Brian E. Nichols

New normative data for the Farnsworth-Munsell 100-hue test

Color vision testing is an important part of the assessment of both retinal and optic nerve function. The Farnsworth-Munsell (FM) 100-hue test is widely accepted as a sensitive tool for detecting subtle deficits in hue discrimination. Originally designed in 1943 by Dean Farnsworth to measure color discrimination and to detect congenital dyschromatopsias, the test has also been used to assess a wide variety of acquired dyschromatopsias. The test requires the arrangement of 85 colored chips in consecutive color order. We have made two fundamental changes in the FM 100-hue which improve the test’s specificity and sensitivity for detecting color vision deficits. First, two chips were removed from the original test which results in a more even error score distribution for normals across the entire set of hues. Second, the addition of a white-to-black reliability test allows non-color-vision-related variables such as motivation and understanding to be assessed. In this paper, we present normative data for the revised 83-chip color vision test and the reliability test. We also outline our procedure for administering the FM 100-hue including a description of the illuminant C light source and our computerized barcode-based scoring system.

27 – Identification of Rhodopsin Gene Mutations Using GC-Clamped Denaturing Gradient Gel Electrophoresis

Publisher Summary Several techniques have been developed that make it possible to detect single base changes in DNA. These techniques include allele-specific oligonucleotide (ASO) hybridization, RNase cleavage, chemical cleavage, single-stranded conformation polymorphism (SSCP) analysis, heteroduplex analysis, and denaturing gradient gel electrophoresis (DGGE). Some of these techniques are not suitable for screening DNA for mutations. GC-clamped DGGE makes it possible to detect nearly 100% of single-base changes in DNA fragments of about 500 bp in length. This chapter describes the use of GC-clamped DGGE for the detection of rhodopsin coding sequence mutations. These methods are also applicable to the study of other candidate genes that may be involved in human retinal degeneration. DGGE can physically separate fragments differing by a single-base substitution on the basis of a difference in melting temperature (T m ) of the two molecules. A single-base change alters the T m of a given DNA melting domain by up to 2°C. Melting of a domain changes the conformation of the DNA molecule and, thus, affects its rate of migration through a polyacrylamide gel matrix.