Elevated albumin in retinas of monkeys with experimental glaucoma.

PURPOSE: To establish the identity of a prominent protein, approximately 70 kDa, that is markedly increased in the retina of monkeys with experimental glaucoma compared with the fellow control retina, the relationship to glaucoma severity, and its localization in the retina. METHODS: Retinal extracts were subjected to 2-D gel electrophoresis to identify differentially expressed proteins. Purified peptides from the abundant 70 kDa protein were analyzed and identified by liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) separation, and collision-induced dissociation sequencing. Protein identity was performed on MASCOT (Matrix Science, Boston, MA) and confirmed by Western blot. The relationship between the increase in this protein and glaucoma severity was investigated by regression analyses. Protein localization in retina was evaluated by immunohistochemistry with confocal imaging. RESULTS: The abundant protein was identified as Macaca mulatta serum albumin precursor (67 kDa) from eight non-overlapping proteolytic fragments, and the identity was confirmed by Western blot. The average increase in retinal albumin content was 2.3 fold (P = 0.015). In glaucoma eyes, albumin was localized to some neurons of the inner nuclear layer, in the inner plexiform layer, and along the vitreal surface, but it was only found in blood vessels in control retinas. CONCLUSIONS: Albumin is the abundant protein found in the glaucomatous monkey retinas. The increased albumin is primarily localized to the inner retina where oxidative damage associated with experimental glaucoma is known to be prominent. Since albumin is a major antioxidant, the increase of albumin in the retinas of eyes with experimental glaucoma may serve to protect the retina against oxidative damage.

Do optic nerve head and visual field parameters in patients with obstructive sleep apnea syndrome differ from those in control individuals?

BACKGROUND It has been suggested that sleep apnea syndrome may play a role in normal-tension glaucoma contributing to optic nerve damage. The purpose of this study was to evaluate if optic nerve and visual field parameters in individuals with sleep apnea syndrome differ from those in controls. PATIENTS AND METHODS From the records of the sleep laboratory at the University Hospital in Bern, Switzerland, we recruited consecutive patients with severe sleep apnea syndrome proven by polysomnography, apnea-hypopnea index >20, as well as no sleep apnea controls with apnea-hypopnea index <10. Participants had to be unknown to the ophtalmology department and had to have no recent eye examination in the medical history. All participants underwent a comprehensive eye examination, scanning laser polarimetry (GDx VCC, Carl Zeiss Meditec, Dublin, California), scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II, HRT II), and automated perimetry (Octopus 101 Programm G2, Haag-Streit Diagnostics, Koeniz, Switzerland). Mean values of the parameters of the two groups were compared by t-test. RESULTS The sleep apnea group consisted of 69 eyes of 35 patients; age 52.7 ± 9.7 years, apnea-hypopnea index 46.1 ± 24.8. As controls served 38 eyes of 19 patients; age 45.8 ± 11.2 years, apnea-hypopnea index 4.8 ± 1.9. A difference was found in mean intraocular pressure, although in a fully overlapping range, sleep apnea group: 15.2 ± 3.1, range 8-22 mmHg, controls: 13.6 ± 2.3, range 9-18 mmHg; p<0.01. None of the extended visual field, optic nerve head (HRT) and retinal nerve fiber layer (GDx VCC) parameters showed a significant difference between the groups. CONCLUSION Visual field, optic nerve head, and retinal nerve fiber layer parameters in patients with sleep apnea did not differ from those in the control group. Our results do not support a pathogenic relationship between sleep apnea syndrome and glaucoma.

Intravitreal ranibizumab monotherapy to treat retinopathy of prematurity zone II, stage 3 with plus disease.

BACKGROUND Treatment of retinopathy of prematurity (ROP) stage 3 plus with bevacizumab is still very controversial. We report the outcome of 6 eyes of 4 premature infants with ROP stage 3 plus disease treated with ranibizumab monotherapy. METHODS Six eyes of 4 premature infants with threshold ROP 3 plus disease in zone II, were treated with one intravitreal injection of 0.03 ml ranibizumab. No prior laser or other intravitreal therapy was done. Fundus examination was performed prior to the intervention and at each follow-up visit. Changes in various mean vital parameters one week post intervention compared to one week pre-intervention were assessed. RESULTS The gestational age (GA) of patient 1, 2, 3, and 4 at birth was 24 5/7, 24 5/7, 24 4/7, and 26 1/7 weeks, respectively. The birth weight was 500 grams, 450 grams, 665 grams, and 745 grams, respectively. The GA at the date of treatment ranged from 34 3/7 to 38 6/7 weeks. In one infant, upper air way infection was observed 2 days post injection of the second eye. Three eyes required paracentesis to reduce the intraocular pressure after injection and to restore central artery perfusion. After six months, all eyes showed complete retinal vascularisation without any signs of disease recurrence. CONCLUSIONS Treatment of ROP 3 plus disease with intravitreal ranibizumab was effective in all cases and should be considered for treatment. One infant developed an upper air way infection suspicious for nasopharyngitis, which might be a possible side effect of ranibizumab. Another frequent complication was intraocular pressure rise after injection. More patients with longer follow-up duration are mandatory to confirm the safety and efficacy of this treatment. TRIAL REGISTRATION NUMBER NCT02164604 ; Date of registration: 13.06.2014.

