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Biomedical subjects

H Tabandeh

Publications and source records attributed to H Tabandeh.

At least 19 recordsLinked to original sources
PubMed1999

Idiopathic giant retinal tears in identical twins.

PURPOSE: To report idiopathic unilateral giant retinal tears with retinal detachment in identical twins that occurred 2 weeks apart. METHODS: Case reports. RESULTS: In both patients, giant retinal tear and retinal detachment was treated with pars plana vitrectomy, placement of encircling scleral buckle, fluid-perfluorocarbon exchange, endolaser treatment, perfluorocarbon-air exchange, and 16% perfluoropropane injection. One year after retinal detachment surgery, cataract developed in both postoperative eyes. Phacoemulsification with posterior chamber intraocular lens implantation was performed on both eyes. Three and a half years after retinal surgery, corrected visual acuity in both treated eyes was 20/20, and retinal reattachment was successful. CONCLUSIONS: To our knowledge, this is the first report of idiopathic giant retinal tears in identical twins and raises the issue of genetic influences in the pathogenesis of this disease.

Adult↗
PubMed1999

Effect of potent antiretroviral therapy on recurrent cytomegalovirus retinitis treated with the ganciclovir implant.

PURPOSE: To determine the effect of highly active antiretroviral therapy on cytomegalovirus (CMV) retinitis treated with ganciclovir implants. METHODS: A retrospective cohort study was performed of 15 patients with recurrent CMV retinitis treated with the ganciclovir implant and highly active antiretroviral therapy (cases) and 38 patients with recurrent retinitis treated with ganciclovir implants before availability of improved antiretroviral therapy (controls). Progression was defined as occurrence of new lesions in the treated eye or advancement of the retinitis border by more than 750 microm. RESULTS: Cases and controls were statistically similar in age, ethnicity, and duration of acquired immunodeficiency syndrome (AIDS). Controls had received intravenous ganciclovir for 9.5 +/- 9.5 months vs 3.5 +/- 4.6 months in cases (P = .003). The mean (+/- SE) time to progression of retinitis after implantation of the device was 26.7 +/- 2.4 months (95% confidence interval, 22.1 to 31.3) in the cases receiving highly active antiretroviral therapy vs 6.2 +/- 0.9 months (95% confidence interval, 4.5 to 7.9) in the controls (P = .001). Multivariate analysis, adjusted for preoperative variables, confirmed a significantly prolonged time to progression in patients receiving highly active antiretroviral therapy (P = .0003). The odds ratio for progression in the cases vs controls was 0.034 (95% confidence interval, 0.003 to 0.350). Cases had higher CD4+ T-lymphocyte counts (P = .004) and longer survival (P < .001) than controls. CONCLUSION: Highly active antiretroviral therapy is associated with improved outcomes in patients with AIDS and recurrent CMV retinitis treated with the ganciclovir implant.

AIDS-Related Opportunistic Infections↗
PubMed1999

Suprachoroidal hemorrhage during pars plana vitrectomy. Risk factors and outcomes.

OBJECTIVE: Suprachoroidal hemorrhage (SCH) is an uncommon but serious complication of pars plana vitrectomy (PPV) that can be associated with a guarded visual prognosis. The purpose of this study is to document the risk factors and outcomes of this complication. DESIGN: Case-control study of consecutive cases of intraoperative SCH occurring during PPV (n = 36) and controls of PPV uncomplicated by SCH (n = 116). MAIN OUTCOME MEASURES: Baseline systemic and ocular characteristics, intraoperative findings, surgical procedures, and final anatomic and visual outcomes were measured. RESULTS: Significant risk factors for the development of SCH during PPV included high myopia (22% of cases vs. 5% of controls), history of retinal detachment (RD) surgery (61% vs. 22%), rhegmatogenous RD (97% vs. 60%), use of cryotherapy (75% vs. 33%), scleral buckling at the time of PPV (50% vs. 19%), external drainage of the subretinal fluid (22% vs. 2%), and intraoperative systemic hypertension. In the 34 SCH cases with 3 months' or more follow-up, the final visual acuity was 20/200 or greater in 11 (32%), count fingers in 5 (15%), hand movement in 7 (21%), light perception in 7 (21%), and no light perception in 4 (12%). In the 106 controls with 3 months' or more follow-up, the final visual acuity was 20/200 or greater in 79 (75%), count fingers in 20 (19%), hand movement in 5 (5%), light perception in 1 (1%), and no light perception in 1 (1%). In the eyes with SCH, 17 (50%) had persistent RD, 10 (33%) had secondary glaucoma develop, and 8 (24%) became hypotonic. The visual and anatomic outcomes of the SCH cases were significantly worse than those in the control group (P < 0.001). The visual outcome was more favorable if the SCH did not extend into the posterior pole (P = 0.002). Attempted intraoperative drainage of SCH was not associated with a better outcome. CONCLUSION: Risk factors for the development of intraoperative SCH during PPV are high myopia, previous RD surgery, rhegmatogenous RD, cryotherapy, scleral buckling, external drainage of subretinal fluid, and intraoperative systemic hypertension. Anatomic and visual outcomes are significantly worsened after this complication.

