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At least 595 records · Page 33Linked to original sources

Vitrectomy surgery increases oxygen exposure to the lens: a possible mechanism for nuclear cataract formation.

PURPOSE: To report vitreous oxygen tension before, immediately after, and at longer times after vitrectomy. DESIGN: A prospective, interventional consecutive case series. METHODS: Oxygen was measured using an optical oxygen sensor in patients undergoing vitrectomy. Intraoperatively, oxygen measurements were taken before and after vitrectomy in two intraocular locations: adjacent to the lens and in the mid-vitreous. RESULTS: Sixty-nine eyes underwent oxygen tension measurements at the time of vitrectomy. In baseline eyes, oxygen tension in the vitreous was low, measuring 8.7 +/- 0.6 mm Hg adjacent to the lens and 7.1 +/- 0.5 mm Hg in the mid-vitreous. The difference between the two locations was statistically significant (P < .003), indicating that vitreous gel maintains an intraocular oxygen gradient. Immediately after vitrectomy, oxygen tension in the fluid-filled eye was higher, measuring 69.6 +/-4.8 mm Hg adjacent to the lens and 75.6 +/- 4.1 mm Hg in the mid-vitreous. There was no statistically significant oxygen gradient between the two locations. The difference in oxygen tension pre- and postvitrectomy is highly statistically significant (P < .0001 lens, P < .0001 mid-vitreous). In eyes with a history of vitrectomy and previous removal of the vitreous gel, the intraocular oxygen tension was significantly higher than in eyes with a formed vitreous gel undergoing a first vitrectomy (P < .02 lens, P < .003 mid-vitreous). CONCLUSION: Vitrectomy surgery significantly increases intraocular oxygen tension during and for prolonged periods after surgery. This exposes the crystalline lens to abnormally high oxygen and may lead to nuclear cataract formation.

Aged↗

B-scan ultrasonography of eyes containing intravitreal gas.

Contact B-scan ultrasonography was performed on postoperative eyes containing intravitreal gas. Correlation of the ultrasonograms with the ophthalmoscopic findings disclosed that intraocular gas had a characteristic appearance on B-scan ultrasonography. Gas-fluid and gas-tissue interfaces were so highly reflective that no structures within or behind a bubble could be visualized. Shadowing, reverberation, and reflection artifacts were prominent, and dominated ultrasonographic findings. If the ultrasonographic characteristics of gas are understood, it is possible to use B-scan ultrasonography to determine if intraocular gas is present, whether there are one or several bubbles, and what percentage of the vitreous cavity is filled by gas. Specular reflection from a gas-fluid interface may be used to examine portions of the eye that might not otherwise be easily seen with ultrasonography.

Eye↗

Simultaneous hemofiltration/hemodialysis (HF/HD): short- and long-term tolerance. Introduction of a system for automatic fluid replacement.

Data are presented concerning our experiences with simultaneous hemofiltration and hemodialysis (HF/HD) in uremic patients. Ten randomly selected patients have been treated for two and a half to three years with either conventional hemodialysis (HD, 3 x 4 hours/week, 1.4 m2 surface area Cuprophan dialyzer) or HF/HD (RP-6, 3 x 3 hours/week). No differences could be detected with regard to the blood chemistry or the blood pressure between the two groups of patients. During HF/HD the well-being of the patients was better than during HD, which can be attributed to a greater stability of the blood pressure and of the serum osmolarity and to a decrease of the intraocular pressure during treatment. An apparatus is described which is in use enabling the automatic replacement of the required substitution fluid. With regard to the performance and the tolerance, HF/HD is comparable to hemofiltration, but the treatment sessions are shorter.

Acid-Base Equilibrium↗

Outpatient fluid-air exchange for severe postvitrectomy diabetic vitreous hemorrhage. Long-term results and complications.

