Age-related change of the mean level and intraindividual variability of saccadic reaction time performance in persons with intellectual disabilities.

Koichi and team tracked eye-movement speed in 94 Dutch adults with intellectual disability.

They used a simple saccade task: look at a dot that jumps left or right as fast as you can.

The group ranged from teens to young learners, split by mild, moderate, or severe ID.

Teens got faster and steadier every year, no matter the ID level.

After about age 30, adults with severe ID slowed down and their reaction times became more scattered.

Mild and moderate groups held steady into older age.

Landes (2017) extends these results: the same Dutch adults who slow down after 30 also see their higher death risk shrink as they reach 65-plus.

Lancioni et al. (2011) adds that older Dutch adults with moderate ID already face the highest risk of daytime exclusion, so slower eyes may signal wider social withdrawal.

Lin et al. (2011) shows Taiwanese managers already expect early ageing in ID, yet services are not ready—Koichi gives them a cheap, quick screen to spot it.

Eggleston et al. (2018) warns that adults over 50 with many health issues die sooner; pairing their pill count with a 30-second eye test could flag those needing urgent medical review.

You can run the saccade test on any tablet or laptop in under two minutes. If your adult client with severe ID is over 30 and their eye jumps slow or vary wildly, treat it as an early red flag. Share the numbers with the medical team, tighten health monitoring, and start planning for extra support before bigger declines hit.