Volume 5, Number 51
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Monday, December 26, 2005
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In this issue: (click heading to view article) | ||||
Editorial: Medical Errors | ||||
Diagnostic Testing of Vitrectomy Specimens | ||||
Heritability of Macular Pigment: A Twin Study | ||||
Briefly |
Review of Ophthalmology Online will not be published next week. Dr. Pascucci and the staff of ROO extend warmest wishes to you, your families and your staff members for a wonderful holiday and a healthy and productive new year! |
Diagnostic Testing
of Vitrectomy Specimens Floridas Bascom Palmer Eye Institute assessed the usefulness of diagnostic tests performed on vitrectomy specimens from patients with suspected lymphoma or infection. The noncomparative, retrospective, interventional case series included 78 consecutive patients (84 eyes) who underwent pars plana vitrectomy for diagnostic purposes. Surgeons performed vitrectomy with cytologic, cytofluorographic or microbiologic analysis of vitreous samples. Main outcome measures were the efficiency of diagnostic procedure and positive and negative predictive values (PPV and NPV). Twenty-eight patients (33 eyes) had suspected intraocular lymphoma, and 50 patients (51 eyes) had suspected infection; the latter was subdivided into chronic endogenous endophthalmitis, atypical chorioretinitis or chronic postoperative inflammation. Vitreous testing led to a diagnosis in 48 of 78 patients (61.5 percent); 14 patients with a final diagnosis of lymphoma/leukemia and 34 patients with a final diagnosis of infection. When preoperative indication was compared with final clinical diagnosis, the efficiencies of the diagnostic procedure of cytologic evaluation, flow cytometry and bacterial/fungal culture were 67 percent, 79 percent and 96 percent, respectively. For lymphoma, the PPV of cytologic evaluation was 100 percent and the NPV 60.9 percent. For infection, the PPV of bacterial/fungal culture was 100 percent and the NPV 94.9 percent. CD22(+) B lymphocytes 20 percent or higher of total cells on cytofluorographic analysis had a PPV of 88 percent for lymphoma. A cytofluorographic CD4:CD8 T-lymphocyte ratio of 4 or higher had a PPV of 70 percent for immunologically mediated uveitis. Surgical complications were rare and manageable. The investigators concluded that diagnostic vitrectomy in selected patients with carefully planned testing is an effective means of supporting diagnoses in intraocular lymphoma, chronic intraocular infections and atypical chorioretinitis. Flow cytometry quantitates the percentages and ratios of various cell types and is helpful in contrasting intraocular lymphoma with immunologically mediated uveitis. |
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SOURCE: Davis JL, Miller DM, Ruiz P. Diagnostic testing of vitrectomy specimens. Am J Ophthalmol. 2005;140(5):822-29. |
Heritability
of Macular Pigment: A Twin Study Several studies have reported higher levels of macular pigment (MP) in association with reduced risk for age-related macular degeneration (AMD), a disease to which there is a genetic predisposition. Researchers in England, Ireland and the United States conducted a classic twin study to determine the heritability of MP in the healthy eye. The study included 150 twin pairs, 76 of whom were monozygotic (MZ) and 74 of whom were dizygotic (DZ). The subjects ranged in age from 18 to 50 years. Researchers measured MP optical density psychophysically using heterochromatic flicker photometry (HFP) and an imaging method involving fundus autofluorescence (AF). They then compared the covariance of MP within MZ and DZ twin pairs, and they used genetic modeling techniques to determine the relative contributions of genes and environment to the variation in MP. The mean MP optical density, measured using HFP, was 0.43 +/- 0.21. Using AF, the mean MP optical density, measured at 1 degrees eccentricity, was 0.28 +/- 0.11. MP optical densities correlated more highly in MZ twins than in DZ twins, according to both HFP (MZ: 0.65; DZ: 0.24) and AF (MZ: 0.83; DZ: 0.50). A model combining additive genetic and unique environmental effects provided the best fit and resulted in MP heritability estimates of 0.67 (95 percent CI, 0.52 to 0.77) and 0.85 (95 percent CI, 0.78 to 0.90) for HFP and AF readings, respectively. The authors believe the results demonstrate that genetic background is an important determinant of MP optical density. |
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SOURCE: Liew SH, Gilbert CE, Spector TD, et al. Heritability of macular pigment: a twin study. Invest Ophthalmol Vis Sci. 2005;46(12):4430-6. |
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