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At least 1,099 records · Page 61Linked to original sources

PubMed1998

Intraocular lens changes after short- and long-term exposure to intraocular silicone oil. An in vivo study.

OBJECTIVE: Silicone oil frequently is used as a vitreous substitute after complex vitreoretinal procedures. The authors sought to study the effect of short- and long-term exposure to silicone oil on polymethyl methacrylate (PMMA, MC60BM; Alcon, Ft. Worth, TX), silicone (SI-30NB; AMO, Irvine, CA), and soft acrylic (MA60BM; Alcon) intraocular lenses (IOLs). DESIGN: An experimental animal study. INTERVENTION: Forty-one New Zealand white rabbits underwent lensectomy, vitrectomy, capsulotomy, and placement of one of the three types of IOLs into the ciliary sulcus. All lenses were weighed before implantation and 24 hours after explanation. In the short-term study, an fluid-air exchange was performed followed by the use of silicone oil (1000 centistokes) to coat the posterior lens surface. Immediately thereafter, an air-fluid exchange was performed and the remaining silicone on the posterior lens surface was aspirated or wiped or both for 1 minute using a soft-tipped extrusion cannula for 1 minute. In the long-term study, the posterior segment was filled with 1000 centistokes silicone oil after fluid-air exchange. Animals were observed by slit-lamp biomicroscopy and photographed at 1 week, 1 month, and 3 months after surgery. At 3 months, all animals underwent silicone-fluid exchange, an attempt to manually remove any remaining silicone oil, and lens explanation. RESULTS: In the short-term study, no silicone oil remained after manual wiping and/or aspiration in any of the four rabbits implanted with PMMA or acrylic IOLs. In the animals with silicone IOLs, a significant amount of silicone oil remained on the posterior lens surface of all lenses (P < 0.01 for silicone vs. acrylic and silicone vs. PMMA). No statistically significant difference was found when comparing the lens weights in each group before and after implantation. In the long-term study, aqueous droplet formation was found on the posterior lens surface of six of nine PMMA IOLs and ten of ten silicone IOLs at 3 months. No opacities were observed in the group with acrylic IOLs (P < 0.001 for acrylic vs. silicone, P = 0.0018 for acrylic vs. PMMA, and P = 0.047 for PMMA vs. silicone). Adherent silicone oil remained on two of nine PMMA IOLs and on none of ten acrylic IOLs. In contrast, a significant amount of silicone oil remained on the posterior lens surface of ten of ten silicone IOLs (P < 0.001 for silicone vs. acrylic and silicone vs. PMMA). Furthermore, there was a statistically significant increase in lens weights before and after implantation in the silicone IOL group but not in the PMMA or acrylic group (P < 0.01). CONCLUSIONS: It is extremely difficult or impossible to remove remaining silicone oil from the posterior surface of a silicone IOL after short- or long-term exposure to silicone oil. This oil may interfere with the surgeon's view of the retina and may diminish the patient's visual acuity. In contrast, oil is readily removed from the posterior surface of an acrylic IOL. The authors therefore recommend the use of a soft acrylic or PMMA IOL over a silicone IOL when choosing a lens for implantation in patients who may require vitreoretinal procedures with silicone oil tamponade.

Acrylic Resins↗

PubMed2006

Measuring triamcinolone acetonide in aqueous humor by gas chromatography-electron-capture negative-ion mass spectrometry.

Intravitreal triamcinolone acetonide (IVTA) injection has been used in the treatment of various posterior segment diseases. One of the side effects of IVTA is raised intraocular pressure, which may be secondary to triamcinolone acetonide (TAA)'s effects on the trabecular meshwork that affects aqueous outflow. In order to study the biological effects of TAA on the trabecular meshwork, we firstly need to reliably and accurately detect the concentration of TAA in tissue cells or fluids. In this study we have described a technique of using gas chromatography-electron-capture-negative-ion mass spectrometry (GC-NCI-MS) to develop a simple, sensitive, selective and validated method to detect TAA in aqueous humor (AH) of rabbits following IVTA and subconjunctival TAA injections. We derivatized TAA from extracted aqueous sample by acetic anhydride and BSTFA, respectively, and analyzed by GC-NCI-MS. The detection limit was 0.3ng/ml, linearity over 0.995 from 0 to 300ng/ml. The reproducibility ranged from 10.4 to 3.9 for concentrations from 3 to 300ng/ml, and recovery was over 95% for the concentrations 10, 60, and 200ng/ml. No interference was found from 159 aqueous samples. There was no TAA residue carried to the next injection from previously high concentration injection, 10,000ng/ml. We have provided an alternative, rapid, and robust method other than LC-MS-MS for TAA detection in AH.

