Importance and Benefits of the Clinical Low Vision Examination

Authors: Cindy Bachofer, Certified Low Vision Therapist (CLVT), Outreach Programs, Texas School for the Blind and Visually Impaired, TSBVI

Author’s note: This article pertains to students who meet eligibility for special education services due to a visual impairment. This eligibility requires an eye doctor’s diagnostic report along with additional evaluations. An examination by an ophthalmologist or optometrist is necessary before receiving a clinical low vision examination.

Receiving a clinical low vision evaluation is not simply best practice for children and adults with low vision; it is the standard of care as written in position papers by both the American Association for Pediatric Ophthalmology and Strabismus (AAPOS, 2013) and the American Optometric Association (AOA, 2007). Additionally, the Association for Education and Rehabilitation of the Blind and Visually Impaired (AERBVI)’s position paper Appropriate Prescribing Practices for Optical Device Use in Students with Low Vision (Bachofer & Lusk, 2019) outlines the importance of this exam. 

An appointment with a low vision specialist (ophthalmologist or optometrist with specialization in low vision) is different from an annual eye exam with an eye doctor that is focused only on the health of the eyes. Understanding the purpose and benefits of this specialized evaluation, and sharing the information with students and families, is a critical role of professionals in the field of visual impairment. This exam should not be a matter of chance but rather a routine practice for people with low vision. This article addresses preparation for the low vision exam, components of the exam process (e.g., measuring visual acuity), as well as challenges to getting an exam and problem-solving through those barriers. Based on findings from the exam, the low vision specialist recommends tools, strategies and resources for gaining visual access to many daily tasks.

“I already went to the eye doctor. Why am I going again?” 

This may be the exclamation from a young person who hears they have yet another eye appointment. However, in the low vision exam, the patient is more involved in demonstrating to the doctor what they can do visually, where they are struggling, and identifying what they want to do in completing visual tasks. Through these three steps, the vision professional can help prepare the student for the exam: 

1. Explain the process and provide a description of what to expect to the student. This exam takes longer than a regular eye exam as it has two parts: first, the exam where multiple factors of vision are checked, and second, a focus on increasing functioning across a range of tasks through evaluation and comparison of tools and devices. 
2. Gather samples of materials requiring visual access (e.g., school work, hobbies, extra-curricular activities). The doctor will use these items during the exam to test devices and tools.
3. Work with the student and the family to create a list of questions to ask the doctor after the evaluation is completed.

“Wow—that was a LOT of stuff to cover in one appointment!” 

This was the feeling shared after one student’s low vision exam. It is common to think of eyesight as just a measure of visual acuity, the 20/something number. However, multiple factors combine to make our visual sense possible. The following section gives examples of components of the low vision exam. 

• Acuity: Clarity of what is seen at near and at distance.
  • Distance: Identification of visual targets (e.g., letters, symbols) on an eye chart across the exam room (usually 10’ or closer in a low vision exam)
  • Near: Identification of visual targets (e.g., symbols, words) on a near vision test card held by the patient (eye doctors typically have the card held at 16”). Doctors use a measure of near acuity to provide a recommendation of print size for reading.
• Visual field: Detection of visual targets in the periphery or side vision while looking straight ahead. This can be done with sophisticated, diagnostic instruments or more simply through gross confrontation with the doctor bringing objects in from the four quadrants of the visual field (above/superior, below/inferior, each side/temporal)
• Contrast sensitivity: The distinction of a visual target against its background. For example, seeing a black bear against snow is high contrast, whereas seeing a green frog against green leaves is low contrast. One version of this test is the patient identifying the direction of black, then gray, then lighter gray lines against a white background until the lines become indistinguishable. 
• Filter testing and glare tolerance: Use of shaded lenses (filters) that reduce the intensity of harsh light and glare, whether indoors or out, is important to all of us as a critical aid in eye health and protection from sunlight.
• Refraction: Use of trial lenses to determine if glasses improve the eyesight or sharpen the image of what is seen. This is the familiar part of an optometric exam where the doctor tests different lenses by asking, “Is #1 better? Or #2?” Getting the just-right prescription takes time.

The low vision exam also includes testing depth perception, color discrimination, and response to different types of lighting. Depending on the patient’s needs, the doctor may consider the use of prisms for field expansion, therapeutic contact lenses for light occlusion, a bioptic for driving and distance viewing, or a telemicroscope (a wearable lens system for detailed near work).

