Abstract
Purpose: :
To introduce a standardised methodology and grading system for contrast sensitivity measurement in children with optic pathway/hypothalamic glioma in The Cooperative Multicentre Study for Children and Adolescents with Low Grade Glioma.
Methods: :
A literature search was carried out regarding available contrast sensitivity tests. Particular attention was paid to symbol based tests that were rapid and easy to understand, repeatable, those that had published normal data and tests deemed useful in young children with poor vision. A commercially available contrast sensitivity test was selected based on this information. The test was carried out according to the commercially available instructions and piloted in a cross section of 46 patients (92 eyes) (age range 3–19 years; VA range 0.2 to 1.3 logMar) including 17 patients with intracranial pathology. An original grading system was devised based on these results. The contrast sensitivity results of all the normal eyes in the pilot study were recorded using the Lea contrast sensitivity chart (Good–lite Company, USA). Each subject’s contrast sensitivity threshold was represented by a line of varying gradient (determined by the VA and number of characters read). A mean gradient was taken. This gradient was used to determine the range of symbols a child with normal contrast sensitivity would be expected to see, at a particular level of VA. Based on the number of symbols seen and the patient’s visual acuity, a grading system was devised.
Results: :
8 patients (16 eyes) (VA range –0.1 to 0.45 logMar) underwent testing on 2 or more separate occasions. 5 patients had central nervous system tumours. 3 patients had stable vision impairing pathology. The Lea contrast sensitivity test and grading system had good repeatability and usability in the paediatric population, even in children with poor vision.
Conclusions: :
We have developed a protocol for assessment and grading of contrast sensitivity for subjects enrolled in the Cooperative Multicentre Study for Children and Adolescents with Low Grade Glioma. It should be noted that this grading system requires further validation and the usefulness of this system will be tested as data is submitted from participating centres. We expect to modify this grading system as indicated.
Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • clinical research methodology • contrast sensitivity