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At least 829 records · Page 46Linked to original sources
PubMed1985

Drug effects on the hydraulic conductivity of the isolated rabbit ciliary epithelium.

Three aspects of hydrostatically driven volume flow across the isolated rabbit ciliary epithelium have been examined. (1) Hydraulic conductivity was increased in a dose-dependent manner by amiloride, but not by furosemide, indicating that amiloride may interfere with junctional permeability. The absence of a furosemide effect suggests that regulation of passive fluid movement may be independent of net ionic fluxes of either chloride or bicarbonate. Ethacrynic acid had no effect on hydraulic conductivity at concentrations below 10(-2) M. At 10(-2) M, hydraulic conductivity was decreased, suggesting that fluid pathways may be linked to ionic pathways. (2) Successive in vivo daily treatments with adrenergic agonists result in changes in the intraocular pressure response. Dose-effect curves to in vitro agonists from eyes pre-treated on successive days indicate that isoprenaline caused a lack of response in hydraulic conductivity after 3 d of in vivo treatment, adrenaline caused responses after 2 d which were about half of those found on day 0, while phenylephrine and noradrenaline had no influence on hydraulic conductivity. These data suggest that beta-agonists cause a deactivation or desensitization of some moiety which is coupled with regulation of hydraulic conductivity in a manner similar to that seen for the beta-receptor-coupled adenylate cyclase. (3) While cyclic GMP was without effect, various modifiers of cyclic GMP activity increased hydraulic conductivity. Alteration of cellular cyclic GMP levels appears to exert some regulation over ciliary epithelial permeability.

Amiloride↗
PubMed2006

Experimental studies on nonpenetrating filtration surgery using the CO2 laser.

BACKGROUND: This study evaluated the use of a CO2 laser for performing deep sclerectomy in nonpenetrating filtration surgery. METHODS: Three experimental models were performed: enucleated sheep and cow eyes (n=18) to determine optimal irradiation parameters, live rabbit eyes (n=20) to test feasibility, and cadaver eyes (40 procedures in 20 eyes) to study effects in human eyes tissue. After a half-thickness scleral flap was created, deep sclerectomy was performed by CO2 laser applications on the scleral bed down to the trabeculo-Descemet's membrane. RESULTS: Fluid percolation was repeatedly achieved without penetration in sheep and cow eyes using scanned laser energy of 5-10 W at a pulse duration of 200 micros and a working distance of 35 cm. In live rabbits, deep sclerectomy was achieved without perforation in 19/20 eyes. Intraocular pressure was significantly decreased on the first postoperative day (10.3+/-5.1 mmHg lower, on average, than in the nonoperated fellow eye; P<0.001), and this persisted for 21 days. Operations on all cadaver eyes resulted in effective fluid percolation. Penetration of the scleral wall occurred in five cases only after repeated laser applications with high energy. Histologically, a thin sclerocorneal intact wall was demonstrated at the sclerectomy bed. Collateral tissue damage did not extend beyond 100 microm, and adjacent structures remained unharmed. CONCLUSIONS: CO2 laser-assisted deep sclerectomy is a feasible and apparently safe procedure.

Animals↗
PubMed2001

Classification and management of Coats disease: the 2000 Proctor Lecture.

PURPOSE: To review the methods and results of management in a large series of patients with Coats disease, to determine risk factors for poor visual outcome and enucleation, and to propose a practical classification of Coats disease. METHODS: In a retrospective consecutive series in 150 patients, Coats disease was defined as idiopathic retinal telangiectasia with intraretinal or subretinal exudation without appreciable signs of retinal or vitreal traction. We reviewed our experience with management, including observation, laser photocoagulation, cryotherapy, and various techniques of retinal detachment surgery and enucleation. The anatomic outcome, complications of treatment, visual results, and reasons for enucleation were tabulated. Factors predictive of poor visual outcome (20/200 or worse) and enucleation were determined using Cox proportional hazards regression models. Based on these observations, a staging classification of Coats disease, applicable to treatment selection and ocular prognosis, is proposed. RESULTS: In 117 patients (124 eyes) with a mean follow up of 55 months (range, 6 months to 25 years) primary management was observation in 22 eyes (18%), cryotherapy in 52 (42%), laser photocoagulation in 16 (13%), various methods of retinal detachment surgery in 20 (17%), and enucleation in 14 (11%). Anatomic improvement or stability was achieved in 76% of eyes, and final visual acuity was 20/50 or better in 17 eyes (14%), 20/60 to 20/100 in eight (6%), 20/200 to finger counting in 30 (24%), and hand motion to no light perception in 49 (40%) Enucleation was ultimately necessary in 20 eyes (16%). Risk factors predictive of poor visual outcome (20/200 or worse) included postequatorial (P =.01), diffuse (P =.01), or superior (P =.04) location of the telangiectasias and exudation, failed resolution of subretinal fluid after treatment (P =.02), and presence of retinal macrocysts (P =.02). The main risk factors for enucleation were elevated intraocular pressure (greater than 22 mm Hg; P less than or equal to.001) and iris neovascularization (P less than or equal to.001). Coats disease was classified into stage 1, telangiectasia only; stage 2, telangiectasia and exudation (2A, extrafoveal exudation; 2B, foveal exudation) stage 3, exudative retinal detachment (3A, subtotal; 3B, total); stage 4, total detachment and secondary glaucoma; and stage 5, advanced end-stage disease. Poor visual outcome (20/200 or worse) was found in 0% of eyes with stage 1, 53% with stage 2, 74% with stage 3, and 100% of stages 4 and 5 Coats disease. Enucleation was ultimately necessary in 0% of stages 1 and 2, 7% of stage 3, 78% of stage 4, and 0% of stage 5 disease. CONCLUSIONS: Carefully selected treatment can anatomically stabilize or improve the eye with Coats disease in 76% of eyes. However, poor visual outcome of 20/200 or worse commonly results. Patients who present with stages 1 to 3 Coats disease have the best visual prognosis, and patients with stages 4 and 5 have a poor visual prognosis.