An alternative treatment to repeat vitrectomy in postvitrectomy diabetic vitreous hemorrhage (PDVH) is outpatient fluid-air exchange, but the long-term visual results of this procedure are not known. Between January 1986 and April 1989, a pars plana air-pump technique was used to perform outpatient fluid-air exchange in 20 eyes of 17 patients (17 phakic eyes) within 8 weeks of onset of PDVH. A mean follow-up interval of 78 weeks was obtained. Preoperative vitreous hemorrhage was severe enough to obscure all fundus detail (17 eyes) or produce erythroclastic glaucoma (three eyes). Initial visual acuity was hand motions or light perception in 19 eyes and improved to a median visual acuity of 20/300 soon after resolution of the intraocular air bubble. Early complications included postoperative fibrin formation (one eye) and early postoperative intraocular pressure elevation (two eyes). Recurrent vitreous hemorrhage required repeated fluid-air exchanges in seven eyes. Long-term complications included worsening of posterior subcapsular cataract (10 of 17 phakic eyes, 59%), for which cataract extraction was required in five eyes (29%). Fluid-air exchange appeared to exacerbate cataract formation, justifying a period of observation for PDVH. However, it appeared to be a low-risk alternative to repeat vitrectomy, allowing rapid visual recovery from severe PDVH.

Adult↗

Angle-closure glaucoma associated with occult annular ciliary body detachment.

OBJECTIVE: To evaluate the role of annular ciliary body detachment in the development of postoperative angle-closure glaucoma. DESIGN: Case series. SETTING: Tertiary care glaucoma referral center. METHODS: High-resolution, anterior segment ultrasound biomicroscopy, ophthalmoscopy, and B-scan ultrasonography were performed on 6 eyes of 6 patients with a clinical diagnosis of postoperative malignant glaucoma. RESULTS: Each eye had an elevated intraocular pressure, a shallow anterior chamber, 1 or more patent iridectomies, and no ophthalmoscopic or B-scan ultrasound evidence of serous or hemorrhagic ciliochoroidal detachment. Ultrasound biomicroscopy revealed annular ciliary body detachment in each eye. In 4 eyes, observation with topical medical treatment was associated with deepening of the anterior chamber, reduced intraocular pressure, and resolution of the detachment. Drainage of the supraciliary fluid was performed in 2 eyes. CONCLUSION: Occult, annular, serous detachment of the ciliary body may cause postoperative angle-closure glaucoma. This entity is clinically indistinguishable from malignant glaucoma. Ultrasound biomicroscopy facilitates the diagnosis.

Aged↗

Sterile hypopyon following intraocular lens surgery.

Energy-dispersive x-ray analysis (EDXA) was used to study nine intraocular lenses from one manufacturer. Residual polishing compound was found on two of three dry-sterilized lenses from a "hot lot" associated with a high incidence of sterile hypopyon. Similar material was not present on normal lenses. This polishing compound was apparently fused to the lens surface, preventing its removal by ultrasonic cleaning. In addition, three wet-sterilized lenses were found to be covered with small crystals containing barium. These crystals apparently resulted from leaching of the glass storage vial by the caustic storage fluid. It is suggested that some cases of sterile hypopyon following intraocular lens surgery may be caused by residual polishing compound present on the lens surface.

Anterior Chamber↗

Detection of toxoplasmal antigen and antibody in ocular fluids in experimental ocular toxoplasmosis.

Enzyme-linked immunosorbent assays were used to detect intraocular toxoplasmal antigen and antitoxoplasmal IgG antibodies in a rabbit model of experimental ocular toxoplasmosis. Toxoplasmal antigen could be detected in the vitreous humor of the infected eye at the height of clinical activity of the lesion. Antitoxoplasmal IgG antibodies were detected in the aqueous and vitreous humors of the infected eyes five weeks following the onset of toxoplasmic retinochoroiditis.

Animals↗

[Drainage of subretinal fluid in our clinical studies].

The studies comprised 531 patients (544 eyes) who underwent retinal detachment surgery in the Ophthalmological Clinic in Cracow, in the years 1983-1992. Drainage of subretinal fluid was performed in 54.6% of the eyes and in this group attachment of the retina was achieved in 72.4% of cases; in the group of patients with nondrainage operations it was 74.5%. Intraocular haemorrhages, the only complications, which may be attributed to the drainage of subretinal fluid were found in 18.9% of eyes with drainage and in 8.1% without; this difference was statistically significant (p < 0.01). Statistically significant relationship (p < 0.01) was also found between subretinal fluid drainage and severity of the retinal detachment. The results showed that there were no significant relationships between drainage of subretinal fluid and the results of surgery and that it is indicated first of all in severe cases of retinal detachment in which method of choice is an encirclement procedure.

Adolescent↗

Continuous control of intraocular pressure in pseudophakic retinal detachment surgery.

