Ophthalmic Changes Research Articles

Ophthalmic Changes Following Maxillectomy With or Without Postoperative Radiation Therapy.

To evaluate ophthalmic complications and quantitatively assess anatomic changes following maxillectomy with or without adjuvant radiotherapy in patients with midface malignancy. Twenty-four patients who underwent maxillectomy for sinus and/or paranasal cancer were included for retrospective review. Patients with complete ophthalmic examinations were evaluated for postoperative findings corresponding to sequelae of treatment. When available, anatomical changes including eyelid position were quantified from preoperative and postoperative full-face photos using computer software. The most common complications identified in patients after maxillectomy were retraction/ectropion (50%), epiphora (29%), and exposure keratopathy/dry eye syndrome (25%). Patients treated with maxillectomy with adjuvant radiation therapy were more frequently found to have ophthalmic complications following treatment. In patients with available postoperative photos (n = 10), the mean ipsilateral margin reflex distance (MRD)2 and inferior scleral show were 8.4 mm and 2.4 mm, respectively. In patients with available preoperative photos (n = 5), the mean change in MRD2 and inferior scleral show following maxillectomy was 3.4 mm and 2.8 mm, respectively. Patients undergoing maxillectomy for the treatment of head and neck malignancy may be at significant risk for development of specific periocular complications. Lower eyelid malposition was the most significant postoperative quantitative eyelid change following maxillectomy, which may be exacerbated by adjuvant radiotherapy and inferior orbital rim removal.

An Ophthalmic Changes in Patients with Chronic Obstructive Pulmonary Disease: Case-Control Study

Purpose: To evaluate the prevalence of ophthalmological changes in patients with Chronic Obstructive Pulmonary Disease (COPD) cared for at the Pneumology and Ophthalmology Departments at Medical School Unifacisa-Campina Grande-Paraiba-Brazil.Materials and Methods: Twenty-two smoker patients with COPD (study group) and 22 healthy controls that underwent routine ophthalmological examination (control group) were enrolled in the investigation. They were homogeneous regarding age, gender, presence of Systemic Arterial Hypertension (SAH) and Diabetes Mellitus (DM). They were examined for the presence of cataract and Age Related Macular Disease (AMD).Results: The prevalence of ophthalmologic changes was significantly different in the two groups. Eight (36.4%)patients presented with cataract requiring surgical intervention, while one (4.5%) person in the control group had cataract (p = 0.0212). Regarding AMD, 10 (45.5%) smoker COPD patients had this disease, whereas in the control group, one (4.5%) person had this disease (p = 0.0039).Conclusion: From the results one can conclude that there is strong association between smokers diagnosed with COPD with cataract and AMD patients, reinforcing the need for a protocol for referral of these patients to the ophthalmologist.

Spaceflight-related ocular changes: the potential role of genetics, and the potential of B vitamins as a countermeasure.

Within the last decade, it was realized that during and after long-duration spaceflight, some astronauts experience ophthalmic abnormalities including refractive changes, optic disc edema, globe flattening, choroidal folds, and cotton wool spots. Much research has been initiated and conducted, but little evidence is available to differentiate affected crewmembers. The first published data to distinguish between affected and nonaffected crewmembers identified biochemical differences in affected astronauts: one-carbon pathway metabolite concentrations were higher in these individuals than in nonaffected astronauts, even before flight. These data led to findings that genetics and B-vitamin status were predictors of the incidence of the ophthalmic abnormalities. A multihit hypothesis was developed, with genetics and B-vitamin status as two of several important elements that all contribute to endothelial dysfunction and ultimately to ophthalmic changes after flight. One of these contributing factors - response to carbon dioxide exposure - was recently documented to be affected by the same one-carbon pathway genetics. This line of research may help identify which astronauts are at risk of these ophthalmic changes, and allow targeted treatment. This research may have implications for clinical populations, including patients with polycystic ovary syndrome, that have similar biochemical, endocrine, and genetic characteristics, and it may shed light on why links between cardiovascular disease and the metabolites homocysteine and folate have been elusive and confounded.

EVALUATION OF THE OPHTHALMIC DISEASE AND HISTOPATHOLOGIC EFFECTS DUE TO THE OCULAR TREMATODE PHILOPHTHALMUS ZALOPHI ON JUVENILE GALAPAGOS SEA LIONS ( ZALOPHUS WOLLEBAEKI).

