The effect of acute ingestion of alcohol at 0.05% and 0.10% blood respiratory alcohol concentration on heterophoria

Abstract

Introduction: Alcohol ingestion has a significant effect on speech, vision and coordination. The legal limit for driving under the influence in South Africa is 0.05% blood alcohol concentration (BAC), whilst intoxication is considered to occur at 0.10% BAC. The aim of our study was to investigate the effect of acute alcohol ingestion of 0.05% and 0.10% blood respiratory alcohol concentration (BrAC) on heterophoria.

Methodology: The effect of alcohol ingestion on the oculomotor systems of 31 subjects was the basis of this quasi-experimental quantitative study. Various parameters were compared before and after the ingestion of 10% alc red wine. The Alcoscan ALP-1 breathalyser test was used as an indicator of BrAC. Heterophoric, fusional vergence and near point of convergence (NPC) measurements were measured during an experimental phase at 0.05% and 0.10% BrAC levels and a control phase at a 0% BrAC.

Results: Mean changes in heterophoria for distance showed an increase of 1.13∆ ± 1.34∆ and 2.19∆ ± 1.70∆ towards esophoria at a BrAC of 0.05% and 0.10% respectively. At near, the results showed a mean increase of 0.84∆ ± 1.75∆ and 0.97∆ ± 1.70∆ towards exophoria at a BrAC of 0.05% and 0.10% respectively. There was a further mean decrease in the positive and negative fusional vergences as well as receded NPC break and recovery measurements at 0.05% and 0.10% BAC.

Conclusion: It can be concluded that a BrAC of 0.05% has a minimal effect on heterophoria. However, at a BrAC of 0.1% there is a significant effect on heterophoria, fusional vergences and the NPC. This may or may not be clinically significant.