1. Purple Dragons in modern day Cormyr (1479 DR, the Year of the Ageless One) are tested prior to being assigned to training. These tests run the gamut, and look for traits that might surprise you.
2. The tests attempt to determine magical aptitude. This seems like a no-brainer, but it wasn’t until recently (I’d say the last 25-50 years) that part of the recruitment process included a standardized test any Wizard of War could administer to determine if a Dragon-to-be had aptitude for the Art (i.e. spellcasting ability).
3. The tests also look for recruits that suffer from face blindness (prosopagnosia for those of us here on Earth), as well as super-recognizers, i.e., people who never forget faces like you and I never forget how to ride a bike.
4. Recruits that are bonafide super-recognizers may find themselves destined for jobs within the Royal Court or the Royal Palace, there to become courtiers of midling authority whose real job is to note who comes and goes from a particular area. Others will be kept by the Purple Dragons, and trained to stand watch at any important gate in one of Cormyr’s major cities, there to keep watch for known thieves, miscreants, criminals and spies. Such are recognized thanks to simple wood and board paintings from descriptions of their likenesses (and in some cases by faces conjured up by spell, whenever a War Wizard talented enough to this sort of thing is around), or from past encounters between the Purple Dragon super recognizer and the criminal. Super-recognizers are given tours of the dungeons where prisoners are kept, and are sometimes given the duty of seeing soon-to-be-freed prisoners off, the better to recognize them in the future if they should return to a life of crime.
5. Recruits that are face blind are not turned away. After all, a face blind Purple Dragon can tell the difference between an orc and a human as easily as the next Dragon, and the only thing one needs to swing a sword is a sturdy arm. That, and a face blind Purple Dragon can still hear voices and follow orders, and is just the sort of person you need guarding you when you meet with others in secret and don’t want to worry about your own guard’s tongue waggling loose with descriptions of the participants in the latest secret meeting in the Royal Palace, after the Dragon has downed one too many drinks.
6. When it comes to blindness in Cormyr, any child born blind is expected to make their way in the world. They are neither coddled nor given extra care (beyond the training required to learn to navigate on their own). The major temples to the gods in Cormyr do much of this work–not just in the temple, but outside of it thanks to wandering priests and clerics. Note that it is considered socially unacceptable for a family that is flourishing (read: not dirt poor and starving) to abandon a child of theirs that is blind, or to deliberately give a child up to a temple because of the child’s blindness. This is not technically against Crown law, but a King’s Lord may object to it if he learns such has happened, as will some of the bigger-hearted nobles, and also the fellow Cormyrean citizens that have befriended the family. Social pressure is a real thing in Cormyr.
7. While most temple priests claim their teaching techniques are passed down from the first priest to receive divine inspiration and compelled to aid the blind, most any blind person will tell you they have the dwarves under the mountains to thank because sighted dwarves use the same techniques that blind Cormyreans are taught. The dwarves do this to sound out and “see” tunnels beyond their 60′ darkvision limit, and to survive in regions of magical darkness or while under attack by drow. That, and dwarves blinded in combat are not about to stop improving their homes and working for their clans in the tunnels and mines. And they sure as hell will pick up their hammer and go fight when the halls are under attack. Dwarven instructors are the best teachers of the blind.
8. The training blind children receive, regardless of where it is taught or who does the teaching, usually revolves around learning to make loud, sharp sounds with one’s mouth that reliably echo off of things like stone walls, cobblestone streets, tree trunks, and to a lesser degree people and draft animals. Secondary training involves learning the most common loud sounds to be found where one lives, and learning how to listen to those sounds to see the world. Children born blind are capable of navigating the streets (or trails) beyond their homes by the age of four or five years of age, and are put to work as soon as they are able. 
9. The blind in Cormyr fill a variety of roles. For example, in Arabel there are messenger services that have become part message keeping and retrieving services. These have risen in popularity because they utilize staff members who display prodigious memory skllls and have no ability to see faces. These workers sit in a room joined to an identical room by a common wall, in which a square hole covered by a sliding panel has been built on one side of the wall, and a fine mesh curtain covers the other side of the wall. Customers enter their room, open the panel, and speak clearly and crisply up to 1,000 words in any language they are told the worker knows. The worker memorizes the message and keeps it secret until the day a new customer comes along and speaks the pass phrase that is part of the original 1,000 word message. Then the worker repeats to the new customer all the words in the original message.
10. For a considerable upcharge, the message keeper (aka the worker) will journey with an escort (read: trusted mercenaries or even adventurers looking for work on their downtime or in the Wintertime, when adventuring hits a lull all across the Realms) to meet a specific person at a specific location on a specific date (as spelled out in the original message) and repeat aloud the up to 1,000 words message.
11. Finally, certain forms of spellcasting are dangerous to the sighted, as well as certain spellbooks, magic items, and scrying orbs whose visible emanations ride visible light right through the open eyes of the sighted to cook their brains and burn their memories away. In Cormyr, blind spellcasters are rare, and blind spellcasting assistants are uncommon, but their services are sometimes necessary. (This last is a topic for another day.)
 There is a great article in the New Yorker about the topic of face blindness and the discovery of the opposite condition, and of a team of real-life super recognizers working out of Scotland Yard in Great Britain: The Detectives Who Never Forget A Face.
 This is a real thing, I kid you not. A podcast called Invisibilia featured an episode titled “How to Become Batman” (January 22nd, 2015), where a blind man walks on the sidewalk and navigates hiking trails alone, clucking loudly to see as he walks and climbs.