The Galapagos sea lion ( Zalophus wollebaeki) is an otariid species endemic to the Galapagos archipelago and is currently listed as endangered. The ocular trematode Philophthalmus zalophi was recently reported to affect the survival of juvenile Galapagos sea lions on Santa Cruz Island, resulting in marked ophthalmic changes. This study evaluated the ophthalmic disease and histopathologic effects of P. zalophi on juvenile Galapagos sea lions in the largest rookery located on San Cristóbal Island. Twenty juvenile Galapagos sea lions (10 male and 10 female) were evaluated among five sites in the rookery El Malecón. Ophthalmic examination, including fluorescein staining and evaluation of the adnexa, cornea, and sclera, were performed on each eye. The presence, number, and location of ocular parasites were determined, and parasites were collected for identification. Conjunctival biopsy was performed on 11 animals: 2 that lacked parasites and gross lesions and 9 with both parasites and gross lesions. All parasites collected were confirmed as P. zalophi and identified in 80% (16/20) of the study animals and 70% (28/40) of the examined eyes. Philophthalmus zalophi was most frequently found attached to the nictitating membrane but also located on the palpebral conjunctiva or cornea. The most common clinical signs were varying degrees of conjunctival hyperemia (28/40 eyes), most frequently of the nictitating membrane and mucoid ocular discharge (12/40 eyes). The number of parasites was significantly associated with the degree of conjunctival hyperemia ( P < 0.001). Histopathology of conjunctival biopsies revealed organized lymphoid follicles and lymphoplasmacytic infiltrates. The histopathologic changes and gross lesions were likely due to the parasite's attachment to the conjunctiva. This study provides additional details of P. zalophi infection in juvenile Galapagos sea lions. Further research is warranted to detail the life cycle of this parasite, transmission to sea lions, and potential treatment protocols.

Astronaut ophthalmic syndrome.

During and after missions on the International Space Station, some astronauts experience ophthalmic changes, including choroidal folds, optic disc edema, cotton-wool spots, globe flattening, and refraction changes. Astronauts with ophthalmic issues had significantly higher plasma concentrations of metabolites that are associated with the 1-carbon metabolic pathway than those without ophthalmic issues. We hypothesized that genetic differences might explain the metabolite differences. Indeed, genetics and B vitamin status were significant predictors of ophthalmic issues. We now have developed a hypothesis regarding the mechanisms that link 1-carbon pathway genetics and the condition that we suggest calling, "astronaut ophthalmic syndrome." We maintain that this condition is genetically predisposed and is associated with endothelial dysfunction that is induced by oxidative stress. Subsequent edema can hinder cerebrospinal fluid efflux and can lead to locally increased pressures in the subarachnoid space within the orbit, which impinges on the optic nerve and/or eye in affected individuals. Confirming this hypothesis will help characterize the genetics of 1-carbon pathway metabolism, homocysteine, oxidative stress, endothelial dysfunction, and cardiovascular and potentially other diseases.-Zwart, S. R., Gibson, C. R., Gregory, J. F., Mader, T. H., Stover, P. J., Zeisel, S. H., Smith, S. M. Astronaut ophthalmic syndrome.

Lower body negative pressure reduces optic nerve sheath diameter during head-down tilt

The microgravity ocular syndrome (MOS) results in significant structural and functional ophthalmic changes during 6-mo spaceflight missions consistent with an increase in cerebrospinal fluid (CSF) pressure compared with the preflight upright position. A ground-based study was performed to assess two of the major hypothesized contributors to MOS, headward fluid shifting and increased ambient CO2, on intracranial and periorbital CSF. In addition, lower body negative pressure (LBNP) was assessed as a countermeasure to headward fluid shifting. Nine healthy male subjects participated in a crossover design study with five head-down tilt (HDT) conditions: -6, -12, and -18° HDT, -12° HDT with -20 mmHg LBNP, and -12° HDT with a 1% CO2 environment, each for 5 h total. A three-dimensional volumetric scan of the cranium and transverse slices of the orbita were collected with MRI, and intracranial CSF volume and optic nerve sheath diameter (ONSD) were measured after 4.5 h HDT. ONSD increased during -6° (P < 0.001), -12° (P < 0.001), and -18° HDT (P < 0.001) and intracranial CSF increased during -12° HDT (P = 0.01) compared with supine baseline. Notably, LBNP was able to reduce the increases in ONSD and intracranial CSF during HDT. The addition of 1% CO2 during HDT, however, had no further effect on ONSD, but rather ONSD increased from baseline in a similar magnitude to -12° HDT with ambient air (P = 0.001). These findings demonstrate the ability of LBNP, a technique that targets fluid distribution in the lower limbs, to directly influence CSF and may be a promising countermeasure to help reduce increases in CSF.NEW & NOTEWORTHY This is the first study to demonstrate the ability of lower body negative pressure to directly influence cerebrospinal fluid surrounding the optic nerve, indicating potential use as a countermeasure for increased cerebrospinal fluid on Earth or in space.

