Asymmetrical accommodation in hyperopic anisometropic amblyopia

Abstract

Background/aims: To investigate the presence of asymmetrical accommodation in hyperopic anisometropic amblyopia.

Methods: Accommodation in each eye and binocular vergence were measured simultaneously using a PlusoptiX SO4 photorefractor in 26 children aged 4-8 years with hyperopic anisometropic amblyopia and 13 controls (group age-matched) while they viewed a detailed target moving in depth.

Results: Without spectacles, only 5 (19%) anisometropes demonstrated symmetrical accommodation (within the 95% CI of the mean gain of the sound eye of the anisometropic group), whereas 21 (81%) demonstrated asymmetrical accommodation. Of those, 15 (58%) showed aniso-accommodation and 6 (23%) demonstrated 'anti-accommodation' (greater accommodation for distance than for near). In those with anti-accommodation, the response gain in the sound eye was (0.93±0.20) while that of the amblyopic eye showed a negative accommodation gain of (-0.44±0.23). Anti-accommodation resolved with spectacles. Vergence gains were typical in those with symmetrical and asymmetrical accommodation.

Conclusion: The majority of hyperopic anisometropic amblyopes demonstrated non-consensual asymmetrical accommodation. Approximately one in four demonstrated anti-accommodation.

Keywords: Vision; child health (paediatrics); optics and Refraction.

Figure 1

Infant vision laboratory. (A) Motorised beam. (B) Target monitor. (C) Upper concave mirror. (D) Lower concave mirror. (E) Hot mirror. (F) PlusoptiX SO4 PowerRef II. (G) Headrest.

Figure 2

The accommodation response in the sound/left eye and amblyopic/right eye for each individual in the control and anisometropic group. The black lines denote the mean response.

Figure 3

An example of a participant in each of the four groups (control, SYM, ANISO and ANTI) to demonstrate the types of accommodation response with and without spectacles. The black lines represent demand of the target moving from a demand of 3 D, to 0.5 D, 4 D, 1 D and then 2 D. The blue lines represent convergence. The green line represents the accommodation response in the sound eye of the anisometropes (left eye of control participant). The purple line represents the accommodation response in the amblyopic eye of the anisometropes (right eye of control participant). The separation between the green and purple line denotes anisometropia. In the SYM group, the difference in accommodation response between the sound eye and amblyopic eye was similar across target distances. The ANISO group had a larger accommodative difference between the eyes at near than in the distance as the amblyopic eye accommodated less. In the ANTI group, the sound eye accommodated appropriately but the amblyopic eye relaxed for near fixation. ANISO, aniso-accommodation; ANTI, anti-accommodation; SYM, symmetrical accommodation.

Figure 4

Vergence and accommodation responses in the control group and each anisometropic group without glasses for demands of 0.5 D, 1 D, 2 D and 3 D. In all the graphs, the grey line represents an ideal response and the vergence response is in blue. In the control group, the green line and purple line represent the accommodation response of the right eye and the left eye, respectively. In the anisometropic groups, the green and purple lines represent the accommodation response in the sound eye and amblyopic eye respectively. Error bars denote ±95% CI. ANISO, aniso-accommodation; ANTI, anti-accommodation; SYM, symmetrical accommodation.