Estimates of genetic correlations among clinical measures of the eye.

In a quantitative genetic investigation of seven clinical tests, five pairs were significantly correlated: (1) cover test measures and corneal power, (2) corneal power and divergence recovery points, (3) convergence and divergence recovery points, (4) divergence break and recovery points, and (5) convergence break and recovery points. Common genes may account entirely for the gene influence on cover test measure; thus, parents who are above the population mean for corneal power will have offspring with a tendency toward an exodeviation (phoria). The two convergence amplitudes may depend on the same gene differences, whereas the two divergence amplitudes only partly reflect a common function, suggesting that they may be indexing somewhat different underlying physiologic mechanisms.