The continuous growth of the eyeball length results in short or near-sightedness, which is referred to as myopia up to a certain level of refractive error. If this level is exceeded because the eyeball continues to lengthen, this is referred to as progressive myopia. The increase in length can result in excessive stretching of the retina, causing it to develop small tears or breaks. Liquid can enter the eye through these tears or breaks, and may accumulate between the retinal pigment epithelium (responsible for the retinal epithelium metabolism and the removal of dead photoreceptor cells) and the neuroretina (photoreceptor cells/amacrine cells/bipolar cells/ganglion cells). In the worst case, the accumulated liquid can lead to retinal detachment.
First signs of retinal detachment include metamorphopsia, perceived flashes of light, a sudden shower of little red/black dots across the field of vision or a kind of dark curtain moving up.