Modelling adaptation effects in vergence and accommodation after exposure to a simulated virtual reality stimulus.

Natural viewing conditions place equal demands on the vergence and accommodation systems. The two responses are co-ordinated via the interactive components which couple the two systems: accommodative vergence and vergence accommodation. The crosslink components are usually quantified by the AC/A and CA/C ratios. Whether these ratios are stable entities, genetically determined, or modifiable by experience has been the subject of some debate. A 'Virtual Reality' stimulus was used to place unequal demands on the vergence and accommodation systems. Pre-task and post-task measures of AC/A and CA/C were objectively determined. The changes in the post-task measures are discussed with reference to a dual interactive model of vergence and accommodation. Model simulations suggest that adaptation of the vergence and accommodative controllers (tonic adaptation) may also play a part by altering the open loop bias. The results therefore support the idea that vergence accommodation and accommodative vergence are capable of adaptation.