Visual disturbances during prolonged space missions.

PURPOSE OF REVIEW: During prolonged spaceflight, astronauts often experience ocular changes, due to constant head-ward fluid shifts in space as compared with Earth. This article reviews symptoms, likely causes, and potential solutions, such as lower body negative pressure, to counteract space-associated neuroocular syndrome (SANS). RECENT FINDINGS: Low gravity conditions and other aspects of spaceflight affect the eye detrimentally, causing SANS which is characterized by optic disc edema, choroidal thickening, cotton wool spots, and a hyperopic shift. SANS is probably caused by altered hemodynamic flows in the head and neck as well as mildly elevated intracranial and intraocular pressures. Carbon dioxide and other chemicals in space-craft may influence SANS as well. SANS may be counteracted by using lower body negative pressure, thigh cuffs, spacecraft engineering, and/or artificial gravity by a centrifuge. SUMMARY: Prolonged space missions are associated with optic disc edema, choroidal thickening, cotton wool spots, and a hyperopic shift. Possible causes and countermeasures are currently being researched to reduce the risk of SANS. Although many countermeasures to SANS are under investigation lower body negative pressure exhibits great promise in counteracting the headward fluid shifts in space. Understanding and prevention of SANS is critical to future space exploration, especially to long-duration missions to the moon and Mars.

Grosor coroideo macular en la neuropatía óptica isquémica anterior no arterítica / Macular choroidal thickness in non-arteritic ischemic optic neuropathy

OBJETIVO: Analizar el grosor coroideo macular (GCM) en la neuropatía óptica isquémica anterior no arterítica (NOIA-NA). MATERIAL Y MÉTODOS: Un total de 22 pacientes diagnosticados de NOIA-NA (22 ojos) y 42 sujetos sanos (42 ojos) fueron estudiados usando tomografía de coherencia óptica con técnica Enhanced Depth Imaging (EDI-OCT). Se realizó un escáner de una línea horizontal centrado en la fóvea 3 meses después del inicio de NOIA-NA. Se tomaron 3 medidas desde la parte posterior del epitelio pigmentario hasta la unión esclerocoroidea a intervalos de 500 μm en las 1.500 μm centrales de la mácula. Los resultados fueron analizados estadísticamente comparando la media de GCM entre grupos y correlacionando el GCM con otros parámetros oculares y sistémicos. RESULTADOS: Excepto en el error refractivo (p = 0,01), no hubo diferencias significativas en longitud axial (p = 0,53), edad (p = 0,88) ni en otros parámetros oculares ni epidemiológicos entre grupos. La media de GCM en la NOIA-NA y en el grupo control fue 236,21 ± 63,29 μm y 269,13 ± 52,28, respectivamente. La media del GCM fue significativamente más delgada en ojos con NOIA-NA que en sanos (p = 0,03). El adelgazamiento del GCM estuvo asociado con el diagnóstico de NOIA-NA después de ajustar por error refractivo (p = 0,04). CONCLUSIONES: Los ojos afectos con NOIA-NA mostraron un GCM significativamente más adelgazado que en sujetos sanos, después de ajustar por error refractivo

OBJECTIVE: To analyse macular choroidal thickness (MCT) in non-arteritic ischaemic optic neuropathy (NAION). MATERIALS AND METHODS: An analysis was made on 22 patients diagnosed with NAION (22 eyes) and 42 healthy controls (42 eyes) using enhanced-depth imaging of spectral-domain optical coherence tomography. A horizontal raster scan centred on the fovea was obtained per eye 3 months after the onset of NAION. Three measurements of MCT were obtained from the posterior edge of the retinal pigment epithelium to the choroid-sclera junction at 500 μm intervals. Statistical analysis was used to compare the mean MCT and to correlate MCT with other ocular and systemic parameters. RESULTS: Except for refractive error (P=.01), there were no statistically significant differences between both groups in axial length (P=.53), age (P=.88) and other epidemiological and ocular parameters. Mean MCT in NAION eyes and control group was 236.21 ± 63.29 μm and 269.13 ± 52.28, respectively. Mean MCT was significantly thinner in NAION eyes than in healthy eyes (P=.03). Thinner MCT, adjusted for refractive error, was associated with the diagnosis of NAION (P=.04). CONCLUSIONS: Eyes affected by NAION showed significantly thinner MCT compared with healthy control eyes after adjusting for refractive error

Choroidal effusion and suprachoroidal hemorrhage during phacoemulsification: intraoperative management to prevent expulsive hemorrhage.

