Axial Length, Accommodation & Myopia Progression

Here's a new study that I find very interesting. It possibly links myopia progression with reading. We have long suspected that heavy near-work could & probably does increase nearsightedness over time, but now here's a postulated theory on the exact mechanism of that myopia progression. It doesn't immediately change how we're going to go about treating myopia progression: I still don't believe "eye exercises" will reverse myopia, as is claimed by many (especially those selling books on the subject). I am still going to treat/prevent myopia progression in children by recommending ortho-k for its "negative image shell" mechanism of action that has been proven to work. After all, can I realistically tell a parent & child "sorry, your child's myopia progression is caused by too much reading, so stop"? That's not feasible. Plus, how much reading is "too much"? Just like everything, its probably different for every child, and children who are already myopic are probably more likely to get more nearsighted with less reading vs non-myopic children. Atropine can & does stop accommodation...maybe now we know how that method of treatment could prevent associated axial lengthening? All very interesting, however I don't foresee me recommending a lot of atropine for children: too many side effects & not enough evidence that it works. Plus the compliance is really low. A drop that burns like fire AND ALSO makes your vision terrible...hmmmm...yeah kids don't like that a lot.

So basically I doubt I'll be doing anything too differently, but I still think this is a fascinating finding.

Axial Length Changes During Accommodation in Myopes and Emmetropes

A total of 40 young adult subjects had ocular biometry measured using a noncontact optical biometer (Lenstar LS 900) based on the principle of optical low coherence reflectometry under three different accommodation demands (0 D, 3 D, and 6 D) to investigate the influence of accommodation on axial length (AXL) and a comprehensive range of ocular biometric parameters in populations of young adult myopic and emmetropic subjects. Subjects were classified as emmetropes (n = 19) or myopes (n = 21) based on their spherical equivalent refraction (mean emmetropic refraction –0.05 ± 0.27 D sphere and mean myopic refraction –1.82 ± 0.84 D sphere).

AXL changed significantly with accommodation, with a mean increase of 11.9 ± 12.3 µm and 24.1 ± 22.7 µm for the 3 D and 6 D accommodation stimuli, respectively. A significant axial elongation associated with accommodation was still evident even after correction of the AXL data for potential error because of lens thickness change. The mean “corrected” increase in AXL was 5.2 ± 11.2 µm and 7.4 ± 18.9 µm for the 3 D and 6 D stimuli, respectively.

There was no significant difference between the myopic and emmetropic populations in terms of the magnitude of change in AXL with accommodation, regardless of whether the data were corrected or not. A number of other ocular biometric parameters, such as anterior chamber depth, lens thickness, and vitreous chamber depth also exhibited significant change with accommodation. The myopic and emmetropic populations also exhibited no significant difference in the magnitude of change in these parameters with accommodation.

The eye undergoes a significant axial elongation associated with a brief period of accommodation, and the magnitude of this change in eye length increases for larger accommodation demands, however, there is no significant difference in the magnitude of eye elongation in myopic and emmetropic subjects.

SOURCE: Read SA, Collins MJ, Woodman EC, Cheong SH. Axial Length Changes During Accommodation in Myopes and Emmetropes. Optom Vis Sci. 2010 Jun 17

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  1. To my brother,

    I will also use an add with someone with eso posture in distance, there is evidence to show that this reduction in accommadative demand slow the progress, do you have any numbers on axial myopes and the use of bifocals and refractive myopes and the same?

    Christian, father, and optometrist, too!


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