Eirini Nitoda

Ocular actions of platelet-activating factor: clinical implications

Introduction: To summarize the currently available evidence of platelet-activating factor (PAF) implication in the pathogenesis of inflammatory ocular diseases. Areas covered: PAF is a potent mediator of inflammation, implicated in the pathogenesis of chronic inflammatory disorders, allergic reactions, oncogenic transformation, wound repair and hypoxia-induced angiogenesis. It seems to be involved in the protection of ocular surface against various harmful agents through inflammatory processes, which can lead to chronic allergic reactions or even corneal neovascularization and haze, if they do not undergo regulation. Pathogenesis of uveitis, which is significant cause for the blurring of the visual system, has also been associated with PAFs activity. The hypoxia and the breakdown of the blood–retina barrier, observed in severe vascular retinal diseases, such as age-related macular degeneration and diabetic retinopathy, are associated with PAF ocular activity. Expert opinion: Understanding the pathophysiology of vision threatening diseases could enhance clinical treatment and encourage experimental studies, which could be based on potential beneficial effects of new agents, such as PAF antagonists.

Pathophysiology of visual disorders induced by phosphodiesterase inhibitors in the treatment of erectile dysfunction

Aim The aim of this review was to summarize the ocular action of the most common phosphodiesterase (PDE) inhibitors used for the treatment of erectile dysfunction and the subsequent visual disorders. Method This is a literature review of several important articles focusing on the pathophysiology of visual disorders induced by PDE inhibitors. Results PDE inhibitors have been associated with ocular side effects, including changes in color vision and light perception, blurred vision, transient alterations in electroretinogram (ERG), conjunctival hyperemia, ocular pain, and photophobia. Sildenafil and tadalafil may induce reversible increase in intraocular pressure and be involved in the development of non-arteritic ischemic optic neuropathy. Reversible idiopathic serous macular detachment, central serous chorioretinopathy, and ERG disturbances have been related to the significant impact of sildenafil and tadalafil on retinal perfusion. Discussion So far, PDE inhibitors do not seem to cause permanent toxic effects on chorioretinal tissue and photoreceptors. However, physicians should write down any visual symptom observed during PDE treatment and refer the patients to ophthalmologists.

Ophthalmological Assessment of OCT and Electrophysiological Changes in Migraine Patients.

Background: A cross-sectional study to investigate the morphological and functional changes of the visual pathway taking place in patients with migraine. Methods: Fifteen patients (14 female, 1 male) diagnosed with migraine with aura and 23 patients (21 female, 2 male) diagnosed with migraine without aura were compared with 20 healthy volunteers (18 female, 2 male). All the participants underwent optical coherence tomography scan, electroretinogram (ERG), visual evoked potentials, and multifocal electroretinogram (mf-ERG) recording. Results: Assessing ERG recordings, no significant differences in mean N1-P1 amplitudes were measured among the groups. The mean visual evoked potentials N80-P100 amplitudes were not significantly different among the three groups (one way analysis of variance: P = 0.075, F = 2.718). No significant difference was found in P100 latency times among groups. The mean retinal response density of mf-ERG in ring 1 was higher in healthy individuals compared with migraineurs, with statistical significance (Kruskal–Wallis analysis of variance and Dunn multiple comparisons test; P < 0.001, mean rank difference = −24.857 and P < 0.001, mean rank difference = −20.9, for migraine with aura-control and migraine without aura-control comparisons, respectively). In migraine with aura subjects, retinal nerve fiber layer thickness in superior and inferior quadrants was significantly decreased compared with healthy individuals, whereas in migraine without aura group, only the superior quadrant was significantly thinner compared with the control group. Conclusions: Retinal response density in mfERG of all migraineurs was significantly lessened compared with healthy individuals. There was no significant difference in visual evoked potentials N80-P100 amplitudes or P100 latencies among the groups. Moreover, retinal nerve fiber layer thinning observed in patients with migraine compared with control subjects, appeared statistically significant in some quadrants. The authors may be able to defend the retinal blood flow decrease theory in migraine. The results also indicate that several levels of the visual pathway seem to be affected in migraineurs.

Assessment of hydroxychloroquine maculopathy after cessation of treatment: an optical coherence tomography and multifocal electroretinography study.