Ophthalmological Evaluation of Integrated Resistance and Aerobic Training During 70-Day Bed Rest.

We evaluated ophthalmic changes in healthy individuals who underwent integrated resistance and aerobic training (iRAT) during 70-d 6° head-down tilt (HDT) bed rest (BR). Participants were selected using NASA standard screening procedures. Standardized NASA BR conditions were implemented. Subjects were randomly assigned to the iRAT protocol or no exercise during HDTBR. Weekly ophthalmic examinations were performed in the sitting (pre/post-BR only) and HDT (BR only) positions. Mixed-effects linear models compared pre- and post-HDTBR intraocular pressure (IOP), Spectralis OCT circumpapillary retinal nerve fiber layer (cpRNFL) thickness, and peripapillary retinal thickness observations between groups. Six controls and nine exercisers completed the study. There was an overall effect of BR on our outcomes. Except Goldmann IOP (mean pre/post difference in controls and exercisers: -0.47 mmHg vs. +1.14 mmHg), the magnitude of changes from baseline was not significantly different between groups. There was a +1.38 mmHg and a +1.63 mmHg iCare IOP increase during BR in controls and exercisers, respectively. Spectralis OCT detected a +1.33 μm average cpRNFL thickness increase in both groups, and a +9.77 μm and a +6.65 μm peripapillary retinal thickening post-BR in controls and exercisers, respectively. Modified Amsler grid, red dot test, confrontational visual field, color vision, and stereoscopic fundus photography were unremarkable. HDTBR for 70 d induced peripapillary retinal thickening and cpRNFL thickening without visible signs of optic disc edema. The magnitude of such changes was not different between controls and exercisers. A slight IOP increase during BR subsided post-BR. Further study should evaluate whether different physical exercise paradigms may prevent/mitigate the risk of space-related visual impairment.Taibbi G, Cromwell RL, Zanello SB, Yarbough PO, Ploutz-Snyder RJ, Godley BF, Vizzeri G. Ophthalmological evaluation of integrated resistance and aerobic training during 70-day bed rest. Aerosp Med Hum Perform. 2017; 88(7):633-640.

Ophthalmic changes associated with long-term exposure to microgravity

This review discusses recent publications on the problem of ophthalmic changes associated with long-term effects of microgravity during space flights. Described changes include hyperopic shift of refraction, change in intraocular pressure, increased intracranial pressure, changes in the choroid and retina tissues, and swelling of the optic nerve. These effects are caused by redistribution of blood and fluid to the upper half of the body, increased intracranial pressure and congestion of venous blood and lymph in the upper half of the body and head. The reviewed also discusses other factors that may triggervision impairment caused by microgravity. Photographic illustrations of changes are also provided.

Intracranial and Intraocular Pressure During Various Degrees of Head-Down Tilt.

More than half of astronauts develop ophthalmic changes during long-duration spaceflight consistent with an abnormal intraocular and intracranial pressure (IOP, ICP) difference. The aim of our study was to assess IOP and ICP during head-down tilt (HDT) and the additive or attenuating effects of 1% CO2 and lower body negative pressure (LBNP). In Experiment I, IOP and ICP were measured in nine healthy subjects after 3.5 h HDT in five conditions: -6°, -12°, and -18° HDT, -12° with 1% CO2, and -12° with -20 mmHg LBNP. In Experiment II, IOP was measured in 16 healthy subjects after 5 min tilt at +12°, 0°, -6°, -12°, -18°, and -24°, with and without -40 mmHg LBNP. ICP was only found to increase from supine baseline during -18° HDT (9.2 ± 0.9 and 14.4 ± 1 mmHg, respectively), whereas IOP increased from 15.7 ± 0.3 mmHg at 0° to 17.9 ± 0.4 mmHg during -12° HDT and from 15.3 ± 0.4 mmHg at 0° to 18.7 ± 0.4 mmHg during -18° HDT. The addition of -20 mmHg LBNP or 1% CO2 had no further effects on ICP or IOP. However, the use of -40 mmHg LBNP during HDT lowered IOP back to baseline values, except at -24° HDT. A small, posterior intraocular-intracranial pressure difference (IOP > ICP) is maintained during HDT, and a sustained or further decreased difference may lead to structural changes in the eye in real and simulated microgravity.Marshall-Goebel K, Mulder E, Bershad E, Laing C, Eklund A, Malm J, Stern C, Rittweger J. Intracranial and intraocular pressure during various degrees of head-down tilt. Aerosp Med Hum Perform. 2017; 88(1):10-16.

