Inflow of ocular surface fluid through clear corneal cataract incisions: a laboratory model.
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Body Fluids↗
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Results for “Intraocular fluid”
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Ultrasound biomicroscopy in Sturge-Weber-associated glaucoma.
PURPOSE: To evaluate Sturge-Weber-associated glaucoma using ultrasound biomicroscopy. METHOD: Case report. Clinical examination combined with ultrasound biomicroscopy was performed in a patient with Sturge-Weber-associated glaucoma. RESULTS: In the patient's left eye, which had Sturge-Weber-associated glaucoma, a 360-degree supraciliary effusion, dilated superficial and intrascleral vessels, and an open angle were detected by ultrasound biomicroscopy. CONCLUSION: The presence of dilated intrascleral vessels and supraciliary fluid support the hypothesis of increased episcleral venous pressure as the cause of elevated intraocular pressure in this syndrome.
Adolescent↗
Grossly false applanation tonometry associated with interface fluid in susceptible LASIK patients.
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Acetazolamide↗
Choroidal tubercles in disseminated tuberculosis diagnosed by the polymerase chain reaction of aqueous humor. A case report and review of the literature.
PURPOSE: Disseminated tuberculosis occurs due to the hematogenous spread of pulmonary tuberculosis systemically. Polymerase chain reaction (PCR) of various body fluids has been found to be beneficial in the diagnosis of disseminated tuberculosis, including intraocular tuberculosis. We describe the role of PCR of the aqueous aspirate in a case of disseminated tuberculosis involving the choroid. METHODS: Single-step PCR fusing primers coding for the IS6110 gene and nested PCR (nPCR) for the detection of the MPB64 gene were performed on the aqueous aspirate in a case of disseminated tuberculosis with miliary involvement of the choroid. RESULTS: On PCR, the aqueous aspirate showed the Mycobacterium tuberculosis genome, thereby confirming the diagnosis of intraocular tuberculosis. CONCLUSION: PCR is a highly sensitive and specific diagnostic test and PCR of intraocular specimens like the aqueous can be supportive of the diagnosis of miliary tuberculosis of the choroid.
Aqueous Humor↗
Bacterial endophthalmitis after retinal surgery.
Two cases of postoperative endophthalmitis caused by Staphylococcus epidermidis occurring in 10,000 routine scleral buckling operations are reported. Intraocular access of bacteria is suspected through scleral perforations used for release of subretinal fluid and for air injection. In case 1, despite vigorous treatments with vitrectomy, corticosteroids, and antibiotics, visual acuity decreased to light perception. In case 2, with intensive therapy, visual acuity of 6/12 (20/40) was retained. The visual outcome seems to depend on the rapidity of diagnosis and the promptness of aggressive therapy before irreparable structural damage occurs.
Adult↗
Iris involvement in leukaemia.
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Acetazolamide↗
Expression of cell surface transmembrane carbonic anhydrase genes CA9 and CA12 in the human eye: overexpression of CA12 (CAXII) in glaucoma.
PURPOSE: Carbonic anhydrase enzymes (CAs) are universally involved in many fundamental physiological processes, including acid base regulation and fluid formation and movement. In glaucoma patients, CA inhibitors are very effective in lowering intraocular pressure by reducing the rate of aqueous humour secretion mediated by the CAs in the ciliary epithelium. In this work, we investigated the expression and tissue distribution of two recently discovered CA genes CA9 (CAIX) and CA12 (CAXII) in fetal, neonatal, and adult human eyes with and without glaucoma. METHODS: CAIX and CAXII expression in 16 normal and 10 glaucomatous eyes, and in cultured non-pigmented ciliary epithelial cells (NPE) from normal and glaucoma eye donors was assessed by immunostaining. In addition, northern blot hybridisation was performed to assess expression of CA4, CA9, and CA12 mRNA in cultured NPE cells from normal and glaucoma donors. RESULTS: CAXII was localised primarily to the NPE with its expression prominent during embryonic eye development but which decreased significantly in adults. CAIX expression in the NPE was very low. The epithelium of cornea and lens occasionally expressed both enzymes at low levels during development and in adult eye, and no expression was detected in the retina. The NPE from glaucoma eyes expressed higher levels of CAXII, but not CAIX, in comparison with normal eyes. This expression pattern was retained in cultured NPE cell lines. NPE cells from a glaucoma patient showed a five-fold increase in the CA12 mRNA level with no detectable expression of CA9 mRNA. Also, no expression of the CA4 gene encoding a GPI anchored plasma membrane protein was detected on these northern blots. CONCLUSIONS: Transmembrane CAIX and CAXII enzymes are expressed in the ciliary cells and, thus, may be involved in aqueous humour production. CA12 may be a targeted gene in glaucoma.