Objective This study was conducted to evaluate the macular status of patients treated with hydroxychloroquine before and after cessation of treatment. Methods Forty-two patients with systemic lupus erythematosus underwent ocular examination based on visual acuity evaluation, optical coherence tomography retinal thickness measurements, and multifocal electroretinography (mfERG) records at first visit. The tests were repeated 6 months after treatment withdrawal and compared to the findings at their first visit. Results Mean visual acuity (measured in log minimum angle of resolution) of both eyes was statistically increased after hydroxychloroquine discontinuation (difference in means: 0.06 [P<0.0001] and 0.01 [P=0.003] for the right and left eyes, respectively). Retinal response amplitudes of central and peripheral areas were significantly improved for both eyes. The following values were observed for central responses: the difference in means was −19.9 (P<0.0001) and −13.6 (P<0.0001) for the right eye and the left eye, respectively; for peripheral responses, difference in means was −10.3 (P<0.0001) and −9.5 (P<0.0001) for right eye and left eye, respectively, after the 6-month examination. There were no statistically significant differences in the retinal thickness of patients after cessation of treatment. The visual acuity of the patients was correlated to central and peripheral mfERG responses (r=−0.53 [P<0.0001] and r=−0.53 [P<0.0001], for the right eye and the left eye, respectively). Conclusion The visual acuity of patients receiving hydroxychloroquine improves along with the amplitudes of the mfERG responses 6 months after discontinuation of the drug, but no difference in retinal thickness is identified.

Estimation of depression prevalence in patients with Stargardt disease using PHQ-9 and Zung scores.

Purpose To evaluate the psychological impact and depression prevalence in patients with Stargardt disease. Methods We conducted a case-control study including 39 patients with Stargardt disease and 32 age- and sex-matched healthy controls. All participants underwent a complete ophthalmologic examination and completed the Patient Health Questionnaire-9 (PHQ-9) and the Zung Depression Inventory questionnaire. Results were analyzed using IBM SPSS 22.0 software. Results The patient group consisted of 19 men and 20 women with mean age of 36.9 ± 5.4 years and control group of 19 men and 13 women with mean age of 42.5 ± 10.1 years. The mean values of PHQ-9 and Zung scores for patients and healthy individuals were 10.9 ± 4.9, 46.7 ± 11.1, 6.7 ± 5.4, and 41.1 ± 8.5, respectively. There were statistically significant differences between the 2 groups in PHQ-9 scores (independent samples t test: p = 0.001), but not in Zung scores (Mann-Whitney test: p = 0.053). The PHQ-9 and Zung scores appeared to be moderately but significantly correlated (Pearson coefficient 0.44, p<0.0001). In addition, PHQ-9 score seems to be raised along with age, whereas both scores are low when best-corrected visual acuity is high. Conclusions Patients with Stargardt disease exhibited more depressive symptoms compared to healthy individuals according mainly to PHQ-9 scores. Moderate depression was significantly correlated visual function decline.

Correlation of platelet activating factor and age-related macular degeneration

Objective: To investigate the role of Platelet Activating Factor (PAF) in the pathogenesis and development of Age-Related Macular Degeneration (ARMD). Research design and methods: Fifty six patients with ARMD (24 patients with dry ARMD and 32 patients with wet ARMD) and 25 age-matched control participants underwent ophthalmological examination, including visual acuity measurement and evaluation of the retina. The participants were classified into three groups according to their retinal status, based on indirect fundoscopy, Optical Coherence Tomography and fluorescein angiography findings. In order to evaluate the concentrations of PAF in serum, blood samples were collected from all participants and were analyzed with ELISA technique. Results: The concentrations of PAF differed significantly according to macular lesions and were found to be lower in patients with ARMD than control participants. Conclusions: PAF levels are decreased along with the severity of ARMD. Understanding the role of PAF in pathogenesis of ARMD could be the impetus for the development of new therapies field of treatment of ARMD or even other retinal diseases.

Response to: Comment on "The Impact of Chronic Tobacco Smoking on Retinal and Choroidal Thickness in Greek Population".

