• My Dashboard My Education Find an Ophthalmologist
  • Home
  • Coronavirus
  • For Ophthalmologists
    • Meetings
      • AAO 2022
        • Meeting Information
          • Past and Future Meetings
          • Mobile Meeting Guide
          • Contact Information
          • Annual Meeting News
          • Health and Safety
          • Policies and Disclaimers
        • Program
          • Program Highlights
          • Subspecialty Day
          • Virtual Meeting
          • Program Committees
          • CME
          • Meeting Archives
        • Expo
        • Registration
        • Hotels & Travel
          • Hotel Reservation Information
          • Chicago
          • International Attendees
          • Hotel Meeting Space
        • Presenter Central
          • Presenter Central
          • Abstract Selection Process
          • Submission Policies
          • Subject Classification/Topics
          • Instruction Courses and Skills Transfer Labs
          • Papers and Posters
          • Videos
          • Grand Rounds Symposium
          • Program Participant and Faculty Guidelines
          • Faculty Development Program
        • Exhibitors
          • Exhibitor Central
          • Exhibitor Portal Information
          • Exhibitor Prospectus
          • New Exhibiting Companies
          • Exhibitor Resources
          • International Exhibitors
          • Promotional Opportunities
          • Exhibitor Hotel Reservations
      • Mid-Year Forum
        • Registration and Travel
        • Congressional Advocacy Day
        • Advocacy Ambassador Program
        • Program
        • Schedule
        • Sponsored Attendees
        • News
      • Codequest
        • Codequest Instructors
        • Claim Codequest CME or CEU Credit
      • Eyecelerator
    • Clinical Education
      • COVID-19
      • Education
        • Browse All Education
        • Courses
        • Cases
        • Learning Plans
        • Interactive
        • Focal Points
        • Wills Eye Manual
        • Disease Reviews
        • Clinical Webinars
        • Diagnose This
        • Self-Assessments
        • Educational Centers
          • Glaucoma Education Center
          • Pediatric Ophthalmology Education Center
          • Laser Surgery Education Center
          • Myopia Resources
          • Oculofacial Plastic Surgery Center
          • Redmond Ethics Center
      • Journals
      • Guidelines
        • Browse All Practice Guidelines
        • Preferred Practice Patterns
        • Clinical Statements
        • Compendium Guidelines
        • Complementary Therapy Assessments
        • Medical Information Technology
        • Ophthalmic Technology Assessments
        • Patient Safety Statements
        • Choosing Wisely
        • Low Vision
        • Eye Care for Older Adults
        • Eye Disease Statistics
        • About the Hoskins Center
      • Video and Image Library
        • Browse All Videos
        • Clinical and Surgical Videos
        • Presentations and Lectures
        • 1-Minute Videos
        • Master Class Videos
        • Basic Skills Videos
        • Interviews
        • Images
        • Submit an Image
        • Submit a Video
      • Podcasts
        • Browse All Audio and Podcasts
        • Experts InSight
        • Ophthalmology Journal
      • News
        • Browse All Clinical News
        • Editors' Choice
        • Headlines
        • Current Insight
      • CME Central
        • Browse All CME Activities
        • Claim CME Credit and View Transcript
        • CME Planning Resources
        • Complete Your Financial Disclosure
        • Joint Sponsorship Portal
        • LEO Continuing Education Recognition Award
        • Safe ER/LA Opioid Prescribing
        • Check Your Industry Payment Records
      • MOC
      • Resident Education
        • Resident Education Home
