Biomedical subjects
Publications and source records attributed to A Loewenstein.
We prospectively studied all the deaths that occurred in Sourasky Medical Center (Ichilov Hospital), Tel Aviv, from 1 July through 30 September 1989 for possible eye donation. Of the 135 suitable candidates 29 donations were obtained (21.5%). In the course of the study the procurement rate progressively increased as a result of a higher level of effort and awareness by the hospital medical staff.
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In three patients with thioridazine toxicity, the electroretinogram (ERG) to red light was found to be below the average normal range. A significant increase in its amplitude appeared with cessation of therapy in two cases. A further deterioration of the ERG amplitude to all stimulus conditions (white, blue, and red lights) occurred when the dose of the medication was increased in the third patient.
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PURPOSE: To evaluate ocular parameters that may predispose to the development of branch retinal vein occlusion (BRVO). METHODS: This prospective study included patients with unilateral BRVO evaluated in the authors' clinic. The mean period from the acute phase was 2.29 +/- 1.57 years (range 1-6 years). All patients underwent a complete ophthalmologic examination including subjective refraction, axial length measurements, and keratometry readings. The fellow eye served as a control in each patient. The variables of interest were compared between the affected eye and the fellow eye using the parametric t-test and the nonparametric Wilcoxon test. RESULTS: Twenty-four consecutive patients (14 women, 10 men, mean age 62.4 years) were included in the study. The mean axial length in the affected eye was significantly shorter compared to the mean fellow eye length. No difference was found between the two eyes in mean subjective refraction or mean keratometry readings. CONCLUSIONS: The authors found that eyes with BRVO have a shorter axial length compared to the fellow eye in the same patient.
Post-traumatic thrombosis of cavernous sinus and orbital veins has been reported in conjunction with carotid-cavernous sinus fistula (CCSF). CCSF are abnormal communications between the carotid artery and the cavernous sinus. Spontaneous thrombosis of a CCSF is a rare event mainly seen in the indirect (dural) type of fistula. We report on a patient with a possible post-traumatic CSSF which underwent partial spontaneous thrombosis and presented with an extreme degree of proptosis.
Atropine is accepted generally as the most efficient cycloplegic agent. Although it is considered a relatively safe drug, toxic local and systemic side effects do occur. The recommended regimen for atropine cycloplegia has been 7 to 10 applications within 3 to 4 days. We compared the cycloplegic effect of four instillations of atropine drops to the effect of eight instillations. The results showed that the cycloplegia obtained after eight instillations was not greater than after four instillations.
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The aim of this report is to present the effects of spherical photorefractive keratectomy (PRK) by excimer laser on myopic astigmatism. Spherical PRK was performed in 96 eyes with myopia associated with astigmatism of between 0.75 and 2.00 diopters (D) using the Summit excimer laser. The reduction both in sphere and in cylinder was found to be highly statistically significant (P < 0.0001 for both). The mean reduction of cylinder was 46%. Astigmatic error of less than 2.00 D can be corrected significantly by spherical PRK.
The aim of this study was to find out whether the outcome of excimer laser photorefractive keratectomy (PRK) in the second eye can be predicted from the results of the first, and to determine whether we should modify our therapeutic approach to the second eye according to the results of the first. Bilateral PRK was performed in 73 patients using the Summit Technology excimer laser. All patients included in this study had a follow-up of at least 12 months in both eyes. The change of refraction and the haze of the two eyes were compared. Sixty percent of patients had a difference in refraction between the two eyes smaller than 0.50 diopters (D), and 75% had a difference smaller than 1.00 D. The degree of symmetry in response to treatment was greater in patients with a preoperative spherical equivalent refraction of less than -6.00 D. Most patients had a similar degree of haze in both eyes. The results of our study demonstrate that a considerable degree of symmetry in the outcome of surgery exists between the two eyes of the same patient undergoing PRK, especially in low to moderate myopia.
BACKGROUND: Waterjet cutting is an advanced technology. It consists of a cutting tool that uses a very thin stream of ultra-high-pressure water forced at high velocity through a very small nozzle, creating a very sharp knife. We report on the first experimental use of waterjet technology to reshape the cornea. METHODS: The system was used in vitro on 10 bovine eyes, and in vivo on 10 albino rabbit eyes. Using the waterjet keratome (Lipshitz-Bass knife, LBK) lamellar corneal incisions were performed. Histological examinations were performed. RESULTS: A waterjet stream was found to be capable of incising corneas at relatively low energy levels (4000 PSI). Good surface quality could be obtained, and there was no collateral damage to the remaining portion of the cornea, lens, or retina. In the in vivo experiments, the epithelium healed within 48 hours. CONCLUSIONS: These preliminary experiments suggest that waterjet technology can be an effective instrument for reshaping the cornea.