Blotting, Northern↗
Low pressure hydrocephalus and ventriculomegaly: hysteresis, non-linear dynamics, and the benefits of CSF diversion.
Low pressure hydrocephalus (LPH) is a rare clinical condition. We report our experience with 10 patients treated at the Johns Hopkins Hospital. We reviewed the records of 10 patients (five men, five women; mean age 43 years) treated between 1996 and 2000. All underwent intracranial pressure (ICP) monitoring and subatmospheric cerebrospinal fluid (CSF) drainage with an intraventricular or lumbar catheter. All patients developed ventriculomegaly: five following aneurysmal subarachnoid haemorrhage; one after meningitis; one after intraventricular haemorrhage. Three patients presented with chronic aqueductal stenosis. Ventriculomegaly was clinically detected on average 12 days after presentation. Mean ICP was 4.8 mmHg (range 0-10). All patients improved only in the setting of negative pressure CSF drainage, and were subsequently treated with low pressure ventriculo- or lumboperitoneal shunts. At 1 year, eight patients (80%) showed good recovery to minimal disability; seven patients (70%) had resolving ventriculomegaly. The mechanism of low pressure hydrocephalus remains unclear. In our cohort, different aetiologies were responsible for the change in compliance/elastance of the brain parenchyma and subsequent development of ventriculomegaly. We propose that while ventriculomegaly (and therefore neuronal dysfunction) can be initiated in the setting of high ICP, the maintenance of ventriculomegaly at normal or low ICP is a physiological example of hysteresis. This behaviour, which has been characterized by the chaos theory of non-linear dynamics as a Hopf bifurcation, explains how a system can exhibit two different states (ventricular size) at a single parameter value (ICP). Most importantly, it helps to explain how lowering ICP in the setting of LPH can resolve ventriculomegaly and its neurologic sequelae.
Adult↗
[Mechanism of disordered ophthalmic tonus regulation of toxic etiology. Experimental, histomorphological and histochemical investigations].
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Animals↗
Cerebral blood velocity and other cardiovascular responses to 2 days of head-down tilt.
Spaceflight induces a cephalad redistribution of fluid volume and blood flow within the human body, and space motion sickness, which is a problem during the first few days of spaceflight, could be related to these changes in fluid status and in blood flow of the cerebrum and vestibular system. To evaluate possible changes in cerebral blood flow during simulated weightlessness, we measured blood velocity in the middle cerebral artery (MCA) along with retinal vascular diameters, intraocular pressure, impedance cardiography, and sphygmomanometry on nine men (26.2 +/- 6.6 yr) morning and evening for 2 days during continuous 10 degrees head-down tilt (HDT). When subjects went from seated to head-down bed rest, their heart rate and retinal diameters decreased, and intraocular pressures increased. After 48 h of HDT, blood flow velocity in the MCA was decreased and thoracic impedance was increased, indicating less fluid in the thorax. Percent changes in blood flow velocities in the MCA after 48 h of HDT were inversely correlated with percent changes in retinal vascular diameters. Blood flow velocities in the MCA were inversely correlated (intersubject) with arterial pressures and retinal vascular diameters. Heart rate, stroke volume, cardiac output, systolic arterial pressure, and at times pulse pressure and blood flow velocities in the MCA were greater in the evening. Total peripheral resistance was higher in the morning. Although cerebral blood velocity is reduced after subjects are head down for 2 days, the inverse relationship with retinal vessel diameters, which have control analogous to that of cerebral vessels, indicates cerebral blood flow is not reduced.
Adult↗
Optical quality of intraocular lenses.
The ANSI Z80.7 standard for intraocular lens quality is being updated. This paper identifies areas that require revision and suggests that a clear distinction between the lens design and the quality control test methods be made. The standard monofocal lens design consists of two spherical surfaces, and lens power can be specified by the thick lens equation, using body temperature refractive index values at a wavelength of 550 nm. Interferometry might be used as a primary manufacturing test method for poly(methyl methacrylate) lenses; tolerance values for lens surface errors are suggested. Other test methods can also be used. Measuring the modulation transfer function in fluid may be the most useful.