        • Browse All Resident Content
          • Courses
          • Flashcards
          • Interactive Cases and Simulations
          • Videos
          • Webinars
        • OKAP and Board Exam Resources
          • OKAP Exam
          • Board Prep Resources
          • OKAP and Board Review Presentations
          • Study Flashcards
        • Cataract Master
        • Diversity and Inclusion Education
        • News and Advice from YO Info
        • Pediatric Ophthalmology Education Center
        • PGY-1 and PGY-2 Resources
        • Simulation in Resident Education
    • Membership
      • Join
      • Renew
      • Current Member
      • Volunteer
      • Physician Wellness
      • Member Directory
      • Member Obituaries
      • AAOE Membership
    • Advocacy
      • Advocacy News
      • Get Involved
        • Ways to Give
        • How to Get Involved
        • Congressional Advocacy
        • Support the Academy's Agenda
        • Research Legislation
        • Find Your Legislators
        • I Am an Advocate
        • Advocacy at Home
        • Advocate Tools
        • Best Practices for Advocating at Home
        • Social Media Toolkit
        • Letter to Editor
        • Town Hall Guide
        • Guide to Engaging With New Lawmakers
        • Resources
        • Attending a Political Fundraiser
      • OPHTHPAC
        • About Us
        • Join OPHTHPAC
        • OPHTHPAC Blog
      • Surgical Scope Fund
        • Support Surgery By Surgeons
        • Surgery By Surgeons Blog
    • Publications
      • EyeNet Magazine
        • Latest Issue
        • Archive
        • Subscribe
        • Advertise
        • Write For Us
        • Corporate Lunches
        • Contact
        • MIPS 2022
      • Focal Points
      • Ophthalmology
      • Ophthalmology Glaucoma
      • Ophthalmology Retina
      • YO Info
      • Scope
    • Subspecialties
      • Cataract/Anterior Segment
      • Comprehensive Ophthalmology
      • Cornea/External Disease
      • Glaucoma
      • Neuro-Ophthalmology/Orbit
      • Ocular Pathology/Oncology
      • Oculoplastics/Orbit
      • Pediatric Ophthalmology/Strabismus
      • Refractive Management/Intervention
      • Retina/Vitreous
      • Uveitis
    • IRIS Registry
      • About
      • Using the Registry
        • User Guide
        • Medicare Reporting
        • Maintenance of Certification
        • Non-EHR Reporting
      • Sign Up
        • Application Process
        • Why Participate
        • Once You've Applied: Getting Started
        • What Practices Are Saying About the Registry
      • Requirements
        • EHR Systems
        • Data & Technical Needs
      • Research
      • Registry Dashboard
      • News
      • Medicare & MIPS
    • Medicare Information
    • Diversity, Equity, and Inclusion
  • For Practice Management
    • Managing Your Practice
      • Managing Your Practice Topics
      • Coronavirus Resources
      • Reopening & Recovery
      • Practice Forms Library
      • Practice Management News and Advice
      • AAOE-Talk
      • Video Library
      • Ophthalmology Job Center
      • Benchmarking and Salary Tools
      • Academy Consultations
      • Consultant Directory
    • Coding
      • Coding Topics
      • Codequest Events
      • Ask the Coding Experts
      • Coding Updates and Resources
      • Coding for Injectable Drugs
      • EM Documentation
      • ICD-10-CM
      • Ophthalmic Coding Specialist (OCS) Exam
      • Retina
      • Savvy Coder
    • Webinars and Events
      • Annual Meeting
      • Codequest Courses
      • Mid-Year Forum
      • Webinar Recordings
    • IRIS Registry
      • Merit-Based Incentive Payment
    • Medicare and MIPS
      • MIPS
        • Quality
        • Promoting Interoperability
        • Improvement Activities
        • Cost
        • Avoid a Penalty