Case-Control Studies↗
PubMed1998

Effect of exposure to balanced salt solution upon the hardness of the crystalline lens.

BACKGROUND: The nucleus confers most of the hardness upon the lens, water content decreases towards the centre of the nucleus and a relative dehydration accompanies increased hardness in some cataractous lenses. It is a possibility that exposure and incubation of the inner layers of the nucleus to balanced salt solution (BSS) can result in the softening of the nucleus. PURPOSE: This study aimed to investigate the effect of BSS upon the lens hardness. METHODS: Nuclear colour element of cataract was graded biomicroscopically. Following extracapsular cataract surgery the lens nucleocortex was divided into two equal parts and each half was allocated randomly to incubation in BSS or air for 5 min before the hardness of each section was assessed by an automated guillotine. RESULTS: Following incubation with BSS the mean force necessary to bisect the lens was 0.50 N and in the control air group the mean force was 0.64 N. The lenses in the BSS-treated group were consistently softer than those in the control group, with a mean softening of 18.3% (P=0.001). The amount of softening was not related to the nuclear colour (P=0.6) or age (P=0.1). CONCLUSION: Softening of the lens through physical disruption has previously been reported. This study describes the phenomenon of nuclear softening following exposure to BSS, indicating that lens softening can occur through biochemical means.

Aged↗
PubMed1998

Disturbance of sleep in blindness.

PURPOSE: To determine the prevalence and severity of sleep disturbance in blind subjects and its relation to the form and duration of visual loss. METHODS: Of 403 blind subjects (visual acuity of less than 20/200 or a visual field of less than 5 degrees) recruited for the study, 15 were excluded because of affective disorder as identified by Montgomery Asberg Depression Scale. The remaining 388 subjects and a comparison group of 44 normally sighted individuals underwent an interview, and the Pittsburgh Sleep Quality Index questionnaire was administered. Sleep disturbance was classified as mild, moderate, or severe. RESULTS: Disturbance of sleep was recorded in 189 (48.7%) of the blind subjects. The prevalence was higher and the sleep disturbance was more severe in those with no perception of light than in those with light perception or better visual acuity. In the comparison group, four (9.1%) had mild sleep disturbance only. The differences between blind subjects and normally sighted individuals were highly significant (P < .001). The most common sleep-related problem among the blind subjects was interrupted sleep, followed by increased sleep latency, short sleep duration, and daytime naps. Among the blind subjects, no correlation was found between the extent of sleep disturbance and the duration and pattern of visual loss. CONCLUSIONS: Blind subjects who retain light perception, as well as those with total loss of vision, have a high frequency of sleep disturbance, although disorder is more common and more severe in subjects with no light perception. Management of the sleep disturbance may improve the quality of life in the visually handicapped.

Adult↗
PubMed1998

HLA antigens in lyophilised corneal lenticules.

PURPOSE: To investigate the presence of Human Leukocyte Antigens (HLA) in organ cultured corneas, in lyophilised epikeratophakia lenticules prepared by dry state lathing, and in lenticules subjected to prolonged rehydration in Balanced Salt Solution (BSS). METHODS: Twelve lenticules and 3 organ cultured corneas were studied for the presence of HLA-ABC (class I), and HLA-DR, -DQ, and -DP (class II), antigens using the immunoperoxidase technique. RESULTS: HLA-ABC antigens were detected in all lenticules. HLA-DR antigen was also detected in low concentrations in 6 out of 12 lenticules. HLA-DQ and -DP antigens were generally absent. Incubation in BSS for 24 and 48 hours did not change the expression of antigens. CONCLUSIONS: HLA-class I, and to some degree HLA-class II antigens, are present in the stroma of both organ cultured corneas, and in lyophilised lenticules. Incubation in BSS for up to 48 hours did not reduce the expression of antigens.

