describes an original and promising method based on the use of non-radioactive heavy isotopes, which might enable living cells to resist the free-radical oxidation and consequently allow us to live a healthier, longer life.