Abstract
Abstract: :
Purpose: The interpretation of altered VER can be of great diagnostic value but it is very important to be aware of limitations of these technique which can result in misinterpretations of the recordings, such that they are similar to disease related changes. The aim of our study was to study the inter-subject variability of the Latency and Amplitudes in normal emmetropic population. Methods: We studied Transient Pattern Reversal VER in 30 emmetropic eyes with 6 different check sizes. (3.2’’, 7.5’’, 15", 30, 60", 120’’). The Latency and amplitude was studied. The recordings were done with Amplaid MK-15 VER machine at a distance of 1 metre from TV screen projecting pattern reversal checkerboard patterns of different sizes, subtending different angles. Results: The check sizes of 15’’ and 30’’ gave quite consistent results with least amount of standard deviation. The larger or smaller check sizes tend to give increase in mean latency and decrease in mean amplitude values with large standard deviations. Conclusion: There is a wide variation in results obtained with the Latency and Amplitude responses of VER waveforms in normal emmetropic patients, sometimes mimicking disease states. Thus it is very essential to keep this fact in mind while interpreting VER results in the absence of a known ocular pathology. These values are more variable with larger or smaller check sizes.
Keywords: pattern vision • electrophysiology: clinical • vision and action