      • Resources
      • Medicare Participation Options
      • Medicare Advantage Plans
      • New Medicare Card
      • Provider Enrollment, Chain and Ownership System (PECOS)
    • Regulatory Compliance
      • HIPPA Resources
      • Office of Inspector General
      • Audits
      • OSHA
    • AAOE Membership
      • Join AAOE
      • Membership Benefits
      • Renew/Pay Dues
    • About AAOE
      • AAOE Board of Directors
      • AAOE Content Committee
      • Volunteer Opportunities
  • For Public & Patients
    • Eye Health A-Z
    • Symptoms
    • Glasses & Contacts
    • Tips & Prevention
    • News
    • Ask an Ophthalmologist
    • Patient Stories
    • No Cost Eye Exams
    • Español
      • A - Z de Salud Ocular
      • Síntomas
      • Anteojos y Lentes de Contacto
      • Consejos y Prevención
      • Noticias
      • Relatos de Pacientes
      • Exámenes de la vista sin costo
      • English
  • AAO 2022
    • Meeting Information
      • Past and Future Meetings
      • Mobile Meeting Guide
      • Contact Information
      • Annual Meeting News
      • Health and Safety
      • Policies and Disclaimers
    • Program
      • Program Highlights
      • Subspecialty Day
      • Virtual Meeting
      • Program Committees
      • CME
      • Meeting Archives
    • Expo
    • Registration
    • Hotels & Travel
      • Hotel Reservation Information
      • Chicago
      • International Attendees
      • Hotel Meeting Space
    • Presenter Central
      • Presenter Central
      • Abstract Selection Process
      • Submission Policies
      • Subject Classification/Topics
      • Instruction Courses and Skills Transfer Labs
      • Papers and Posters
      • Videos
      • Grand Rounds Symposium
      • Program Participant and Faculty Guidelines
      • Faculty Development Program
    • Exhibitors
      • Exhibitor Central
      • Exhibitor Portal Information
      • Exhibitor Prospectus
      • New Exhibiting Companies
      • Exhibitor Resources
      • International Exhibitors
      • Promotional Opportunities
      • Exhibitor Hotel Reservations
  • About
    • Who We Are
      • What We Do
      • About Ophthalmology
      • The Eye Care Team
      • Ethics and the Academy
      • History
      • Museum of Vision
      • Values
    • Governance
      • Council
      • Board of Trustees
      • Committees
      • Academy Past Presidents
      • Secretariats
      • Elections
      • Academy Blog
      • Academy Staff Leadership
    • Leadership Development
    • Awards
      • Laureate Recognition Award
      • Outstanding Advocate Award
      • Outstanding Humanitarian Service Award
      • International Blindness Prevention Award
      • Distinguished Service Award
      • Guests of Honor
      • Secretariat Award
      • Straatsma Award
      • Achievement Award Program
      • Artemis Award
      • EnergEYES Award
      • International Education Award
      • International Scholar Award
      • Commitment to Advocacy Award
      • Visionary Society Award
    • Financial Relationships
    • Policy Statements
    • Related Organizations
      • Subspecialty/Specialized Interest Society Directory
      • State Society Directory
      • Subspecialty/Specialized Interest Society Meetings
      • State Society Meetings
      • Resources for Societies
    • Year in Review
      • 2020 Year in Review
  • Foundation
    • About
      • 2020-2021 Annual Report
      • Annual Report Archives
      • News From the Chair
      • Foundation Staff
    • Our Impact
      • Partners for Sight
      • Donor Spotlights
      • Global Ophthalmic Community
      • Sponsorships
      • Patients and the Public
    • Giving Options
      • Our Supporters
      • Estate and Planned Giving
      • Ophthalmic Business Council
      • Parke Center Campaign
