Purchase this article with an account.
D. R. Neal, C. D. Baer, H. Vogelsang; The Effect of Aberrations on Accommodative Response. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5629.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Obtaining a reliable objective measurement of accommodation is increasingly important for evaluation of new presbyopia treatment modalities. However, often there is a discrepancy between measured changes in ocular power and the clinical result. There are cases where the subject reports excellent clinical result, and is obviously reading easily, yet does not show a significant change in the measured accommodation. It is important to be able to understand and quantify this phenomenon.
We developed a method for providing a fully binocular view of an external target that is very natural in appearance to the subject. Targets can be presented as far/near/far or near/far/near and the change in accommodation recorded dynamically. Higher order terms are also measured. Comparing the refractions including higher orders with those computed using only lower orders provides information that is useful in understanding the anomalous results.
The full binocular target is much more intuitive than other means for accommodation measurements. The objective measurements measure only the optical component of accommodation, and are hence generally show less accommodation than subjective methods. For a young subject (21 y.o.), the accommodative response is low when only the 2nd order terms are considered (6.5 D in Figure 1). However, when the higher order terms were included, the accommodative response was much greater (8.5 D in Figure 2). This is a typical result for subjects with larger pupil sizes.
The accommodative process not only changes the lower order terms, but also affects the higher orders, especially spherical aberration. If the spherical aberration is not taken into account, then an inaccurate estimate of the accommodative range will be derived. In cases with higher total aberration, there may be less stimulus for the accommodative response, such that the subject may still have good clinical accommodation, but does not show much objective response.
This PDF is available to Subscribers Only