Animals↗

PubMedDate not supplied

[Morphometric analysis of the structure of tear and aqueous humor in senile cataract].

The parameters of the wedge dehydrated samples of aqueous humor and tear taken from patients with senile cataract were compared by a morphometric assay. Computer-aided processing of the images of the test biological fluids was made on a Morphotest-1 hardware-software complex. The study has provided evidence for the uniformity of distribution of major structural components in the dehydrated samples of tear and aqueous humor in each specific examinee. This fact opens up possibilities for studying the signs of different intraocular pathological conditions from the morphological pattern of tear.

Aged↗

PubMedDate not supplied

Intraocular lymphoma. Cytologic diagnosis and the role of immunologic markers.

We retrospectively reviewed the cytology and immunohistochemistry of vitreous cells from 14 patients with benign or malignant intraocular diseases. Nine patients had intraocular lymphoma and five had benign forms of diffuse uveitis. The most useful cytologic criteria for lymphoma included an irregular nuclear outline, a coarse chromatin pattern and prominent nucleoli. In several cases, it was necessary to obtain more than one specimen to establish the diagnosis of lymphoma. When vitreous fluid was mixed with a balanced salt solution prior to processing, a resulting artifact interfered with interpretation of the specimen. A diagnosis of lymphoma was established by cytology in all nine patients; immunohistochemical techniques were less sensitive than was cytology.

Adult↗

PubMed2000

Complete capsular bag distension syndrome.

After conventional extracapsular cataract extraction and in-the-bag intr aocular lens (IOL) implantation 3 years previously, the partially cut su perior one-third of the anterior capsulotomy flap resealed in the eye of a 55-year-old woman. With the integrity of the capsular bag restored, it distended fully; the IOL was in the center and milky fluid accumulated inside. A neodymium:YAG laser was used to drain the milky fluid and di srupt the opacified anterior and posterior capsules, restoring vision.

Capsulorhexis↗

PubMed2003

Transscleral fixation of a foldable intraocular lens in aphakic vitrectomized eyes.

PURPOSE: To evaluate the clinical outcomes of transscleral fixation of a foldable intraocular lens (IOL) in eyes that had pars plana lensectomy combined with pars plana vitrectomy for severe vitreoretinal disease. SETTING: Seoul National University Hospital, Seoul, Korea. METHODS: The medical records of 21 patients who had a transscleral fixation of a foldable IOL after previous vitrectomy combined with lensectomy for severe posterior segment pathology were reviewed. The underlying vitreoretinal diseases were complicated proliferative diabetic retinopathy (n = 9), proliferative vitreoretinopathy (n = 5), traumatic retinal detachment (n = 3), intraocular foreign body (n = 2), and uveitic retinal detachment (n = 2). The postoperative best corrected visual acuity (BCVA) was compared with the preoperative BCVA. Autorefractometry and keratometry measurements and central endothelial cell counts were evaluated 1 day preoperatively and 6 months postoperatively. RESULTS: The mean age of the patients was 54.5 years. The preoperative aphakic period ranged from 2 to 22 months. The visual acuity reached the preoperative BCVA by 2 months after surgery and was better than the preoperative BCVA at 6 months (P =.006) and at the final visit (P =.003). Six months postoperatively, the mean myopic shift by cycloplegic autorefractometry was -1.0 diopter (D) and the mean scalar shift in surgically induced keratometric cylinder, 1.0 D. The mean central corneal endothelial loss at 6 months was 6.7% (range 2.4% to 22.2%). The only vitreoretinal complications were a transient vitreous hemorrhage and a reopened macular hole that was reattached after fluid-gas exchange. CONCLUSION: Transscleral fixation of a foldable IOL was safe and led to favorable visual outcomes in aphakic vitrectomized eyes with previous severe vitreoretinal disease.

Adult↗

PubMed1983

Retinal pigmented epithelium culture: current applications.

