Insight into Low Vision

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Low Vision and the Law: Who Is Legal to Drive?

Written by Terri Cyr in The Experience of Vision Loss

drivers view of a road with traffic on a rainy day

Driving is one of the most valued symbols of independence, and losing the ability to drive can feel like losing a vital connection to daily life. Yet, determining who is legally permitted to drive with vision loss is not straightforward. Each state sets its own standards, balancing public safety with individual capability. Understanding these regulations—and how they apply to drivers with low vision—is essential for making informed, responsible decisions about staying behind the wheel.

Driving regulations for people with vision loss vary widely from state to state. While visual acuity is often the first standard considered, most states now recognize that visual function involves more than just clarity of sight. Factors such as visual field, contrast sensitivity, and light adaptation can also affect safe driving. Because each state sets its own licensing standards, the rules can differ dramatically—some are highly specific and regulated, while others are more flexible or vague.

The Unrestricted License

Despite the variations, most states share common standards for issuing unrestricted driver’s licenses. Typically, a person qualifies if they have visual acuity of 20/40 or better in one eye, although a few states accept visual acuity of 20/50 or even 20/60.

Visual field requirements, however, vary even more. Some states have no specific visual field requirement, while others require a horizontal field of 120 to 140 degrees. A few states distinguish between binocular (both eyes) and monocular (one eye) visual fields, while others include vertical field standards as well.

All states, however, permit driving with one functional eye (monocular vision), provided the individual meets the state’s visual acuity and field criteria. An unrestricted license allows driving at any time and in any location—and this, perhaps, is the only aspect of licensing that approaches uniformity across the country.

The Restricted License

Most states offer a restricted driver’s license for individuals with subnormal or low vision. These licenses permit driving under specific conditions, which may include:

  • Daylight-only driving
  • Restricted driving radius or local area limits
  • No highway or interstate driving
  • Mandatory use of adaptive devices, such as a bioptic telescope

The minimum visual acuity requirement for a restricted license varies considerably by state—ranging from 20/40 to 20/200, the federal definition of legal blindness. Some states require a specialized road test for restricted-license applicants, while others rely on vision testing alone.

The majority of states now allow driving with a bioptic telescope, a miniature telescope mounted on eyeglasses that allows the driver to spot distant objects, such as road signs or traffic lights. Regulations differ, however, on whether acuity measured through the telescope can be used to meet the minimum vision standard. In many states, bioptic training is required before licensing.

Finding State Regulations

Each state’s Department of Motor Vehicles (DMV) maintains its own rules on vision and driving. Some are easier to locate than others, but your eye care provider can often assist in obtaining this information.

For a convenient summary of each state’s licensing requirements, consult the American Automobile Association (AAA) Exchange database:
Drivers Licensing Policies and Practices Database – http://lpp.seniordrivers.org/Opens in a new tab.

You can also search online using:

“Your state driver license vision standards.”

Experience and Safety

Ultimately, the privilege of driving depends on meeting measurable visual qualifications. Yet, visual tests only estimate performance—they cannot fully predict how someone actually drives. In my experience, many low vision drivers are highly attentive, cautious, and deliberate, compensating for visual limitations with experience, awareness, and discipline behind the wheel.

Conclusion

Driving represents far more than transportation—it symbolizes freedom, independence, and connection to the world. For those with vision loss, maintaining that independence requires honest self-assessment, ongoing dialogue with eye care professionals, and, when necessary, adaptive training or restricted licensing. While vision standards determine legal eligibility, true driving safety depends on an individual’s awareness, judgment, and willingness to adapt. With proper support and realistic understanding of one’s visual abilities, many people with low vision can continue to drive safely and confidently for years to come.

Testing Hope: How Clinical Research Shapes Eye Health Innovations

Written by Terri Cyr in Eyeglass TEchnology

image of pills, tablets and thermometer

Clinical trials are the essential human phase of testing new drugs, procedures, or therapies for diseases, including inherited eye diseases. They are conducted only after promising preliminary results have been gathered from initial pre-clinical research, such as studies conducted in vitro (in test tubes or petri dishes) and in animal models.

How Clinical Trials Are Conducted

Clinical trials are highly structured studies typically conducted at specialized medical centers, hospitals, and university settings that possess established research capabilities.

Research Teams and Protocol A multidisciplinary research team oversees the trial, often including physician-scientists, research nurses, technical medical support staff, and administrators.

