I didn't realize any programs might be requiring a chairman letter. Difficult when you are a student at school without an ophtho program available. Of the 61 programs I reviewed, not a single one had any mention of a chairman letter requirement. Most don't talk about any requirements. Please do let the rest of us know if you find programs that do require this letter!
As a side note, I did see that three schools on my list require supplemental materials to CAS:
UC Irvine: Interested applicants should forward their C.V. and a photo directly to the program.
Tulane application, 2 photographs and curriculum vitae.
Georgetown CV and Photo must be sent directly to institution.