Cryosurgery↗
PubMed1978

Surgical complications of pars plana vitreous surgery.

Evaluation of 200 consecutive pars plana vitrectomies shows delayed corneal epithelial healing after intentional scraping and formation of a posterior subcapsular cataract, presumably due to exposure to inadequate infusion fluids. Posterior retinal holes occur frequently, whereas entrance site complications have been reduced to an acceptable minimum. Temporary rise in intraocular pressure is common.

Cataract↗
PubMed2004

Prostaglandins F2alpha and E2 in aqueous humor of patients with cataract surgery.

To understand the role of prostaglandins F(2alpha) and E(2) in aqueous humor under the normal condition, their concentrations were measured by enzyme immunoassay in aqueous fluid obtained from either eye of 60 patients during cataract surgery and correlated with clinical factors as the age and intraocular pressure. The concentrations of prostaglandin F(2alpha) in the aqueous of all patients were below the level of detection. The concentrations of prostaglandin E(2) in the aqueous were below the level of detection in 37 patients while ranged from 9 to 48 pg/mL (median, 31) in 23 patients. The levels of prostaglandin E(2) did not have correlation with the age of the patients or the intraocular pressure of the eyes. In conclusions, the concentrations of prostaglandin E(2) were apparently higher than the concentrations of prostaglandin F(2alpha) in the aqueous. This study could not prove the relationship between prostaglandin levels and the intraocular pressure or the age.

Adult↗
PubMed1998

Glycerol. Biochemistry, pharmacokinetics and clinical and practical applications.

Glycerol is a naturally occurring 3-carbon alcohol in the human body. It is the structural backbone of triacylglycerol molecules, and can also be converted to a glycolytic substrate for subsequent metabolism. Serum glycerol concentrations approximate 0.05 mmol/L at rest, and can increase to 0.30 mmol/L during increased lipolysis associated with prolonged exercise or caloric restriction. When glycerol is ingested or infused at doses greater than 1.0 g/kg bodyweight, serum concentrations can increase to approximately 20 mmol/L, resulting in more than a 10 mOsmol/kg increase in serum osmolality. Glycerol infusion and ingestion have been used in research settings for almost 60 years, with widespread clinical use between 1961 and 1980 in the treatment of cerebral oedema resulting from acute ischaemic stroke, intraocular hypertension (glaucoma), intracranial hypertension, postural syncope and improved rehydration during acute gastrointestinal disease. Since 1987, glycerol ingestion with added fluid has been used to increase total body water (glycerol hyperhydration) by up to 700 ml, thereby providing benefits of improved thermoregulation and endurance during exercise or exposure to hot environments. Despite the small number of studies on glycerol hyperhydration and exercise, it appears to be an effective method of improving tolerance to exercise and other heat-related stressors.

Dehydration↗
PubMed2003

Droplets on posterior surface of intraocular lens in silicone oil filled eye.

Silicone oil adherence to silicone IOLs after silicone oil removal is a known complication in pseudophakic patients. Droplet removal is difficult and may require IOL exchange. We describe two cases in which silicone oil droplets were observed early in the postoperative period in PMMA pseudophakic eyes and disappeared during silicone oil-fluid exchange--a phenomenon that has not been reported earlier in human PMMA pseudophakic eyes.

Drainage↗
PubMed2005

[Simultaneous cataract and glaucoma surgery. Selection of trabeculectomy site].

