Abstract
Purpose :
Young children with hyperopia must accommodate more than a typical adult to achieve focused retinal images and promote typical visual development. In coordinating the coupling between accommodation and vergence they could underaccommodate to the target to maintain alignment, accommodate and converge relatively accurately, or accommodate accurately but over-converge leading to esophoria (with good fusional divergence) or esotropia. This study looked at the accommodation, vergence and fusional abilities of young uncorrected hyperopes.
Methods :
A PlusOptix PowerRef3 (Simultaneous Purkinje image eye tracking and eccentric photorefraction) recorded the alignment and refractive state of 20 hyperopic children (0-10 yrs; Sph. Equiv. refractive error: +2.25 to +6.50D) and 49 control participants (0-10 yrs; Sph. Equiv. refractive error: -0.25 D to +2.00 D) while they viewed cartoon movies at 33cm. Accommodative performance and vergence position were determined in monocular and binocular conditions and prism bars were introduced to drive fusional vergence. Fusional limits were defined as the last prism for which alignment was maintained and, in each case, the role of accommodation was assessed simultaneously.
Results :
The median accommodative error was 1.6D lag for hyperopes (range: 0.50D lead to 4.3D lag) and 1.5D lag for the controls (range: 0.80D lead to 3.5D lag) at 33 cm. The median phoria was 1pd exophoria for hyperopes (range: 2pd esophoria to 5pd exophoria) and 3pd exophoria for controls (range: 9pd esophoria to 8pd exophoria). The median fusional vergence ranges in the hyperopic group were 16 pd of divergence (range: 4-32 pd) and 24 pd of convergence (range: 12-40pd) which were similar to the control group (16 pd of divergence, range: 4-24pd & 20pd of convergence, range: 20-40pd). In the hyperopic participants, the median relaxation of accommodation was 1.2D during divergence with a median increase of 1.2D during convergence. The median changes in the control group were 1.7D relaxation of accommodation during divergence and median increase of 1.2D during convergence. These values were less than predicted by a typical AC/A ratio.
Conclusions :
Most of the hyperopes had a small exophoria and a typical accommodative lag. Their fusional range and ability to manipulate accommodation to achieve fusion were also clinically similar to the control group. They seemed able to accommodate typically and maintain alignment for this task.
This is a 2021 ARVO Annual Meeting abstract.