Glucose-Induced Temporary Visual Recovery in Primary Open-Angle Glaucoma: A Double-Blind, Randomized Study

Purpose To investigate the effect of topical glucose on visual parameters in individuals with primary open-angle glaucoma (POAG). Design Double-blind, randomized, crossover study. Participants Nondiabetic pseudophakic patients with definite POAG were recruited; 29 eyes of 16 individuals participated in study 1. A follow-up study (study 2) included 14 eyes of 7 individuals. Intervention Eyes were randomly allocated to receive 50% glucose or saline eye drops every 5 minutes for 60 minutes. Main Outcome Measures The contrast sensitivity and best-corrected logarithm of the minimum angle of resolution (logMAR). Results The 50% glucose reached the vitreous in pseudophakic but not phakic individuals. Glucose significantly improved the mean contrast sensitivity at 12 cycles/degree compared with 0.9% saline by 0.26 log units (95% confidence interval [CI], 0.13–0.38; P < 0.001) and 0.40 log units (95% CI, 0.17–0.60; P < 0.001) in the follow-up study. The intraocular pressure, refraction, and central corneal thickness were not affected by glucose; age was not a significant predictor of the response. Conclusions Topical glucose temporarily improves psychophysical visual parameters in some individuals with POAG, suggesting that neuronal energy substrate delivery to the vitreous reservoir may recover function of “sick” retinal neurons.

The function of math5 and myocilin in mammalian eye development and disease

Complex molecular events underlie vertebrate eye development and disease. The eye is composed of two major tissue types: the anterior and posterior segments. During development, the retinal progenitor cells differentiate into six neuronal and one non-neuronal cell types. These cell types later organize into the distinct laminar structure of the mature retina which occupies the posterior segment. In the developed anterior segment, both the ciliary body and trabecular meshwork regulate intraocular pressure created by the aqueous humor. The disruption in intraocular pressure can lead to a blinding condition called glaucoma. To characterize molecular mechanisms governing retinal development and glaucoma, two separate mouse knockout lines carrying mutations in math5 and myocilin were subjected to a series of in vivo analyses. ^ Math5 is a murine homologue of Drosophila atonal , a bHLH proneural gene essential for the formation of photoreceptor cells. The expression of math5 coincides with the onset of retinal ganglion cell differentiation. The targeted deletion of mouse math5 revealed that a null mutation inhibits the formation of a majority of the retinal ganglion cells. The mutation also interferes with the normal development of other retinal cell types such as amacrine, bipolar and photoreceptor cells. These results suggest that math5 is a proneural gene responsible for differentiation of retinal ganglion cells and may also have a role in normal development of other neuronal cell types within the retina. ^ Myocilin has two unique protein coding regions bearing homology to non-muscle myosin of Dictyostelium discoideum and to olfactomedin, an extracellular matrix molecule first described in the olfactory epithelium of the bullfrog. Recently, autosomal dominant forms of myocilin mutations have been found in individuals with primary open-angle glaucoma. The genetic linkage to glaucoma suggests a role of myocilin in normal intraocular pressure and ocular function. However, the analysis of mice heterozygous and homozygous for a targeted null mutation in myocilin indicates that it is dispensable for normal intraocular pressure or ocular function. Additionally, the lack of a discernable phenotype in both heterozygous and null mice suggests that haploinsufficiency is not a critical mechanism for MYOC-associated glaucoma in humans. Instead, disease-causing mutations likely act by gain of function. ^ In summary, these studies provide novel insights into the embryonic development of the vertebrate retina, and also begin to uncover the molecular mechanisms responsible for the pathogenesis of glaucoma. ^

Vaccination for protection of retinal ganglion cells against death from glutamate cytotoxicity and ocular hypertension: Implications for glaucoma

