Which condition could potentially result in a permanent disqualification for a driver?

Severe vision impairment is a condition that can result in a permanent disqualification for a driver because it directly affects their ability to operate a vehicle safely. Vision requirements for commercial drivers are stringent as poor eyesight can severely limit the driver's ability to perceive essential road signs, judge distances, and respond appropriately to sudden changes in the driving environment.

In general, vision standards for driving include a minimum visual acuity and a certain field of vision. If a driver's vision is below these standards due to severe impairment, they would be deemed unfit to drive, thus leading to potential disqualification.

The other conditions mentioned, while they may require careful management and monitoring, typically do not result in an immediate permanent disqualification. Controlled hypertension can often be managed with medication, history of heart disease can be acceptable if the individual is stable and cleared by a physician, and regular check-ups for diabetes suggest management of the condition, allowing for continued driving eligibility as long as the individual does not have complications that impair driving functions.