Search PubMed⌕ Search

Biomedical subjects

A Loewenstein

Publications and source records attributed to A Loewenstein.

At least 55 records · Page 3Linked to original sources
PubMed1997

Bilateral retinal vein occlusion associated with 5,10-methylenetetrahydrofolate reductase mutation.

PURPOSE: To report on the occurrence of 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency, known to cause mild to moderate hyperhomocystinemia and increased risk of vascular occlusive disease, in a young patient with bilateral central retinal vein occlusion. METHODS: A 25-year-old man was initially examined with central retinal vein occlusion in the right eye, followed 4 months later by a central retinal vein occlusion in the left eye. Studies for risk factors predisposing to thrombosis were performed. RESULTS: Hematologic studies failed to detect any pathology. However, the patient was found to be homozygous for 677C-T mutation in MTHFR enzyme. CONCLUSION: Central retinal vein occlusion may be associated with a mutation in MTHFR.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed1997

Late onset corneal haze after photorefractive keratectomy for moderate and high myopia.

BACKGROUND: Corneal haze after photorefractive keratectomy (PRK) usually appears within 4 weeks after the procedure. A new type of corneal haze, starting relatively late after PRK, is reported. METHODS: The authors reviewed the files of their first 1000 consecutive patients who completed a follow-up of 12 months or more and identified all those who had clear corneas for at least 4 months, after which corneal haze appeared. The clinical course in these patients was evaluated. RESULTS: Late onset corneal haze (LOCH) had occurred in 18 eyes of 17 patients (incidence, 1.8%), appearing 4 to 12 months after PRK and resulting in decreased visual acuity and regression. Treatment with topical steroids or reoperation resulted in partial reversibility of haze and regression. CONCLUSIONS: A new entity of LOCH is described. The appearance of LOCH suggests that corneal healing and remodeling continue for at least 1 year after PRK.

Administration, Topical↗
PubMed1997

Delay of corneal wound healing in patients treated with colchicine.

BACKGROUND: Colchicine has a known adverse effect on wound healing through its inhibitory effect on tubulin-dependent cell functions and through collagenase activation. In the cornea, it has been shown in animal and in vitro studies to inhibit epithelium mitosis, fibroblast mitosis and migration, as well as to reduce collagen deposition. The authors report on two patients with corneal ulcers refractory to conventional treatment while the patients were undergoing oral colchicine therapy. CASE REPORTS: The first patient was an 86-year-old woman who had been treated with oral colchicine because of rheumatoid arthritis. She was admitted to the authors' department with a deep corneal ulcer in the right eye for which she had been treated for 3 weeks with local antibiotics without any improvement. The second patient, a 60-year-old woman, was hospitalized because of a corneal ulcer in her left eye. She had been receiving oral colchicine therapy for mixed connective tissue disease. Treatment with local antibiotics was initiated but the condition of the eye worsened, ultimately resulting in corneal perforation. RESULTS: Withdrawal of oral colchicine therapy was followed by rapid corneal wound healing in both patients. CONCLUSION: The findings in these two patients suggest that colchicine may delay corneal wound healing. The authors suggest that in patients with corneal ulcers refractory to conventional treatment who are receiving colchicine, cessation of colchicine therapy should be considered.

Aged↗
PubMed1997

Macular hemorrhage after excimer laser photorefractive keratectomy.

We describe three patients with high myopia, 13.0 to 20.0 diopters (D), who had typical myopic macular hemorrhages 1 to 6 months after photorefractive keratectomy (PRK). The hemorrhages eventually resolved, with resultant permanent decrease in vision and pigmentary and atrophic changes in the macula. Highly myopic eyes are predisposed to bleeding in areas of lacquer cracks and to myopic choroidal neovascularization formation. Awareness of potential retinal pathology in patients having PRK and follow-up retinal examinations are warranted.

Adult↗
PubMed1997

Complications of excimer laser photorefractive keratectomy for myopia.

PURPOSE: To evaluate the safety and complication rates of excimer laser photorefractive keratectomy (PRK). SETTING: Assutah Laser Center, Tel-Aviv, Israel. METHODS: This retrospective study evaluated the complication rate after PRK in 825 consecutive patients who had PRK for myopia and had a follow-up of at least 12 months. RESULTS: At 12 months postoperatively, 4.0% of patients suffered from overcorrection and 8.6% from undercorrection. Induced astigmatism developed in 1.4% of all operated eyes. Three percent of the patients had haze, and 3.6% reported glare or halos. Twenty-three eyes (2.7%) lost one line or more of best corrected visual acuity (BCVA). Ptosis developed in 0.4% of the eyes, and 3.5% had a significant increase in intraocular pressure resulting from corticosteroid treatment. There were no complications in 678 eyes (82.5%). CONCLUSION: Eighty-two percent of eyes having PRK did not develop complications. In 18.0% one or more complication, mainly undercorrection, overcorrection, or loss of BCVA, occurred.

Administration, Topical↗
PubMed1997

Excimer laser reablation.

