There seems to have been some misunderstandings in this area in the past. But perhaps DVLA have updated their website recently. It now says the following:
You can be fined up to £1,000 if you don’t tell DVLA about a medical condition that affects your driving. You may be prosecuted if you’re involved in an accident as a result.
The key words are '...that affects your driving...' so if it does NOT affect your driving you do not need to use Form H1 to inform DVLA. Am I correct in my understanding?