The testing of optical devices such as handheld magnifiers to see at near, and telescopes to see in the distance, is another feature of the exam. In the last ten years, the smartphone has become a popular tool of choice for many people with low vision, but it can be limiting to access, depending on the setting and task, if it is the only tool used. As a final part of the visit, the patient will work with a team member in the office, such as a certified low vision therapist (CLVT) to test high tech digital tools such as electronic video magnifiers. These have a range of screen sizes and built-in accessibility features. Having quick access to visual information is a universal goal, and exploring the array of tools available during the clinical low vision exam is valuable (Bachofer & Lusk, 2019).

The low vision exam also includes testing depth perception, color discrimination and response to different types of lighting. Addressing all these components in the exam explains how the clinical low vision exam can take 1-2 hours compared to a less comprehensive 30-minute routine eye exam. It is important to talk with the office staff when making the appointment to ensure that it is for a comprehensive, clinical low vision exam to consider the full visual system. An appointment for re-evaluation is necessary and a standard of care when a person’s vision changes or visual demands increase, such as transitioning into middle school or heading to college or the workplace (generally every three years).

While a well-meaning adult is able to purchase an optical device from the internet or pull one from a bin of devices and estimate what “feels like a right fit” for the student to use,  this method bypasses the expertise of the low vision specialist explained above. Provision of the wrong power of a telescope or magnifier can be frustrating for a student to use and discourages their interest to try tools in the future. Additionally, without this appointment the student is not able to voice their goals for visual access in the clinic setting, discover the expansive range of available tools and equipment, or ask the questions that develop a fuller understanding of their unique eyesight. 

A shortage of low vision specialists exists in the US, and getting an appointment made in a timely manner can be frustrating. Urban areas are more likely to have these doctors, and wait times can extend into months. Travel to the appointment, paying for the exam, and implementing the recommendations are three factors that require planning and teamwork. Consider these suggestions for troubleshooting: 

• Is a mobile clinic available in your region, or can one be planned? Is paratransit available for medical rides either through rural transit or city bus systems? Does a local Lions club or eye-care non-profit offer support for travel? Is a friend or family member available to assist with transportation? 
• Talk with the school district and/or Texas Workforce Commission (TWC) about payment for the exam. The Texas Education Agency (TEA) guidelines stipulate that the Functional Vision Evaluation (FVE) must address the need for a Clinical Low Vision Evaluation (CLVE):
  • The CLVE may be warranted if it is necessary to determine “whether any additions or modifications to the special education and related services are needed to enable the child to meet the measurable annual goals set out in the IEP of the child and to participate, as appropriate, in the general education curriculum” CFR, §300.305(a)(2)(iv)). 
  • Additionally, TEA asserts in Students with Visual Impairments: Eligibility for Special Education PDF in section on Functional Vision Evaluation (page 9), “Information from a clinical low vision evaluation is an important component for students with low vision in determining whether there are optical and/or electronic devices as well as other recommendations” that will assist the student in efficiently accessing print.
  • Through TWC’s vocational rehabilitation services, the CLVE may be covered as it relates to furthering educational goals or securing employment. 

• After the appointment, discuss a plan as a team (e.g., student, family, educators) to build use of the prescribed devices and recommendations into daily tasks across home, school/work, and community. Continue to collaborate with clinic staff and the doctor as questions or concerns come up. In the doctor’s office, the tools can feel appealing and important to use. Back home or at the grocery store, for example, it can feel awkward as using this tool draws unwanted attention. Set up instruction time with the vision professionals on the team to develop skills for efficient use of these tools. It takes time to adjust to new eyeglasses, and it takes time to build device use into personal habits. 

Getting a clinical low vision exam is not simply best practice for children or adults with low vision; it is the standard of care. Considering the multiple factors of vision, the focus of this exam is to improve functioning by increasing access to visual information through the use of tools and strategies. Hearing the student say, “I am glad we made that happen! I’ve got some new ideas now for what I can do,” is proof of the impact of the low vision exam.

At the clinical low vision evaluation testing monocular vs. binocular vision

References

American Academy of Ophthalmology. (PPP, 2017). Patient Preferred Patterns: Vision Rehabilitation PPP.  Retrieved from https://www.a.oaorg/preferred-practice-pattern/vision-rehabilitation-ppp-2017

American Academy of Ophthalmology Vision Rehabilitation Committee. (2013). Vision rehabilitation: Preferred practice pattern ® guidelines. American Academy of Ophthalmology. <www.aao.org/ppp>. 

American Optometric Association. (2007). Optometric clinical practice guideline: Care of the patient with visual impairment (low vision rehabilitation).

Bachofer, C. & Lusk, K. (2019). Appropriate prescribing practices for optical device use in students with low vision. Association for Education and Rehabilitation of the Blind and Visually Impaired Position Paper. 

Texas Education Agency (2021). Students with Visual Impairments: Eligibility for Special Education 00913209000_55_BENE_DESIG_RQST (1).pdf