Laboratory investigations of the ability of human and other Retinal Pigmented Epithelium cells to survive have provided guidelines for the handling and preparation of RPE from normal and pathologic eyes for culture. Rapid post-mortem enucleation and rapid cooling and storage at 4 degrees C, if immediate processing is not possible, are crucial to the regular, successful establishment of RPE cells in vitro. Cultured cells have been used to investigate the composition and biologic activity of various intraocular tissues, including the RPE by itself and in combination with other cell types. Although cultured RPE cells lack certain activities associated with RPE in vivo, they do retain a number of differentiated functions and, thus, are useful in the investigation of questions related to the promotion of differentiation, survival, fluid transport and extracellular matrix production, among others. Future refinements and improvements in culture conditions should augment the utility of these cells in vision research.

Animals↗

PubMed2006

[Injector implantation of a scleral-fixated intraocular lens].

BACKGROUND: In this pilot study, a new injector technique for small-incision implantation of scleral-fixated intraocular lenses (IOLs) was evaluated for IOL stability and visual rehabilitation. PATIENTS AND METHODS: Secondary lens implantation was performed in 18 aphakic eyes using a new small incision technique with injector implantation. This allowed for haptic suturing with the lens body inside the cartridge. All patients were followed-up for best-corrected visual acuity, refraction, IOL evaluation and ultrasound biomicroscopy. RESULTS: In all eyes the IOL was stable without tilt or torque. Best-corrected visual acuity improved 2.2 ETDRS lines after 1 week and 3.1 lines after a mean follow-up time of 7.9+/-2.8 months. Two eyes were complicated with small, peripheral transillumination defects (n=2), but no pigmentary glaucoma occurred. CONCLUSION: By using a self-sealing tunnel incision and injector technique, significant fluid egress and consecutive transient hypotony is minimized throughout the whole procedure. The technique shows a high IOL stability without tilt and assures rapid visual rehabilitation.

Adult↗

PubMed1989

Effects of intraocular pressure change on movement of FITC-dextran across vitreous-aqueous interface.

In an attempt to study the effect of change in the intraocular pressure (IOP) on the status of the vitreous-aqueous interface, the effect of topical bunazosin was studied in the rabbit eye using the new Johnson-Maurice method. This entails an intravitreal injection of FITC-dextran and measurements of its concentration changes in the anterior chamber many days after the injection. Repeated instillations of bunazosin solution reduced the IOP by about 5 mmHg, without changing the aqueous flow rate as determined by the method of fluorometry. On the other hand, the FITC-dextran concentration in the anterior chamber increased, indicating that the movement of FITC-dextran from the vitreous into the aqueous was greater when the IOP was lowered. This increase in the FITC-dextran movement into the anterior chamber was thought to be mainly attributable to an increase in the anteriorly directed fluid movement across the vitreous-aqueous interface. The increase in the fluid movement was estimated to be about 1.3 microliter/hour. This study suggested that a reduction in the IOP generated a small fluid flow from the vitreous into the aqueous, and that the new Johnson-Maurice method can be a useful means for noninvasive investigations of the physiology of the vitreous-aqueous interface.

Adrenergic alpha-Antagonists↗

PubMed2002

Drug delivery to the posterior segment from drops.

The published evidence that instilled drugs can affect the blood supply to the retina and optic nerve head in humans is examined. As a background, seven techniques that have been used to measure flow are briefly described and criticized. For timolol, the corresponding measurements, obtained by a number of investigators are evaluated. The outcome is very erratic and does not allow any conclusion as to the effect of this drug on flow. Consideration is then given to the possible mechanism whereby a drug could affect blood flow; directly, by diffusion to receptors on the vessels, or indirectly, through more anterior receptors. The question is raised whether the small changes in circulation induced by drugs would not be swamped by those resulting from natural alterations in the ambient light level. The literature was analyzed in the hope of identifying discrete entry pathways, for example, through the lens or the suprachoroidal space, that are sufficiently permeable to allow a significant quantity of drug to pass. There was an indication that a drug might diffuse through the lens cortex in sufficient quantity to cause a measurable rise in its concentration in the vitreous. In general, however, there was insufficient quantitative data to allow any meaningful predictions to be made. Stimulated by recent evidence, it is suggested that drug penetration from the tear fluid takes place by direct diffusion across the conjunctiva into the sclera and orbit when the head is supine.

Administration, Topical↗

PubMed1997

[Transitory blindness after transurethral resection of the prostate].

