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Volume 4, Number 43
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Monday, October 25, 2004
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| Post-operative
Aphakia in Modern Cataract Surgery Investigators at Sweden’s Blekinge Hospital (Lund) conducted a two-part study of 62 community-run or private clinics participating in the Swedish National Cataract Register. They aimed to determine the incidence of aphakia after cataract extraction and to evaluate the relative risk for this outcome in subgroups of patients based on pre-operative conditions; they also studied the incidence of aphakia after cataract surgery, the surgical complications that can lead to it and the visual outcome of aphakia after cataract surgery. In Part 1, investigators prospectively collected data on cataract extractions from 1997 through 2001. The set of data also covered type of surgery and type of intraocular lens (IOL), including a "no lens implanted" option. All information was stored in a database. Researchers made database calculations of frequencies and risk ratios of post-operative aphakia in the subgroups of patients based on pre-operative conditions. For the entire study period, post-operative aphakia was reported in 1,410 of 287,951 surgeries, for which complete IOL data were available, corresponding to an overall frequency of 0.49 percent. The occurrence of ocular comorbidity and poor pre-operative visual acuity (less than or equal to 0.1) in the eye to be operated on was significantly related to post-operative aphakia for each year of the study. Glaucoma and poor visual acuity (less than or equal to 0.1) in the surgical eye meant a 12.8 higher risk for aphakia after surgery than a better visual acuity (greater than 0.1) and no ocular comorbidity. The results showed that in routine cataract surgery performed during the study, one of every 200 operations ended in post-operative aphakia. Poor visual acuity in the eye to be operated on, combined with ocular comorbidity, was the highest risk factor for post-operative aphakia. In Part 2 of the study, investigators collected data prospectively on cataract extractions from 1997 through 2001 including type of surgery and type of intraocular lens, including a "no lens implanted" option. All data were stored in a database and were supplemented with data on the intended type of surgery, type of complications, possible second surgery and visual outcome. The overall incidence of post-operative aphakia was 0.65 percent. In 87.1 percent of cases, the aphakia was not planned--an incidence of 0.48 percent. Unplanned aphakia was significantly related to poor pre-operative vision, old age and the presence of ocular comorbidity. The most frequent reasons for unplanned aphakia were intra-operative capsule problems and vitreous loss. In two-thirds of cases, patients underwent a second operation. In 41 percent of all cases, final visual acuity was 0.5 or better, and in 27.7 percent it was worse than 0.1. The incidence of surgical complications leading to unplanned aphakia and a final visual acuity worse than 0.1 (20/200) was 7.8 per 10,000 operations in cases with no ocular comorbidity and 27.6 per 10,000 operations in cases with ocular comorbidity. |
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SOURCE: 1) Lundstrom M, Brege KG, Floren I, et al. Post-operative aphakia in modern cataract surgery; Part 1: analysis of incidence and risks based on 5-year data from the Swedish National Cataract Register. J Cataract Refract Surg 2004;30(10):2105-10. 2) Lundstrom M, Brege KG, Floren I, et al. Post-operative aphakia in modern cataract surgery; Part 2: detailed analysis of the cause of aphakia and the visual outcome. J Cataract Refract Surg 2004;30(10):2111-5. |
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| Prevalence of
Ocular Glaucomatous Abnormalities in Systemic Sclerosis Cardiovascular diseases, vasospasm and dysimmunity have been implicated in normal-tension glaucoma. Researchers in France recently conducted a study aimed at determining the prevalence of ocular abnormalities suggestive of glaucoma damage in systemic sclerosis (SSc). The study included 61 patients with SSc and 37 control subjects with osteoarthritis. The mean age of SSc patients was 56.2 years, mean disease duration was 9.9 years; 41 had limited cutaneous disease. The mean age of control subjects was 55.9 years. All were systematically referred to an ophthalmologist. Evaluation was based on applanation tonometry, ophthalmoscopy with retinal photography (evaluation of cup/disc ratio), and automated static perimetry (determination of mean defects). Statistical analyses were performed with the chi(2), Mann-Whitney and Spearman tests. Mean visual acuity and intraocular pressure were similar in both groups. Twenty-seven eyes of patients with SSc and five eyes of controls showed an excavation with a cup/disc ratio greater than 0.3. Four eyes from patients with SSc and no control eyes showed a cup/disc ratio greater than 0.7. Visual field defects (mean defects less than -2 dB) were found in 55 eyes from patients with SSc and in 18 eyes from controls. A concomitant cup/disc greater than 0.3 and mean defects less than -2 dB was found in 21 eyes from 12 patients with SSc but in none of the control eyes. Results showed that ocular abnormalities suggesting glaucomatous neuropathy without ocular hypertension were dramatically more prevalent in patients with SSc. Although the abnormalities seemed mild, the authors believe that they justify long-term follow-up, and that they are consistent with the vascular pathogenic hypothesis for normal-tension glaucoma. |
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SOURCE: Allanore Y, Parc C, Monnet D, et al. Increased prevalence of ocular glaucomatous abnormalities in systemic sclerosis. Ann Rheum Dis 2004;63(10):1276-8. |
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| Novel Proteins
