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Test yourself with these two sticky situations.

With almost 250 different diagnosis codes to choose from, it’s no wonder that diabetes is among the most difficult diseases to code. And with so many variables, coding for ophthalmic complications of diabetes gets even trickier.

Fortunately, the decision tree created by the American Academy of Ophthalmology (AAO) makes your job a whole lot easier. All you have to do is ask the following six simple questions, and you’ll land on the right code the first time, every time.

Question 1: What Is the Diabetes Type?

ICD-10-CM describes four kinds of diabetes mellitus (DM), each one with its own etiology:

• E08.- (Diabetes mellitus due to underlying condition) describes conditions where the diabetes is caused by underlying conditions such as cystic fibrosis or diseases of the pancreas
• E09.- (Drug or chemical induced diabetes mellitus) describes conditions where the diabetes is caused by drug or toxin poisoning
• E10.- (Type 1 diabetes mellitus) describes a condition where the pancreas makes insufficient or no insulin to break down glucose in the body
• E11.- (Type 2 diabetes mellitus) describes a condition where the body is resistant to insulin and cannot use it to break down glucose
• E13.- (Other specified diabetes mellitus) describes conditions where the diabetes is caused by genetic defects and pancreatectomy

Importantly, you must pinpoint the type of diabetes to arrive at the most specific code for an ophthalmic complication resulting from DM. That means you should not use E11.- as the default for the condition if the diabetes type is not specified in the medical record. Each type of diabetes is different, and treatment for them varies in complexity and duration. However, each condition can result in ophthalmic complications, which you will report beginning with 4^th character 3 (… with ophthalmic complications).

Question 2: Does the Patient Have Retinopathy?

Once you’ve correctly identified the patient’s diabetes type, the next coding decision involves determining whether or not the patient has retinopathy. If the answer is no, the AAO suggests defaulting to EXX.9 (… diabetes mellitus without complications). However, this may not be the most specific code for you to use “given that most people with diabetes have either suboptimal control, complications, or both,” according to Joy Dugan and Jay Shubrook, authors of “International Classification of Diseases-10 Coding for Diabetes.”

Instead, you might look at EXX.649 (… diabetes mellitus with hypoglycemia without coma) for patients with blood sugar levels below 70 mg/dL or EXX.65 for hyperglycemia (… diabetes mellitus with hyperglycemia) for patients with blood sugar levels above 130 mg/dL, though the actual choice of code will, obviously, rest with your ophthalmologist.

Question 3: Is the Retinopathy Proliferative?

A positive answer to this question will logically lead you to EXX.35 (… diabetes mellitus with proliferative diabetic retinopathy). In that code group, you have a number of 6th character options to consider:

• 1: with macular edema
• 2: with traction retinal detachment involving the macula
• 3: with traction retinal detachment not involving the macula
• 4: with combined traction retinal detachment and rhegmatogenous retinal detachment
• 5: with stable proliferative diabetic retinopathy
• 9: without macular edema

So, you’ll use E10.359- (Type 1 diabetes mellitus with proliferative diabetic retinopathy without macular edema) if the patient’s type 1 diabetes has led to proliferative diabetic retinopathy (PDR) but the diabetic complication does not involve macular edema (ME).

A negative answer will lead you to code for nonproliferative diabetic retinopathy (NPDR), leading you to ask the next questions.

Question 4: What Is the Severity of the NPDR and Is it Accompanied by ME?

To code for NPDR, you’ll begin by adding the following 5th character to EXX.3- to identify severity:

From there, code assignment depends on whether the patient has been diagnosed with macular edema (ME); you’ll add the 6th character “1” if ME is present or “9” if it is not.

For example, you’ll document a patient with type 2 diabetes who has moderate NPDR and no ME as E11.339- (Type 2 diabetes mellitus with mild nonproliferative diabetic retinopathy without macular edema).

Question 5: What Is the Laterality?

All the DM ophthalmic complication codes require a 7th character for completion. This means searching the medical record to determine if the condition occurs in the patient’s right eye (7th character 1) or left eye (2), or whether the condition is bilateral (3). In the unlikely event the medical record does not contain the condition’s laterality, you’ll use 7th character 9 to indicate the laterality is unspecified.

Question 6: Do Other DM Ophthalmic Complication Codes Apply?

The EXX.3 codes list three other conditions not included in the AAO decision tree that you may be called upon to use:

• EXX.36- (… diabetes mellitus with diabetic cataract)
• EXX.37- (… diabetes mellitus with diabetic macular edema, resolved following treatment)
• EXX.39 (… diabetes mellitus with other diabetic ophthalmic complication)

Don’t forget the “Use additional code” instruction for code EXX.39-, which tells you to use either a code from H40.- (Glaucoma) or H42 (Glaucoma in diseases classified elsewhere).

Test yourself (1): Your provider diagnoses severe bilateral NPDR and ME in a patient with DM caused by cystic fibrosis. In this situation, E08.3413 (Diabetes mellitus due to underlying condition with severe nonproliferative diabetic retinopathy with macular edema, bilateral) would apply.

Test yourself (2): Your provider diagnoses a type 1 diabetic patient with glaucoma in the right eye. In this situation, you need two codes: E10.39 and H42. Per the instructional note accompanying H42, you’ll code the DM ophthalmic complication first.

Bruce Pegg, BA, MA, CPC, CFPC, Managing Editor, AAPC