Once a drug or treatment has shown effectiveness in the lab, the decision to proceed to human testing is made. Every clinical trial adheres to a strict protocol—a detailed, written plan that meticulously documents the study’s goals, research methods, materials, procedures, and duration.

Participant Selection Participants, or test subjects, are carefully chosen based on established inclusion and exclusion criteria. These criteria, which vary by study, ensure that the selected population—based on factors like age, disease status, and general health—will best support the study’s goals and yield meaningful data.

Ethics and Oversight

Participation in a clinical trial is voluntary. Researchers have an ethical obligation to be completely transparent with participants about any potential risks. Before starting, every participant must provide Informed Consent—a written agreement that outlines the study plan, associated risks, and duration. Research team members must be available to address any questions or concerns from the participant and their family.

To ensure participant safety and rights, human clinical trials in the United States are subject to very strict ethical protocols. They must be approved and continuously monitored by an Institutional Review Board (IRB) and the U.S. Food and Drug Administration (FDA). These governing bodies ensure the trial maintains an appropriate benefit-to-risk balance for all participants.

Benefits of Participation

  1. Access to cutting-edge treatments: Participants may receive promising therapies not yet available to the public.
  2. Expert medical care: Trials are often led by specialists and researchers who are among the most knowledgeable in their fields.
  3. Contribution to future care: Participants help advance medical knowledge that may benefit others with the same condition.
  4. Potential personal benefit: Some participants experience improvement in their own disease as a result of the treatment.

Risks of Participation

  1. The Unknown: Despite prior animal research, human responses may differ. Side effects, complications, or lack of benefit remain uncertain until the trial is complete.
  2. Time and Travel: Participation often requires multiple visits over months or years. The travel, testing, and waiting can be time-consuming and physically tiring.
  3. Costs: Research staff can help determine whether a participant’s insurance will cover testing or treatment. Out-of-pocket costs vary by study type, treatment status, and insurance coverage.
  4. No Guarantees: Clinical trials are designed to explore effectiveness and safety—not to provide assured treatment success.

Clinical Trial Phases

Clinical trials proceed through a four-stage, stepwise process known as phases. Each phase depends on the successful completion of the previous one, characterized by increasing dosages and a growing number of participants.

PhasePrimary GoalKey Characteristics
Phase ISafetyTests small dosages on a small group of participants (often healthy volunteers or those with the disease). The focus is identifying the safest dosage range and monitoring for serious side effects.
Phase IIEfficacy (Effectiveness)If Phase I shows acceptable safety, this phase expands to a larger group of people with the disease. Researchers adjust dosages and monitor to determine if the drug or treatment has a beneficial effect.
Phase IIIExpansion and ConfirmationWith favorable results from the first two phases, this phase enlists a large cohort of participants. The goal is to confirm the effectiveness, monitor for side effects over a longer term, and compare the new treatment to the current standard of care (if one exists).
Phase IVPost-Market SurveillanceAfter the drug or treatment has been approved by the FDA and is available to the public, this phase involves continuous monitoring. Researchers gather long-term data on the drug’s effectiveness, potential side effects in diverse populations, and optimal use.

Clinical trials are the cornerstone of medical progress. For individuals with eye diseases—especially those with limited existing treatments—participating in a trial can be both a personal opportunity and a meaningful contribution to the future of vision care.

Feature Cell Phones Designed for the visually Impaired

Written by Terri Cyr in Electronic Technology,Low Vision Aids,The Experience of Vision Loss

Feature phones are mobile devices that bridge the gap between basic, call-and-text-only cell phones and full-fledged smartphones. Within this category, a specialized niche exists for phones created specifically for the blind and visually impaired, often referred to as accessible feature phones or simplified devices. While many standard feature phones offer basic accessibility (like large buttons), the specialized models incorporate comprehensive features essential for independent use.

These accessible phones typically forgo complex touchscreens for highly tactile interfaces with large, physical buttons (keypads). Their core design is centered on robust auditory and visual cues to ensure every function is accessible.

Key Accessibility Features of these Specialized Phones:

  1. Comprehensive Voice Guide: The phone is fully speaking. It reads aloud everything on the screen, including the menu, contact lists, received text messages, and other information.
  2. Tactile and Verbal Feedback: It speaks the keys as they are pressed, providing immediate auditory confirmation of input.
  3. Visual Customization: For users with residual vision (low vision), the screen supports essential customizations such as adjusting font size, brightness, high contrast modes (e.g., inverse mode, like white text on a black background), and color schemes.
  4. Hands-Free Communication: Features include speaking caller ID, customizable ringtones, and voice-activated dialing from the contact list.
  5. Voice-to-Text Capabilities: Users can dictate text messages using voice recognition, often integrated with a text-to-speech function for reading received messages.
  6. Safety and Utility: Includes spoken time and date, a dedicated SOS or programmable emergency button, and the ability to set alerts and reminders.

