Treated Prevalence of Diagnosed Vision Disorders
Our estimates of treated prevalence and the treated prevalent population are listed in tables 3.3 and 3.4, respectively. To estimate the treated prevalence of diagnosed vision disorders, we identified International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes related to eye and vision conditions.[10, 17] We included a broad range of disorders, including conjunctivitis, eyelid problems, and eye injuries and burns, although these categories are reported separately. We grouped ICD-9 codes into like conditions. We then estimated the prevalence (and standard error) of each code as a primary diagnosis using pooled data from the 2003–2008 Medical Expenditure Panel (MEPS) data conditions file (Table 3.3). MEPS assigns ICD-9 codes to survey respondents based on their descriptions of existing medical conditions, past diagnoses, or the nature of medical care received.
Table 3.3. Treated Prevalence of Vision Diagnoses, 2003–2008 MEPS
Table 3.4. Treated Prevalent Population in Thousands, 2003–2008 MEPS
An important consideration of MEPS data are that visual correction and optometry care are not included in the medical provider component and are assessed separately. Possibly due to this structure, MEPS includes few persons with ICD-9 codes for Disorders of refraction and accommodation. Also, MEPS only includes 3-digit ICD-9 codes. This means that MEPS cannot identify conditions coded at the 4th or 5th digit, such as amblyopia and different types of retinal disorders other than retinal detachment (361). Thus, both diabetic retinopathy (362.0) and macular degeneration (362.5) are coded under 362. To attempt to distinguish these, we created a condition “retinal disorders, with diabetes” for persons diagnosed with retinal disorders (361 or 362) and self-report diabetes, and “retinal disorder, no diabetes” for persons with retinal disorders (361 or 362) but do not report diabetes. While this approach is very limited, we assume it will provide an approximation of actual diagnoses of diabetic retinopathy and other retinal disorder including macular degeneration.