Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 8647987

The lunula.

P R Cohen
View original source ↗Export metadata ↓

Abstract

The lunula is the visible portion of the distal nail matrix that extends beyond the proximal nailfold. It is white, half-moon-shaped, appears by week 14 of gestation, has unique histologic features. The lunula has a primary structural role in defining the free edge of the distal nail plate. Lunular anomalies include changes in form and structure and in color. Lunular dysmorphologic features can be characterized by macrolunula, microlunula or anolunula, and nonconvex lunula. Lunular dyschromias can be confluent or spotted or can be characterized by longitudinal colored bands that traverse the lunula. Alterations in the morphologic features or color (or both) of the lunula can be an indication of either a cutaneous or a systemic disorder.

Explore related subjects

ColorDiseaseHumansNail DiseasesNailsNails, MalformedSkin DiseasesJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P R Cohen. 1996. The lunula.. https://doi.org/10.1016/s0190-9622(96)90269-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1999

Simple and powerful visual stimulus generator.

We describe a cheap, simple, portable and efficient approach to visual stimulation for neurophysiology which does not need any special hardware equipment. The method based on an animation technique uses the FLI autodesk animator format. This form of the animation is replayed by a special program ('player') providing synchronisation pulses toward recording system via parallel port. The 'player is running on an IBM compatible personal computer under MS-DOS operation system and stimulus is displayed on a VGA computer monitor. Various stimuli created with this technique for visual evoked potentials (VEPs) are presented.

Color↗
PubMed1999

Effect of yellow filters on pupil size.

The purpose of this study was to investigate the size of the pupil while viewing through yellow and neutral density (ND) filters. Previous studies have shown that the pupil of the human eye is relatively more sensitive to short wavelengths than indicated by the photopic luminosity curve. We first measured the consensual horizontal pupil diameter of 11 observers as a function of luminance (0.144 to 18,150 cd/m2) to establish the luminance-response function for each observer. We then measured the pupil diameter while the observer viewed through a Corning Photochromic Filter (CPF) 550 lens and two ND filters (ND 0.5 and 1.0). The pupil diameters obtained with each filter were compared to the diameters at an equivalent luminance based upon each observer's luminance-response function. Our results show that the pupil diameter is larger with the yellow lens than when viewing a broad spectrum white field at an equivalent luminance. We speculate that our results may explain some, but not all, of the well-known subjective brightness enhancement that occurs when viewing through yellow filters.

Color↗