The role of the retinal pigment epithelium in eye growth regulation and myopia: A review

Abstract

Myopia is increasing in prevalence world-wide, nearing epidemic proportions in some populations. This has led to expanded research efforts to understand how ocular growth and refractive errors are regulated. Eye growth is sensitive to visual experience, and is altered by both form deprivation and optical defocus. In these cases, the primary targets of growth regulation are the choroidal and scleral layers of the eye that demarcate the boundary of the posterior vitreous chamber. Of significance to this review are observations of local growth modulation that imply that the neural retina itself must be the source of growth-regulating signals. Thus the retinal pigment epithelium (RPE), interposed between the retina and the choroid, is likely to play a critical role in relaying retinal growth signals to the choroid and sclera. This review describes the ion transporters and signal receptors found in the chick RPE and their possible roles in visually driven changes in eye growth. We focus on the effects of four signaling molecules, otherwise implicated in eye growth changes (dopamine, acetylcholine, vasoactive intestinal peptide (VIP), and glucagon), on RPE physiology, including fluid transport. A model for RPE-mediated growth regulation is proposed.

A genome-wide linkage scan in Tunisian families identifies a novel locus for non-syndromic posterior microphthalmia to chromosome 2q37.1

“…The CHRND and CHRNG are members of nicotinic/cholinergic acetylcholine receptors which are involved in eye growth control. Indeed, the muscarinic antagonist atropine retards the development of myopia in chicken, monkey and humans (Stone et al 2001;Rymer and Wildsoet 2005;Liu et al 2007). KCNJ13/Kir7.1 is highly expressed in human retinal pigment epithelium (RPE) cells (Yang et al 2008a, b).…”

Developmental Basis of Nanophthalmos:MFRPIs Required for both Prenatal Ocular Growth and Postnatal Emmetropization

“…During normal emmetropization, visual input to the retina is somehow evaluated to extract information concerning focus, and signals that speed up or slow down growth of the eye are produced by the retina (30,31). It has been suggested that these signals are received by the RPE, which then relays this information to the choroid and sclera (32). How this signaling is achieved and how MFRP is involved in this process remains completely unknown.…”

Ionic control of ocular growth and refractive change

“…The most fundamental aspect of our theory (6), namely, that slowing of fluid outflow across the RPE causes retention of fluid within the vitreous chamber, has been referred to in a recent review of the area (31). However, rather than acknowledge that fluid itself could cause the vitreous chamber to grow and thus affect the refractive state, the authors favored the transport of specific scleral growth signaling molecules (as yet unknown) by the RPE as the most likely mechanism of growth.…”