Macular thickness, as measured by OCT, is one of the key outcome measures used in most clinical trials, especially those on diabetic macular edema and AMD. Because Stratus TD-OCT was the most common commercially available OCT instrument in the past decade, most trials are designed based on Stratus OCT.
A percentile (or a centile) is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations fall. For example, the 20th percentile is the value (or score) below which 20% of the observations may be found. The term percentile and the related term percentile rank are often used in the reporting of scores from norm-referenced tests.
A percentile is the score at or below which a specified percentage of scores in a distribution falls. STATISTICA 6 (Statsoft Inc.) The percentile (this term was first used by Galton, 1885a) of a distribution of values is a number xp such. that a percentage p of the population values are less than or equal to xp.