Macular pigment density in monozygotic twins

Macular pigment density in monozygotic twins

results may affect management of optic neuritis, and answers to some of the most frequently asked ques­ tions about the validity of the results, parti...

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results may affect management of optic neuritis, and answers to some of the most frequently asked ques­ tions about the validity of the results, particularly with respect to the development of multiple sclerosis." Criteria for entry into the study included a diagnosis of acute unilateral optic neuritis with visual symptoms of eight days or less, age between 18 and 46 years, no previous history of optic neuritis or ophthalmoscopic signs of optic atrophy in the affected eye, no evidence of a systemic disease that might be associated with the optic neuritis, and no previous treatment with corticosteroids for optic neuritis in the fellow eye. Two primary treatment recommendations were derived from the trial: ( 1 ) oral prednisone therapy should be abandoned; and (2) patients should undergo magnet­ ic resonance imaging and be treated with intravenous corticosteroids if the scans demonstrate two or more signal abnormalities. Although magnetic resonance imaging is the largest additional expense evoked by the study's recommendations, it offers important prognostic information about the chances of develop­ ing further neurologic sequelae of multiple sclerosis. —George B. Bartley

that included determination of scotopic vision using a luxometer. The mean serum vitamin A level was lowest among children identified as night blind by both their parents and the investigators and was highest among those identified as not night blind by both parents and investigators. The authors conclud­ ed that parents' reports of their children's night blindness had low sensitivity compared with diagnosis using a luxometer and recommended that future studies of the prevalence of night blindness include a standard method of screening random samples of children.—George B. Bartley

"Centre for International Health, University of Bergen, Haukeland Hospital, N-5021 Bergen, Norway.

• Macular pigment density in monozygotic twins. Hammond BR Jr*, Fuld K, Curran-Celentano J. Invest Ophthalmol Vis Sci 1995;36:2531-41.

T *]aeb Center for Health Research, Inc., 3010 E. 138 Ave., Suite 9, Tampa, FL 33613.

• Diagnosis of night blindness and serum vitamin A level: a population-based study. Hussain A*, Kvβle G, Φdland M. Bull World Health Organ 1995;73:469-76.

H

YPOVITAMINOSE A IS THE MOST COMMON CAUSE

of irreversible blindness in children. Although most field assessments of childhood night blindness have relied on parents' reports, the validity of this method has been questioned. Among a crosssectional survey of 5,420 children in northern Ban­ gladesh, 124 were reported by their parents to have night blindness. One hundred five of these children, along with control subjects matched for age, sex, and neighborhood, underwent measurement of serum vitamin A level and an ophthalmologic examination

V0L.121, N o . 2

HE DENSITY OF MACULAR PIGMENT (XANTHOPHYLL)

varies widely among individuals, but the reasons for these differences have not been determined. Because macular pigment is thought to protect the retina and the retinal pigment epithelium from the toxic effects of short-wavelength light, decreased levels of xanthophyll may be related to diseases of the central retina, such as age-related maculopathy, and to the short-wavelength sensitivity loss of normal aging. In this study of ten pairs of monozygotic twins, the authors determined the density of macular pig­ ment by psychophysical means, the concentration of serum carotenoids by liquid chromatography, and dietary patterns with a questionnaire. Statistically significant differences in macular pigment optical density were found for five of the ten twin pairs; the differences were moderately related to differences in the intake of dietary fat, iron, linoleic and oleic acid, fiber, and total calories. There was no significant relationship between macular pigment density and carotenoids in the serum and diet. The authors concluded that macular pigment density is not deter­ mined entirely by genetic predisposition, but rather that xanthophyll deposition is influenced by several

ABSTRACTS

233

factors, some of which may be modified for protective purposes.—George B. Bartley

• The value of brain imaging in children with headaches. Maytal J*, Bienkowski RS, Patel M, Eviatar L. Pediatrics 1995;96:413-6.

*Schepens Eye Research Institute, 20 Staniford St, Boston, MA 02114.

T

• Intravitreous and plasma concentrations of ganciclovir and foscarnet after intravenous therapy in patients with AIDS and cytomegalovirus retinitis. Arevalo JF, Gonzalez C, Capparelli EV, Kirsch LS, Garcia RF, Quiceno JI, Connor JD, Gambertoglio J, Bergeron-Lynn G, Freeman WR*. J Infect Dis 1995;172:951-6.

T

HE INTRAVITREOUS AND

PLASMA CONCENTRA-

tions of ganciclovir and foscarnet after intrave­ nous administration were determined in patients with the acquired immune deficiency syndrome, cytomega­ lovirus retinitis, and retinal detachment. Undiluted vitreous samples were obtained from 60 eyes (52 patients) during pars plana vitrectomy. Thirty three plasma samples (from 33 eyes in 27 of the 52 patients) were obtained simultaneously. High-pressure liquid chromatography demonstrated that the mean vitreous ganciclovir concentration in 24 patients on induction therapy (10 mg/kg body weight/day) was 4.7 ± 1 . 5 μΜ, compared with 3.3 ± 1.8 μΜ in 30 patients on maintenance therapy (5 mg/kg body weight/day; P = .005). The simultaneous plasma ganciclovir concen­ trations were less than the vitreous concentrations in 78% of the patients. The average vitreous foscarnet concentrations were 189 ± 177 μΜ and 163 ± 167 μΜ in five patients receiving induction therapy (180 mg/kg body weight/day) and four patients on mainte­ nance therapy (120 mg/kg body weight/day), respec­ tively (P > .20). The mean foscarnet vitreous:plasma concentration ratio was 1.43. The authors concluded that the drugs and dosages used in this study result in borderline or progressively subtherapeutic concentra­ tions for the treatment of cytomegalovirus retinitis.— George B. Bartley *Department of Ophthalmology, University of California, San Diego, Shiley Eye Center 0946, La Jolla, CA 92093.

234

HE AUTHORS REVIEWED THE MEDICAL RECORDS OF

133 patients age three to 18 years who were referred during a two-year interval to a pediatrie neurology clinic for evaluation of headaches. The majority of patients (n = 69; 52%) had some variant of a vascular migrainous headache. Twenty-eight children (21%) had chronic tension headaches, whereas the headache was not classifiable in 25 patients (19%). Seventy-eight patients (59%) under­ went magnetic resonance imaging, computed tomog­ raphy, or both. In most instances, brain imaging studies were performed in patients with atypical headache pattern, the presence of neurologic abnor­ malities during the headache, systemic symptoms such as weight loss or fatigue, or because of a concern about a brain tumor. Cerebral abnormalities were detected in only four patients; none of the abnormali­ ties was related to the headaches and none was treatable. The authors estimated that the maximal frequency at which cerebral abnormalities might appear in a similar population of patients is 3.8% and concluded that "brain imaging studies have very limited value in evaluating headaches in pediatrie patients without clinical evidence of an underlying structural lesion."—George B. Bartley 'Division of Pediatrie Neurology, Schneider Children's Hospital, Long Island Jewish Medical Center, New Hyde Park, NY 11040.

• Prevalence of intracranial lesions in children initially diagnosed with disconjugate nystagmus (spasmus nutans). Arnoldi KA, Tychsen L*. J Pediatr Ophthalmol Strabismus 1995;32:296-301.

B

ECAUSE A SMALL NUMBER OF CHILDREN WITH SPAS-

mus nutans (disconjugate nystagmus, torticollis, and head titubation) harbor an intracranial glioma, some authors recommend that patients who exhibit this sign undergo neuroimaging studies. In this study, the authors reviewed the medical records of 67

AMERICAN JOURNAL OF OPHTHALMOLOGY

FEBRUARY 1996