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Quan V Hoang, Sally A McFadden; The effect of a common tissue preservative on form deprivation myopia in the guinea pig. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5869.
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© ARVO (1962-2015); The Authors (2016-present)
Myopia is predicted to affect 50% of the global population by 2050, with nearly 1 billion at risk of blindness from high myopia. Although remodelling in scleral collagen is known to underlie excessive ocular elongation in myopia and lead to scleral dysfunction in high myopia, there is no safe, effective therapy to fortify eye wall collagen. Formaldehyde releasing agents (FARs) are used as cosmetic preservatives and can stiffen tissue by crosslinking collagen. We studied the effect of a posterior injection of a FAR on the progression of form deprivation (FD) myopia in the guinea pig.
Twelve tri-coloured guinea pigs were raised under white light. Half of each litter received a posterior injection under the retractor bulbi muscle of a FAR on day 3 and 4, and half received vehicle injection only on day 3. All animals were monocularly form-deprived in the injected eye on day 7 for 3 weeks. Measures were made of refractive error in cyclopleged animals and axial length in anaesthetised animals using high frequency ultrasound, after 1 and 3 weeks of FD, and after 1 and 3 weeks of recovery from FD.
Sham control animals developed normal FD myopia after 1 and 2 weeks (mean difference (Diff) between the eyes of -5.7D and -6.5D respectively), which returned to normal after 1 and 3 weeks of recovery (MD -0.5 and -0.08D respectively). Experimental animals developed significantly less myopia (Diff -2.4D and -2.5D, p < 0.01) and recovered the same as controls. Sham treated eyes became longer after 1 week of FD and grew again during recovery. In contrast, FAR treated eyes failed to elongate (95 μm vs. 21 μm), and reduced their eye length by 75 μm after 3 weeks of FD. This relative shrinkage was due to a smaller vitreous chamber and was still present 6 weeks after surgery.
Early treatment of the posterior sclera with a FAR can inhibit myopia induced by FD and reduce posterior globe elongation in a relatively permanent way suggesting such fortifying treatments might be a way to limit the development of sight threatening staphyloma and associated stresses on the eye wall in high myopia. The fact that the eye can recover from myopia despite a smaller eye suggests that the retina senses the refractive state and the eye responds appropriately via alternative means that are likely to be optical.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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