What do you find most confusing about the Military Health System(MHS)?

You bring up several good points. The first is health insurance coverage. This is the most confusing part of any "healthcare" system. There are many options(which can be good for individuals) but for a medical provider to keep up with every insurance company and their associated plans is nearly impossible...certainly, one person can't memorize this all. Tricare itself has no less than 15 different plans. Tricare's website also makes it easier than it used to be to find a doctor and check coverage but the bottom line is it's confusing. As a medical provider, my wife and I have to call Tricare to see what is an is not covered for our family. Same issue applies to what is an is not covered and what you have to prior auth first. Tricare Prime is for active duty members and is free to them however, that comes with downsides...you can't go anywhere you want unless you are prior authorized. Tricare Reserve Select costs money but you have freedom of movement. You have to balance free health insurance with a loss of free choices. Eye exams are covered for active duty members as outlined on Tricare's website here..http://www.tricare.mil/CoveredServices/Vision/EyeExams.aspx...here is part of the site excerpted:
Routine Eye Exams
A routine eye exam checks your vision and eye health. You can visit an Optometrist An optometrist is considered a “primary eye care provider.” Optometrists focus on regular vision services (eye exams, screenings, etc.) and can prescribe drugs, rehabilitation, eyeglasses and contact lenses. or Ophthalmologist An ophthalmologist is considered a “specialist” so you will need a referral and/or authorization, depending on your health plan option. Ophthalmologists provide regular vision services (like an optometrist) but they also provide medical and surgical services for your eyes. for a routine eye exam.

You’ll get a prescription for glasses or contacts if you need them
A routine eye exam is more than the simple vision screening test your primary care doctor may do with a standard eye chart
In general, TRICARE covers routine eye exams at no cost ($0):

As needed for active duty service members to maintain fitness for duty
Once a year for active duty family members
Every two years for all other TRICARE Prime beneficiaries (e.g. retired service members, their families, etc.)
Once a year for diabetic patients in TRICARE Prime
Well-Child Eye Exams
TRICARE covers well-child eye exams from an Optometrist An optometrist is considered a “primary eye care provider.” Optometrists focus on regular vision services (eye exams, screenings, etc.) and can prescribe drugs, rehabilitation, eyeglasses and contact lenses. or Ophthalmologist An ophthalmologist is considered a “specialist” so you will need a referral and/or authorization, depending on your health plan option. Ophthalmologists provide regular vision services (like an optometrist) but they also provide medical and surgical services for your eyes..

Every two years
Between the ages of three and six
Includes screening for amblyopia (lazy eye) and strabismus (crossed eyes)
No cost for well-child exams, regardless of plan

Awesome. I will ensure to pass this on to my Soldiers (AGRs and TPUs).