Effects of Obstructive Carotid Artery Disease on Ocular Circulation and the Safety of Carotid Artery Stenting

The aims of this study were to examine the ophthalmic artery flow changes in patients with obstructive carotid artery disease, evaluate the orbital blood flow changes after carotid artery stenting and assess the safety of carotid stenting procedure by using transorbital colour and spectral Doppler sonography. Thirty-one consecutive patients scheduled for carotid stenting with severe internal carotid artery stenosis (>60%; the study group) and 30 control subjects were included. Ophthalmic artery (OA) Doppler sonography was performed in the control group and study group before and after stenting. Peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistive index (RI) and systolic/diastolic ratio (S/D) in the ophthalmic artery were recorded. Statistical comparisons were made between controls and study group before stenting and before and after stenting in the study group. Comparison between control and study group before stenting revealed a statistically significant decrease in OA PSV (51.5±14.5 vs. 39.7±19cm/sec, p= 0.008) and EDV (15.2±4.5 vs. 11.3±5.7cm/sec, p=0.004) in the study group. Differences in PI (1.3±0.14 vs. 1.36±0.4, p=0.47), RI (0.7±0.04 vs. 0.75±0.21, p=0.19), and S/D (3.5±0.6 vs. 3.6±1, p= 0.5) ratio were not statistically significant between groups. Peak systolic velocity (39.7±18.9 vs. 51.3±22.2cm/sec, p <0.001), RI (0.75±0.21 vs. 0.81±0.13, p=0.16) and S/D ratio (3.6±1 vs. 4.6±1.5, p= 0.001) were found to be significantly increased in the study group after stenting compared to baseline. There were no statistically significant differences in EDV and RI EDV(11.3±5.7 vs. 11.7±5.7cm/sec, p=0.66), PI (1.36±0.4 vs. 1.6±0.6, p =0.047) after stenting. Ophthalmic artery flow parameters were significantly lower in patients with severe carotid artery stenosis compared to control, indicating compromised ocular blood flow in severe carotid stenosis. Flow indicators significantly improved after stent implantation suggesting the importance of revascularisation in restoring ocular blood flow and safety of carotid stenting.

Commentaries on Viewpoint: Standardization of bed rest studies in the spaceflight contextCommentaries on Viewpoint: Standardization of bed rest studies in the spaceflight contextCommentaries on Viewpoint: Standardization of bed rest studies in the spaceflight contextCommentaries on Viewpoint: Standardization of bed rest studies in the spaceflight contextCommentaries on Viewpoint: Standardization of bed rest studies in the spaceflight context

to the editor: The work presented by Sundblad et al. ([5][1]) is important and is likely to improve present international efforts to develop countermeasures against, for example, cardiovascular deconditioning during spaceflight. However, one aspect that is not addressed to a sufficient extent is the

Characterization of the mechanical behavior of the optic nerve sheath and its role in spaceflight-induced ophthalmic changes.

Visual impairment and intracranial pressure (VIIP) syndrome is characterized by a number of permanent ophthalmic changes, including loss of visual function. It occurs in some astronauts during long-duration spaceflight missions. Thus, understanding the pathophysiology of VIIP is currently a major priority in space medicine research. It is hypothesized that maladaptive remodeling of the optic nerve sheath (ONS), in response to microgravity-induced elevations in intracranial pressure (ICP), contributes to VIIP. However, little is known about ONS biomechanics. In this study, we developed a custom mechanical testing system that allowed for unconfined lengthening, twisting, and circumferential distension of the porcine ONS during inflation and axial loading. Data were fit to a four-fiber family constitutive equation to extract material and structural parameters. Inflation testing showed a characteristic "cross-over point" in the pressure-diameter curves under different axial loads in all samples that were tested; the cross-over pressure was [Formula: see text]mmHg ([Formula: see text]). Large sample-to-sample variations were observed in the circumferential strain, while only modest variations were observed in the circumferential stress. Multiphoton microscopy revealed that the collagen fibers of the ONS were primarily oriented axially when the tissue was loaded. The existence of this cross-over behavior is expected to be neuroprotective, as it would avoid optic nerve compression during routine changes in gaze angle, so long as ICP was within the normal range. Including these observations into computational models of VIIP will help provide insight into the pathophysiology of VIIP and could help identify risk factors and potential interventions.

