Purchase this article with an account.
S. Diether, F. Schaeffel, C. Fritsch, A.U. Trendelenburg, R. Payor, G. Lambrou; Contralateral inhibition of lens induced myopia in the chick by ipsilateral intravitreal atropine application: can a simple dilution model account for the effect? . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1238.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose:We have tested whether ipsilateral intravitreal atropine application can inhibit myopia development in the fellow eye and whether this effect can be explained by systemic dilution of atropine. Methods: Monocular intravitreal injections of atropine solution (12.5 µl, 6 or 3 different concentrations) were performed daily for a period of 4 successive days. The contralateral eye received saline. After the first injection, the 7–day–old chickens were fitted with –7D lenses, either over the atropine injected eye only (exp 1) or over both eyes (exp 2). After 4 days, refractive error (RE) was measured by infrared photoretinoscopy and axial length (AL) was measured by A–scan ultrasonography. Results: With monocular lens treatment atropine suppressed myopia in a dose–dependent way (interocular difference; exp 1: RE±SEM: 0 µg (saline): –6.51±0.71D, 0.25 µg: –5.92±0.47D, 2.5 µg: –4.10±1.00D, 25 µg: –3.63±0.53D*, 250 µg: –2.2±0.81D***, 750µg: +0.02±0.79D***, 2500µg: +1.32±0.41D***) (*p<0.05, **p<0.01, ***p<0.001 compared to 0 µg, Dunnett’s Method). With bilateral lens treatment (exp 2) it was found that atropine also inhibited myopia in the saline–injected eye; however, higher doses were needed for such contralateral effects (ipsi– vs. contralateral RE±SEM: 0 µg: –1.59±0.88D vs. –1.27±0.67D, 25 µg: –0.11±1.18D vs. –2.77±0.87D, 250 µg: +1.85±1.13D* vs. –0.77±1.05D, 2500 µg: +7.47±0.48D*** vs. +4.43±1.05D***). Axial length also decreased in both eyes (ipsi– vs. contralateral AL±SEM: 0 µg: 8.71±0.06mm vs. 8.74±0.05mm, 25 µg: 8.52±0.09mm vs. 8.59±0.09mm, 250 µg: 8.48±0.06mm* vs. 8.57±0.08mm, 2500 µg: 8.36±0.04mm** vs. 8.52±0.05mm). The dose for 50% suppression of myopia in the atropine injected eye was 80 µg. For 50% suppression of myopia in the fellow eye, an about 6.5 times higher ipsilateral dose was necessary which is less than the vitreous volume to blood volume ratio (about 1:23). Conclusions: The contralateral effect of atropine appears too large to be explained by a simple dilution model, since atropine will not only be diluted but also be metabolized and bound to proteins in the body. Another, perhaps neuronal pathway seems to be involved.
This PDF is available to Subscribers Only