Humans↗
Laboratory model of tissue adhesive (2-octyl cyanoacrylate) in sealing clear corneal cataract wounds.
PURPOSE: To determine the efficacy of a tissue adhesive (2-octyl cyanoacrylate with parabens; Liquid Bandage, Johnson & Johnson, Skillman, New Jersey) in sealing clear corneal cataract wounds. DESIGN: Laboratory investigation. METHODS: Seven human donor globes were prepared for Miyake video microscopy. A 3.0-mm clear corneal incision was created. A transscleral cannula was inserted and connected to a bottle of saline. The bottle height was varied to alter intraocular pressure. Droplets of India ink were placed on the wound. Main outcome measure was any influx of India ink into the anterior chamber as viewed through the Miyake system with intraocular pressure (IOP) fluctuation or with manual pressure. If India ink was present in the eye, it was irrigated out, and the experiment was repeated with IOP fluctuation and manual pressure after the application of 2-octyl cyanoacrylate to the wound. RESULTS: One eye demonstrated the presence of India ink inside the eye on IOP reduction to <5 mm Hg. Three eyes demonstrated the presence of India ink inside the eye with manual pressure. Three eyes did not leak with manual pressure or IOP variation. All seven eyes without glue leaked with exaggerated manual pressure at the wound edge. Of the seven eyes with tissue adhesive, none demonstrated influx of India ink with IOP variation or manual wound manipulation. CONCLUSIONS: Our laboratory model demonstrates that 2-octyl cyanoacrylate prevents the influx of ocular surface fluid independent of IOP and manual wound manipulation. Further investigations in clinical models are necessary to determine the future use of this adhesive barrier substance.
Anterior Chamber↗
[Cerebrospinal fluid findings in ophthalmology. In hypertension].
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Blood Pressure↗
[Vitreoretinal surgery with intraocular C3F8 tamponade for retinal detachment due to macular hole without face-down positioning].
OBJECTIVE: To evaluate the effectiveness of vitreoretinal surgery with 16% perfluoropropane (C3F8) tamponade without face-down positioning in treatment of retinal detachment due to macular hole. METHODS: Twenty-seven consecutive eyes in 27 patients with retinal detachment due to myopic macular hole underwent closed vitrectomy, membrane peeling, gas-fluid exchange with C3F8 tamponade in the whole vitreous chamber. In 3 eyes, phacoemulsification was performed, and 2 of them received intraocular lens implantation. Postoperatively, except avoiding the supine position, the body position was not restricted. RESULTS: Twenty-one cases (78%) obtained successful retinal reattachment without the postoperative face-down positioning. In another 6 cases, because of the relatively quick absorption of the gas, the white macular hole and the subretinal proliferation, the operation was not successful, the hole being not sealed and the retinal detachment at the lower part still existing. In the 3 cases with quick absorption of the gas, on the 10th day after the operation, the body position was changed into a face-down one. In 2 of them, the retinal reattachment occurred. After > 6 months of follow-up, the retinal reattachment remain the same in 22 cases (81%), the macular hole was healed, and the visual acuity was elevated to > or = 0.1 in 19 cases. The main complications were lens opacity in 6 cases (31%), temporary elevation of intraocular pressure in 3 cases (11%). CONCLUSION: Use the methods for the treatment of macular hole and retinal detachment mentioned above may obtain relatively good therapeutic results, particularly suitable for senile and unhealthy cases.
Aged↗
Systemic but not intraocular Epo gene transfer protects the retina from light-and genetic-induced degeneration.
Molecules with neurotrophic activity are being evaluated for treatment of retinitis pigmentosa in animal models. In particular, great interest has been focused recently on erythropoietin (Epo). Evidence of its neurotrophic activity comes mainly from data demonstrating photoreceptor protection in a rodent light-damage model through systemic administration of a recombinant form of this hormone. Our goal was to test whether Epo retinal gene transfer can rescue or delay photoreceptor cell death. We delivered adeno-associated viral vectors encoding Epo intraocularly and, for comparison, intramuscularly to one light-induced and two genetic models of retinal degeneration. Intraocular Epo gene transfer resulted in sustained hormone expression in the eye, which was undetectable systemically. In contrast, Epo intramuscular gene transfer resulted in hormone secretion in the circulation, which was not detected in ocular fluids. The protein secreted from muscle and retina is of the same molecular weight as a commercial recombinant human Epo. Interestingly, following systemic but not intraocular Epo delivery, morphological photoreceptor protection was observed in the light-damage and rds/peripherin (Prph2) models of retinal degeneration. In the light-damage model, the morphological rescue was accompanied by a significant electrophysiological improvement of photoreceptor function. In contrast, no photoreceptor rescue was observed following Epo gene transfer in the rd10 model. This suggests that different apoptotic mechanisms, with varying sensitivities to Epo, occur in different retinal degeneration models. In conclusion, our data support Epo as a neuroprotective agent in some, but not all, retinal degenerations. Further, rescue is observed in specific models after systemic but not intraocular Epo gene transfer.