Effect of acute hypercapnia during 10-day hypoxic bed rest on posterior eye structures.

To gain insights into microgravity-induced ophthalmic changes (microgravity ocular syndrome), and as part of a project investigating effects of future planetary habitats, we investigated the effect of acute hypercapnia following 10-day bed rest and hypoxia on posterior eye structures. Female subjects (N = 7) completed three 10-day experimental interventions: 1) normoxic bed rest [NBR; partial pressure of inspired O2 (PiO2 ) = 132.9 ± 0.3 Torr]; 2) hypoxic ambulatory confinement (HAMB; PiO2 = 90.4 ± 0.3 Torr); and 3) hypoxic bed rest (HBR; n = 12; PiO2 = 90.4 ± 0.3 Torr). Before and on the last day of each intervention, optical coherence tomography (OCT) of the optic disk was performed, and the thicknesses of the retinal nerve fiber layer (RNFL), retina, and choroid were measured. OCT examinations were conducted with the subjects breathing the prevailing normocapnic breathing mixture (either normoxic or hypoxic) and then following a 10-min period of breathing the same gas mixture, but with the addition of 1% CO2 Choroidal thickness was greater during both bed-rest conditions (NBR and HBR) compared with the ambulatory (HAMB) condition (ANOVA, P < 0.001). Increases in RNFL thickness compared with baseline were observed in the hypoxic trials (HBR, P < 0.001; and HAMB, P = 0.021), but not the normoxic trial (NBR). A further increase in RNFL thickness (P = 0.019) was observed after the 10-min hypercapnic trial in the NBR condition only. The fact that choroidal thickness was not affected by Po2 or Pco2, but increased by bed rest, suggests a hydrostatic rather than a vasoactive effect. The increments in RNFL thickness were most likely associated with local hypoxia and hypercapnia-induced dilatation of the retinal blood vessels.

Ophthalmic Complications and Ocular Changes in Pregnancy- A Review

Pregnancy results in metabolic, hemodynamic, vascular, and immunologic changes. These physiological changes affect multiple organ systems including the visual system. The ophthalmic changes that occur during pregnancy are divided into physiological or pathological. Although ocular changes are common in pregnancy, many are mild, temporary, and require little to no treatment. However, it is important to recognize that serious ophthalmic pathology can occur which requires immediate medical intervention. This article is a review of the pathological and physiological changes which occur within the parturient as well as the safety of medication used to treat various conditions. Objective:The aim of this study was to review physiologic and pathologic ocular changes that are associated with pregnancy in pregnant women. After reading this article, readers should be able to: i. Distinguish physiological pregnancy-related ocular changes from pathological ii. Assess the relevance of ocular disease to the choice of childbirth method iii. Ophthalmic medication safe for pregnancy Conclusion:Pregnancy provides a great opportunity for physicians to establish care in a younger population who otherwise would not seek medical attention. As a result, physicians are able to treat and screen for several common pathologies during pregnancy. Certain ocular changes, whether physiological or pathological, may be increased during pregnancy. Thus, it is important to be educated on pathophysiological changes that are common in pregnancy in order to better counsel women who are pregnant or planning to become pregnant. Although many ocular changes are mild, temporary, and require little to no treatment, allocular symptoms in pregnancy requires ophthalmologic examination and management. However, long term data on ophthalmic drugs during pregnancy and lactation is insufficient. Thus, doctors should always be cautious and consult expert opinion before using any topical or systemic treatment on the patient.

Беременность и заболевания глаз (обзор литературы)

It presents historical data on the management of pregnancy in women with diseases of the eye, showing ophthalmic manifestations in various pathological conditions by the organs of sight and order management of pregnancy and childbirth in women with ophthalmic pathology, including in ophthalmic morphological and functional changes associated with the development of gestational complications. Noting also the permissibility of performing laser-surgical procedures in pathological changes in the organs of a pregnant woman and ophthalmic changes are taken into account when choosing a mode of delivery.