Our group recently demonstrated that autoimmune T cells directed against central nervous system-associated myelin antigens protect neurons from secondary degeneration. We further showed that the synthetic peptide copolymer 1 (Cop-1), known to suppress experimental autoimmune encephalomyelitis, can be safely substituted for the natural myelin antigen in both passive and active immunization for neuroprotection of the injured optic nerve. Here we attempted to determine whether similar immunizations are protective from retinal ganglion cell loss resulting from a direct biochemical insult caused, for example, by glutamate (a major mediator of degeneration in acute and chronic optic nerve insults) and in a rat model of ocular hypertension. Passive immunization with T cells reactive to myelin basic protein or active immunization with myelin oligodendrocyte glycoprotein-derived peptide, although neuroprotective after optic nerve injury, was ineffective against glutamate toxicity in mice and rats. In contrast, the number of surviving retinal ganglion cells per square millimeter in glutamate-injected retinas was significantly larger in mice immunized 10 days previously with Cop-1 emulsified in complete Freund's adjuvant than in mice injected with PBS in the same adjuvant (2,133 ± 270 and 1,329 ± 121, respectively, mean ± SEM; P < 0.02). A similar pattern was observed when mice were immunized on the day of glutamate injection (1,777 ± 101 compared with 1,414 ± 36; P < 0.05), but not when they were immunized 48 h later. These findings suggest that protection from glutamate toxicity requires reinforcement of the immune system by antigens that are different from those associated with myelin. The use of Cop-1 apparently circumvents this antigen specificity barrier. In the rat ocular hypertension model, which simulates glaucoma, immunization with Cop-1 significantly reduced the retinal ganglion cell loss from 27.8% ± 6.8% to 4.3% ± 1.6%, without affecting the intraocular pressure. This study may point the way to a therapy for glaucoma, a neurodegenerative disease of the optic nerve often associated with increased intraocular pressure, as well as for acute and chronic degenerative disorders in which glutamate is a prominent participant.

Cellular responses following retinal injuries and therapeutic approaches for neurodegenerative diseases

Retinal neurodegenerative diseases like age-related macular degeneration, glaucoma, diabetic retinopathy and retinitis pigmentosa each have a different etiology and pathogenesis. However, at the cellular and molecular level, the response to retinal injury is similar in all of them, and results in morphological and functional impairment of retinal cells. This retinal degeneration may be triggered by gene defects, increased intraocular pressure, high levels of blood glucose, other types of stress or aging, but they all frequently induce a set of cell signals that lead to well-established and similar morphological and functional changes, including controlled cell death and retinal remodeling. Interestingly, an inflammatory response, oxidative stress and activation of apoptotic pathways are common features in all these diseases. Furthermore, it is important to note the relevant role of glial cells, including astrocytes, Müller cells and microglia, because their response to injury is decisive for maintaining the health of the retina or its degeneration. Several therapeutic approaches have been developed to preserve retinal function or restore eyesight in pathological conditions. In this context, neuroprotective compounds, gene therapy, cell transplantation or artificial devices should be applied at the appropriate stage of retinal degeneration to obtain successful results. This review provides an overview of the common and distinctive features of retinal neurodegenerative diseases, including the molecular, anatomical and functional changes caused by the cellular response to damage, in order to establish appropriate treatments for these pathologies.

Orbscan Topography in Primary Open-Angle Glaucoma

Purpose: To compare anterior and posterior corneal curvatures between eyes with primary open-angle glaucoma (POAG) and healthy eyes. Methods: This is a prospective, cross-sectional, observer-masked study. A total of 138 white subjects (one eye per patient) were consecutively recruited; 69 eyes had POAG (study group), and the other 69 comprised a group of healthy control eyes matched for age and central corneal pachymetry with the study ones. Exclusion criteria included any corneal or ocular inflammatory disease, previous ocular surgery, or treatment with carbonic anhydrase inhibitors. The same masked observer performed Goldmann applanation tonometry, ultrasound pachymetry, and Orbscan II topography in all cases. Central corneal thickness, intraocular pressure, and anterior and posterior topographic elevation maps were analyzed and compared between both groups. Results: Patients with POAG had greater forward shifting of the posterior corneal surface than that in healthy control eyes (p < 0.01). Significant differences in anterior corneal elevation between controls and POAG eyes were also found (p < 0.01). Conclusions: Primary open-angle glaucoma eyes have a higher elevation of the posterior corneal surface than that in central corneal thickness–matched nonglaucomatous eyes.