Animals↗
Additional intravitreal gas injection in the early postoperative period for an unclosed macular hole treated with internal limiting membrane peeling.
PURPOSE: To study the efficacy of additional intravitreal gas injection for unclosed macular holes within 2 weeks after surgery with internal limiting membrane peeling. METHODS: We reviewed the results for five consecutive eyes receiving additional intravitreal gas injection for unclosed macular holes within 2 weeks after initial macular hole surgery with internal limiting membrane peeling. The initial surgery consisted of standard pars plana vitrectomy with phacoemulsification and intraocular lens implantation, indocyanine green-assisted peeling of the retinal internal limiting membrane, and fluid-gas exchange with 20% sulfur hexafluoride. The patients were instructed to assume face down positioning for > or =7 days after surgery. If an unclosed macular hole was found after the residual gas volume decreased to <30% of the eyeball volume, fluid-gas exchange was performed using 15% octafluoropropane. RESULTS: All five eyes receiving additional intravitreal gas 7 to 14 days after vitrectomy had complete macular hole closure with macular flattening, as shown by optical coherence tomography 1 month after the additional gas injection. Visual acuity improved (range, 20/100 to 20/30). A minimum of 9 months of follow-up revealed no reopening or serious complications. CONCLUSION: Additional gas injection during the early postoperative period is recommended for eyes with unclosed macular holes that have undergone vitrectomy with internal limiting membrane peeling.
Aged↗
Oculab Tono-Pen, Goldmann applanation tonometry, and pneumatic tonometry for intraocular pressure assessment in gas-filled eyes.
We performed 84 intraocular pressure measurements with the Oculab Tono-Pen, Goldmann applanation tonometer, and pneumatic tonometer in 47 eyes that had undergone pars plana vitrectomy and gas-fluid exchange. Measurements made by using the Tono-Pen were accurate when compared to those made by Goldmann tonometry (mean difference, 0.74 mm Hg). In a subset of eyes with increased intraocular pressure (greater than or equal to 25 mm Hg), the Tono-Pen provided measurements similar to those made by Goldmann applanation tonometry (P greater than .60), with only three of 39 readings (8%) underestimating the Goldmann pressure by more than 3 mm Hg. Pneumatic tonometry significantly underestimated the intraocular pressure in eyes with increased pressure (P less than .001), with 20 of 39 readings (51%) underestimating the Goldmann pressure by 5 mm Hg or more.
Evaluation Studies as Topic↗
Fluid permeability of monkey ciliary epithelium in vivo.
Four months after total iridectomy, the aqueous humor of each of six cynomolgus monkeys was perfused at the spontaneous intraocular pressure under urethane anesthesia. The perfusate solution consisted of mock aqueous humor containing trace amounts of 14C-dextran (70,000 mol. wt.). The aqueous was stirred to bathe the ciliary epithelium. Aqueous flow was calculated from the tracer dilution. The aqueous humor was then perfused with bovine serum albumin (35 mg/ml) added to the perfusate. A new aqueous flow value was determined. Aqueous flow during mock aqueous perfusion was 1.28 +/- 0.12 microliters/min and 1.64 +/- 0.12 microliters/min during mock aqueous plus albumin perfusion. From the increase in aqueous flow due to the osmotic effect of the albumin solution (13.2 mm Hg), the osmotic fluid permeability of the ciliary epithelium was calculated to be 0.027 +/- 0.007 microliters/min/mm Hg. This permeability value places the ciliary epithelium in the category of membranes with "leaky" tight junctions. However, the low fluid permeability of the ciliary epithelium suggests a minor role for ultrafiltration in aqueous humor formation in the monkey.
Animals↗