Ophthalmic changes in cleft lip and palate

The current study aimed to analyze through a literature review evidence of association between ocular changes and non-syndromic cleft lip and/or palate (NSCL/P). A literature review was carried out in accordance with the Cochrane Collaboration Group protocol. PubMed, Scopus, Academic Google and ISI Web of Science databases were systematically searched. A total of 16 studies were accessed, and three made up the final sample.All three studied ocular abnormalities in patients with NSCL/P.The articles found ocular abnormalities in 6.21%, 17.54% and 1.03% of patients respectively.The presence of ocular abnormalities in patients with NSCL/P was significant in this systematic review, but the articles all agreed that future studies should explore the possibility of a greater occurrence of ocular changes in individuals with NSCL/P.

Genotype, B-vitamin status, and androgens affect spaceflight-induced ophthalmic changes.

Ophthalmic changes have occurred in a subset of astronauts on International Space Station missions. Visual deterioration is considered the greatest human health risk of spaceflight. Affected astronauts exhibit higher concentrations of 1-carbon metabolites (e.g., homocysteine) before flight. We hypothesized that genetic variations in 1-carbon metabolism genes contribute to susceptibility to ophthalmic changes in astronauts. We investigated 5 polymorphisms in the methionine synthase reductase (MTRR), methylenetetrahydrofolate reductase (MTHFR), serine hydroxymethyltransferase (SHMT), and cystathionine β-synthase (CBS) genes and their association with ophthalmic changes after flight in 49 astronauts. The number of G alleles of MTRR 66 and C alleles of SHMT1 1420 both contributed to the odds of visual disturbances. Preflight dehydroepiandrosterone was positively associated with cotton wool spots, and serum testosterone response during flight was associated with refractive change. Block regression showed that B-vitamin status and genetics were significant predictors of many of the ophthalmic outcomes that we observed. In one example, genetics trended toward improving (P = 0.10) and B-vitamin status significantly improved (P < 0.001) the predictive model for refractive change after flight. We document an association between MTRR 66 and SHMT1 1420 polymorphisms and spaceflight-induced vision changes. This line of research could lead to therapeutic options for both space travelers and terrestrial patients.

Vision Issues and Space Flight: Evaluation of One‐Carbon Metabolism Polymorphisms

Intermediates of the one‐carbon metabolic pathway are altered in astronauts who experience vision‐related issues during and after space flight. Serum concentrations of homocysteine, cystathionine, 2‐methylcitric acid, and methylmalonic acid were higher in astronauts with ophthalmic changes than in those without (Zwart et al., J Nutr, 142:427‐31, 2012). These differences existed before, during, and after flight. Potential confounding factors did not explain the differences. Genetic polymorphisms could contribute to these differences, and could help explain why crewmembers on the same mission do not all have ophthalmic issues, despite the same environmental factors (e.g., microgravity, exercise, diet). A follow‐up study was conducted to evaluate 5 polymorphisms of enzymes in the one‐carbon pathway, and to evaluate how these relate to vision and other ophthalmic changes after flight. Preliminary evaluations of the genetic data indicate that all of the crewmembers with the MTRR GG genotype had vision issues to one degree or another. However, not everyone who had vision issues had this genetic polymorphism, so the situation is more complex than the involvement of this single polymorphism. Metabolomic and further data analyses are underway to clarify these findings, but the preliminary assessments are promising. This study was funded by the Human Health Countermeasures Element of the NASA Human Research Program.