When considering these devices, additional factors that contribute to functionality include internet access and web browsing (for more advanced models), camera and photo storage, and the availability of multiple language options.

Cell phones made specifically or primarily for the blind and visually impaired often feature highly tactile interfaces, dedicated accessibility apps, and comprehensive voice guidance.

Some examples of devices designed specifically for this user group include:

  • Smartphones with Physical Keypads:
    • SmartVision3: A fully functional smartphone, certified by Google, that is unique for including a tactile keypad along with a touchscreen. It’s designed to provide full smartphone access while being easier to navigate for those with vision loss.
    • BlindShell Classic 2/3: These are fully speaking, tactile button cell phones that offer the ease of a traditional button phone but with modern smartphone features and a simplified Android operating system.
  • Simplified Phones and Flip Phones:
    • RAZ Memory Cell Phone: Focuses on extreme simplicity, often for users with cognitive decline as well as vision loss. It has an ultra-simplified interface with a single screen displaying contacts as pictures and names, with no complex menus or apps.
    • MiniVision2+ Cell Phone: A big-button cell phone that is a simple, talking phone, taking care of basic telecommunications with voice commands and a voice guide that speaks everything on the screen.
    • IRIS Easy Flip or Jitterbug Flip2: These are standard flip phones that are popular choices due to their large, tactile keypads, simple flip design, and often include features like a talking voice guide and emergency buttons.

Examples:

Important Note on Mainstream Smartphones:

While the above are specialized devices, many blind and visually impaired individuals use mainstream smartphones like the Apple iPhone and Google Pixel due to their robust and highly advanced built-in accessibility features, which are arguably the most widely used tools. These features include:

  • Screen Readers: VoiceOver (iPhone) and TalkBack (Android/Google Pixel) provide audible descriptions of everything on the screen, allowing users who are completely blind to navigate with gestures.
  • Magnification and Display Customization: Features like Zoom/Magnifier and options for high contrast, enlarged text, and color filters for users with low vision.
  • Voice Assistants: Siri and Google Assistant allow for hands-free operation and are integrated with many functions.
  • Specialized Apps: Access to third-party accessibility apps like Be My Eyes or Lookout, which leverage the phone’s camera and AI for visual assistance.

Conclusion

Feature phones designed for the blind and visually impaired provide a vital bridge between traditional phones and complex smartphones, offering independence without unnecessary complexity. Through tactile keypads, full voice guidance, and adjustable visual displays, these devices ensure that users can communicate, navigate, and manage daily tasks with confidence. For many individuals with vision loss, accessible feature phones serve as more than communication tools—they are lifelines to safety, connection, and self-sufficiency.

Talking Books: The Daisy System for the Print Disabled

Written by Terri Cyr in Low Vision Aids,The Experience of Vision Loss

image of the NLS digital audio player

DAISY (Digital Accessible Information System) is the international technical standard for digital talking books and other accessible reading materials, including textbooks, magazines, and newspapers. It was specifically designed to provide a complete and navigable audio substitute for print material for people with print disabilities, such as blindness, low vision, and dyslexia.

Unlike traditional audiobooks, DAISY books are structured for advanced navigation. A user can move instantly and precisely through the material, jumping not just by chapter, but often by subsection, page, paragraph, or even sentence, offering the same flexibility as reading a print book. This enhanced structure has significant benefits for students and professionals.

The DAISY Standard and Format

The DAISY Consortium, an international non-profit organization, develops and maintains the DAISY standard. The standard outlines the requirements for structural markup (indexing), synchronization, and navigation control within the digital files. The level of navigation—how fine-grained the jumps can be—is determined by the producer of the DAISY file based on the complexity of the source material. For example, a textbook will typically have more navigation points than a novel.