We describe a method for continuous control of intraocular pressure in pseudophakic retinal detachment surgery done shortly after extracapsular cataract extraction and posterior chamber intraocular lens implantation. The system consists of a special needle inserted into the anterior chamber through the corneal limbus. The needle is attached by a regular intravenous administration set to an infusion bag. This allows fluids to exit the eye when the eyeball is compressed and to return to the eye when pressure on the eye is released. The presence of an intact posterior capsule and an intraocular lens do not impose a significant barrier to the passage of fluids between the anterior chamber and the vitreous cavity. Using this technique, intraocular pressure can be stabilized throughout the operation. The implementation of this system is demonstrated by a case report.

Cataract Extraction↗

Spontaneous pulsation of the retinal veins.

The classical theory of spontaneous pulsation of the retinal veins is that during systole intraocular pressure exceeds venous pressure, causing the veins to collapse. We show that this theory is internally inconsistent and not in accord with experimental data. It is inconsistent in assuming both (a) that oscillations of intraocular pressure (IOP) occur because the veins cannot immediately discharge the systolic arterial inflow and (b) that retinal venous pressure (RVP) can fluctuate independently of IOP during the cardiac cycle. It is not in accord with experimental data, which shows that RVP always exceeds IOP and that fluctuations in the latter are instantly transmitted to the former. We present an alternative theory that does not have these problems. We assume the following. (1) Inflow to the retinal venous tree from the capillaries is constant, the pulsatile arterial flow having been completely damped by the arterioles and capillaries. (2) Outflow from the central retinal vein (CRV) varies during the cardiac cycle because oscillations of IOP, transmitted to the intraocular CRV, are of greater amplitude than oscillations in cerebrospinal fluid pressure, transmitted to the extraocular CRV. By showing that the radial blood flow distending the veins obeys a diffusion equation and by employing an "equivalent cylinder" analysis of the branched venous tree to simplify the boundary conditions, we demonstrate that, with the above assumptions and the additional assumption of low amplitude of radial flow, the CRV will pulsate, and the pulsations will remain confined to a small segment near the exit point. The proposed theory can explain disappearance of pulsation with intracranial hypertension, intensification of pulsation in glaucoma, and variability in the linear extent and amplitude of pulsation among normal individuals. The theory may also be applied to other venous pulsations, such as the respiratory pulsation of the terminal portions of large veins entering the thorax or the cardiac cycle pulsation of the superior vena cava.

Animals↗

Vitrectomy techniques in late-stage Coats'-like exudative retinal detachment.

Retinal telangiectasia is the hallmark of Coats' disease. In the late stages, leakage from these abnormal vessels can result in a total, bullous exudative retinal detachment with cholesterol-laden subretinal fluid. Secondary angle-closure glaucoma may result in a blind and painful eye which may require enucleation or evisceration. Surgical reattachment of the retina and destruction of the retinal telangiectasia may preserve these eyes. We have found that vitrectomy, internal drainage of subretinal fluid and cholesterol, direct treatment of the retinal telangiectasia with intraocular diathermy and intravitreal gas or silicone oil injection are effective surgical techniques for salvaging these severely damaged eyes.

Adult↗

Does vitrectomy followed by intraocular gas tamponade offer sufficiently effective treatment of retinal detachment due to holes in the posterior pole?

We report on 17 consecutive cases of retinal detachment due to macular hole surgically treated by one of the authors (S.B.) between the fall of 1982 and 1985. The standard method used was pars plana vitrectomy and intraocular air tamponade. In cases of subsequent reaccumulation of subretinal fluid, the macular hole was cautiously coagulated. With repeated redetachment and as a last resort, silicone oil was injected into the vitreous cavity. After a follow-up period ranging from 5 to 42 months, 13 of the 17 eyes were cured; in 2 aphakic eyes treatment remained unsuccessful; in 2 eyes a small central detachment with some accumulation of subretinal fluid persisted but did not progress. Vitrectomy and gas tamponade alone, without coagulation, constitute the safest and most sparing treatment of this type of retinal detachment. Unfortunately, approximately one half of these cases require subsequent additional photocoagulation because of renewed accumulation of subretinal fluid. In about one fourth of macular hole retinal detachments, however, lasting reattachment is achieved only by silicone oil tamponade following initial vitrectomy and air/gas tamponade.

Adult↗

Acute unilateral leukemic hypopyon in an adult with relapsing acute lymphoblastic leukemia.

