Field notes / plate 004 / canine vision
The domestic dog eye.
Canis lupus familiaris
An eye in fine ink: follow a returning ray, find a regional reflector, and explore the structures that gather and protect light.
Choose a part · opens an enlarged inspection view
Tapetum lucidum
A regional reflector in the dorsal choroid, behind the retina. It is absent from the ventral wall in this illustration.
01 / A separate retinal view
A region, not a pit.
The area centralis is a zone of densely packed photoreceptors. It is distinct from the deeper tapetal reflector. This map does not invent a human foveal pit in the dog.
A regional dorsal reflector in the choroid, behind the retina. Shape, extent and appearance vary among individual dogs.
Right-fundus schematic: nasal left, temporal right, dorsal up. The area centralis is placed temporal and slightly dorsal to the disc, following canine retinal topography. It is a density region, not a hole or a separate reflective layer.
Positions and spacing are schematic. Retinal topography and tapetal appearance vary among dogs; this is not a universal breed map.
02 / An enlarged local wall sample
Light gets a return journey.
Some light that passes through the retina is reflected back by the tapetum, giving the photoreceptors another opportunity to absorb it.
First pass through the retina
This is a local sample through the tapetal region, not the entire eye lining. Layers and path are enlarged and simplified. Playback speed is illustrative; the returning path is offset for visibility.
The tapetum helps use available dim light. It creates no light and cannot provide vision in complete darkness. This sequence does not quantify visual performance.
03 / Outside the internal cutaway
Protection at the inner corner.
The third eyelid, or nictitating membrane, rests at the medial corner near the nose, beneath the lower lid. It can move across the cornea.
Resting at the medial corner
External view, with nose side left. Slow, controllable movement; no measured blink timing or exact tissue dimensions are implied.
Sources, drawing notes & toolkit credit
The ink cutaway is an AI-generated anatomical illustration, guided by original code geometry and checked against the listed veterinary and primary sources. Labels and interactions are separate code. It is a stylized educational drawing, not a specimen photograph or resolved histology.
Not to scale. Cut-wall thickness, tissue texture, tapetal plates and fine fibres are enlarged or interpreted for clarity. The area centralis is mapped separately rather than forced into this section. The external third eyelid is a separate view. Individual dogs vary; no diagnosis, breed measurement or numerical human-versus-dog superiority is claimed.
Made using Anatomy by Ryan (wheresryan22): SVG composition, figure/page frames and interaction guidance. Our art and adaptations imply no creator endorsement or scientific validation. About this collection and the upstream MIT licence.
- Merck Veterinary Manual: eye structure and function in dogs — optical structures, limited focusing changes, area centralis and medial third eyelid.
- Merck: the ocular fundus in animals — upper tapetal and ventral nontapetal regions; retina, choroid, sclera and optic disc.
- Lesiuk & Braekevelt, Journal of Anatomy, 1983 (verified paper PDF) — canine choroidal tapetal structure and light reflection; no sampled dimensions generalized here.
- Mowat et al., Molecular Vision, 2008 — cone topography and area centralis in studied beagle retinas; position used schematically, not as a universal numerical map.
- Domestic dog on Wikipedia — species overview.