Visual function alterations in essential tremor: A case report

Our purpose is to report alterations in contrast sensitivity function (CSF) and in the magno, parvo and koniocellular visual pathways by means of a multichannel perimeter in case of an essential tremor (ET). A complete evaluation of the visual function was performed in a 69-year old patient, including the analysis of the chromatic discrimination by the Fansworth–Munsell 100 hue test, the measurement of the CSF by the CSV-1000E test, and the detection of potential alteration patterns in the magno, parvo and koniocellular visual pathways by means of a multichannel perimeter. Visual acuity and intraocular pressure (IOP) were within the ranges of normality in both eyes. No abnormalities were detected in the fundoscopic examination and in the optical coherence tomography (OCT) exam. The results of the color vision examination were also within the ranges of normality. A significant decrease in the achromatic CSFs for right eye (RE) and left eye (LE) was detected for all spatial frequencies. The statistical global values provided by the multichannel perimeter confirms that there were significant absolute sensitivity losses compared to the normal pattern in RE. In the LE, only a statistically significant decrease in sensitivity was detected for the blue-yellow (BY) channel. The pattern standard deviation (PSD) values obtained in our patient indicated that there were significant localized losses compared to the normality pattern in the achromatic channel of the RE and in the red-green (RG) channel of the LE. Some color vision alterations may be present in ET that cannot be detected with conventional color vision tests, such as the FM 100 Hue.

Cirurgia de catarata e glaucoma

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Abordagem multidisciplinar do glaucoma congénito primário : caso clínico

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Glutamate transporter localization does not correspond to the temporary functional recovery and late degeneration after acute ocular ischemia in rats

Purpose: To determine whether the localization of retinal glutamate transporters is affected by retinal ischaemia and whether their ability to transport glutamate decreases with the progression of ischemic retinal and optic nerve degeneration. Methods: Retinal ischemia was induced in rats by acutely increasing the intraocular pressure (IOP, 110 mmHg/60 min). Reperfusion was permitted for periods up to 60 days post-ischemia. Functional evaluation was performed by monitoring the pupil light reflexes (PLRs) and electroretinograms (flash, flicker ERG and oscillatory potentials). Glutamate transporter localization and D-aspartate (glutamate analogue) uptake were assessed by immunohistochemistry. Results: Intense immunoreactivity for the retinal glutamate transporters (GLAST, GLT1, EAAC1 and EAAT5) was observed at all time points after the insult, despite severe retinal degeneration. D-aspartate was also normally accumulated in the ischemic retinas. Ten days post-operatively the PLR ratio (ratio = indirect/direct PLR = 34 +/- 7(.)5%) was significantly less than the pre-operative value (pre-op = 76(.)7 +/- 2 (.)6%, p < 0(.)05). However, 25 and 35 days post-operatively PLR ratios did not differ significantly from pre-operative values (44(.)4 +/- 6(.)9 and 53(.)8 +/- 9(.)6%, p > 0(.)05). Forty-five and 60 days post-operatively the PLR ratio declined again and was significantly lower than the pre-operative value (33(.)8 + 8(.)7 and 26(.)2 + 8(.)9%, p < 0(.)05). Statistical analysis revealed that all tested ERG components had significantly higher values at 32, but not at 42 and 58 days post-operatively when compared to the first time point recorded post-operatively (10 days). Conclusions: While retinal glutamate transport is compromised during an acute ischemic insult, consequent retinal recovery and degeneration are not due to a change in the excitatory amino acid transporter localization or D-aspartate (glutamate analogue) uptake. Rat retina and optic nerve are capable of spontaneous, but temporary, functional recovery after an acute ischemic insult. (C) 2004 Elsevier Ltd. All rights reserved.

