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Biomedical subjects

M Lazar

Publications and source records attributed to M Lazar.

At least 55 records · Page 3Linked to original sources
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

The mechanism of intraocular pressure rise during cyclocryotherapy.

PURPOSE: Intraocular pressure (IOP) spikes that occur during cyclocryotherapy for advanced glaucoma may further injure the already damaged glaucomatous optic nerve and be responsible for visual impairment that may occur after this treatment. The authors investigated the mechanism of pressure rise to see whether it can be avoided and thus prevent further optic nerve injury. The authors postulated that intraocular ice forms during the cryo procedure and causes the pressure changes. METHODS: Intraocular pressure was monitored using a pneumatonometer during 15 cryocycles of four patients with advanced glaucoma and 21 cryocycles of five normal rabbits. A simple thermal model was developed to analyze the relation between volume expansion and pressure rise in the eye. The physical effect of freezing rabbit eye structures was investigated in vitro. RESULTS: The largest pressure spikes observed during the cryocycles in this work were increases of 32 mm Hg for humans and 25 mm Hg for rabbits. The mean value of the IOP immediately before and after the cryo freezing stage was 53 +/- 1 and 68 +/- 2 mm Hg, respectively, for humans and 22 +/- 1 and 32 +/- 1 mm Hg for rabbits. The parameters of the thermal model were determined from the observed IOP spikes. Calculated thaw times were consistent with measured times for return to precryo IOPs. In vitro cryoapplication (rabbit eye) showed the formation of an ice ball internal to the eye. CONCLUSIONS: Volumetric increase of the intraocular content related to the formation of an ice ball in the eye, is the mechanism of pressure spikes during cyclocryotherapy. Because this complication is unavoidable, other cyclodestuctive methods may be more prudent, particularly in patients with advanced glaucoma.

Animals↗
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↗
PubMed1996

The mydriatic effect of topical glycopyrrolate.

BACKGROUND: Glycopyrrolate, an anticholinergic agent that does not cross the blood-brain barrier, has several indications, but its mydriatic effect has never been tested. This study was carried out in order to compare the mydriatic effect of glycopyrrolate 0.5% to that of atropine sulfate 1%. METHODS: Glycopyrrolate 0.5% and atropine 1.0% were instilled separately in the eyes of albino rabbits. Pupil diameter and intra-ocular pressure were monitored. RESULTS: Mydriasis was noted within 5 min of glycopyrrolate instillation, reached near-maximal level at 15 min and persisted for 1 week. Glycopyrrolate 0.5% showed a faster, stronger and more persistent mydriatic effect than atropine 1.0%. Administration of glycopyrrolate 0.5% solution b.i.d. for 1 week did not affect intra-ocular pressure or produce any adverse reaction. CONCLUSION: Glycopyrrolate solution has the potential to deliver an ocular anticholinergic effect without causing associated central anticholinergic hazards.

Administration, Topical↗
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

Effect of oral nifedipine on ocular blood flow in patients with low tension glaucoma.

AIM: To investigate the effect of oral nifedipine on ocular blood flow in patients with low tension glaucoma (LTG). METHODS: In this prospective study we examined the effects of 3 weeks of treatment with oral nifedipine 30 mg/day in 11 patients with LTG, by using colour Doppler ultrasound imaging to measure haemodynamic variables in the central retinal (CRA), short posterior ciliary (SPCA), and ophthalmic (OA) arteries. Intraocular pressure (IOP) and blood pressures were also evaluated. RESULTS: Nifedipine failed to alter IOP nor did it change peak systolic velocity, end diastolic velocity,or the resistance index in any of the three ocular vessels studied (p > 0.05). However systolic and diastolic systemic arterial blood pressure measurements varied significantly after nifedipine treatment compared with baseline (p < 0.05). CONCLUSION: Our study failed to demonstrate a significant effect of nifedipine on retrobulbar circulation of patients with LTG.

Administration, Oral↗
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

Nitric oxide synthase inhibitors protect rat retina against ischemic injury.

Elevation of the ocular pressure in the anterior chamber of the rat eye caused major ischemic damage, manifested as changes in retinal morphology. The two most affected structures were the inner plexiform layer, which decreased in thickness by 90%, and the number of ganglion cells, which decreased by 80%. Pretreatment of the animals with N omega-nitro-L-arginine, a nitric oxide (NOS) inhibitor, almost completely abolished the ischemic damage. Administration of aminoguanidine, a NOS inhibitor selective for the inducible enzyme, partially abolished the ischemic damage. Moreover, administration of the NOS inhibitors 1 h after ischemia, also protected the retina from damage, suggesting that similarly acting drugs could be used clinically to limit ischemic injury in humans. We conclude that NOS, and therefore NO, may be involved in the mechanism of ischemic injury to the retina.

Animals↗
PubMed1995

Transcriptional up-regulation of the mouse gene for the muscle-specific subunit of enolase during terminal differentiation of myogenic cells.

The glycolytic enzyme enolase (EC 4.2.1.11) exists as dimers formed from three structurally related subunits alpha, beta, and gamma, encoded by separate genes. The gene encoding the beta-subunit is expressed only in striated muscles. We have previously shown that the beta-enolase gene belongs to a small subset of muscle-specific genes showing transcriptional activity in cultured myoblasts, prior to withdrawal from the cell cycle. An increase in the level of beta-enolase mRNA occurs during terminal differentiation of myoblasts. To investigate the mechanisms underlying this increase, we have simultaneously estimated, under steady state conditions, the rate of synthesis and the stability of beta-enolase mRNA in proliferating C2.7 myoblasts as well as in differentiating myotubes. The method used is based on the isolation of newly synthesized RNA from the total RNA pool, following pulse-labeling of intact cells in the presence of 4-thiouridine. The results described here demonstrate a coordinate increase in newly synthesized and total beta-enolase mRNA, while the mRNA half-life, about 4 hr, remains unchanged in the course of terminal differentiation. The expression of the gene for insulin-like growth factor-II (IGF-II), a major positive regulator of myogenesis, was analyzed using the same approach. It is concluded that the up-regulation of beta-enolase as well as IGF-II gene expression in differentiating muscle cells reflects an increased rate of entry of newly synthesized mRNAs into the general pool of transcripts without changes in their respective half-lives.

Animals↗
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↗