DAISY books can be produced in three primary formats:

  1. Audio-Only: These files contain only the narrated audio, with minimal or no corresponding text. This format is most often used for recreational reading and typically features human narration. The National Library Service (NLS) for the Blind and Print Disabled often produces DAISY audio-only books.
  2. Text-Only: This format contains only the marked-up text and no pre-recorded audio. It is read using a device or software that employs a text-to-speech engine or a refreshable braille display. The quality of the “narration” depends on the synthesizer’s voice. Organizations like Bookshare use this format, which offers the advantage of very small file sizes.
  3. Synchronized Audio and Text (Full-Text/Full-Audio): This is the most feature-rich format, where the text and its corresponding pre-recorded audio are perfectly synchronized (often with on-screen text highlighting). This allows the user to listen to human-narrated audio while simultaneously seeing the text, which is particularly helpful for users with dyslexia or for understanding the layout and structure of the document. Learning Ally is a key provider of synchronized DAISY books.

Accessing DAISY Books

DAISY format evolved from analog tape cassettes to digital files in the 1990s. The files can be played on various platforms, which fall into two main categories:

1. Software Applications

Specialized software can be downloaded and installed on general-purpose devices like PCs, laptops, smartphones, and tablets. These applications offer features such as adjustable reading speed without voice distortion, highlighting text (for synchronized books), and bookmarking for future reference.

  • Open Source Options: The DAISY Consortium provides open-source software like AMIS for free download.
  • Requirements: A computer needs speakers, a sound card, and a keyboard. For CD-based files, a CD-ROM drive is also required.
  • Software Compatibility: When selecting software, ensure it’s compatible with your operating system (e.g., Windows, macOS, iOS) and the specific DAISY version you plan to use (e.g., DAISY 2.02 or DAISY 3/ANSI/NISO Z39.86-2005).

2. Dedicated Hardware (Digital Talking Book Readers)

These are stand-alone, purpose-built devices, ranging from small, palm-sized players to portable tabletop units. They are designed for ease of use by the print-disabled community, often featuring tactile buttons and audio prompts.

  • Examples of Dedicated Readers: Include models from companies like HumanWare (Victor Reader Stream) and the NLS Digital Talking Book Machines (DTBMs).
  • Media Sources: DAISY files can be loaded onto these devices via internet download, CDs, SD memory cards, or USB flash drives.

The National Library Service (NLS) distributes its books on specialized digital cartridges. For copyright protection, these files use the Protected Digital Talking Book (PDTB) encryption standard. Eligible NLS patrons are provided with an encryption key that “unlocks” the book files for playback on NLS-provided equipment or authorized commercial players.

Summary

As digital accessibility continues to evolve, the DAISY standard remains a cornerstone of inclusion—bridging the gap between print and digital media for millions of readers worldwide. Its ongoing development by the DAISY Consortium ensures that accessible reading will continue to grow more versatile, user-friendly, and universally available in the years to come.

The Americans with Disabilities Act and Low Vision

Written by Terri Cyr in Adjustment,The Experience of Vision Loss

image of an American flag with the letters ADA imprinted on it

A Guide to Your Rights

The Americans with Disabilities Act (ADA) is a landmark federal civil rights law enacted in 1990 to prevent discrimination and guarantee equal opportunity for those with disabilities. It addresses equal access in employment, state and local government services, public accommodations, transportation, and telecommunications.

Prior to the ADA, individuals with disabilities lacked the comprehensive federal civil rights protections that existed for other groups. The law was set forth to help equalize social, economic, employment, and education disadvantages in the public domain.

Given the opportunity and appropriate accommodations, those with the disability of low vision can become full functioning, productive, and self-sufficient members of society.

Defining Disability and Vision Impairment

The ADA defines an individual with a disability using a three-pronged approach:

  1. A person who has a physical or mental impairment that substantially limits one or more major life activities (like seeing, reading, or learning).
  2. A person who has a record of such an impairment.
  3. A person who is regarded as having such an impairment.

The ability to see is explicitly listed as a major life activity.

The Impact of the ADA Amendments Act (ADAAA)

The ADA was clarified and broadened by the ADA Amendments Act of 2008 (ADAAA). This is critical for people with low vision:

  • Mitigating Measures: The determination of whether an impairment substantially limits a major life activity must generally be made without regard to the ameliorative effects of mitigating measures.
  • Low Vision Devices: This means the positive effects of low-vision devices (such as magnifiers, telescopes, and specialized computer software) must not be considered when determining if a person is disabled. If you need low-vision devices because of an underlying vision condition, that condition constitutes a disability.
  • Ordinary Eyeglasses/Contacts: The one exception is for ordinary eyeglasses or contact lenses (lenses intended to fully correct visual acuity or eliminate refractive error). Their beneficial effect is considered. Therefore, a person whose vision is fully corrected to the level of the general population using standard prescription lenses may not be considered disabled. However, if the underlying vision impairment still substantially limits the person’s ability to see, even when using those lenses, or if the individual has an impairment that, in the absence of eyeglasses or contacts, substantially limits seeing, they meet the definition of disability.

