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Biomedical subjects

C Ohrloff

Publications and source records attributed to C Ohrloff.

At least 55 records · Page 3Linked to original sources
PubMed1993

Permeability of the blood-retinal barrier and the blood-aqueous barrier in type I diabetes without diabetic retinopathy: simultaneous evaluation with fluorophotometry.

For the evaluation of a possible malfunction of the blood-retinal barrier (BRB) and the blood-aqueous barrier (BAB) in type I diabetes without manifest angiopathy after i.v. injection of sodium fluorescein, the permeability of the BRB (P) and the permeability coefficient of the BAB [P(a)] were simultaneously determined by fluorophotometry in 34 eyes of 34 type-I diabetics [hemoglobin (Hb)A1c = 6.6% +/- 0.9%] without retinopathy whose age ranged from 19 to 38 years (mean, 30.5 +/- 5 years); the diabetes duration was between 5 and 18 years. Fluorescein angiography was performed to exclude nonperfused areas. In all, 34 eyes of 34 healthy volunteers whose age ranged between 23 and 34 years (mean, 28.5 +/- 3.3 years) served as controls; in this group, fluorophotometry was performed twice to evaluate reproducibility. The mean BAB permeability coefficient in diabetics [P(a) = 5.3 +/- 1.8 x 10(-4)/min] was significantly increased (P = 0.00003) as compared with control values [P(a) = 3.7 +/- 0.7 x 10(-4)/min]; BRB permeability in diabetics (P = 3.2 +/- 1.4 x 10(-7) cm/s) was raised, with this elevation being of lower significance (P = 0.019; controls, P = 2.6 +/- 0.7 x 10(-7) cm/s). We found a decrease in BRB permeability depending on diabetes duration (r = -0.15; P = 0.007) that was not significant in the BAB (r = -0.1; P = 0.24). No correlation was found to exist between permeability and hemoglobin (Hb)A1c values either in the BAB or in the BRB. The reproducibility in controls was 9% in BRB determinations and 12% in BAB measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Capsular sack suture PMMA intraocular lens. Comparative study of centering behavior after phacoemulsification and planned extracapsular cataract extraction].

The position of bag-fixated intraocular lenses after phacoemulsification or extracapsular cataract extraction (ECCE) was compared in order to determine the relationship to the method of operation and the type of capsular opening. Photographs were taken from 71 eyes 6 months after in-the-bag implantation of a one-piece posterior chamber lens. Centering was determined with respect to the pupillary center. Forty-six eyes were operated on by phacoemulsification after continuous circular capsulorhexis with closed edges and 25 eyes by ECCE after capsulorhexis with a radial incision of the capsular rim at the 12 o'clock position. Ninety-four percent of the intraocular lenses implanted after phacoemulsification and 92% of the intraocular lenses implanted after ECCE were decentered less than 0.5 mm. The centering of bag-fixated intraocular lenses is related to the technique of opening the anterior capsule. Phacoemulsification with continuous capsulorhexis offers conditions similar to that in ECCE with capsulorhexis and radial capsular rim incision for good centering of one-piece posterior chamber lenses.

Adult↗
PubMed1992

Quantification of blood-aqueous barrier function using laser flare measurement and fluorophotometry--a comparative study.

Fluorophotometry allows calculation of the permeability coefficient k(a) of the blood-aqueous barrier to fluoresceine after i.v. dye application; aqueous flare can be graded objectively by laser flare measurement and permits in vivo estimation of over-all protein concentration in the aqueous humor. To evaluate a formal relationship between both procedures we performed laser flare measurements on 40 eyes (clinically ranged from healthy to mild uveitis) before and during fluorophotometry. Laser flare count [mec-1] raises exponentially (r = 0.8; p = 0.05) with an increasing permeability coefficient to fluoresceine k(a) [10(-4)min-1]. Laser flare count during the fluorophotometry procedure is not increased (p = 0.05) compared to the prescan. Reproducability was 14% +/- 7.5% for laser flare measurements and 13% +/- 5% for fluorophotometry. Malfunction of the blood aqueous barrier possibly increases the permeability to molecules of high molecular weight not proportional to that of hydrophilic particles of low molecular weight. The exponential regression between the data achieved with both procedures suggests that fluorophotometry is more sensitive in detecting early changes in blood aqueous barrier function whereas laser flare detection could be appropriate in more severe cases of barrier dysfunction.

Adult↗
PubMed1992

[Aspects of physiology, pathology and epidemiology of cataract].

