Question: California Subscriber Answer: CMS has established guidelines for how often you can perform visual fields on a patient. The allowed testing frequency is based on the severity of the disease process, as follows: • Glaucoma suspect or mild damage with good control: Visual field once every 12 months. "If unique clinical circumstance prevents secure establishment of a baseline with the initial study, a second study within the first 12 months may be obtained with appropriate documentation of medical necessity," Medicare says. • Glaucoma with moderate/advanced damage, good control: Once every 12 months. Medicare defines "good control" as "achievement of an IOP (intraocular pressure) at or below the target pressure without significant adverse effects. Subsequent observation confirms appropriateness of target pressure level by documenting lack of significant glaucoma progression." • Glaucoma with moderate/advanced or mild damage, borderline control: Two times every 12 months. Medicare defines "borderline control" as "achievement" of an IOP near but higher than the target pressure. The IOP is "judged possibly capable of inducing further significant glaucomatous damage. Typically further IOP reduction requires surgical intervention or additional marginally tolerated medications. Careful observation of disc and visual fields is required." • Uncontrolled glaucoma: Three times every 12 months. "In those unique clinical circumstances where a higher frequency of evaluation is indicated, documentation supporting medical necessity must be included with the claim." "Uncontrolled glaucoma" is marked by evidence of glaucoma progression and IOP significantly above target pressure. "All acute glaucoma is by definition uncontrolled," Medicare says.