Biomedical subjects

Gerardo Villarreal

Publications and source records attributed to Gerardo Villarreal.

6 recordsLinked to original sources

PubMed2005

Normal visual acuity in 17--18 year olds.

PURPOSE: The aim of this work was to establish visual acuity norms in 17-18-year-olds. METHODS: In a previous, population-based study carried out in 1998, a total of 1046 12-13-year-old children were examined with a full eye examination. In 2003, 25% (n=262) of these children were randomly selected and invited to a re-examination; 147 subjects agreed to participate and 116 attended. The examined group did not significantly differ from the original sample in terms of the prevalence of ocular and visual disorders. Best corrected monocular visual acuity (VA) was assessed with the revised 2000 ETDRS logMAR chart. RESULTS: Mean best corrected VA was -0.10 logMAR across the examined group. There was no significant difference between right and left eyes. By excluding nine subjects who had significant ametropia and/or ocular or visual pathology, mean VA increased to -0.12 logMAR (SD 0.07). The mean interocular difference in VA among normal subjects was 0.04 logMAR. CONCLUSIONS: Visual acuity in teenagers is significantly better than 0.0 logMAR and the interocular difference is low in healthy eyes.

Adolescent↗

PubMed2004

Reduced area of the corpus callosum in posttraumatic stress disorder.

Magnetic resonance imaging (MRI) studies have revealed decreases in the mid-sagittal area of the corpus callosum (CC) in pediatric posttraumatic stress disorder (PTSD), but at present no data are available in adult PTSD patients. We have previously reported decreased whole-brain white matter (WM) volume in adults with PTSD and now report corpus callosum area from the same sample. MRI was used to obtain whole-brain images in 12 adult patients with PTSD and 10 matched controls. Total parenchyma (white matter plus gray matter [GM]) volume, mid-sagittal area of the CC and seven sub-regions of this structure were calculated. In PTSD patients, the total CC area, absolute and normalized to total brain parenchyma, was smaller compared with control values. Several absolute and normalized CC sub-regions were also smaller in PTSD patients: genu (region 2), mid-body (region 5) and isthmus (region 6). There was also a trend for the anterior mid-body (area 4) to be smaller in PTSD patients. No differences were found in the rostrum (region 1), rostral body (region 3) or splenium (region 7). Adult patients with PTSD had decreased CC area after correcting for total brain tissue, indicating that these differences are not attributable to generalized white matter atrophy. These findings are similar to previous results in children with PTSD and suggest specific changes in the CC.

Adult↗

PubMed2003

Visual acuity, amblyopia, and ocular pathology in 12- to 13-year-old children in Northern Mexico.

PURPOSE: The aim of this study was to establish visual acuity (VA) and the prevalence of amblyopia and other ocular disorders in a population of 12- to 13-year-old children in Mexico who have not been vision screened. METHODS: A total of 1,035 12- to 13-year-old children were examined in a field study. The examination included VA, stereopsis, cover testing, refractive retinoscopy, and examination of the red reflex and posterior pole. In cases with unexplained subnormal VA, visually evoked potential/visually evoked response was also performed. RESULTS: A >or=20/20 in at least one eye was found in 93% of the subjects. Bilateral VA <or=20/40 was found in 0.3% of cases. None of the subjects had bilateral VA <20/60. Amblyopia (<or=20/40) was found in 26 subjects (2.5%). In 10 cases, the cause of subnormal VA was unexplained. Ocular albinism was found in 3 cases, whereas strabismus was found in 24 subjects (2.3%). There were very few ocular opacities or posterior pole abnormalities. CONCLUSIONS: The visual status in the Mexican 12- to 13-year-old children tested was good. The prevalence of amblyopia was similar to that in other unscreened populations.

Adolescent↗

PubMed2002

Reduced hippocampal volume and total white matter volume in posttraumatic stress disorder.

BACKGROUND: Reduced hippocampal volumes in posttraumatic stress disorder (PTSD) patients are thought to reflect specific changes of this structure. Previous magnetic resonance imaging (MRI) studies have not consistently examined indices of overall brain atrophy, therefore it cannot be completely ruled out that hippocampal changes are explained by whole-brain atrophy. The purpose of this study was to assess hippocampal and whole-brain volume in civilian PTSD. METHODS: Twelve subjects with PTSD and 10 control subjects underwent brain MRI. Hippocampal volumes were visually quantified using a computerized volumetric program. Whole-brain volumes were obtained with automated k-means-based segmentation. RESULTS: No differences were found in intracranial volumes (ICV). Subjects with PTSD had higher cerebrospinal fluid (CSF)/ICV ratios and lower white matter/ICV ratios, consistent with generalized white matter (WM) atrophy. The effect of age on CSF/ICV was more pronounced in the PTSD group. Subjects with PTSD had smaller absolute and normalized bilateral hippocampal volumes. These differences persisted after adjusting for lifetime weeks of alcohol intoxication. Posttraumatic stress disorder and depression scores correlated negatively with left hippocampal volume, but PTSD scores were a better predictor of hippocampal volumes. CONCLUSIONS: Our results replicate previous findings of reduced hippocampal volume in PTSD but also suggest independent, generalized, white matter atrophy.

Adult↗

PubMed2002

Screening for amblyopia and strabismus with the Lang II stereo card.

PURPOSE: To evaluate the effectiveness of the Lang II stereo card as a screening test for amblyopia and/or strabismus. METHODS: A total of 1046 children aged 12-13 years were examined in a field study in the Göteborg area, Sweden. In addition to the Lang II stereo card, the examination included visual acuity, cover testing, cycloplegic refraction, and inspection of the optical media and posterior pole. RESULTS: If every incorrect subject response was considered a reason for referral, the Lang II test would have correctly identified 82% (23 subjects) of the 28 children with manifest strabismus and 38% (11 subjects) of the 29 children with amblyopia. The test failed to refer 45% (21 subjects). Of all subjects referred, 44 (63%) were found to be ophthalmologically normal. CONCLUSIONS: The Lang II stereo card is neither a reliable nor an efficient method of screening for amblyopia and/or strabismus.

Adolescent↗

PubMed2002

Proton magnetic resonance spectroscopy of the hippocampus and occipital white matter in PTSD: preliminary results.

OBJECTIVE: Previous proton magnetic resonance spectroscopy (1H-MRS) studies in posttraumatic stress disorder (PTSD) report decreased hippocampal N-acetylaspartate (NAA), an indicator of neuronal integrity. However, other areas of the brain need to be explored. The objective of this study was to investigate the specificity of hippocampal NAA concentration changes in PTSD by also examining a control region, the occipital white matter (OWM). METHODS: Eight patients with PTSD and 5 control subjects underwent single-voxel 1H-MRS of the hippocampi and bilateral OWM. Absolute neurometabolite concentrations were determined. PRELIMINARY RESULTS: Trends toward reduced left hippocampal NAA and creatine (Cre) were found in the PTSD group. PTSD subjects also had reduced bilateral OWM Cre. CONCLUSIONS: The preliminary results of our study in civilians with PTSD replicate previous MRS studies and are consistent with decreased hippocampal neuronal integrity without effects in the OWM. Replication of our findings is needed.

Adult↗