OBJECTIVE: To describe a case of transient blindness post-TURP, a complication of the foregoing procedure. METHODS/RESULTS: The patient developed transient blindness following transurethral prostatic resection, ascribable to the resorption of the irrigation fluid (1.5% glycine), since this condition coincided with high serum glycine levels and its metabolites. CONCLUSION: The toxicity of glycine resorption during TURP is attributed to its metabolization to ammonia. Hyperammonemia encephalopathy causes inhibition of the brain neurotransmitters at different levels of the CNS, as well as in the retina. High intraocular concentrations of glycine affect the retinal amacrine cells, causing transient histological changes.

Absorption↗

PubMed2006

Accommodative microfluctuations and iris contour.

Mechanical interaction between aqueous humor, iris, and intraocular structures can alter the iris profile from its normal curvature. In particular, significant changes to the iris profile occur during accommodation as the anterior lens movement forces the iris into greater posterior bowing. We extended a previous mathematical model of the anterior segment and investigated the response of this coupled fluid-solid system due to accommodative microfluctuations. The results showed that the system response exhibited the same waveform as the stimulus for small-amplitude microfluctuations generally associated with the high-frequency component. Low-frequency microfluctuations with relatively larger amplitudes elicited a response different from the stimulus, indicating that the forces generated by the lens movement significantly affected the aqueous-iris mechanical interaction.

Accommodation, Ocular↗

PubMed1979

The effects of topical pilocarpine on the morphology of the outflow apparatus of the baboon (Papio cynocephalus).

The morphology of the outflow system of the baboon (Papio cynocephalus) was studied by light microscopy and transmission electron microscopy in tissue from eyes treated with topical pilocarpine. In one group of five animals the intraocular pressure (IOP) was maintained at 18 mm /g in both the experimental and the control eye of each baboon for the duration of the experiment. The endothelial meshwork was more distended, and there was a significantly greater number of giant vacuoles in the lining endothelium of Schlemm's canal in the pilocarpine-treated eyes than in the corresponding controls. However, in another series of animals, IOP was not maintained, and the differences between the treated and untreated eyes was much less striking. There appeared to be little evidence that the increase in vacuolation was produced by the direct action of pilocarpine on the endothelium of Schlemm's canal; more likely, it was a consequence of an increased passage of fluid through the drainage system. In addition, we have been able to show that (1) the mode of primary fixation can produce partial reversal of the pilocarpine effect and (2) the mechanical manipulation which is required to determine outflow facility has a deleterious effect on the morphology of the outflow tissues.

Animals↗

PubMed2006

[Efficiency of air tamponade in prevention of early recurrence of vitreal hemorrhage in diabetic patients with vitrectomy].

PURPOSE: To evaluate the efficacy and safety of air endo-tamponade in preventing early recurrence of vitreous hemorrhage in diabetic vitrectomy. MATERIALS AND METHODS: Prospective, consecutive, interventional, non-randomized study including 40 eyes (from 40 patients) with persistent or recurrent vitreous hemorrhage related to proliferative diabetic retinopathy. At the end of vitrectomy 20 cases (study group) were assigned to complete fluid--air exchange while the other 20 cases (control group) were left with BSS Plus. RESULTS: Early postoperative bleeding occurred in 9 out of 40 cases--22.5% (3 cases from the study group--15% and 6 cases from the control group--30%, p < 0.05). There was no statistically significant difference in visual acuity, intraocular pressure or incidence of late-onset hemorrhage recurrence between both groups during 6-month postoperative follow-up. In the study group there was a higher rate of lens opacities appearance. CONCLUSIONS: Air endo-tamponade seems a simple and efficient way of preventing early recurrence of vitreous hemorrhage in diabetic vitrectomy. Higher rate of lens opacities appearance may counteract this advantage thus this technique could be safely and electively used in pseudophakic patients.

Adult↗

PubMed1997

[Acute angle-closure glaucoma after total hip replacement surgery].

Acute angle-closure glaucoma is a rare complication of surgery. We experienced a case of postoperative acute glaucoma after total hip replacement under general anesthesia. A 49-year-old female without signs or symptoms of glaucoma was premedicated with the intramuscular administration of secobarbital, atropine and ranitidine. Following rapid induction with thiopental and vecuronium, anesthesia was maintained with N2O-O2-sevoflurane. PGE1 was administered intravenously for induced hypotension during the surgery. Hemorrhagic shock with a systolic blood pressure of 60 mmHg continued for 15 min during the surgery. Large amounts of fluid and ephedrine were required for treating this hypotensive episode. Vecuronium was reversed by bolus injection of neostigmine and atropine at the end of surgery. Soon after recovery from anesthesia, she complained of pain and blurred vision in her both eyes. The consulting ophthalmologist made a diagnosis of acute glaucoma due to high intraocular pressure (IOP). Treatment with glycerol and pilocarpine had no effect on the elevated IOP. The laser iridotomy performed on her at 5th and 7th post-operative days improved her vision completely. The post-operative glaucoma may cause serious permanent loss of vision. An early diagnosis of this post-operative complication and its treatment with drugs and surgery should be emphasized.

