{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://openvisual.org/schema/nyctalopia/1.0",
  "title": "OVS: Nyctalopia",
  "description": "Impaired vision in dim light (night blindness): the scene appears darker, desaturated and bluish, and in VSS the visual snow typically becomes denser as light levels drop. HPO Nyctalopia (HP:0000662), frequent in VSS.",
  "allOf": [
    {
      "$ref": "https://openvisual.org/schema/symptom-base/1.0"
    },
    {
      "type": "object",
      "properties": {
        "ovs_type": {
          "const": "ovs:nyctalopia"
        },
        "snow_increase_in_dark": {
          "type": "boolean",
          "description": "Whether visual snow density is reported to increase in low light"
        }
      }
    }
  ]
}