"Recommendations: Please collect at least 2 letters of recommendation from faculty members familiar with your work. If the recommendation is written by a health professions advisory committee, only one comprehensive summary of your academic evaluation is necessary. The recommender must provide an original letter on their stationary. Personal recommendations are not required, but may be submitted in support of your application. You may submit up to two personal recommendation letters. All recommendation letters must be mailed to OPTOMCAS in order to complete your file."
They don't have to be science teachers. This also says they they need to submit the recommendation on their own stationary, but I emailed NECO and they said an electronic submission via optomCAS is also okay. This is found on the link you had in your last post.
