Convenience sample of VSP vision insurance members, representing more than 25% of the US population.
VEHSS Topics Included
Medical Diagnoses (limited coverage)
VSP Global is the nation’s largest managed vision care provider, operating as a nonprofit corporation for 60 years. Managed vision care is a specialized supplemental insurance provided through employers, commercial health plans, Medicare/Medicaid supplement plans, the federal employees health benefits program (FEHB), tribes, or purchased individually to provide routine vision care coverage. Generally, VSP data includes optometric exams and procedures, diagnoses (refractive errors, eye disease, systemic disease, acute issues), vision correction utilization, prescriptions and materials dispensed, costs, provider information, and patient demographics.
VSP does not report their patient volume, but report that more than one in four Americans have VSP coverage. VSP processes claims in every state, but market penetration varies by state. VSP’s national network contains about 33,000 eye care professionals. Approximately 85% are OD’s (optometrist), and 15% are MD’s (ophthalmologist).
VSP claims contain the age and sex of patients, but do not include race/ethnicity. Medical diagnosis coverage in VSP claims are limited. Medical diagnoses are generally not required for payment, thus their inclusion in claims by the billing practice is optional. VSP claims cannot alone be considered as disease prevalence estimates.
For the VEHSS project, VSP analyzed their 2016 claims databases to estimate the annual prevalence rate of treated diagnoses and the rate of clinical procedures. VSP analyzed the claims data and provided NORC with de-identified summary reports of frequencies and rates, summarized by state and by age group, race/ethnicity, and sex.
NORC further analyzed the summary data files, mapping outcomes to VEHSS-defined categories, calculating confidence intervals, and data cleaning. Results were further suppressed if the numerator was <3 and the denominator was less than 30, or the numerator was ≥3 and the denominator was ≤30.
NORC found that about 8% of VSP patients who had no claims filed during the year did not have a state of residence identified. State of residence for these patients was imputed based on the state-distribution of beneficiaries with a state location on file. VSP stated that they did not believe that there were any systematic reasons why the inclusion of beneficiary’s address information would vary by state, and thus this adjustment would be unlikely to bias results. In addition, this adjustment is only relevant to state-specific rates. National rates are not affected.
Service Utilization measured in VSP claims is the proportion of patients who underwent an eye exam per year of observation. The rate of exams represents the proportion of patients who have at least one eye exam during the year of observation, and is a single number representing the average for each patient group. The Eye Exam indicators analyzed in VSP claims data are listed in Table 1.
Table 1. Service Utilization Topic Indicators
Service Utilization Topic Indicators
By provider type
By ophthalmologists and other physicians
By optometrists and opticians
VEHSS categorizes diagnosis codes into medical diagnosis categories and subgroups. Individual Medicare beneficiaries were assigned to diagnosis categories and subgroups based on International Classification of Diseases 10 (ICD10) diagnosis codes on any patient claim during the year of observation. As reported in the “VEHSS Diagnosis Code Categories and Crosswalk Cdc-pdf[PDF – 2.1 MB]External,” we identified all eye and vision related ICD10 diagnosis codes, and organized them into a 2-level categorization structure, including 17 Categories and 79 Subgroups, as listed in Table 2.
Table 2. Medical Diagnosis Indicators Analyzed in VEHSS
Unqualified vision loss in one eye, or unspecified visual loss
Vision impairment one eye
Moderate or severe vision impairment better eye; profound vision impairment of lesser eye
Moderate or severe vision impairment both eyes
Profound vision impairment, bilateral, or legal blindness
Strabismus and Amblyopia
Injury, Burns and Surgical Complications of the Eye
Disorders of Optic Nerve and Visual Pathways
Optic nerve disorders
Visual pathway disorders
Other Visual Disturbances
Visual field defect
Other/unspecified visual disturbances
Infectious and Inflammatory Diseases
Eyelid infection and inflammation
Other inflammatory conditions
Lacrimal system and orbit inflammation
Orbital and External Disease
Other/unspecified orbital or external disease
Dry eye syndrome
Disorders of the globe
Cancer and Neoplasms of the Eye
Malignant neoplasm of the eye
Benign neoplasm of the eye
Endothelial dystrophy (inc Fuchs)
Other corneal disorders
Other Eye Disorders
Denominators used to Calculate Prevalence Rates
VSP requested that no patient counts or denominator information be publicly released. The patient denominators used to calculate rates include those patients who were enrolled in VSP at any time during the calendar year. VSP enrollment data is based primarily on employer-provided enrollment data, and may not accurately reflect the actual number of patients enrolled in VSP over the course of the year. In addition, some patient enrollment data is incomplete. In particular, state of residence is not always reported, with 8% of enrollees not having a state of residence on file. For the purposes of this analysis, we distributed patients with missing state in the denominators to a state based on the distribution of patients with known state location. We will continue to investigate possible approaches to improve state location coverage, and mitigate any potential bias of this limitation.
This analysis is subject to a number of potential limitations:
VSP data is a convenience sample and is not nationally representative, although on the basis of on our review, about 1 in 4 Americans have VSP coverage and VSP claims represent the majority of the overall US vision insurance market.
VSP claims are intended for billing purposes only. Diagnosis information included on claims is intended to justify payment. VSP provides payment primarily for routine eye exams and refraction correction, and therefore medical diagnoses are not generally required for payment. Diagnosis data on claims may therefore suffer from bias or limited detail. For example, even if a patient has an eye disease, this diagnosis may not be present on a claim filed for routine eye exams or glasses. Medical diagnoses in VSP claims are likely to underrepresent the true burden of disease, and cannot alone be considered prevalence estiamtes.
VSP primarily covers routine vision and optometry care, and will not include eye care services that are billed to medical insurers, nor any out-of-pocket or unbilled services.
VSP enrollment data is limited and is based primarily on employer provide enrollment rolls. This data is not updated continuously, and may differ from actual numbers of patients.
Approximately 8% of patients in enrollment data do not have a state of residence, and are therefore listed as missing. However, all claims are assigned to a state using the provider location, which is always known. VSP cannot directly link patient claims to enrollment data. This could potentially inflate all calculated rates for individual states because the denominator for that state would not include residents who did not have state locations included in their enrollment data. For the purposes of this analysis, we allocated the denominator count with missing state information to states using the distribution of known state locations. However, this may potentially bias results. In addition, the use of provider location in the numerator and, in some cases patient location from enrollment data in the denominator could also skew results. On the basis of internal analysis, VSP states that the potential impact of this bias is minimal. This approach may actually have a benefit of more accurately capturing patient location.