      • Minority Ophthalmology Mentoring Campaign
      • Museum of the Eye Campaign
    • Orbital Gala
      • Why Attend
      • Photo Recap
      • Corporate Support Opportunities
      • Tribute Gifts
      • Silent Auction
      • Corporate Sponsors
    • Donate
    • Museum of the Eye Campaign
      • Museum Supporters
  • Museum of the Eye
    • Visit
    • What's On
      • Museum Galleries
      • Special Exhibitions
      • Current Events
      • Past Events
    • Explore
      • Research and Resources
      • Collection Search
      • Previous Exhibits
      • Oral Histories
      • Biographies
    • Volunteer
    • Mailing List
    • Donate
    • About the Museum
      • Museum Blog
  • Young Ophthalmologists
    • YO Info
    • Learn to Bill
    • Engage with the Academy
  • Senior Ophthalmologists
    • Scope
    • Practice Transitions
  • International Ophthalmologists
    • Global Programs and Resources for National Societies
    • Awards
    • Global Outreach
  • Residents
  • Medical Students
×
Shop
Log In Create an Account
  • For Ophthalmologists
  • For Practice Management
  • For Public & Patients
  • Coronavirus
  • About
  • Foundation
  • Museum of the Eye
  • COVID-19
  • Journals
  • Education
    • Education
    • Courses
    • Cases
    • Learning Plans
    • Interactive
    • Focal Points
    • Wills Eye Manual
    • Disease Reviews
    • Clinical Webinars
    • Diagnose This
    • Self-Assessments
    • Education Centers
      • Glaucoma Education Center
      • Pediatric Ophthalmology Education Center
      • Laser Surgery Education Center
      • Oculofacial Plastic Surgery Center
      • Redmond Ethics Center
      • Myopia Resources
      • Thyroid Eye Disease Resources
  • Guidelines
    • Practice Guidelines
    • Preferred Practice Patterns
    • Clinical Statements
    • Ophthalmic Technology Assessments
    • Patient Safety Statements
    • Complementary Therapy Assessments
    • Compendium Guidelines
    • Medical Information Technology
    • Low Vision
    • Choosing Wisely
    • Eye Care for Older Adults
    • Eye Disease Statistics
    • About the Hoskins Center
    • Artificial Intelligence
    • Premium IOLs
    • Patient-Reported Outcomes with LASIK Symptoms and Satisfaction
  • Multimedia
    • Multimedia Library
    • Video
      • 1-Minute Videos
      • Presentations and Lectures
      • Master Class Videos
      • Basic Skills Videos
      • Clinical and Surgical Videos
      • Interviews
      • Resident Lectures
      • Submit a Video
      • YO Video Contest
    • Podcasts
      • Browse Podcast Archive
      • Experts InSight Podcast
      • Ophthalmology Journal Podcast
    • Images
      • Submit an Image
  • News
    • Clinical News
    • Editors' Choice
    • Headlines
    • Current Insight
  • CME
    • CME Central
    • Claim CME Credit and View Transcript
    • CME Planning Resources
    • Complete Your Financial Disclosure
    • Joint Sponsorship Portal
    • LEO Continuing Education Recognition Award
    • Safe ER/LA Opioid Prescribing
    • Check Your Industry Payment Records
  • MOC
  • Residents
    • Resident Education Home
    • Browse All Resident Content
      • Courses
      • Flashcards and Study Presentations
      • Interactive Cases and Simulations
      • Videos
      • Webinars
    • Cataract Master
    • Diversity and Inclusion Education
    • News and Advice from YO Info
    • OKAP and Board Exam Resources
      • OKAP Exam
      • Board Prep Resources
      • OKAP and Board Review Presentations
      • Study Flashcards
    • Pediatric Ophthalmology Education Center
    • PGY-1 and PGY-2 Resources
    • Resident Knowledge Exchange
    • Simulation in Resident Education
    • Clinical Education /
    • Book Excerpts /
    • Basic and Clinical Science Course - Excerpt
  • 2020–2021 BCSC Basic and Clinical Science Course™