World Health Organization estimates that 23 million people have a visual acuity of 0.05 or less. For 12-15 million people cataract is the cause of poor visual acuity or blindness and the majority of those afflicted live in Third World countries. It is estimated that in the year 2025 around 40 million people will become blind due to cataract. The therapeutic procedure of choice is surgical removal of the lens. The high success rate of this procedure in highly industrialized countries has been achieved by the constant improvement in technology and operative technique. This, however, does not hold true for Third World countries. The etiology and pathogenesis of cataract are not yet completely understood. This paper reports on the clinical findings and epidemiology of cataract and deals with the physiology and pathology of the lens. The aim of the study was to recognize possible cataractogenic risk factors. A decrease in the blindness rate caused by cataract in Third World countries can best be achieved through prevention.

Cataract↗
PubMed1992

[Image quality of various types of intraocular lenses (mono-, bi- and multifocal) in air and water].

Most of the monofocal intraocular lenses tested in air and water showed good-to-high resolution in water. There was low resolution in the outer zone of the image in some models. The bifocals tested had a lower resolution efficency with less contrast and change of colors. The diffractive IOL had poor central resolution efficiency with changing colors and double vision. There was a spherical change like a fish-eye. When tested in air there was paracentral double vision in the diffractive IOL with a change of color bands.

Humans↗
PubMed1991

[Therapeutic alternative or 2d choice drug. Trisodium phosphonoformate in cytomegalovirus retinitis].

From 01. 01. 1988 to June 1990, a total of 275 patients with AIDS had been examined in our ophthalmological out-patient clinic. The clinical diagnosis of a cytomegalovirus (CMV) retinitis was recorded in 56 of these patients (= 20.1%). The initial therapy, as usual, took the form of infusions of the virustatic drug ganciclovir at an induction dose of 10 mg/kg body weight per day (3 weeks), with a maintenance dose of 3.5-5 mg/kg body weight per day (5 days per week) thereafter. During maintenance therapy recurrences were observed in 15 cases and herpes simplex retinitis in 3, with progressive retinal destruction. Therefore we began treatment with trisodium phosphonoformate (Foscavir) at a dosage of 60 mg/kg body weight per day (3 weeks), continuing with maintenance therapy at 90 mg/kg body weight per day (7 days a week). After the induction dose 14 patients showed subjective improvement and satisfactory cicatrization of the retinal lesions. We monitored the retina by a standardized method and 50 wide-angle retinal photographs. One case of acute retinal necrosis (ARN) did not show any response to foscavir therapy. Typical side-effects of therapy with trisodium phosphonoformate were seldom seen: adverse events included renal dysfunction, neutropoenia, and asymptomatic hypocalcaemia. We conclude that trisodium phosphonoformate is an effective and well-tolerated agent for the treatment and prevention of relapse of CMW retinitis and can be used as an alternative ganciclovir.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Role of the posterior capsule in the aqueous-vitreous barrier in aphakic and pseudophakic eyes.

Clinical observations have shown that an intact posterior capsule between aqueous and vitreous may function as a barrier to low and high molecular weight substances, e.g., prostaglandins or the angiogenic factor. To determine if this protective barrier breaks down after posterior capsulotomy, we examined the distribution of fluorescein in human eyes after intracapsular cataract extraction (ICCE), extracapsular cataract extraction (ECCE) and intraocular lens (IOL) implantation with capsulotomy, and ECCE and IOL implantation without capsulotomy in 12 patients each. After ICCE and after ECCE and IOL implantation with capsulotomy, diffusion of fluorescein into the vitreous showed similar values. These values were significantly higher than those obtained in patients after ECCE or ECCE and IOL implantation without capsulotomy. This leads us to believe that an intact posterior capsule prevents the diffusion of soluble substances.

Aphakia↗
PubMed1990

[Comparative evaluation of intracapsular cataract extraction, extracapsular cataract extraction and phacoemulsification].

In 1978 at the beginning of the modern lens implantation era, 6160 posterior chamber lenses (PCL) were implanted in the USA; 1,110,000 PCL were implanted in 1986. With reference to the total number of lenses implanted, PCL implantations amounted to 4% in 1978 and to 89% in 1986. The increasing use of PCL has mainly been due to the fact that patients with these lenses had significantly better visual acuity and fewer complications after surgery than patients with anterior chamber lenses (ACL). As an example, an FDH study in 1983 should be mentioned: more vision in an otherwise normal eye was more than 0.5: 90% (ACL) versus 94% (PLC); ablatio: 0.9% versus 0.5%; secondary glaucoma: 1.2% versus 0.5%; cystoid edema of the macula: 2.2% versus 0.8%. The considerable advantage in extracapsular extraction of a cataract lies in the fact that the anatomical and physiological conditions of the eye structure may be nearly completely maintained, and this is because the intact posterior capsule--similar to the lens with zonular fibers in the normal eye--forms a diaphragm between the vitreous and aqueous humor. Thus the stability of the eye will be maintained and prolapse of the vitreous with possible traction at the retina cannot occur. Phacoemulsification and ECCE are well-established methods. The clinical results of both methods are practically identical, except for a significantly lower rate of astigmatism with phacoemulsification, which was examined 8 to 10 weeks following surgery (phaco: 1.0 +/- 0.49; expression: 3.3 +/- 1.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Cataract Extraction↗
PubMed1990

Permeability of the limiting cell layers of the cornea in vivo.

