title: No evidence for loss of short-wavelength sensitive cone photoreceptors in normal ageing of the primate retina.
abstract: In old world primates including humans, cone photoreceptors are classified according to their maximal sensitivity at either short (S, blue), middle (M, green) or long (L, red) wavelengths. Colour discrimination studies show that the S-cone pathway is selectively affected by age and disease, and psychophysical models implicate their loss. Photoreceptors have high metabolic demand and are susceptible to age or disease-related losses in oxygen and nutrient supply. Hence 30% of rods are lost over life. While comparable losses are not seen in cones, S-cones comprise less than 10% of the cone population, so significant loss would be undetected in total counts. Here we examine young and aged primate retinae stained to distinguish S from M/L-cones. We show there is no age-related cone loss in either cone type and that S-cones are as regularly distributed in old as young primates. We propose that S-cone metabolism is less flexible than in their M/L counterparts, making them more susceptible to deficits in normal cellular function. Hypoxia is a feature of the ageing retina as extracellular debris accumulates between photoreceptors and their blood supply which likely impacts S-cone function. However, that these cells remain in the ageing retina suggests the potential for functional restoration.
authors.affiliation: Institute of Ophthalmology; University College London, London, EC1V 9EL, United Kingdom.
authors.forename: Tobias W
authors.initials: TW
authors.lastname: Weinrich
authors.affiliation: Division of Optometry and Visual Sciences; City, University of London, London, EC1V 0HB, United Kingdom.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Powner
authors.affiliation: Institute of Ophthalmology; University College London, London, EC1V 9EL, United Kingdom.
authors.forename: Aisling
authors.initials: A
authors.lastname: Lynch
authors.affiliation: Department of Ophthalmology and Vision Science; University of California, Davis, Sacramento, CA 95817, United States of America.
authors.forename: Ravi S
authors.initials: RS
authors.lastname: Jonnal
authors.affiliation: Department of Ophthalmology and Vision Science; University of California, Davis, Sacramento, CA 95817, United States of America.
authors.forename: John S
authors.initials: JS
authors.lastname: Werner
authors.affiliation: Institute of Ophthalmology; University College London, London, EC1V 9EL, United Kingdom.
authors.forename: Glen
authors.initials: G
authors.lastname: Jeffery
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D002452:Cell Count; D011323:Primates; D012160:Retina / Q000378:metabolism* / Q000503:physiopathology; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*