Aged↗
PubMed1998

Intraocular lens implants and risk of endophthalmitis.

AIM: To investigate the possible association between the use of three piece foldable silicone polypropylene (SPP) intraocular lenses (IOLs) and an increased risk of postoperative endophthalmitis. METHODS: A retrospective analysis was conducted of all cases of postoperative endophthalmitis following phacoemulsification surgery in a single unit over a 3 year period. The incidence of postoperative endophthalmitis in eyes with SPP IOLs was compared with the incidence in eyes with single piece polymethylmethacrylate (PMMA) IOLs. RESULTS: 772 cataract extractions by phacoemulsification were performed. One (0.16%) of the 622 patients with PMMA IOLs developed endophthalmitis. Excluding one patient who had aplastic anaemia, five (3.33%) of 150 patients with SPP IOLs developed endophthalmitis. The relative risk for postoperative endophthalmitis associated with the use of the SPP IOL compared with the PMMA IOL was 20.1 (p = 0.015). CONCLUSION: This study adds further evidence to the concept that SPP IOLs can be a significant risk factor in the development of postoperative endophthamitis.

Aged↗
PubMed1997

Relationship between napping and melatonin in the blind.

Daytime sleepiness is a common complaint in blind subjects. Abnormally timed melatonin has been invoked as a possible cause of both daytime sleepiness and nighttime awakening. In free-running blind individuals, there is an opportunity to assess the relationship between endogenous melatonin rhythms and subjective sleepiness and naps. The aim of this study was to characterize melatonin rhythms and simultaneously to evaluate subjective napping. A total of 15 subjects with no conscious light perception (NPL) were studied for 1 month. Prior to the study, sleep disorders were assessed using the Pittsburgh Sleep Quality Index. Cosinor and regression analysis revealed that 9 of the 15 NPL subjects had free-running 6-sulphatoxymelatonin (aMT6s) rhythms (period [tau] range = 24.34 to 24.79 h), 3 were entrained with an abnormal phase, and 3 were normally entrained. Most of the subjects (13 of 15) had daytime naps; the 2 individuals who did not made conscious efforts not to do so. Subjects with abnormal aMT6s rhythms had more naps of a longer duration than did those with normal rhythms. Free-running nap rhythms occurred only in subjects with free-running aMT6s rhythms. The 2 abnormally entrained subjects who napped did so at times that coincided with high levels of aMT6s (mean aMT6s acrophase [phi] +/- SD = 14.30 +/- 1.08 h, 20.30 +/- 0.62 h; mean nap time +/- SD = 14.01 +/- 3.60 h, 18.23 +/- 3.20 h, respectively). Regardless of aMT6s rhythm abnormality, significantly more naps occurred with a 4-h period before and after the estimated aMT6s acrophase. In 4 free-running subjects, aMT6s acrophase (phi) passed through an entire 24-h period. When aMT6s was in a normal phase position (24:00 to 06:00 h), night-sleep duration tended to increase with a significant reduction in the number and duration of naps. Sleep onset and offset times tended to advance and delay as the aMT6s rhythms advanced and delayed. Our results show a striking relationship between the timing of daytime production of melatonin and the timing of daytime naps. This suggests that abnormally timed endogenous melatonin may induce sleepiness in blind subjects.

Adult↗
PubMed1997

Relationship between melatonin rhythms and visual loss in the blind.