It is important to note that while the ADA mandates accommodations, none of its provisions require entities to provide individuals with personal items such as eyeglasses, contact lenses, or other personal low-vision devices.

Employment (Title I)

Employment (Title I)Title I of the ADA prohibits discrimination in employment. This applies not just to hiring but also to job advancement, training, compensation, and “other terms, conditions, and privileges of employment.”

  • Who Must Comply: An employer must comply if they have 15 or more employees for each working day in each of 20 or more calendar weeks in the current or preceding calendar year.
  • Qualified Individual: The core protection is for a “qualified individual on the basis of disability.” A qualified person must be able to perform the essential functions of the job, with or without reasonable accommodations.
  • Reasonable Accommodation: Employers must make “reasonable accommodation” for a disabled employee, providing there is no “undue hardship” for the employer. Hardship is determined based on cost, financial resources, the type of operation, and the overall impact on the facility.

Employer Tax Incentives

Federal law offers incentives to help employers offset the cost of accommodations.

  • Disabled Access Credit (Section 44): Available to small businesses (those with $$$1 million or less in revenue or 30 or fewer full-time employees). It covers 50% of eligible access expenditures between $$$250 and $$$10,250, with a maximum credit of $$$5,000 per year.
  • Architectural/Transportation Barrier Removal Deduction (Section 190): Available to all businesses for a maximum deduction of $$$15,000 per year for expenses of removing qualified barriers.

For more information, refer to the U.S. Equal Employment Opportunity Commission (EEOC), which enforces Title I. The document, Questions and Answers About Visual Disabilities in the Workplace and the Americans with Disabilities Act, offers detailed guidance.

Public Services (Title II)

Title II covers the programs, activities, and services of state and local government entities, regardless of their size or receipt of federal funds. This includes public education, transportation, health care, social services, courts, and voting.

  • The Mandate: These entities must not discriminate against individuals with disabilities and must ensure their programs and services are accessible.
  • Accessibility and Communication: For the visually impaired, this involves ensuring effective communication by providing auxiliary aids and services at no additional cost. Examples include qualified readers, accessible digital files, taped texts, Braille material, and large-print documents.

Education and Health Services Enforcement

  • Education: The U.S. Department of Education, Office for Civil Rights (OCR), enforces the education portion of the ADA, ensuring the rights and protection of students with disabilities. Modifications for qualified students—like time extensions, modified computers with text readers, or voice recognition software—must be reasonable and cannot fundamentally alter the program. However, educational institutions are not required to provide students with personal assistive devices.
U.S. Dept. of Education, OCR Contact
Phone:1-800-421-3481
TDD:1-800-877-8339
Email:ocr@ed.gov
Web Site:https://www.ed.gov/ocrOpens in a new tab.

  • Health and Social Programs: The U.S. Department of Health and Human Services (HHS), Office for Civil Rights, enforces the health and social programs portion of Title II, ensuring non-exclusion from services offered by state and local government agencies.

Public Accommodations and Services Operated by Private Entities (Title III)

Title III addresses private-sector businesses and non-profit organizations that are open to the public, including places of lodging, restaurants, retail stores, movie theaters, private schools, and health care offices.

  • Exclusions: Title III excludes private clubs and religious organizations.
  • Readily Achievable: Covered entities must make readily achievable accommodations. This means “easily accomplishable and able to be carried out without much difficulty or expense,” considering the entity’s financial resources, the nature and cost of the action, and the size and type of business.
  • Communication: Reasonable modifications to policies must be made to ensure access to goods and services. For the visually disabled, this is often about communication, such as having an employee read a menu or price information. For more complex documents (contracts, forms), the visually disabled have the right to request access via alternate formats, such as computer disc, audio, or email.
  • Signage: The ADA Standards for Accessible Design, Chapter 7, details requirements for permanent signage (restrooms, room identifiers, exits). This includes specifications for Braille, tactile (raised lettering), visual contrast, and sign location.

The U.S. Department of Justice (DOJ), Civil Rights Division, enforces both Title II and Title III of the ADA.