PURPOSE: To describe the intraoperative management of choroidal effusion (CE) or suprachoroidal hemorrhage (SCH) during cataract surgery with the phacoemulsification technique. METHODS: The study is a retrospective interventional study through which we describe the intraoperative management adopted in 6 cases of CE or SCH during cataract surgery. The study involved 6,400 eyes (phacoemulsification) in 6 years observational time (incidence rate 0.094%). The surgical time at which these complications happened differed: nucleolus phacoemulsification in 2 eyes, cortex removal by bimanual irrigation-aspiration in 3 eyes, and intraocular lens implant for 1 eye. Once the complication was recognized, each patient was quickly moved to an extreme reverse Trendelenburg position and pharmacologically treated to manage high blood pressure, pain, and anxiety (150 mL of an 18% mannitol solution delivered in rapid infusion intravenously; 1-3 mg intravenous midazolam; 5 nifedipine sublingual drops). RESULTS: In all the cases reported, the surgery was completed after resolution of the acute choroidal exudation or SCH. In the follow-up evaluation, the intraocular pressure was normal at each examination. The visual acuity of the patients was between 6/7.5 and 5/6 Snellen after 4 weeks. We observed a statistically significant reduction in endothelial cells in the 2 eyes in which the CE or SCH happened during the phacoemulsification compared with the other cases; this finding likely results from mechanical damage (p = 0.04 [95% confidence interval]). CONCLUSIONS: Choroidal effusion or SCH can be intraoperatively managed to avoid expulsive hemorrhage and maintain the possibility of completing the surgery.

Surgical results of Ahmed valve implantation combined with intravitreal triamcinolone acetonide injection for preventing choroidal detachment.

BACKGROUND: To investigate the surgical results of Ahmed valve implantation with intravitreal triamcinolone acetonide injection (IVTA) in patients with aphakic or pseudophakic glaucoma. METHODS: Fifty-nine patients who underwent Ahmed valve implantation were consecutively recruited from November 2005 to August 2011 at the Beijing Tongren Hospital. In the IVTA group (29 eyes), 4 mg of TA was injected into the vitreous cavity during Ahmed valve implantation was performed. In the control group (30 eyes), only Ahmed valve implantation was performed. The primary outcome was intraocular pressure (IOP). The visual acuity (VA), supplemental medical therapy and complications were evaluated as secondary outcomes. RESULTS: The IVTA and control groups were followed up for a mean of 22.7 and 31.4 months, respectively. IOP decreased in both groups at 1 day, 1 week, 1 month and the final follow-up points after the surgery. However, there was no significant difference between 2 groups at all intervals (P > 0.05). The rate of shallow anterior chamber and choroidal detachment in IVTA group was significantly lower than control group (6.9% vs. 40%, P = 0.007; 0% vs. 26.7%, P = 0.009). CONCLUSIONS: Ahmed valve implantation combined IVTA seems to be effective to reduce the incidence of complications for treatment of aphakic or pseudophakic glaucoma.

Vitreoretinal complications of the Boston Keratoprosthesis.

The Boston Keratoprosthesis has allowed for visual restoration in patients with corneal blindness; however, vitreoretinal complications remain a significant cause of ocular morbidity. Retroprosthetic membranes, infectious endophthalmitis, sterile vitritis, vitreous hemorrhage, vitreous opacities, retinal detachment, cystoid macular edema, choroidal detachments, retinal vascular occlusion, and epiretinal membrane have all been described, may require the intervention of a vitreoretinal specialist, and are reviewed herein. A strong familiarity with associated posterior segment complications is important to maximizing patient outcomes.

A simple method for detecting vitrectomy infusion line position in hazy media, in case of poor visualization.

PURPOSE: To introduce a simple and practical method for detecting vitrectomy infusion line position in a hazy media. METHODS: The position of the infusion cannula was evaluated before and during vitrectomy in 17 eyes of 17 patients with hazy media. This procedure was performed by using the light pipe inserted partially into the cannula and determining the color of transmitted light into the vitreous cavity. Dark red or brownish color was considered as suprachoroidal placement and bright whitish color as the correct position of the cannula tip. RESULTS: In 13 patients, the position of the cannula was considered as a precise position by using the aforementioned method at the beginning of the operation, and vitrectomy was performed without any infusion line-related complications. In two cases, the incorrect placement of the infusion cannula was confirmed with this technique, and the cannula was reinserted and repositioned. In two cases, secondary slippage of the cannula in suprachoroidal space was detected by using this method during vitrectomy, and another cannula was tried in another position. CONCLUSION: Using the color of light pipe inserted partially into the cannula is a safe and simple method for evaluating the position of the infusion line in the eye.

