Glaucoma: ICD-10-CM Coding
Excessive pressure from fluid in the eye can lead to a hypertensive condition called glaucoma. When ocular pressure rises, pathological changes occur that can damage vision. The fluid in the front of the eye flows through an anatomical pathway. If this pathway is blocked, pressure against blood vessels can cut off blood to the eye, leading to blindness. The physician can perform surgery to revise the flow of aqueous in the eye and reduce the pressure. Glaucoma codes are found in ICD-10-CM category H40—except for congenital glaucoma, which is found in subcategory Q15.0.
ICD-10-CM codes for Glaucoma include the type and stage
Glaucoma is classified according to the type of angle closure. The angle referenced is along the exterior ring of the iris, where it joins the trabecular meshwork at the base of the cornea. This meshwork collects aqueous that has flowed through the anterior chamber so that it can be recirculated in the eye. If the angle is closed, the flow of aqueous is reduced or shut off, creating a surplus of aqueous and raising the pressure within the eye. Closed-angle glaucoma is also known as narrow-angle. Increased pressure causes the iris to bulge forward, narrowing or blocking the drainage angle formed by the cornea and iris. Acute closed-angle glaucoma occurs quickly; for example, within minutes or hours following an injury to the eye. Chronic closed-angle glaucoma can be due to a defect caused by illness or age. Open-angle (also known as wide-angle) glaucoma (chronic glaucoma), is the most common type of glaucoma, and it is the leading cause of blindness in adults in the United States. It can only be detected by regular eye exams. Gradually the pressure increases in the eye due to clogging of the drainage system or overproduction of aqueous fluid.
A seventh character identifies the stage of disease. Unspecified equals not documented; indeterminate stage means the physician is unable to determine the stage.
0 stage unspecified
1 mild stage
2 moderate stage
3 severe stage
4 indeterminate stage
Laterality is also a factor: Coding Guidelines dictate that when a patient has bilateral glaucoma that is documented as the same type and stage, you should assign a code for bilateral glaucoma with the appropriate seventh character for the stage. When the patient has bilateral glaucoma with different type or different stage, assign a code for each eye, instead of a bilateral code. Specific guidelines exist for subcategories H40.10-, H40.11-, and H40.20- (I.C.7.a.), with attention to how the codes are indexed in the Alphabetic Index.