PURPOSE: Analysis of the results of simultaneous surgery using phacotrabeculectomy technique and standard phacoemulsification and trabeculectomy from two separate incisions. MATERIAL AND METHODS: Analyzed group included 41 patients /44 eyes/, aged 68 +/-18 years with combined glaucoma and cataract. In 28 operated eyeballs phacotrabeculectomy from single incision was performed and in 19 operated eyeballs phacotrabeculectomy and phacoemulsification from two separate incisions was used. RESULTS: In both analyzed groups authors obtained reduction in intraocular pressure and transparent optical system. In group of patients operated on from two separate incisions three times more often anterior chamber had become shallower with conjoined choroidal detachment and two times more often hypotension below 10 mmHg and breakdown of blood - aqueous fluid barrier were observed. Blood in anterior chamber was observed in 1/5 of operated patients with equal frequency in both analyzed groups. In addition in three months follow-up patients from two separate incisions presented more elevated intraocular pressure and more often required additional pharmacological therapy. CONCLUSIONS: Simultaneous cataract and glaucoma surgery effectively reduces elevated intraocular pressure and improves transparency of optical system. Phacotrabeculectomy is safer and gives fewer complications than standard operation from two separate incisions.

Aged↗
PubMed1992

A new endoscope for ophthalmic microsurgery.

We present an endoscope designed for ophthalmic microsurgery. The handpiece contains a charge-coupled device, a solid-state imager (250,000 pixels), and a probe (either 0.89 or 1.5 mm in diameter), including the light guide. The light source is a halogen lamp. The clear views the instrument provides of the ciliary sulcus and ciliary body behind the iris make it useful in secondary posterior chamber intraocular lens implantation using the ciliary sulcus suturing technique, and in endolaser photocoagulation of the ciliary body in end-stage glaucoma. It also is useful in performing vitrectomy in cases in which visualization is difficult because of corneal opacification or fluid-gas exchange.

Cataract Extraction↗
PubMed1989

[2 new possibilities for using balloon occlusion in relation to the indentation effect].

Two new applications of the balloon are described which exploit its variable indentation: in the first case, the volume is reduced by withdrawal of fluid; in the second it is increased by additional injection. In both cases the procedure consists in two steps performed in subconjunctival anesthesia. In the first case the balloon provides intraocular space prior to gas injection (giant tear detachment). In the first step the balloon is inserted into the parabulbar space. After one to two hours this results in a deep indentation of the globe. In the second step the balloon indentation is used to compensate for the rise in IOP induced by the gas injection. With this "balloongasprocedure", a kind of fluid-gas-exchange is performed by injecting 1.0 ml of an expanding perfluorocarbon gas without prior drainage or pars plana vitrectomy. In the second case, the balloon is used in cases of detachment to interrupt retinal circulation prior to occlusion of a recurrently hemorrhaging vessel using the laser. In the first step, the tear is tamponaded by the parabulbar balloon and with this, the artery crossing the horseshoe tear is attached as well. In the second step, by increasing the balloon volume, retinal circulation is interrupted prior to occlusion of the artery by laser with reduced risk of hemorrhage. In both applications of the balloon a relatively complex detachment operation is divided into two smaller principle of less risky procedures on the surgery in small steps.

Catheterization↗
PubMed1994

No-stitch, small incision cataract surgery with flexible intraocular lens implantation.

Small incision cataract surgery has several advantages over conventional surgery, including faster postoperative visual rehabilitation. We evaluated 100 consecutive cases of no-stitch, small incision surgery with a square sclerocorneal tunnel and a flexible intraocular lens. Permanent self-sealing of the wound seemed to increase intraoperative safety considerably. With the specific incision used, corneal trauma and irrigation fluid outflow were minimal. Refraction and K-readings stabilized within the first postoperative week, which is when most eyes attained best final visual acuity. No early peak or protracted drift of astigmatism occurred. Minimally leaking wounds in three eyes were left unsutured; a transient filtering bleb was observed in two of these eyes after resorption of an intracameral air bubble. Our results support the theoretical concept and justify the use of no-stitch, small incision surgery.

Cataract Extraction↗
PubMed2004

["AID" implanted in eyes with silicone oil tamponade].

OBJECTIVE: To summarize the clinical results of the artificial iris diaphragm (AID implantation for eyes with silicone oil longstanding tamponade. METHODS: In this study the operation indications results and complications of 11 consecutive cases of artificial iris diaphragm implantation for eyes with silicone oil longstanding tamponade were studied. RESULTS: In all of the 11 primary ocular disorder cases, 7 cases (7/11) were serious ocular trauma, 2(2/11)cases were diabetic retinopathy with traction retinal detachment, 1 case (1/11) was recurrent retinal detachment with complicated PVR, and 1 case (1/11) was Coats disease; The silicone oil was retained completely behind the surface of artificial iris diaphragm in 7(7/11) of all the 11 cases in which no visual acuity was affected The complications were low intraocular pressure IOP and heavy fibrosis on the surface of artificial iris diaphragm. CONCLUSION: Open type artificial iris diaphragm implantation in eyes with longstanding silicone oil tamponade can effectively prevent the silicone oil from cotacting the cornea causing complication by spontaneously blocking and rescuing anterior chamber fluid circulation.