We would like to thank Uzun for his observations [1]. Indeed choroidal thickness is influenced by several factors such as age, axial length, corneal curvature, intraocular pressure, systolic blood pressure, ocular perfusion pressure, and time of measurement [2]. Margolis and Spaide reported a 15.6-micron decrease in choroidal thickness every decade [3]; similarly, a 14-micron decrease every decade was reported by Ikuno et al. [4]. Wei et al. noted a thinning in subfoveal choroidal thickness among people around 65 years, estimating this reduction around 4 μm per year of age. Regarding axial length Wei et al. reported that the subfoveal thickness decreases by 15 microns for every increase in myopic refractive error of 1 D or by 32 microns for every increase in axial length of 1 mm [5]. Fujiwara et al. reported that choroidal thickness decreases by 12.7 μm for each decade of life and by 8.7 μm for each diopter of increasing myopia [6]. Gupta et al. supported that peripapillary choroidal thickness on average is decreased by 13.02 μm and 36.72 μm for each millimeter increase in axial length and corneal curvature, respectively. They also noted that each increment of myopic diopter resulted in the reduction of mean peripapillary choroidal thickness by 5.39 μm. On the other hand, they estimated that choroidal thickness augmented by 1.40 μm and 0.74 μm, when the intraocular pressure was increased by a millimeter of mercury or the retinal nerve fibre layer was raised by a micrometer, respectively [7].

Impact of prostaglandin glaucoma drops on platelet-activating factor action: an in vitro study

Aim The aim of this study was to investigate the effect of different prostaglandin analogs on platelet-activating factor (PAF) levels. Methods Three prostaglandin analogs were selected: bimatoprost 0.3 mg/mL, latanoprost 50 μg/mL, and tafluprost 15 μg/mL. Each drug sample was tested for its ability to cause platelet aggregation, which was measured as PAF-induced aggregation, before and after the addition of various concentrations of the examined sample, creating a linear curve of percentage inhibition (ranging from 0% to 100%) versus different concentrations of the sample. The concentration of the sample that inhibited 50% PAF-induced aggregation was calculated based on this curve, and this value was defined as IC50. In addition, the effect of eye drops on PAF metabolism was examined, through an in vitro analysis on PAF basic metabolic enzymes (PAF-cholinephosphotransferase, PAF-acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase, and PAF-acetylhydrolase). Results The IC50 values for Lumigan UD® (bimatoprost 0.3 mg/mL), Monoprost® (latanoprost 50 μg/mL), and Saflutan (tafluprost 15 μg/mL) were 8.7, 0.28, and 1.4 μg/mL, respectively. Discussion All three prostaglandin analogs suspended PAF, but bimatoprost induced the most potent inhibition, compared to tafluprost and to the weak effect of latanoprost.

Age-Related Macular Degeneration: Pathogenesis, Genetic Background, and the Role of Nutritional Supplements

Age-related macular degeneration (ARMD) is the leading cause of severe vision loss and blindness worldwide, mainly affecting people over 65 years old. Dry and wet ARDM are the main types of the disease, which seem to have a multifactorial background. The aim of this review is to summarize the mechanisms of ARMD pathogenesis and exhibit the role of diet and nutritional supplements in the onset and progression of the disease. Environmental factors, such as smoking, alcohol, and, diet appear to interact with mutations in nuclear and mitochondrial DNA, contributing to the pathogenesis of ARMD. Inflammatory mediators and oxidative stress, induced by the daily exposure of retina to high pressure of oxygen and light radiation, have been also associated with ARMD lesions. Other than medical and surgical therapies, nutritional supplements hold a significant role in the prevention and treatment of ARMD, eliminating the progression of macular degeneration.

The Role of mf-ERG in the Diagnosis and Treatment of Age-Related Macular Degeneration: Electrophysiological Features of AMD

ABSTRACT Introduction: Age-related macular cegeneration (AMD) is the leading cause of visual dysfunction worldwide, affecting 9–25% of individuals between 65 and 75 years old. Methods: We have reviewed the published articles investigating the role of multifocal electroretinogram (mf-ERG) in the diagnosis and treatment of AMD. Results: Visual evoked potentials have revealed decreased amplitudes and higher latencies in patients with AMD, while the degeneration of photoreceptors and abnormalities of retinal pigment epithelium can be identified by electro-oculogram recordings. Moreover, ERG can detect the functional abnormalities observed in AMD and evaluate each therapeutic approach. The record of local electrophysiological responses coming from different retinal areas can be accurately performed by mfERG. Conclusion: The accuracy of mfERG in detecting the degeneration of photoreceptors, as well the disturbances of macular function, could be useful both in the early diagnosis of AMD and the assessment of treatment efficacy.