Retinal serotonin, eye growth and myopia development in chick

Myopia (short-sightedness) is a visual problem associated with excessive eye growth and vitreous chamber expansion. Within the eye serotonin (5-hydroxytryptamine, 5-HT) appears to have a variety of effects, it alters retinal amacrine cell processing, increases intraocular pressure, constricts ocular blood vessels, and is also mitogenic. This study sought to determine the role of the retinal serotonin system in eye growth regulation. Myopia was produced in 7-day-old chicks using -15 D spectacle lenses (LIM) and form deprivation (FDM). The effect on LIM and FDM of daily intravitreal injections of a combination of 5-HT receptor antagonists (1, 10, 50 mu M), 5-HT2 selective antagonist (Mianserin 0.5, 20 mu M) were assessed. Counts were performed of serotonin and tyrosine hydroxylase positive neurons and the relative density used to account for areal changes due to eye growth. The effect of LIM and lens-induced hyperopia (LIH) on the numbers of 5-HT-containing amacrine cells in the retina were then determined. The combination of the 5-HT receptor antagonists inhibited LIM by approximately half (1 mu M RE: -7.12 +/- 1.0 D, AL: 0.38 +/- 0.06 mm vs. saline RE: -13.19 +/- 0.65 D, AL: 0.64 +/- 0.03 mm. RE: p < 0.01, AL: p < 0.01), whereas FDM was not affected (1 mu M RE: -8.88 +/- 1.10 D). These data suggest that serotonin has a stimulatory role in LIM, although high doses of serotonin were inhibitory (1 mu M RE: -9.30 +/- 1.34 D). 5-HT immunoreactivity was localised to a subset of amacrine cell bodies in the inner nuclear layer of the retina, and to two synaptic strata in the inner plexiform layer. LIM eyes had increased numbers of 5-HT-containing amacrine cells in the central retina (12.5%). Collectively, these results suggest that manipulations to the serotonin system can alter the eye growth process but the role of the transmitter system within this process remains unclear. (c) 2005 Elsevier Ltd. All rights reserved.

Clinical evaluation of rebound tonometer

Purpose: To evaluate the reliability and repeatability of intraocular pressure (IOP) measurements using a new rebound tonometer. Methods: Intraocular pressure was measured in 42 healthy human eyes of subjects aged 18-30 years (mean ± standard deviation [SD] 21.5 ± 3.2 years) using the ICare Rebound and Goldmann tonometers in two separate sessions. Results: Intraocular pressure measurements were found to read slightly, but not significantly, higher with the ICare tonometer compared with the Goldmann instrument in both sessions (first session: mean bias ± SD + 0.50 ± 2.33 mmHg; second session: mean bias ± SD + 0.52 ± 1.92 mmHg). Limits of agreement between repeated readings were ± 5.11 mmHg for measurements taken with the ICare tonometer, compared with ± 3.15 mmHg for measurements taken with the Goldmann method. Conclusion: Measurement of IOP in normal, healthy subjects using the ICare rebound tonometer produced a small, statistically insignificant, positive bias when compared with the Goldmann tonometer. Intersessional repeatability of IOP taken with the ICare is poorer than that of IOP taken with the Goldmann tonometer, but is comparable with that of other non-Goldman-type tonometers currently available. Copyright © Acta Ophthalmol Scand, 2006.

Ocular blood flow measurements in healthy human myopic eyes

Background. To evaluate the haemodynamic features of young healthy myopes and emmetropes, in order to ascertain the perfusion profile of human myopia and its relationship with axial length prior to reaching a degenerative state. Methods The retrobulbar, microretinal and pulsatile ocular blood flow (POBF) of one eye of each of twenty-two high myopes (N=22, mean spherical equivalent (MSE) =-5.00D), low myopes (N=22, MSE-1.00 to-4.50D) and emmetropes (N=22, MSE±0.50D) was analyzed using color Doppler Imaging, Heidelberg retinal flowmetry and ocular blood flow analyser (OBF) respectively. Intraocular pressure, axial length (AL), systemic blood pressure, and body mass index were measured. Results. When compared to the emmetropes and low myopes, the AL was greater in high myopia (p<0.0001). High myopes showed higher central retinal artery resistance index (CRA RI) (p=0.004), higher peak systolic to end diastolic velocities ratio (CRA ratio) and lower end diastolic velocity (CRA EDv) compared to low myopes (p=0.014, p=0.037). Compared to emmetropes, high myopes showed lower OBFamplitude (OBFa) (p=0.016). The POBF correlated significantly with the systolic and diastolic blood velocities of the CRA (p=0.016, p=0.036). MSE and AL correlated negatively with OBFa (p=0.03, p=0.003), OBF volume (p=0.02, p<0.001), POBF (p=0.01, p<0.001) and positively with CRA RI (p=0.007, p=0.05). Conclusion. High myopes exhibited significantly reduced pulse amplitude and CRA blood velocity, the first of which may be due to an OBF measurement artefact or real decreased ocular blood flow pulsatility. Axial length and refractive error correlated moderately with the ocular pulse and with the resistance index of the CRA, which in turn correlated amongst themselves. It is hypothesized that the compromised pulsatile and CRA haemodynamics observed in young healthy myopes is an early feature of the decrease in ocular blood flow reported in pathological myopia. Such vascular features would increase the susceptibility for vascular and age-related eye diseases.