Etiopathogenesis and diagnostics of autoimmune thyroid diseases

The pathogenesis of Graves-Basedow's disease is similar to that of Hashimoto’s disease (chronic autoimmune thyroiditis) and it is assumed that these two forms are the opposite poles of the same autoimmune disease. The name of the first disease derives from the surnames of two scientists who described it in the literature: Robert James Graves (1835) and Karl Adolf von Basedow (1840). The first description of the second disease was presented in 1912 by Hakaru Hashimoto. Genetic, environmental and endogenic factors are involved in the pathogenesis of autoimmune diseases. Genetic predisposition to an autoimmune disease depends on many genetic loci, of which three seem to be most important: alleles of the major histocompatibility system genes (human leukocyte antigen – HLA), mainly of class II HLA-DR3 and DR5; alleles of the gene encoding antigen-4 associated with the cytotoxic T lymphocyte (cytotoxic T lymphocyte associated antigen-4 – CTLA-4) and alleles of the gene encoding the lymphocytic tyrosine phosphatase (Protein Tyrosine Phosphatase Non Receptor – Type 22 - PTPN22). Epidemiological studies also confirm that genetic factors are responsible for autoimmune thyroid diseases with a high prevalence in patients’ relatives, especially among monozygotic twins. The environmental factors responsible for the presence of thyroid autoantigens on thyrocyte surface include viral infection, extreme stress, an excessive iodine content in diet, the action of some drugs (interferon α, amiodarone) and a huge number of chemical compounds in polluted surroundings. The most important endogenic factors include female sex and the phenomenon of foetal microchimerism in pregnant women. An organ-specific suppressor T lymphocyte defect develops in genetically predisposed people, which leads to an excessive stimulation of the T-helper lymphocytes. As a consequence, B lymphocytes experience excessive stimulation with subsequent production of plasma cells, which are responsible for the disproportionate production of antibodies against thyroid antigens – mainly the TSH receptor, thyroglobulin and thyroid peroxidase. In Graves-Basedow's disease, TSH receptor is the main autoantigen against which the antithyroid antibodies are directed. High titres of ATG and anti-TPO may suggest the coexistence of Hashimoto’s disease. In 80% cases of Graves-Basedow's disease, TSHR antibodies are stimulatory (thyroid stimulating immunoglobulins – TSI). In some cases, antibodies that inhibit thyrotropin binding to thyroid cells are produced (thyrotropin binding inhibiting immunoglobulins – TBII), which may lead to the development of hypothyroidism. In Hashimoto’s disease, cytotoxic lymphocytes, able to destroy thyroid follicular cells, receive considerable stimulation. Apart from cytotoxic lymphocytes, macrophages and the phenomenon of programmed cell death (apoptosis) also take part in the process of thyrocyte destruction. Clinical diagnosis of Graves-Basedow's disease is based on the detection of evenly enlarged thyroid gland with tactile fremitus and/or audible vascular murmur and the occurrence of the typical ophthalmic changes. Some patients also suffer from pretibial myxoedema and thyroid acropathy. Ultrasonography is a very useful imaging tool in the diagnosis of Graves-Basedow's disease – the thyroid gland is usually enlarged and has a homogenous, hypoechoic structure. Scintigraphy is not obligatory in each case of Graves-Basedow's disease, but it is very helpful in patients with the features of nodular structure and in the form without the goitre in which diagnostic difficulties occur. In the classical form of Hashimoto’s disease, a painless goitre of intensified cohesion presents with a butterfly-like shape because of the palpable pyramidal lobe. Patients complain of pressure and feeling of obstruction within the neck, and can report swallowing disorders and hoarseness. Chronic autoimmune thyroiditis can also occur in the atrophic, focal and juvenile form. Additionally, there are two variants of Hashimoto’s disease: postpartum thyroiditis and silent, painless thyroiditis. High anti-TPO antibody concentrations confirm the diagnosis of Hashimoto’s disease or any of its variants. The absence of antibodies in serum does not exclude lymphocytic thyroiditis as they are provided by intrathyroid lymphocyte infiltrations. Some authors attribute a special diagnostic significance to fine-needle aspiration biopsy in seronegative forms. Ultrasound thyroid examination is helpful in establishing correct diagnosis. Heterogeneous and distinctly hypoechoic structures of the thyroid gland are typical sonographic manifestations.

Microgravity-induced fluid shift and ophthalmic changes.

Although changes to visual acuity in spaceflight have been observed in some astronauts since the early days of the space program, the impact to the crew was considered minor. Since that time, missions to the International Space Station have extended the typical duration of time spent in microgravity from a few days or weeks to many months. This has been accompanied by the emergence of a variety of ophthalmic pathologies in a significant proportion of long-duration crewmembers, including globe flattening, choroidal folding, optic disc edema, and optic nerve kinking, among others. The clinical findings of affected astronauts are reminiscent of terrestrial pathologies such as idiopathic intracranial hypertension that are characterized by high intracranial pressure. As a result, NASA has placed an emphasis on determining the relevant factors and their interactions that are responsible for detrimental ophthalmic response to space. This article will describe the Visual Impairment and Intracranial Pressure syndrome, link it to key factors in physiological adaptation to the microgravity environment, particularly a cephalad shifting of bodily fluids, and discuss the implications for ocular biomechanics and physiological function in long-duration spaceflight.