BACKGROUND: To determine whether the outcomes of photorefractive keratectomy (PRK) for myopia are age-dependent. METHODS: The influence of age on PRK outcomes was analyzed for one eye of each of 72 patients divided into two groups: 39 patients (18 to 26 years) and 33 patients (35 to 54 years). The influence of the amount of preoperative myopia (low myopia less than -4.00 diopters (D); moderate to high myopia -4.00 or more D) was also evaluated. All patients were followed for at least 1 year, and all underwent cycloplegic refractions. RESULTS: One year after PRK, the average refraction was -0.15 D in the younger group and +0.38 D in the older group. The achieved refraction was higher than the attempted by +1.00 D or more only in eyes with moderate to high myopia (-4.00 to -10.00 D); 11.54% (3 eyes) of the younger group and in 34.78% (8 eyes) of the older group. CONCLUSIONS: After PRK for myopia, patients between the ages of 35 and 54, with moderate to high myopia, obtained more refractive change with the same intended dioptric correction compared to younger patients with moderate to high myopia. Attempted correction should be adjusted according to age and amount of myopia.
PURPOSE: To examine patient satisfaction following photorefractive keratectomy (PRK) in a large number of subjects. METHODS: We used a questionnaire to examine overall patient satisfaction in 173 patients (173 first-operated eyes) at least 1 year after they had undergone PRK. Mean preoperative spherical equivalent refraction was -7.05 +/- 3.73 D (range, -1.50 to -15.00 D). Fifty-one patients had unilateral surgery and 122 had bilateral surgery, 60 of whom had follow-up of 1 year for both eyes. Visual and refractive results, the use of corrective lenses, and subjective side effects were also studied. RESULTS: Eighty percent of 173 patients reported they were satisfied or very satisfied with the surgical outcome, while 19.7% reported they were dissatisfied. The average satisfaction score was 7.92 +/- 2.22 out of a possible 10. After PRK, 77.5% reported improvement or great improvement in their general quality of life; 16.8% were very disturbed by subjective visual symptoms. Of the 51 bilateral patients, 85% required no corrective lenses after surgery. Patients who had bilateral operations were more satisfied than those who had unilateral ones. Statistically significant associations were found between patient satisfaction and initial refraction: as preoperative refraction increased, percentage of satisfied or very satisfied patients decreased. CONCLUSION: Patient satisfaction after PRK was generally high, but subjective visual symptoms remain a problem.
OBJECTIVE: The aim of this study was to compare the results of excimer laser photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in the same patient. METHODS: All consecutive patients who underwent PRK in one eye and LASIK in the second eye using the same excimer laser (Nidek EC-5000) and had at least 12 months of follow-up were included in this retrospective study (N = 23). Uncorrected and spectacle-corrected visual acuity, final spherical equivalent refraction, and degree of haze were compared. RESULTS: Mean postoperative spherical equivalent refraction in the group of eyes that underwent PRK was +0.73 D (range, -5.50 to +3.50 D). Mean postoperative spherical equivalent refraction in the group of eyes that underwent LASIK was +0.07 D (range, -1.25 to +3.50 D) (P = .046). CONCLUSION: In our study, eyes treated with LASIK had better results than eyes treated with PRK.
PURPOSE: The aim of this study was to compare the results of excimer laser photorefractive keratectomy (PRK) in patients who underwent PRK using the Summit Apex (Omnimed) excimer laser in one eye and the Nidek EC-5000 excimer laser in the other. METHODS: All consecutive patients who underwent PRK with the Summit Apex laser (Omnimed) in one eye and the Nidek laser (EC-5000) in the second and had at least 12 months of follow-up were included in this retrospective study (n=30). Uncorrected and spectacle-corrected visual acuity, final spherical equivalent refraction, and grade of subepithelial haze were compared. The average preoperative spherical equivalent refraction of eyes treated with the Summit laser was -6.00 D (range, -2.50 to -8.75 D), and for Nidek-treated eyes it was -5.57 D (range, -2.50 to -8.80 D). RESULTS: Forty-seven percent of Summit-treated eyes and 53% of Nidek-treated eyes had uncorrected visual acuity of 6/6 or better; 61% of Summit-treated eyes and 63% of Nidek-treated eyes had uncorrected visual acuity of 6/7.5 or better; 95% of Summit-treated eyes and 95% of Nidek-treated eyes had uncorrected visual acuity of 6/12 or better (difference not statistically significant). Seventy-three percent of eyes treated with the Summit laser and 80% of eyes treated with the Nidek laser had a postoperative refraction within +/-0.50 D of emmetropia; 97% of Summit-treated eyes and 87% of Nidek-treated eyes had a postoperative spherical equivalent refraction within +/-1.00 D of emmetropia; the difference between the two lasers was not statistically significant. However, the percent of eyes with persistent hyperopia was smaller in the Nidek group after 3 months (P=.0062) and after 6 months (P=.07) than in the Summit group. Videokeratography was not done. CONCLUSION: Both lasers were effective with relatively low side effects. No significant difference was found between the two lasers in postoperative uncorrected visual acuity or refractive outcome. Eyes operated with the Nidek laser had less persistent hyperopia and stabilized earlier.