Ying-Sheng Hu, Ph.D.

Associate Professor

Statistical Research

College of Optometry

University of Houston

 

 

 

                             Learning Patterns of Amblyopic Patients and Change Analysis

 

 

Amblyopia is a spatial vision disorder that causes patients to suffer significant reduction in visual acuity and positional acuity. Unfortunately, this serious condition cannot be corrected with ordinary optical system, and it is irreversible if treated late.

 

In searching for effective remedies, optometry clinicians and visual scientists have developed a special vision-training program for patients. According to the neural plasticity and cognitive theory, one hopes that intensive visual practicing will allow patients to accumulate their experience incrementally, until the positive experience they have collected reaches a certain threshold where perceptual learning should occur. This slow-sudden learning-phase transaction may repeat until training has stopped.

 

More than 20 patients were accepted into the training program during 1996-1997, and most patients experienced some visual improvements after training. To assess the training effect on patients’ visual function (particularly in vernier acuity), the following questions should be answered: (1) Is perceptual learning really obtainable through training? (2) If a patient did learn, when did the learning take place? and (3) What would the learning curve look like? 

 

Statistical approach. (1) The definition of perceptual learning: The instant at which learning occurs is transactional, the mean vernier acuity prior to the moment changes to a different level of vernier acuity. (2) We use CuSum method to locate the level change point in a series of observations on vernier acuities. (3) We use an optimal approximation approach to determine single or multiple level change points. (4) Segmented regression.

 

Discussion. (1) The equivalence between the CuSum and optimal approximation approaches. (2) Assessment of the probability of a change.