    Go to Academy Store Learn more and Purchase.

    3 Clinical Optics

    Introduction: Quick-Start Guide to Optics and How to Refract

    Part 2: How to Refract

    Step 3: Obtain Initial Estimate of the Refractive Error

    Having established that a patient needs to be refracted, obtain the best-available initial estimate of the refractive correction (if any) and dial it into the phoropter or place it in a trial frame.

    The phoropter is a device that holds trial lenses on geared wheels to facilitate exchanging lenses in front of the patient’s eyes during a manifest refraction (Figure I-24A). An alternate term is refractor; the term Phoroptor is a trademark of Reichert Technologies (Depew, NY).

    Each side of the phoropter holds lenses for a large range of plus sphere and minus sphere power. The “cylinder battery,” or array of cylindrical lenses, contains cylinders of only 1 sign, either plus or minus, depending on the individual instrument. Before beginning a refraction, you must determine whether the phoropter in front of you is a plus cylinder or minus cylinder instrument. Note: On American-made instruments and their knock-offs, minus cylinders are indicated with red numbers (Fig I-24); plus cylinders are indicated with black numbers.

    Figure I-24 Phoropter. A, A minus cylinder phoropter. B, The red numbers indicate the cylinder power.

    Perform Either Step 3a or Steps 3b and 3c

    Step 3a. Use prior information to obtain initial estimate of refractive error

    • Measure the patient’s current eyeglasses, if available, and dial these values into the phoropter. (Use of the lensmeter to measure—“neutralize”—glasses is described in Chapter 8.) Use the result of a previous refraction, such as a previous prescription for glasses as provided by the patient, or as recorded in the patient’s medical record.

    • Perform retinoscopy (see Chapter 4).

      • If lenses in the phoropter are clean, retinoscopy may be performed through the phoropter, so that the results of the retinoscopy will be immediately available as the phoropter settings to serve as the starting point for subjective refraction. It is a good habit to write down the retinoscopic findings for comparison with the final refraction.

    • Use an autorefractor or a photorefractor.

      • This procedure seldom saves time if you have to take the patient to a different room. Autorefractors are essentially automated retinoscopes. They work well on eyes with clear media and adequate pupils in patients with steady, central fixation. In patients with media opacities, small pupils, or an inability to sit still—just the patients with whom you could appreciate some automated help—they generally fail.

    • If there is no known astigmatic correction, proceed directly to step 5; if there is an astigmatic correction, go to step 4.

    Step 3b. Make direct initial measurement of spherical refractive error

    • If no preliminary estimate is available from old glasses, the medical record, retinoscopy or autorefraction, determine the best spherical correction by offering the patient successive choices of alternative spherical corrections. Starting with the spherical power at 0.00, use the low-power sphere lens wheel on the phoropter (or hand-held lenses if using a trial frame), offer the patient a choice between a spherical lens power of +0.25 D or –0.25 D. This gives the patient a choice between spherical lenses that differ by 0.50 D. (If the patient’s visual acuity is very poor, offer a greater difference between the 2 choices of sphere power.) Use the language “Which is better, 1 or 2?” This “forced choice” is referred to as a binary comparison.

      • Make certain the patient is referring to your choice between lens 1 or lens 2, not line 1 or line 2 of the eye chart. If necessary, mask off all but 1 line of the chart.

      • If the patient’s acuity is very poor, it may be preferable to offer binary comparisons with choices that differ by 1.00 D.

    • Advance the sphere setting 0.25 D toward the preferred alternative, and then offer the next binary comparison to bracket the patient’s most recent choice of sphere power setting, again with a 0.50 D difference. (For example, if the patient’s initial preference is for the –0.25 lens, the next choice offered should be between 0.00 and –0.50 D lenses.)

    • Repeat this process until the patient suggests that the 2 choices are about the same.

    • Recheck this endpoint, using choices that differ by only 0.25 D.

    • Generally, try to move most of the time from more plus to less plus (or from less minus to more minus). By offering the more plus or less minus choice first, you will stimulate accommodation only minimally.

      • Try to be sensitive to the patient’s responses. As you near the endpoint, responses are typically slower. The patient may simply stop responding rather than volunteer that the choices are about the same. This is still useful information.

    • Do not worry about making a mistake by going too far—the method is self-correcting.

    • Once the best possible spherical correction has been determined, go to step 3c to determine if there is any astigmatic refractive error.

    Step 3c. Detect astigmatism

    Now that you have found the optimal correction by using only spheres, determine whether there is any astigmatism as follows.

    (Directions for use with a minus cylinder phoropter)

    1. Dial in –0.50 D of the cylinder.

    2. Increase the sphere power by +0.25 D.

    3. Rotate the cylinder axis knob slowly once or twice around, and ask the patient to tell you to stop when he or she perceives the clearest vision. (Alternatively, you may ask the patient to turn the knob and leave it where his or her vision is best.)

    4. If the patient reports that rotating the dial makes no difference to the visual clarity—even if the vision is rather poor—then you may assume that the patient has no significant astigmatism, and proceed to step 5. If the patient can select a preferred axis, you have detected an astigmatic refractive error. Leave the cylinder dial at the preferred axis orientation, and proceed to step 4.

    (Directions for use with a plus cylinder phoropter)

    1. Dial in +0.50 D of the cylinder.

    2. Decrease the sphere power by –0.25 D.

    3. Rotate the cylinder axis knob slowly once or twice around, and ask the patient to tell you to stop when he or she perceives the clearest vision. (Alternatively, you may ask the patient to turn the knob and leave it where his or her vision is best.)