in Retinal Neovascularization Identifying novel proteins involved in retinal neovascularization may facilitate new and more effective molecular-based treatments for proliferative retinopathy. Tubedown-1 (Tbdn-1) is a novel protein expressed in normal retinal endothelium, but it is specifically suppressed in retinal endothelial cells from patients with proliferative diabetic retinopathy. Researchers at the Memorial University of Newfoundland investigated the importance of Tbdn-1 expression in retinal blood vessels in vivo using a mouse model. Investigators produced a bi-transgenic mouse model that enabled conditional knockdown of Tbdn-1 specifically in endothelial cells. They used molecular, histologic and immunohistochemical techniques and morphometric analysis in their study. Tbdn-1-suppressed mice exhibited retinal and choroidal neovascularization with intra- and pre-retinal fibrovascular lesions similar to human proliferative retinopathies. Retinal lesions observed in Tbdn-1-suppressed mice increased in severity with prolonged suppression of Tbdn-1. Compared to normal retina, the retinal lesions displayed alterations in the basement membrane of blood vessels and in the distribution of glial and myofibroblastic cells. Moreover, the pathologic consequences of Tbdn-1 knockdown in endothelium were restricted to the retina and the choroid. The results suggest that the maintenance of Tbdn-1 expression is important for retinal blood vessel homeostasis and for controlling retinal neovascularization in adults. The investigators believe that restoration of Tbdn-1 protein expression and/or activity may provide a novel approach for treating proliferative retinopathies in humans. |
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SOURCE: Wall DS, Gendron RL, Good WV, et al. Conditional knockdown of Tubedown-1 in endothelial cells leads to neovascular retinopathy. Invest Ophthalmol Vis Sci 2004;45(10):3704-12. |
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| Donor Corneal
Button Contamination and Post-transplant Ocular Infection Contamination of the donor corneal button before transplantation may result in one of the most serious complications of corneal transplantation, post-operative ocular infection, which may result in loss of the eye. Israeli researchers recently conducted a study to evaluate the prevalence of donor corneal button contamination, the spectrum of the contaminating microorganisms and their sensitivity to antimicrobial agents. The study included 469 corneal transplantations at a tertiary referral medical center. Investigators obtained microbial cultures from the corneoscleral rims of the donor corneal buttons for isolation of bacteria and fungi and for their sensitivity to antimicrobial agents. They also obtained ocular microbial cultures from corneal transplanted patients with clinical signs of ocular infection (i.e., corneal scrapes from corneal ulcers and vitreous tap from eyes with endophthalmitis). Seventy-nine of the donor corneal buttons (16.8 percent) had positive bacterial cultures; none had positive fungal culture. Staphylococci spp. (63.7 percent) and Streptococci spp. (11.3 percent) were the most common isolated bacteria. Sensitivity to vancomycin, amikacin and gentamicin was found in 71.3 percent, 28.5 percent and 22.3 percent of all isolated bacteria, respectively. Malignancy and cardiac diseases as causes of donor death were associated with donor button contamination; septicemia was a marginally significant risk factor. Age and gender of the donor, duration from death to corneal button harvesting and time from harvesting to transplantation were not significant risk factors for contamination. Six of the corneal transplanted patients (1.27 percent) had infected corneal graft ulcer and one (0.22 percent) had endophthalmitis. The infected corneal ulcer appeared between three and 14 days (average five days), and endophthalmitis was disclosed eight months after transplantation. Two (33 percent) of the six patients with corneal ulcer had the same species as the donor corneal rim. Post-operative ocular infection occurred in two (2.5 percent) patients out of 79 who received contaminated corneal buttons, compared with five (1.3 percent) out of 390 patients who received sterile corneal buttons. The authors of the study conclude that postkeratoplasty infection of the recipient eye is infrequent despite relatively high prevalence of microbial contamination of the corneal buttons. They believe this suggests that other risk factors for post-operative ocular infection are involved. |
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SOURCE: Rehany U, Balut G, Lefler E, Rumelt S. The prevalence and risk factors for donor corneal button contamination and its association with ocular infection after transplantation. Cornea 2004;23(7):649-54. |
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| Cardiovascular
Disease, Mortality, and Retinal Microvascular Characteristics in Type
I Diabetes Diabetic retinopathy and proteinuria, manifestations of microvascular abnormalities, occur early in the course of diabetes mellitus; in contrast, macrovascular cardiovascular complications usually occur later. Investigators at the University of Wisconsin’s Department of Ophthalmology and Visual Sciences conducted a longitudinal cohort study of patients with Type I diabetes to evaluate whether retinal vessel characteristics may be informative about risk of cardiovascular disease in persons with diabetes. The study included 996 people in 11 counties in Wisconsin who were receiving care for Type I diabetes. Subjects were examined at baseline (1980 to 1982), and four, 10, 14 and 20 years later. Evaluations included medical history and measurements of height, weight, blood pressure and glycosylated hemoglobin. Fundus photographs were graded for diabetic retinopathy at baseline, and the same photographs were graded later for the diameters of retinal blood vessels. At each examination, investigators obtained a history of cardiovascular disease events since the last examination (and prior to baseline). Mortality was monitored yearly. The 20-year age-adjusted cumulative incidences were 18.1 percent for angina, 14.8 percent for myocardial infarction, and 5.9 percent for stroke. Severity of diabetic retinopathy was associated with angina and stroke. Arteriovenous ratio was associated with myocardial infarction. Of 273 deaths, 176 involved heart disease. The severity of retinopathy and arteriovenous ratio was associated with heart disease mortality. Nephropathy was more informative about the cardiovascular end points than were the blood vessel characteristics. |
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SOURCE: Klein BE, Klein R, McBride PE, et al. Cardiovascular disease, mortality, and retinal microvascular characteristics in Type 1 diabetes: Wisconsin epidemiologic study of diabetic retinopathy. Arch Intern Med 2004;164(17):1917-24. |
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BRIEFLY
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