Introduces a functional tapetum lucidum — the reflective layer behind the retina that gives cats their night vision and eye-shine. The modification dramatically improves low-light vision, allowing the user to see in conditions that would leave an unmodified human effectively blind. The trade-off is reduced visual acuity in bright light and the distinctive eye-shine visible when light strikes the eyes at the right angle. Combined with prismatic iris resequencing, the result is eyes that glow faintly in darkness — functional and unsettling in equal measure. Helix Biosystems' premium version includes an adaptive dimming response that reduces the bright-light penalty. Street versions lack this refinement and require tinted lenses in daylight. In the Gray Zone's underlevels, where reliable lighting is a luxury, tapetum integration is considered a practical necessity rather than a vanity modification.