Acute Disease↗

PubMedDate not supplied

[Changes in intraocular pressure during dialysis].

We studied 29 patients on dialysis for terminal uremia, of whom one showed a dramatic rise in intraocular pressure (IOP) during dialysis. We examined the blood pressure (BP) and body weight (BW) before and after treatment in each patient and visual acuity by gonioscopic examination and optic disk status. After dialysis the statistically significant fall in BP and BW was observed in all patients, and in 28 subject an significant rise in IOP was noted. Only one patient experienced a dramatic rise in IOP, and he was the only one suffering from angular glaucoma during the last two years. All this time he was continually treated for glaucoma. After dialysis his IOP was 45 mmHg. With the adequate medication, his IOP lowered to the point when he was able to bear iridectomy which was done with argon and YAG laser. After the surgery his IOP reached the normal values. His visual acuity was good (1.0), visual field was normal, gonioscopic findings showed a narrow angle (Shaffer I, with normal pigmentation), and the optic disk had no abnormalities. It is not yet clear what was the cause of IOP rise during dialysis. It might be that the increased production of aqueous humor, which has been reported in such cases, might be caused by imbalance between blood and aqueous osmolality. If dialysis causes decrease in blood osmolality and if, at some time, blood becomes hypotonic in relation to ocular fluid, then the regular osmotic forces transfer the fluid to the ocular fluid into the eye. This case suggests that all patients on dialysis should undergo a minute ocular anamnesis and examination, and if needed administered adequate medication during the treatment.

Adult↗

PubMedDate not supplied

Cytologic findings in vitreous fluids. Analysis of 74 specimens.

OBJECTIVE: To review the cytologic findings of vitreous specimens and propose a simplified approach to them. STUDY DESIGN: Seventy-four vitreous specimens from 60 patients obtained either during a pars plana vitrectomy or by vitreous aspiration were reviewed. Clinical correlation was obtained on all patients. RESULTS: Findings suggestive of a specific disorder were present in 30 specimens (41%); cytologic examination of the remaining 44 showed nonspecific changes. A lymphoproliferative disorder, the intraocular malignancy suspected most often in this series, was identified in eight specimens (11%). Large cell lymphomas were evident in 5 specimens, 2 specimens were suspicious for lymphoma, and 1 specimen was consistent with plasmacytoma. Twelve specimens (16%) contained hemorrhage. In rare instances, specific infectious agents, such as parasites (5%), bacteria (1%) and fungi (3%), could be identified. The diagnosis of viral infections required ancillary studies. Lens fragments were identified in four cases (5%), and a diagnosis of lens-induced endophthalmitis could be rendered in one case (1%). Changes consistent with sarcoidosis were present in 3% of cases. CONCLUSION: Based on this experience with vitreous specimens submitted for clinical reasons, we found that they could be divided into three broad diagnostic categories: inflammation/infection (54 specimens/41 patients), hemorrhage (12 specimens/12 patients) and malignancy (8 specimens/7 patients).

Adolescent↗

PubMed1986

Temporary use of intraocular silicone oil in the treatment of complicated retinal detachment.

Complicated retinal detachments in 99 eyes were successfully managed by intraocular injections of silicone oil with or without pars plana vitrectomy. The silicone was then subsequently removed after panretinal photocoagulation. Any remaining anterior vitreous cortex near the vitreous base and/or preretinal proliferative tissue causing traction of the retina was also removed by a vitrectome or extracted by a hooked needle after the silicone-fluid exchange had been performed. The preretinal proliferation occurred in some cases even after silicone oil had been removed. Recurrent detachments were discovered in 8 of the 99 eyes and were managed successfully by reinjections of the silicone. Other silicone reinjections were required in two eyes with diabetic retinopathy and two nondiabetic eyes because of frequent rebleeding into the vitreous cavity.

Eye↗