Presumed air by vitrectomy embolisation (PAVE) a potentially fatal syndrome.

BACKGROUND: Since first being reported in the ophthalmology literature in 2010, three cases (one fatal) of suspected venous air embolism (VAE) during vitrectomy have received little notice, and the vitrectomy/VAE connection has been described as unproven. We investigated the ability of air to exit the eye through vortex veins after accidental suprachoroidal air infusion. METHODS: Vitrectomy was performed on four donor eyes. Unsutured cannulas were partially withdrawn during air fluid exchange, producing choroidal detachments that emulated accidental suprachoroidal air infusion from a slipping cannula. Eyes with and without clamping of the vortex vein stumps were partially submerged in a water bath. RESULTS: Extensive choroidal detachment was created in all eyes during air infusion. All eyes with open vortex veins demonstrated rapid air extravasation/bubbling. An eye with clamped vortex vein stumps showed no air extravasation until the clamps were removed. CONCLUSIONS: When combined with existing clinical reports of suspected VAE in the eyes of living patients during ocular air fluid exchange, this experiment justifies recognition of presumed air by vitrectomy embolisation (PAVE) as a rare but potentially fatal vitrectomy complication. Simple surgical precautions can change PAVE from a 'rare event' to a 'never event', beginning with acknowledgment of its existence.

Sclerochorioretinal abnormalities in hypercholesterolemic rabbits treated with rosiglitazone.

BACKGROUND AND OBJECTIVE: To evaluate early retinal, choroidal, and scleral abnormalities induced by a hypercholesterolemic diet and the prevention of these abnormalities after oral administration of rosiglitazone in rabbits. MATERIALS AND METHODS: Fifty-four New Zealand rabbits were divided into four study groups: control group, normal diet; group 1, hypercholesterolemic diet; group 2, hypercholesterolemic diet associated with daily administration of 3 mg of rosiglitazone from day 14 after beginning the diet; and group 3, hypercholesterolemic diet associated with daily administration of 3 mg of rosiglitazone since the beginning of the experiment. Sclera and choroid underwent histologic and histomorphometric analyses. Retina underwent immunohistochemical analysis with anti-calretinin and anti-glial fibrillary acidic protein (GFAP) antibodies. RESULTS: No abnormalities were observed in the control group. Group 1 had significant increases in scleral and choroidal thicknesses compared with the control group (P < .01) and group 3 (P < .05). Group 1 presented significant increases in immunoreactivity (P < .001) to the anti-calretinin antibody compared with the other groups. Groups 2 and 3 had significant (P < .002) increases in calretinin immunoreactivity compared with the control group. GFAP was negative in all groups. CONCLUSION: The hypercholesterolemic diet induced early retinal, choroidal, and scleral abnormalities. Rosiglitazone preserved the structural anatomy.

Choroidal detachment following retinal detachment surgery: an analysis and a new hypothesis to minimize its occurrence in high-risk cases.

PURPOSE: To determine factors predisposing to the development of choroidal detachment following conventional retinal detachment surgery, to evaluate its clinical course, and to identify possible measures to reduce its occurrence. METHODS: Analysis of 25 consecutive cases of choroidal detachment following retinal detachment surgery out of a total of 510 cases undertaken at a tertiary care referral eye center over a period of 15 months. RESULTS: The incidence of developing choroidal detachment was 4.9%. The mean age was 61 years (range 28 to 76 years) and there was no sex predilection. Hypertension was present in 16% (n=4). A total of 44% (n=11) of patients had myopia and with respect to the lens status, 44% (n=11) were phakic, 36% (n=9) were pseudophakic, and 20% (n=5) were aphakic. Redetachment of the retina was observed in 12% (n=3) of cases. Elevated intraocular pressure developed in 12% (n=3). In one patient with an anterior chamber intraocular lens and "kissing" choroidal detachment, drainage of the choroidals was undertaken to prevent corneo-lenticular touch and corneal decompensation. In two patients with redetachment, anatomic settlement of the retina was achieved only following vitreoretinal surgery. CONCLUSIONS: The following preoperative and intraoperative factors are associated with a significantly increased risk of choroidal detachment following retinal detachment: higher age, myopia, posteriorly placed explants even if its extent is less, anteriorly placed explants whenever its extent is large, drainage of subretinal fluid, and intraoperative hypotony. Choroidal detachment may also occur in patients with only a radial sponge. Designing a notch intraoperatively in the region of the explants overlying the vortex veins may help to reduce the risk of choroidal detachment following conventional retinal detachment surgery.