Melatonin rhythms were assessed in 49 registered blind individuals by measurement of the urinary metabolite of melatonin, 6-sulfatoxymelatonin (aMT6s). Subjects had different causes of visual loss and were classified as having light perception or better (LP; n = 19) or having no perception of light (NPL; n = 30). Subjects collected four-hourly urine samples (eight-hourly overnight) for 48 h at weekly intervals for 3-5 weeks. The majority of LP subjects (14 of 19) had normally entrained aMT6s rhythms (mean acrophase range, 2.4-6.2 h), 4 were abnormally entrained to 24 h (mean acrophase range, 8.9-1.0 h), and 1 was unclassified. Conversely, most NPL subjects had abnormal rhythms (23 of 30), the incidence of which was greater in uni- and bilaterally enucleated subjects. The majority of NPL subjects (17 of 30) had free-running aMT6s rhythms period range, 24.13-24.79 h), 5 were abnormally entrained to 24 h (acrophase range, 7.2-20.6 h), and 1 was unclassified. Output (micrograms of aMT6s per 24 h) and amplitude (micrograms per h) of aMT6s production did not vary between LP and NPL subjects (mean 24-h output +/- SD, 12.7 +/- 7.5 and 9.4 +/- 6.4 micrograms aMT6s/24 h, respectively; mean amplitude +/- SD, 0.6 +/- 0.4 and 0.5 +/- 0.3 microgram/h, respectively). These results indicate that a higher proportion of NPL subjects have abnormal melatonin rhythms compared to those with LP.

Adult↗
PubMed1996

A comparison of slit-lamp supported versus hand-held biometry.

Biometry allows determination of the final refractive outcome following cataract extraction with intraocular lens implantation. We compared the accuracy of axial length measurement performed with the slit-lamp supported biometry probe versus a hand-held technique. The two methods of biometry were performed on 32 patients undergoing endocapsular cataract extraction with lens implantation. One of the methods was selected at random in order to predict implant power for a desired refractive outcome using the SRK-T formula. There was no difference in 'within-subject' variance of axial length measurement between the two methods (t = 1.74, p = 0.091), and there was no difference in refractive outcome when the power calculations for the two techniques were compared (t = 0.12, p = 0.906). The hand-held technique provides a useful alternative method of biometry in 'difficult' patients.

Biometry↗
PubMed1995

Phenylephrine and pilocarpine in the treatment of post-operative irido-corneal adhesion.

Following cataract surgery, entrapment of the iris within the surgical wound is often managed by intensive use of miotics. As the radial fibres stretch, only a small amount of fraction is exerted upon the entrapped iris. Application of a combination of phenylephrine and pilocarpine drops causes simultaneous contraction of the pupil sphincter and the radial muscle fibres. This study investigated the relative magnitude of forces induced in the iris periphery by pilocarpine and phenylephrine and the effectiveness of adding g. phenylephrine 10% to g. pilocarpine 4% drops in the treatment of postoperative irido-corneal adhesions. The investigation was divided into two parts. First, the forces induced in the iris periphery upon exposure to pilocarpine and phenylephrine were measured in 6 cadaver irises. The mean force was 27.5 +/- 5.7 x 10(-3) N for pilocarpine and 23.3 +/- 4.0 x 10(-3) N for phenylephrine. The combination of the two drugs produced a force of 54.2 +/- 6.6 x 10(-3) N (p < 0.05). In the second part of the study intensive pilocarpine 4% drops were administered to 17 patients who had iris-wound entrapment on the first post-operative day. Patients with persistent adhesion were commenced on intensive g. phenylephrine 10% and assessed after 90 minutes. Of the 17 patients, 6 responded to pilocarpine drops alone; in a further 7 the irido-corneal adhesion was released only by the addition of phenylephrine drops, and in 4 patients drops were ineffective in relieving the adhesion. This study indicates that addition of phenylephrine 10% to pilocarpine 4% drops enhances the effectiveness of pharmacological treatment of post-operative irido-corneal adhesion.

Cataract Extraction↗
PubMed1995

Auditing ophthalmology audits.

Medical audit is now a well-established part of the routine of ophthalmology departments. Accomplishing a complete audit is a complex task and its effectiveness depends on how it is performed. In order to evaluate the procedure in our department a retrospective analysis of 18 audits was carried out with particular reference to the level, objectives, beneficial effects, and effects on current practice. Our practice was critically analysed using these factors. One audit fulfilled the criteria for a full audit. Eleven (60%) were partial or potential and six (30%) were an attempt in planning an audit. The majority omitted plans for implementing change or targets for future assessment. Seven had educational benefit. There was little effect on patient care, cost-effectiveness or communication. Medical audit can be clinically effective, educational and stimulating. Failure to complete all stages affects the outcome. This study identifies the difficulties involved in performing complete audits and suggests improving the procedure by auditing audits on a regular basis.

Education, Medical↗