Adolescent↗
PubMedDate not supplied

The effect of intraoperative antibiotics in irrigating solutions on aqueous humor contamination and endophthalmitis after phacoemulsification surgery.

PURPOSE: To determine the efficacy of intraoperative antibiotic use in irrigating solutions on aqueous humor contamination during phacoemulsification surgery and to evaluate the corresponding risk of postoperative endophthalmitis. METHODS: 644 eyes of 640 patients who underwent phacoemulsification surgery with foldable intraocular lens (IOL) implantation were included in this study. Preoperative conjunctival smears were taken and eyes were allocated to receive irrigating infusion fluid containing either balanced salt solution (BSS)-only (group 1; 322 eyes) or BSS with antibiotics (vancomycin and gentamycin) during surgery (group 2; 322 eyes). Bacterial contamination rates of aqueous humor samples taken in the beginning and at the end of operation were compared. Predictive factors for the development of postoperative endophthalmitis were determined by clinical and microbiologic analyses. RESULTS: The rates of culture-positivity were similar between group 1 and group 2 for both preoperative conjunctival smears and aqueous samples (p > 0.05). Aqueous samples taken at the end of operation were found to be contaminated in 68 (21.1%) eyes in group 1 and 22 (6.8%) eyes in group 2, and the difference was significant (p = 0.0001; OR = 3.65 (2.1-6.0)). Capsular rupture was associated with higher rate of contamination in both groups (p = 0.0001; OR = 7.7 and p = 0.0001; OR = 8.1). Two eyes in the BSS-only group developed postoperative endophthalmitis and these cases had posterior capsular rupture during the surgery and culture-positivity for staphylococcus epidermidis throughout the study. CONCLUSIONS: Intraoperative antibiotic irrigation decreases aqueous humor contamination during phacoemulsification. Further studies are warranted to determine the interrelationship between aqueous humor contamination and endophthalmitis in eyes with posterior capsular rupture.

Acetates↗
PubMed2005

Accuracy of intraocular pressure measurements in new zealand white rabbits.

PURPOSE: Rabbits are commonly used for the evaluation of drugs and surgery to lower intraocular pressure (IOP). The accuracy of intraocular pressure measurement is therefore critical in the analysis of data and subsequent extrapolation to humans. The purpose of this study was to establish the most reliable technique, from several currently available methods, of measuring IOP in New Zealand White rabbits. METHODS: The IOPs of 11 healthy New Zealand White rabbits were measured with a fluid-filled pressure transducer system that was connected to the anterior chamber of each animal so that the IOP could be varied by altering the height of a bottle of balanced salt solution. Intraocular pressures were recorded over a range of 50 to 0 mm Hg by the transducer system, and comparative measurements at the same pressures were performed with the Tonopen XL (Mentor, Norwell, MA), the Perkins handheld applanation tonometer (Clement Clarke, Harlow, UK), and the Ocular Blood Flow (OBF) pneumatonometer (OBF Laboratories, Wiltshire, UK). RESULTS: All three tonometers underestimated the true IOP, especially at higher pressures. Although the mean difference in actual and tonometric IOP was least in the Tonopen XL, there was a high degree of variability through the entire range of IOPs measured. The Perkins tonometer, although slightly less accurate than the Tonopen XL, was more consistent in measurement. The OBF pneumatonometer was the least-reliable estimate of IOP. CONCLUSIONS: All tonometers underestimate IOP, with increasing inaccuracy at higher pressures. The Perkins applanation tonometer was the most reliable for measuring IOP in the range of 0 to 50 mm Hg in New Zealand White rabbits.

Animals↗
PubMed1981

Endothelial physiology and intraocular lens implantation.

The endothelium is the cellular monolayer which lines the posterior surface of the cornea. This layer is important in clinical ophthalmology because it is vital to maintenance of the transparency of the cornea and vision through its pump and barrier functions which limit the ingress of fluid into the cornea from the aqueous. When the function of the corneal endothelium becomes compromised, the corneal stroma swells as it hydrates. Subsequently, epithelial bullae form with painful recurring epithelial erosions, and finally corneal scarring and blindness result. The relatively vulnerable position of the corneal endothelium renders it susceptible to iatrogenic injury during intraocular procedures, especially IOL implantation: the poor regenerative (mitotic) capacity of the human corneal endothelium limits its ability to recover normal function once it is injured.

Animals↗