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Biomedical subjects

H Tabandeh

Publications and source records attributed to H Tabandeh.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1999

Visual acuity outcomes of patients 50 years of age and older with high myopia and untreated choroidal neovascularization.

OBJECTIVE: To evaluate visual outcomes of untreated submacular choroidal neovascularization (CNV) in patients 50 years of age and older with high myopia. DESIGN: Retrospective observational case series. PARTICIPANTS: Twenty-two eyes in 22 patients were studied. All were 50 years of age and older with myopia of 6.0 diopters (D) or greater or an axial length of 25.5 mm or greater. Patients had untreated CNV documented by clinical examination and fluorescein angiography at two medical centers between 1986 and 1997. INTERVENTION: Demographic and clinical data were abstracted from patients' medical records. MAIN OUTCOME MEASURE: Visual acuity at 1 year after CNV diagnosis. RESULTS: The study included 22 eyes of 22 patients (mean age, 63.1 years; mean refraction, -11.0 D). Baseline visual acuity (VA) in the study eye was 20/40 or greater in 2 (9%) patients, 20/50 to 20/150 in 9 (41%) patients, and 20/200 or less in 11 (50%) patients. Drusen were present in seven (32%) eyes, and lacquer cracks were noted in ten (45%) eyes. Mean refractive error was -7.0 D for patients with drusen and -12.5 D for patients without drusen. Choroidal neovascularization was less than 0.25 disc diameters (DD) in 11 (50%) eyes, 0.25 to 0.5 DD in 5 (23%) eyes, and greater than 0.5 DD in 6 (27%) eyes. Visual acuity in the study eye 1 year after CNV diagnosis was 20/40 or greater in 3 (14%) patients, 20/50 to 20/150 in 3 (14%) patients, and 20/200 or less in 16 (73%) eyes. The presence of drusen was significantly associated with older age and a lower degree of myopia but was not associated with size of the CNV or visual acuity outcome. CONCLUSION: When compared to patients younger than 50 years of age with high myopia and CNV reported in previous publications, the patients in the current series generally have poorer visual outcomes.

Aged↗
PubMed1999

Retinal detachment associated with macular hole surgery: characteristics, mechanism, and outcomes.

OBJECTIVE: To study the frequency, features, and outcomes of retinal detachment (RD) occurring after macular hole surgery. METHODS: Retrospective review of all cases of macular hole surgery. Cases with postoperative RD were identified for study. Outcome measures included baseline demographic and ocular characteristics, RD features, surgical procedure, macular hole status, and final visual and anatomic outcomes. RESULTS: Retinal detachment occurred in 8 (1.8%) of 438 eyes undergoing macular hole surgery. The rate of RD was 3.5% early in the course of the surgeon's experience (first 200 cases) and 0.4% later in the surgeon's experience (after 200 cases) (P = 0.026). Two of the eight eyes with RD had undergone previous macular hole surgery. All six primary cases occurred after repair of stage 3 macular holes, which had involved peeling of the posterior cortical face. The RD involved the inferior quadrants in seven eyes and the macula in two eyes. The pathogenic retinal break was in the equatorial region in four eyes, was anterior to the equator in two eyes, and remained undetermined in two eyes. The retina was attached and the macular hole was closed in all cases at the final follow-up examination (mean 30 months). The macular hole reopened 2 years following successful reattachment of the RD in one eye. Final visual acuity was > or =20/60 in four eyes and <20/200 in one eye. CONCLUSION: Retinal detachment after macular hole surgery is uncommon, and may be related to posterior cortical vitreous stripping. Early detection of RD minimizes adverse visual and anatomic outcomes.

Aged↗
PubMed1999

Choroidal neovascularization following macular hole surgery.

BACKGROUND: Retinal pigment epitheliopathy, a recognized finding in eyes that have undergone macular hole surgery, may limit visual outcome and predispose to the development of choroidal neovascularization (CNV). This study reports on the features and outcomes of CNV following otherwise successful surgery for idiopathic macular holes. METHODS: Case series including three eyes of two patients who developed CNV following macular hole surgery. RESULTS: Choroidal neovascularization developed 3 to 30 months after macular hole surgery. The CNV was crescent-shaped, surrounding a central area of retinal pigment epithelial mottling that corresponded to the site of the macular hole in all three cases. All neovascular membranes were adjacent to the fovea and were associated with substantial leakage of fluorescein. The macular hole remained closed in all cases. CONCLUSION: Choroidal neovascularization is a rare complication following macular hole surgery. Retinal pigment epitheliopathy and defects in the Bruch's membrane, pre-existing or secondary to surgery, may be predisposing factors.

Aged↗
PubMed1999

Combined lensectomy, vitrectomy and scleral fixation of intraocular lens implant after closed-globe injury.

PURPOSE: To describe our experience in the surgical management of cataracts in patients with complications of closed-globe injury using pars plana lensectomy (PPL), pars plana vitrectomy (PPV), and scleral fixation of posterior chamber intraocular lens (PCIOL). METHODS: We retrospectively reviewed charts of all patients with closed-globe injury who underwent PPL, PPV and scleral fixation of PCIOL at our institution between January 1991 and July 1997. We identified 28 eyes; because of less than 2 weeks follow-up, 4 eyes were excluded from the current study. All eyes had lens subluxation/dislocation and visually significant cataract. Additional indications for surgery included secondary glaucoma (10 eyes), vitreous hemorrhage (3 eyes) and retinal detachment (1 eye). RESULTS: The postoperative follow-up interval ranged from 6 to 61 months (mean 18.5 months). Preoperative visual acuity (VA) ranged from 20/60 to hand motion and was 20/100 or better in 6 eyes (25%). Postoperatively, 19 eyes (79%) improved to 20/100 or better. Five eyes had subsequent surgery for the following indications: retinal detachment (2 eyes), poorly controlled glaucoma (2 eyes), and epiretinal membrane formation (1 eye). CONCLUSIONS: In patients undergoing PPL, PPV and scleral fixation of PCIOL for cataract after a closed-globe injury, a substantial visual improvement occurred in a majority of the involved eyes.

Adolescent↗
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↗