    4. If the patient reports that rotating the dial makes no difference to the visual clarity—even if the vision is rather poor—then you may assume that the patient has no significant astigmatism, and proceed to step 5. If the patient can select a preferred axis, you have detected an astigmatic refractive error. Leave the cylinder dial at the preferred axis orientation, and proceed to step 4.

    If the visual acuity is very poor, especially if there is a very large astigmatic refractive error, the patient may be unable to appreciate a variation in visual acuity by rotating a cylinder lens as described above. If possible, check for astigmatism by retinoscopy, by keratometry, or by using the stenopeic slit (see Chapter 4).

    Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.

  • Most Commented
    Loading, please wait...
    There are no comments available.
    Most Viewed
    Loading, please wait...
    Most Viewed content is not available.
  • The Academy Store
    2022-2023 Basic and Clinical Science Course, Complete Print Set
    2022-2023 Basic and Clinical Science Course, Complete eBook Set
    2022-2023 Basic and Clinical Science Course, Complete Print and eBook Set
    2022-2023 Basic and Clinical Science Course, Residency Print Set
    2022-2023 Basic and Clinical Science Course, Residency eBook Set
    2022-2023 Basic and Clinical Science Course Complete Set
    2022-2023 Basic and Clinical Science Course Residency Set
    2022-2023 Basic and Clinical Science Course, Section 01: Update on General Medicine
    2022-2023 Basic and Clinical Science Course, Section 02: Fundamentals and Principles of Ophthalmology
    2022-2023 Basic and Clinical Science Course, Section 03: Clinical Optics and Vision Rehabilitation
    2022-2023 Basic and Clinical Science Course, Section 04: Ophthalmic Pathology and Intraocular Tumors
    2022-2023 Basic and Clinical Science Course, Section 05: Neuro-Ophthalmology
    2022-2023 Basic and Clinical Science Course, Section 06: Pediatric Ophthalmology and Strabismus
    2022-2023 Basic and Clinical Science Course, Section 07: Oculofacial Plastic and Orbital Surgery
    2022-2023 Basic and Clinical Science Course, Section 08: External Disease and Cornea
    2022-2023 Basic and Clinical Science Course, Section 09: Uveitis and Ocular Inflammation
    2022-2023 Basic and Clinical Science Course, Section 10: Glaucoma
    2022-2023 Basic and Clinical Science Course, Section 11: Lens and Cataract
    2022-2023 Basic and Clinical Science Course, Section 12: Retina and Vitreous
    2022-2023 Basic and Clinical Science Course, Section 13: Refractive Surgery
    The Technician Point System: How to Improve Practice Accountability and Bottom Line (Free Member Webinar)
    Transitioning Your Practice: Retiring, Selling or Buying a Practice (Free Member Webinar)
    2022 IRIS Registry (Intelligent Research in Sight) Preparation Kit
    Advances in Medical and Surgical Management: The 2022 Update on Glaucoma
    Presbyopia-Correcting IOLs
    2022 Codequest - Multistate (Recorded March 29)
    2022 Codequest Virtual (Multistate)
    Retina Patient Education Video Collection
    Cataract and Refractive Surgery Patient Education Video Collection
    Glaucoma Patient Education Video Collection
 
  • Contact Us
  • About the Academy
  • Jobs at the Academy
  • Financial Relationships with Industry
  • Medical Disclaimer
  • Privacy Policy
  • Terms of Service
  • Help
  • For Advertisers
  • For Media
  • Ophthalmology Job Center

OUR SITES

  • EyeWiki
  • International Society of Refractive Surgery

FOLLOW THE ACADEMY

Medical Professionals

  • Facebook
  • Twitter
  • LinkedIn
  • YouTube

Public & Patients

  • Facebook
  • Twitter
  • Instagram
  • YouTube

Museum of the Eye

  • Facebook
  • Twitter
  • Instagram
  • YouTube
  • Trip Advisor
  • Yelp
© American Academy of Ophthalmology 2022