BACKGROUND AND OBJECTIVE: To evaluate the outcome of repeated excimer laser keratectomy after photorefractive keratectomy (PRK). PATIENTS AND METHODS: A retrospective study of 32 of 1000 consecutive patients who had a follow-up of at least 12 months and who underwent repeated PRK in the Assutah Laser Center. RESULTS: The mean spherical equivalent (SE) declined significantly as a result of the repeated treatment. As opposed to zero eyes before re-treatment, 19 of 29 eyes (66%) achieved SE of within +/-1 D 6 months after re-treatment. Before re-treatment, 20 of 32 eyes (62%) had medium or severe haze, whereas after re-treatment only 1 of 29 eyes (3%) had medium haze, and none of the eyes had severe haze. At 6 months after reoperation, visual acuity had improved to 20/36, a significant improvement to the mean log MAR equivalent of 20/40 before re-treatment, yet still significantly worse than the log MAR equivalent before initial ablation which was 20/30. CONCLUSION: Repeated excimer laser PRK has the potential for successful treatment of undercorrection, regression, and haze occurring after an initial PRK.

Corneal Opacity↗
PubMed1997

An intraocular telescopic lens for macular degeneration.

Age-related macular degeneration is a leading cause of visual loss in adults older than 60 years of age. Once vision has been seriously compromised, the only means of improving visual function are optical devices that produce magnification of images. These devices fall into three categories: (1) high-plus lenses, (2) external telescopes, and (3) a high-minus center intraocular lens combined with external high-plus glasses. The authors designed a new intraocular lens with an entire telescope in its center. In vitro tests were performed to evaluate modulation transfer function, visual field, and optical aberrations. Implantation in cadaver eyes was performed to test the surgical technique and safety. Test results showed that satisfactory modulation transfer function and optic aberration were achieved, and implantation in cadaver eyes was proven to be feasible and safe. It was concluded that a fully implanted intraocular telescopic lens is an effective optical solution for age-related macular degeneration.

Adult↗
PubMed1997

A flexible infusion micro-cannula for subretinal surgery.

Injection of fluids or drugs into the subretinal space is often necessary during subretinal surgery. The authors have developed a flexible micro-cannula for subretinal surgery that can be used for submacular injection of drugs or for atraumatic hydrodissection of the retina. The novel features of the soft tip include reduced diameter (200 microns), increased length, and material selection for resistance to tip buckling. The authors have used this cannula following pars plana vitrectomy for 14 patients with subfoveal choroidal neovascularization secondary to age-related macular degeneration (13 patients) and angioid streaks (1 patient). The cannula creates a relatively atraumatic retinotomy and allows an efficient, controlled injection of subretinal fluid. This micro-cannula seems to be a valuable tool for the subretinal infusion of fluids or drugs.

Angioid Streaks↗
PubMed1996

Dapiprazole for patients with night haloes after excimer keratectomy.

BACKGROUND: Haloes causing difficulties during the night driving are one of the common complications of photorefractive keratectomy (PRK). The presumed reason for this phenomenon is the different refraction of light through the treated and untreated areas of the cornea. Its magnitude is proportional to the ratio between the treated area and pupil size. At nighttime, when the pupil dilates, rays from treated and untreated areas of the cornea reach the retina at different foci and produce haloes. We investigated whether dapiprazole, a miotic alpha-blocker drug, would be helpful in reducing night haloes in patients after PRK. METHODS: Twenty-four patients who complained of night haloes after PRK participated in our study. All were given dapiprazole 0.5% before night driving. Change in pupil size was recorded, and all patients completed a questionnaire on changes in the severity of haloes after instillation of dapiprazole. RESULTS: Improvement was described as very significant in five patients, moderate in ten and slight in seven. There was no improvement in two patients. The only side effect was slight irritation, which resolved within 1 h. CONCLUSION: Our results demonstrate that dapiprazole improves the subjective discomfort caused by night haloes in post-PRK patients.

Adrenergic alpha-Antagonists↗
PubMed1996

Presumed ocular myasthenia and micropsia. A case report.

A 68-year-old woman presented with diplopia. Fluctuations of dysfunction of lateral rectus muscles in both eyes were detected on consecutive examinations. The diagnosis of ocular myasthenia was proposed. After the initiation of therapy, the patient complained of disturbing micropsia. The micropsia and diplopia were relieved by occlusion of one eye or by a base-out prism over one of the patient's eyeglass lenses. Mechanisms of micropsia are discussed.

Aged↗
PubMed1996

Pupillary block glaucoma due to residual perfluoro-decalin.

Perfluorocarbon liquids are used in vitreoretinal surgery and should be removed by the end of surgery. Removal is not always achieved and a few cases of complications resulting from perfluorocarbon liquid residues have been reported. The authors report a unique case of pupillary block glaucoma resulting from perfluoro-decalin residue in the anterior chamber that blocked a surgical coloboma of the iris at the 6-o'clock position. The perfluoro-decalin residue dissolved spontaneously with antiglaucoma treatment and no surgical intervention was needed. When perfluorocarbon liquids are used during pars plana vitrectomy, the possibility of silicone-induced pupillary block in the presence of an inferior iris coloboma should not be overlooked.

