VISSIT Introduction

An introduction to the Visual Impairment Scale of Service Intensity of Texas (VISSIT); a tool to assist TVIs recommending service minutes, including requirements and recommendations.


One of the requirements of a teacher of students with visual impairments (TVI) working in an itinerant service delivery model is to recommend the type and amount of TVI service for each student. This decision is often made in a variety of ways, but this recommendation is critical in ensuring student success. There are two types of service provided to students with visual impairments:

  • Direct instruction from the TVI, and
  • Support for others on the educational team, including other special education and general education teachers, paraeducators, family members, related service providers, other school personnel, and community partners (Pogrund, Darst, & Munro, 2015).

The Individuals with Disabilities Education Act (IDEA) requires that instructional goals be based upon evaluation of present levels of performance (United States Department of Education, IDEA, 2004, [§300.320(a)(1)]. The Service Intensity Subcommittee of the Texas Action Committee for the Education of Students with Visual Impairments embarked on a journey of creating a tool that connected itinerant service recommendations to Expanded Core Curriculum (ECC) programming based upon student need as demonstrated in the results of student evaluations (Pogrund, Darst, & Munro, 2015).

Evaluation, instruction, and collaboration in the ECC are the primary roles for TVIs. Therefore, the VISSIT was developed around the nine areas of the ECC. Evaluation for students with visual impairments includes all relevant evaluations in the nine areas of the ECC and current versions of the student’s functional vision evaluation and learning media assessment (Pogrund, Darst, & Munro, 2015). The nine areas of the ECC that should be evaluated are:

  • Compensatory skills
  • Assistive technology
  • Social interaction skills
  • Independent living skills
  • Career education
  • Sensory efficiency skills
  • Recreation/leisure skills
  • Orientation and mobility
  • Self-determination

Based on evaluation results, a TVI will use the VISSIT to determine the recommended amount and frequency of TVI services. For the purposes of this scale, services are defined in two separate categories. The first type of service addressed on the VISSIT is direct intervention from a TVI. The second type of service addressed by the tool is collaborative consultation from the TVI with members of the student’s educational team, including family. A student may have a very high need in some areas of the ECC, but some team member other than the TVI may be providing the service to meet this need (e. g., independent living skills may be an area of high need for the student, but the occupational therapist and special education teacher could be providing the majority of the services).  Family support needs are crucial for ensuring carryover and generalization of expanded core curriculum skills, and they are included as a separate element in the scale (Pogrund, Darst, & Munro, 2015).

The VISSIT will help develop recommendations for the amount of time for TVI instructional services (direct and collaborative consultation) per individual student. The VISSIT does not consider any other factors other than student need. Other factors that might impact overall TVI workload are not addressed by the VISSIT. These workload factors include material preparation, travel distances between schools, number of IEP meetings, or case management time (Pogrund, Darst, & Munro, 2015).

Based on a national validation study conducted in 2016, it has been determined that the VISSIT is a valid and reliable tool that can be used to recommend amount of service for students with visual impairments.

Consequential validity (intended and unintended consequences of test [or tool] interpretation and use)of the VISSIT is supported by 87% of the participants stating that the tool’s results matched their professional judgment regarding student need and recommended service time and by 87% of the participants stating that the tool’s results directly translated into the type and amount of service they would recommend

Social validity (the acceptability of and satisfaction with intervention procedures) was supported by 89% of the participants stating that the VISSIT was easy to use as a tool to determine service time. Social validity of the tool’s usefulness was also supported by 93% of the participants saying that they would use the VISSIT in the future

For establishing content validity, the CVR (content validity ratio – Lawshe) was calculated by dividing the number of experts (* only state if asked about a number: *between 49 and 51 depending on the question) that arrived at an acceptable relevance for each item – 3 (quite relevant) or 4 (highly relevant), by the total number of experts evaluating relevance of each items.  A CVR was completed for each item, and then the overall content validity index (CVI) was calculated for the entire instrument’s content validity.  For the item to be considered highly valid, the CVR has to be at least .29 for each item (n=40).  All items on the VISSIT scale were considered highly relevant with the highest item CVR being .94, and the lowest CVR on an item was .54.  The CVI (or content validity of the entire instrument) was .83, indicating that the content of the entire instrument was highly valid.

The rating scale used by the participants to evaluate the entire set of items was a Likert scale of one to five, with one being the rating that indicated the final score represented the student’s need for TVI service.  A factor analysis was conducted on the survey results, and the resulting Cronbach’s alpha for the internal consistency reliability for the set of all items on the entire VISSIT is .955.  A scale is found to be reliable at .7 and over for the Cronbach’s alpha score. The Cronbach’s Alpha score supports the VISSIT‘s significant reliability in that the items on the scale were all related to measuring student need for TVI service.

*Prior to using the VISSIT, go to Frequently Asked Questions, as you may find answers to many of your questions here.

For questions, please contact Rona Pogrund at [email protected] 


Pogrund, R. L., Darst, S., & Munro, M. (2015). Initial validation study for a scale used to determine service intensity for itinerant teachers of students with visual impairments. Journal of Visual Impairment & Blindness, 109(6), 433-444 .

United States Department of Education. (2004). Regulations: Part 300.320. In Building the legacy: IDEA 2004 (Child with a disability). Retrieved from