U.S. Department of Justice Contact
Disability Rights SectionCivil Rights Division, U.S. Department of Justice, P.O. Box 66738, Washington D.C., 20035-6738
Toll-Free:1-800-514-0301
TTY:1-800-514-0383

Summary

The ADA has evolved through court rulings and modifications, notably the ADAAA, which ensured broad coverage for those with impairments, including low vision. Its ultimate goal is to eliminate prejudice, prevent exclusion and segregation, and act as an equalizer. Those with disabilities, including low vision, should be able to move about freely and enjoy all the privileges and advantages available to others.

Electrodiagnostic Testing for Vision Loss

Written by Terri Cyr in Uncategorized

VEP, ERG, and EOG

Electrodiagnostic testing is not part of a routine eye examination, but is included here because it is used in cases where there is suspicion of a disease process based on the findings of the routine eye examination.  The technology for these specialized tests are not found in every doctor’s office.  Testing is most likely to be found at a specialist’s office or a referral center.  It requires someone who is trained to administer the test and someone who is knowledgeable in interpreting the results. 

Each of these electrodiagnostic tests are used to specifically evaluate different parts of the visual system.  The tests are objective, meaning no responses are required on the part of the patient.  These are measurements of the neurological electrical activity of the various cells of the visual system. 

Electrodiagnostic testing is used to:

* Determine the cause of unexplained loss of visual acuity;

* Establish a diagnosis;

* Monitor the progression of a disease; and

* Test the visual acuity and visual  function of a patient that is unable to respond.

1. Visual Evoked Potential (VEP)

Visually evoked potential is also referred to as visual evoked response (VER) and visual evoked cortical potential (VECP).  This electrodiagnostic test is measuring  the electrical responses to light and pattern stimuli by the brain.  VEP is used when the retina appears  normal, but there is an unexplained decrease in vision.  The visual cortex of the brain and the optic nerve, connecting the eye to the brain, need to be evaluated as the potential source of decreased visual acuity or visual function.

The test is done by placing three electrodes on the scalp of the patient.  Light or pattern stimuli are presented to the eye of the patient.  The response of the brain is recorded by the instrument as electrical impulses.  If a  decrease of electrical activity is detected, a problem of the visual cortex of the brain or the optic nerve is suspected.

VEP is most often used for cases of;

* Unexplained decrease in visual acuity;

* Traumatic brain injury;

* Suspected multiple sclerosis (MS);

* Optic nerve disease: and

* Brain lesions along the visual pathway.(1)

It can also be used to measure visual acuity in patients that are unable to respond (infants and disabled adults).

2. Electroretinogram (ERG)

An electroretinogram is used to measure the electrical responses of the photoreceptors and other specialized ganglion cells of the retina.  This test requires one electrode placed on the front of the eye and a second one placed on the skin.  Light and pattern stimuli are presented to the patient, and the electrical response of the specialized cells of the retina are measured.  Measurements can be taken for specific areas of the retina (multifocal ERG) or the retina as a whole.  The test can even be modified to test specifically the rod or the cone photoreceptors.  A decrease in the electrical response indicates a decrease in the function of the light responsive cells of the retina.

ERG is most often used in cases of:

* Unexplained decrease in visual acuity;

* Diagnosis of inherited retinal diseases, like retinitis pigmentosa, Leber’s Congenital  Amaurosis, choroideremia, x-linked retinoschisis, and other rod/cone dystrophies;  

* Central nervous system disorders, with ocular involvement;

* Medical drug toxicity;

* Retinal vascular disease;

* Diabetic retinopathy; and

* Glaucoma.(2)

An ERG can often detect  retinal eye disease before it becomes apparent.

3. Electrooculogram (EOG)

The electrooculogram is a  test used to evaluate visual functioning at the level of the retinal pigment epithelium, which is an important support structure for the retina.  Electrodes are placed on the skin around the eyes.  The patient is asked to move their eyes back and forth between two light stimuli.  First measurements are taken in  the dark, then in the light.  A  decrease in electrical activity indicates a functional problem with the retinal pigment epithelium. 

EOG is more specifically used for cases of:

* Bests’ disease, in which the ERG is normal but the EOG will be depressed; and

* RPE dystrophies like Stargardt’s Disease.(3)

References:

1. Visually Evoked Response (VER) or Potential (VEP). LKC Technologies, 2007-2015. Retrieved from http://www.lkc.com/clinical/

2. Electroretinogram (ERG). LKC Technologies, 2007-2015. Retrieved from http://www.lkc.com/clinical/

3. Electro-oculogram (EOG). LKC Technologies, 2007-2015. Retrieved from http://www.lkc.com/clinical/

4. Creel, Donnell J. The Electroretinogram and Electro-oculogram: Clinical applications.  Webvision The Organization