Acute Disease↗
PubMed1995

The additive miotic effects of dapiprazole and pilocarpine.

BACKGROUND: Since dapiprazole on alpha-adrenergic agent, produces miosis by paralyzing the dilator muscle, and pilocarpine, a parasympathetic drug, causes miosis by affecting the sphincter, we speculated that the two drugs might have additive effects. METHODS: The additive miotic actions of pilocarpine 2% and dapiprazole 0.5% were evaluated by comparing the effects of two drugs given together and alone on the reversal of mydriasis induced by tropicamide (0.5%) and phenylephrine (10%) in one eye each of 60 healthy volunteers. RESULTS: Dapiprazole and pilocarpine together induced miosis significantly faster than each drug alone, showing additive effects. CONCLUSION: Co-administration of dapiprazole and pilocarpine at the end of the eye examination will induce fast pupillary constriction, which might be useful in preventing the development of an acute attack of angle-closure glaucoma in patients with anatomically narrow angles.

Adolescent↗
PubMed1995

The effect of nasolacrimal occlusion on drug-induced mydriasis.

BACKGROUND: Nasolacrimal occlusion has been shown to improve the efficacy of some topically applied ocular drugs. The aim of this study was to investigate the effect of nasolacrimal occlusion on tropicamide-induced mydriasis. METHODS: We compared pupillary dilatation by 0.125% tropicamide with and without nasolacrimal occlusion in 40 healthy volunteers. RESULTS: Analysis of variance with repeated measures failed to show any advantage due to nasolacrimal occlusion in drug-induced mydriasis. CONCLUSION: Nasolacrimal occlusion did not increase the mydriasis obtained with 0.125% tropicamide.

Adult↗
PubMed1995

The effects of lidocaine and bupivacaine on the rabbit retina.

The toxic action of two commercial anesthetics, lidocaine and bupivacaine, on the functional and morphologic integrity of the retina was investigated in albino and pigmented rabbits. The experimental drug was injected into the vitreous of one eye, while saline solution was injected into the fellow eye. Retinal function was assessed from the electroretinogram and the visual evoked potential. Retinal structure was examined at the light microscopic level. Ten milligrams of lidocaine did not affect the electroretinogram and the visual evoked potential responses, though structural damage could be detected close to the site of injection. A lower dose of 5 mg did not produce any detectable physiologic or morphologic damage. The only dose of bupivacaine used, 0.5 mg, was not toxic to the albino and pigmented rabbit retinas, as assessed by the electroretinogram, visual evoked potential, and light microscopy. The results of this study demonstrate that lidocaine and bupivacaine are nontoxic to the rabbit retina at concentrations that are effective for retrobulbar anesthesia.

Anesthetics, Local↗
PubMed1995

Influence of the time interval between instillation of two drops of cyclopentolate 1% on refraction and dilation of the pupil in children.

PURPOSE: Because the usual length of time to instill two drops of cyclopentolate 1% (five to ten minutes) is time-consuming and inconvenient to clinical staff as well as to the child and the child's parents, we investigated the influence of the time interval between the instillation of the two drops on refraction and mydriasis in children. METHODS: We conducted a crossover study on 48 children at the Tel-Aviv Medical Center. Gender, iris color, ethnic origin, and age were recorded. Two cyclopentolate 1% eyedrops were instilled at a one- or five-minute time interval. Retinoscopy was performed and the mydriatic effect was recorded. One week later, the procedure was repeated, this time with a different time interval. RESULTS: The time interval between the instillation of the two drops had no significant influence on retinoscopy results (P = .65 and P = .50 for right and left eyes, respectively) or on pupil dilation (P = .377 and P = .113 for right and left eyes, respectively). CONCLUSIONS: Instilling two drops of cyclopentolate 1% one minute apart is as effective as instilling them five minutes apart.

Child↗
PubMed1995

Congenital fibrosis of the extraocular muscles (autosomal dominant congenital external ophthalmoplegia): genetic homogeneity, linkage refinement, and physical mapping on chromosome 12.

Congenital fibrosis of the extraocular muscles (CFEOM) is an autosomal dominant syndrome of congenital external ophthalmoplegia and bilateral ptosis. We previously reported linkage of this disorder in two unrelated families to an 8-cM region near the centromere of human chromosome 12. We now present refinement of linkage in the original two families, linkage analysis of five additional families, and a physical map of the critical region for the CFEOM gene. In each of the seven families the disease gene is linked to the pericentromeric region of chromosome 12. D12S345, D12S59, D12S331, and D12S1048 do not recombine with the disease gene and have combined lod scores of 35.7, 35.6, 16.0, and 31.4, respectively. AFM136xf6 and AFMb320wd9 flank the CFEOM locus, defining a critical region of 3 cM spanning the centromere of chromosome 12. These data support the concept that this may be a genetically homogeneous disorder. We also describe the generation of a YAC contig encompassing the critical region of the CFEOM locus. This interval has been assigned cytogenetically to 12p11.2-q12 and spans the centromere of chromosome 12. These results provide the basis for further molecular analyses of the structure and organization of the CFEOM locus and will help in the identification of candidate genes.

Chromosome Mapping↗