Prevention of myopia by partial correction of hyperopia: a twins study

Abstract

Purpose

To confirm the prediction of emmetropization feedback theory that myopia can be prevented by correcting the hyperopia of a child at risk of becoming myopic.

Methods

We conducted such myopia prevention treatment with twins at risk. Their hyperopia was partially corrected by one half at age 7 and in subsequent years until age 16.

Results

Hyperopia progressively decreased in all eyes as expected. None of the twins developed myopia. The spherical equivalent refractions of the followed eyes were +1 and +1.25 D at age 16. Feedback theory accurately predicted these values.

Conclusions

The treatment of the twins with partial correction of their hyperopia was successful. Prevention of myopia with this technique is relatively simple and powerful. The use of this myopia prevention treatment has no adverse effects. This prevention treatment is indicated in children with a hyperopic reserve at risk of developing myopia.

Appendix

The feedback system output to an input lens of R diopters in the t-domain is the inverse Laplace transform of the output in the s-domain, which in turn is the transfer function times the step input in the s-domain:

$$\begin{aligned} o(t) & = L^{ - 1} \{ O(s)\} = L^{ - 1} \{ I(s)F(s)\} = \, L^{ - 1} \{ L[i(t)]F(s)\} \\ & = L^{ - 1} \{ R/[s(1 + ks)]\} = R[1{-}\exp ({-}t/k)] \\ \end{aligned}$$

(1)

where t is time, k is the time constant, I(s) is the step input in the s-domain, i(t) is the step input R in the time domain, O(s) is the output in the s-domain, o(t) is the output in the t-domain, L is the Laplace transform, and L ⁻¹ is the inverse Laplace transform.