The permeability of the limiting cell layers of the cornea for solutions is of special interest with respect to the following points of view: 1) Protection against penetration of fluids from the tear film or aqueous into the stroma. 2) Nutrition of various corneal tissues from the tear film or from the aqueous humor. 3) Penetration of topically applied drugs into the anterior segment. 4) Side effects of drugs or surgery on the permeability of epithelial or endothelial layers. Fluoresceine sodium as a hydrophilic weak acid (MG 360) penetrates intercellulary through intact epithelium and endothelium. When topically applied the rise of fluoresceine concentration in the stroma depends on the permeability of the epithelium, whereas that in the aqueous may be controlled by the endothelial permeability. Small impairment of these cell layers leads already to increased permeabilities. This means that valuable information on the pathology of epithelial and endothelial layers may be obtained by quantitative clinical determination of the fluoresceine concentration by aid of sensitive fluorophotometers.

Animals↗
PubMed1990

[The conjunctival flora of HIV-positive patients in an advanced stage].

We evaluated the incidence of bacterial cultures taken from 23 outpatient and nosocomial AIDS patients. It was found that 36.6% of the 11 outpatients had non-pathogenic bacterial flora (Staphylococcus epidermis). Staphylococcus aureus as a pathogenic bacterium was found in 25% of the positive cultures in a group of 12 nosocomial patients. Candida albicans, a fungus, was also found in 25%, and Pseudomonas aeruginosa, the only gram-negative bacteria, was identified in 8.3%. Staphylococcus epidermidis was found in 18.8%. It was concluded that preoperative cultures of the conjunctival sac of hospitalized AIDS patients are essential before intraocular procedures are carried out. There must be no apparent infection of the conjunctiva.

Adult↗
PubMed1990

[Polishing of protein-coated intraocular lenses with the Nd:YAG laser].

Extracapsular cataract extraction with implantation of posterior chamber IOLs has become a standard surgical technique with rare postoperative complications. However, in some patients, as a consequence of a particularly severe post-operative inflammation, proteins and pigment can be deposited on the surface of the IOL in spite of medical treatment. In certain cases such deposits can be removed by using the Nd:YAG-laser. The indications, methods and the postoperative course of this treatment are discussed.

Adult↗
PubMed1989

[Chiasma lesion following severe craniocerebral trauma. Clinical, functional and neuroradiologic characteristics exemplified by a rare case].

The case of a patient who fell from a height of 30 feet is presented. After discharge from the intensive care unit, a decrease in central vision, bitemporal hemianopsia, characteristic changes in the pattern of visual evoked potentials, and bone fractures of the sella turcica were documented. No direct injury to the chiasma could be found by CT or MRI. The possible types of lesions and the mechanisms leading to them are discussed with regard to earlier pathological-anatomical studies.

Adult↗
PubMed1987

Evaluation of endothelial cell function with anterior segment fluorophotometry in pseudophakic patients.

Determining fluorescein permeability of the endothelial cell layer provides information on the endothelial cell barrier. Following topical application of fluorescein, the time dependent change of its concentration in the corneal stroma and in the aqueous humor yields the transfer coefficient (Kc) of the corneal endothelium. Measurements with a fluorophotometer resulted in a Kc of 0.002 minute to 0.005 minute for normal eyes. Patients with corneal barrier dysfunction (cornea guttata, Fuch's dystrophy) showed an increased Kc of 0.006 minute to 0.013 minute. Up to five years postoperatively, none of the patients investigated after phacoemulsification and posterior chamber lens implantation showed a disturbance in the endothelial cell barrier function.

Aged↗
PubMed1987

[Congenital corneal opacity caused by thickening of Bowman's membrane].

Congenital corneal opacifications are rare, yet their causes are manifold. Only a few cases have been described in which the most striking histopathological feature is a thickening of Bowman's membrane. The authors found an isolated thickening of this membrane in the corneas of a baby who, shortly after birth, presented with corneal opacifications in both eyes. Only a few months after penetrating keratoplasty was performed the condition recurred. Bowman's membrane was found to be thickened in the graft as well.

Child, Preschool↗