You can start by asking some general questions with your patient, for example: 

Are you experiencing any blurriness or changes to your vision? Whether it's up close or at distance?
Do you feel any deficits in your visual performance when you're at a computer or at night time? 
Do you have any issues with the comfort of your eyes? Like dryness, itchiness, watery, or redness? 
Do you use any over-the-counter drops? 
Do you ever experience any flashes of light, floaters, eye pain, or sensitivity to light?

If the patient answers yes to any of those questions, you will also need to present a history of present illness that provides a chronological description of how the patient's present illness developed from the first sign or symptom to the present. You can use the CPT guidelines, for example:

Location: what is the site of the problem? Is it unilateral or bilateral?
Quality: what is the nature of the pain? Is it consistent, acute, chronic, improved or worsening?
Severity: describe the pain or redness, for example, on a scale of 1 to 10 with 10 being the worst.
Duration: how long has the problem been an issue?
Timing: is the problem worse in the morning or evening or is it constant?
Context: is it associated with any activity?
Modifying factors: what efforts has the patient made to improve the problem? (like artificial tears)
Associated signs and symptoms: is the problem causing blurred vision headache, twitching, excessive tearing ?

It is the doctor's responsibility to code the exam dependent upon what diagnosis drove the exam, and it is your responsibility to provide enough information, so that they may code adequately.