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Assessment of Rod, Cone, and Intrinsically Photosensitive Retinal Ganglion Cell Contributions to the Canine Chromatic Pupillary Response.
- Source :
-
Investigative ophthalmology & visual science [Invest Ophthalmol Vis Sci] 2017 Jan 01; Vol. 58 (1), pp. 65-78. - Publication Year :
- 2017
-
Abstract
- Purpose: The purpose of this study was to evaluate a chromatic pupillometry protocol for specific functional assessment of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) in dogs.<br />Methods: Chromatic pupillometry was tested and compared in 37 dogs in different stages of primary loss of rod, cone, and combined rod/cone and optic nerve function, and in 5 wild-type (WT) dogs. Eyes were stimulated with 1-s flashes of dim (1 cd/m2) and bright (400 cd/m2) blue light (for scotopic conditions) or bright red (400 cd/m2) light with 25-cd/m2 blue background (for photopic conditions). Canine retinal melanopsin/Opn4 was cloned, and its expression was evaluated using real-time quantitative reverse transcription-PCR and immunohistochemistry.<br />Results: Mean ± SD percentage of pupil constriction amplitudes induced by scotopic dim blue (scDB), scotopic bright blue (scBB), and photopic bright red (phBR) lights in WT dogs were 21.3% ± 10.6%, 50.0% ± 17.5%, and 19.4% ± 7.4%, respectively. Melanopsin-mediated responses to scBB persisted for several minutes (7.7 ± 4.6 min) after stimulus offset. In dogs with inherited retinal degeneration, loss of rod function resulted in absent scDB responses, followed by decreased phBR responses with disease progression and loss of cone function. Primary loss of cone function abolished phBR responses but preserved those responses to blue light (scDB and scBB). Although melanopsin/Opn4 expression was diminished with retinal degeneration, melanopsin-expressing ipRGCs were identified for the first time in both WT and degenerated canine retinas.<br />Conclusions: Pupil responses elicited by light stimuli of different colors and intensities allowed differential functional assessment of canine rods, cones, and ipRGCs. Chromatic pupillometry offers an effective tool for diagnosing retinal and optic nerve diseases.
- Subjects :
- Animals
Dogs
Gene Expression Regulation
Immunohistochemistry
Microscopy, Acoustic
Models, Animal
Photic Stimulation
RNA genetics
Retinal Cone Photoreceptor Cells cytology
Retinal Ganglion Cells cytology
Retinal Rod Photoreceptor Cells cytology
Reverse Transcriptase Polymerase Chain Reaction
Rod Opsins biosynthesis
Rod Opsins genetics
Reflex, Pupillary physiology
Retinal Cone Photoreceptor Cells physiology
Retinal Ganglion Cells physiology
Retinal Rod Photoreceptor Cells physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1552-5783
- Volume :
- 58
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Investigative ophthalmology & visual science
- Publication Type :
- Academic Journal
- Accession number :
- 28061512
- Full Text :
- https://doi.org/10.1167/iovs.16-19865