PURPOSE: To report acute unilateral hypopyon uveitis as an initial presenting feature of relapsing acute lymphoblastic leukemia (ALL) in an adult patient. DESIGN: Observational case report. METHODS: Anterior chamber paracentesis was performed in a 56-year-old male presenting with treatment-resistant unilateral hypopyon while in the remission phase of ALL. RESULTS: Examination of the aqueous humor aspirate revealed presence of malignant cells compatible with the previous bone marrow biopsy and subsequent spinal tap results. CONCLUSIONS: Atypical hypopyon uveitis can be an indication of relapsing ALL, even in adults. Prompt anterior chamber aspiration is required for the correct diagnosis and subsequent treatment.

Anterior Chamber↗

Inflow of ocular surface fluid into the anterior chamber after phacoemulsification through sutureless corneal cataract wounds.

PURPOSE: To report inflow of extraocular fluid after phacoemulsification with use of sutureless corneal incisions. DESIGN: Interventional case series. METHODS: setting: Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, Maryland. patients: Eight patients (three women), aged 58 to 91 years, showing minimal bleeding from the limbal capillary bed during phacoemulsification. intervention: Surgery was performed through a 2.8-mm limbal incision. External pressure simulating patient manipulation was applied before and after wound hydrosealing with an irrigation cannula. main outcome measures: Inflow of blood-tinged tear fluid into the anterior chamber through the wound was monitored by using digital video. RESULTS: Inflow of extraocular fluid was observed in all eyes when the cannula was released, even after wound hydrosealing. Two patients showed spontaneous fluid inflow. CONCLUSIONS: Tested sutureless corneal incisions allow inflow of extraocular fluid into the anterior chamber after phacoemulsification. This may permit intraocular contamination leading to endophthalmitis.

Aged↗

Cataract surgery without preoperative eyedrops.

We present a technique that uses intracameral lidocaine to induce pupil dilation without using preoperative mydriatic eyedrops. After 1 or 2 drops of topical lidocaine hydrochloride 1% (Xylocaine-MPF 1%) are applied to the ocular surface, a 1.0 mm side-port incision is created through which Xylocaine-MPF 1% is injected into the anterior chamber. The lidocaine paralyzes the pupil sphincter, and adequate mydriasis occurs within 90 seconds. Epinephrine (0.3 cc of 1:1000) is added to the irrigation fluid comprising balanced salt solution (BSS), and standard phacoemulsification with intraocular lens implantation is performed. Pupil dilation is maintained or increased during the procedure. Postoperatively, the pupil returns more quickly to normal size and reaction. Using lidocaine for mydriasis instead of standard dilating drops eliminates the cardiac risk of topical sympathetic agents, decreases the time patients wait in the holding area before surgery, reduces the risk of superficial punctate keratopathy, and provides faster recovery of normal pupil function.

Anesthetics, Local↗

Pars plana filtration with multiple laser perforation of the uvea for neovascular glaucoma following proliferative diabetic retinopathy.

PURPOSE: To evaluate the effect of pars plana filtration with multiple laser perforation of the uvea in neovascular glaucoma patients following proliferative diabetic retinopathy. METHODS: In 18 eyes of 13 patients, after a fornix-based conjunctival incision, two 9 x 3 mm, thin, rectangular scleral flaps were created 3-6 mm posterior to the limbus. The remaining layers of sclera under each flap were removed. The exposed uvea was irradiated at a mean of 60.6 spots with an argon laser just to the point of perforation. After the posterior chamber fluid escaped, the flaps were sutured. RESULTS: The mean preoperative intraocular pressure (IOP) was 36.4 +/- 9.0 mm Hg. After an average follow-up of 16.6 +/- 5.9 months, the mean final postoperative IOP was 16.6 +/- 4.4 mm Hg. The postoperative IOP was below 21 mm Hg in 3 (16.7%) of the 18 eyes without medication, in 14 (77.8%) on anti-glaucoma eye drops, and in 16 (88. 9%) on anti-glaucoma eye drops and an oral carbonic anhydrase inhibitor. Snellen visual acuity improved by more than 2 lines in 7 of the 18 eyes, worsened by this amount in 3, and remained within baseline +/- 2 lines in 8. CONCLUSION: This procedure is an effective treatment for neovascular glaucoma patients following proliferative diabetic retinopathy.

Acetazolamide↗