Assessing the need for posterior sclerotomy at the time of filtering surgery in patients with Sturge-Weber syndrome.

PURPOSE: Posterior sclerotomy has been recommended for prevention of intraoperative choroidal hemorrhages and choroidal effusions in patients with Sturge-Weber syndrome (SWS) or Klippel-Trenaunay-Weber (KTW) syndrome undergoing glaucoma filtering surgery. In this study, we evaluated this unproven clinical perception. DESIGN: A retrospective, noncomparative, case series. PARTICIPANTS: Seventeen consecutive patients with SWS or KTW syndrome who underwent glaucoma filtering surgery without prophylactic posterior sclerotomy or other prophylactic measures between January 1973 and March 1997 at a university-based practice. INTERVENTION: Glaucoma filtering surgery without prophylactic posterior sclerotomy. MAIN OUTCOME MEASURES: Incidence of intraoperative and postoperative choroidal effusion, choroidal detachment, or choroidal hemorrhage. RESULTS: No intraoperative choroidal effusion, choroidal detachment, or choroidal hemorrhage occurred in this series. After surgery, 6 patients had a transient choroidal effusion. Surgical drainage was not required in any of them. No suprachoroidal hemorrhages occurred after surgery. CONCLUSIONS: We did not encounter significant intraoperative suprachoroidal hemorrhage, choroidal effusions, or a combination requiring therapeutic intervention in our series. This finding leads us to question the necessity for prophylactic posterior sclerotomy to prevent the occurrence of these complications in patients with SWS and KTW syndrome undergoing glaucoma filtering surgery.

Basic fibroblast growth factor inhibits choriocapillaris atrophy in rabbit.

PURPOSE: To examine the effect of basic fibroblast growth factor on induced choriocapillaris atrophy in vivo. METHODS: Choriocapillaris atrophy was surgically induced in rabbits by a hydraulic retinal detachment followed by debridement of the retinal pigment epithelium under the detached retina. Three concentrations of basic fibroblast growth factor (0.1 microg/0.1 ml, 1 microg/0.1 ml, or 5 microg/0.1 ml) were injected into the subretinal space and into the vitreous cavity 1, 3, and 5 days after the surgery. For control, only Tris buffer was injected in the same manner. The rabbits were euthanized 7 days after the surgery. Choroidal vascular casts were made and examined by scanning electron microscopy. The choriocapillaris atrophy was quantified by computer-assisted image analysis of photographs of the choriocapillaries. The area of the choriocapillaris and number of intercapillary spaces in the choriocapillaris that corresponded to the density of the capillary network were measured. RESULTS: The average area of the choriocapillaris in the eyes treated with 1 microg/0.1 ml of basic fibroblast growth factor was significantly larger at 75.1 +/- 3.0% than that in the control eyes at 67.2 +/- 5.6% (P =.021). The average area of the choriocapillaris in the 0.1 microg/0.1 ml of basic fibroblast growth factor group was not statistically different from the control. The number of intercapillary spaces of the choriocapillaris was 132 +/- 12 in the 0.1 microg/0.1 ml of basic fibroblast growth factor group, 124 +/- 46 in the 1 microg/0.1 ml of basic fibroblast growth factor group, and 75 +/- 14 in the control group. The higher number of spaces in the treated group was statistically significant (P =.026). CONCLUSIONS: Basic fibroblast growth factor decreased the atrophy of the choriocapillaris after removal of the retinal pigment epithelium in rabbit eyes. These results suggest that basic fibroblast growth factor may play a role in the survival of the choriocapillaris in vivo.

[Practical value of preventive posterior sclerectomy in trabeculectomy]. / O prakticheskoi tsennosti profilakticheskoi zadnei skleréktomii pri trabekuléktomii.

The results of prophylactic posterior sclerectomy, carried out to prevent ciliochoroid detachment in antiglaucoma fistulization surgery (trabeculectomy in various modifications) are analyzed. A total of 293 patients (303 eyes) were under study. In 51.8 percent of cases (157 eyes) trabeculectomy was combined with prophylactic sclerectomy, carried out both in the upper (121 eyes) and lower (36 eyes) segments of the eye. The results evidence that prophylactic posterior sclerectomy promoted a 2.3 times reduction (from 28.1 to 12.1 percent) in the incidence of ciliochoroid detachments; the site of this operation (upper of lower segment of the eye) was of no essential importance. The authors recommend prophylactic posterior sclerectomy as an effective method for prevention of ciliochoroid detachment.