The Optometry Admission Test (OAT®) is the standardized exam required for admission to optometry schools in the United States and Canada. Administered by the Association of Schools and Colleges of Optometry (ASCO®), the OAT® measures your knowledge of the natural sciences, your quantitative reasoning ability, your reading comprehension, and your understanding of physics. A solid OAT® score is a critical component of your OptomCAS® application. This page covers the full exam structure, registration process, scoring, study timelines, and the best free resources to prepare.
Exam Format and Structure
The OAT® is a computer-based exam with a total testing time of approximately 4 hours and 50 minutes, including breaks. It contains 230 items divided across four main sections.
Survey of the Natural Sciences (SNS): 100 questions in 90 minutes. Covers biology (40 questions), general chemistry (30 questions), and organic chemistry (30 questions). The biology content emphasizes cell biology, genetics, evolution, ecology, anatomy, and developmental biology. General chemistry topics include stoichiometry, thermodynamics, solutions, equilibrium, and electrochemistry. Organic chemistry focuses on nomenclature, reactions, mechanisms, and stereochemistry.
Reading Comprehension (RC): 40 questions in 50 minutes. Three scientific passages, each followed by comprehension questions. The passages typically cover topics in the natural and health sciences, and you are not expected to have prior knowledge of the specific subject matter.
Physics: 40 questions in 50 minutes. Covers vectors, mechanics, energy, thermodynamics, magnetism, optics, and modern physics. Optics is a particularly important topic given the profession of optometry, and questions on lenses, mirrors, refraction, and diffraction appear frequently.
Quantitative Reasoning (QR): 40 questions in 45 minutes. Tests applied mathematics including algebra, numeric calculations, probability, statistics, geometry, and trigonometry. An on-screen calculator is available for this section.
Registration and Scheduling
The OAT® is offered year-round at Prometric testing centers. Register through the OAT® program on the ASCO® website. The exam fee is approximately $495, which includes one official score report. Additional score reports can be sent for a fee. You must wait at least 90 days between attempts, and there is no limit on the total number of times you can take the exam, though all scores are reported to schools.
Scoring
Each section is scored on a scale of 200 to 400, with 300 as the approximate national mean. You also receive an Academic Average (AA) score that averages across your SNS, RC, Physics, and QR scores. A Total Science (TS) score averages biology, general chemistry, and organic chemistry.
Competitive applicants typically aim for an AA of 320 or above. The average AA for admitted students at most optometry programs falls between 310 and 340, though this varies by school. Research specific program profiles on the ASCO® website or through OptomCAS®. Keep in mind that a strong Physics score can be especially valuable in optometry admissions, given the discipline’s emphasis on optics and visual science.
When to Take the OAT
Most applicants take the OAT® during the spring or summer before they submit their OptomCAS® application. We recommend completing general biology, general chemistry, organic chemistry, and physics before taking the exam. If your program of interest has a specific application deadline, plan to have your OAT® score available at least one month before that date.
How Long to Study
A typical study timeline is 2 to 4 months, with 10 to 20 hours of study per week. Students who have recently completed their prerequisite courses may need less time; those who completed them a year or more ago should budget additional weeks for content review. Begin by taking a diagnostic practice exam to establish your baseline and identify areas that need the most attention. Build your study schedule around your weakest sections and revisit them consistently throughout your preparation period.
We recommend dividing your study period into three phases. During the first phase (approximately one-third of your total time), focus on content review using textbooks and video resources. During the second phase, shift to practice questions and timed section work. During the final phase, take full-length practice exams under test-day conditions and refine your weak areas based on the results.
Recommended Study Resources (Free First)
ASCO® Official OAT® Practice Tests: The most accurate representation of the actual exam. Purchase from the ASCO® website and use these tests as benchmarks during the final weeks of your preparation.
Khan Academy® (Free): Khan Academy® provides free, comprehensive video lessons and practice in biology, general chemistry, organic chemistry, and physics. While the content is not OAT®-specific, it aligns closely with the tested subjects. Start here for content review. See our Khan Academy® guide for tips.
OpenStax Textbooks (Free): Free, peer-reviewed textbooks covering biology, chemistry, and physics are available through OpenStax. These provide thorough foundational review. Visit our free textbooks page for links.
Physics Study Focus (Free Resources): The physics section of the OAT® places special emphasis on optics. Use Khan Academy® physics videos and OpenStax College Physics for general review, then focus additional time on geometric optics, wave optics, lenses, and mirrors. Our physics study guide covers these topics.
Anki Flashcard Decks (Free): Community-created OAT® flashcard decks are available for download on the Anki platform. Use spaced repetition for biology terminology, organic chemistry reactions, and physics formulas. See our spaced repetition guide.
Paid Resources (Consider After Free Options): Several companies offer OAT®-specific question banks and practice exams. If you use paid materials, compare their question style and difficulty to the official ASCO® practice tests before investing. We do not place affiliate links.
Study Strategies by Section
Biology: Prioritize cell biology, molecular biology, genetics, anatomy and physiology (organ systems), ecology, and evolution. The scope is broad, so use flashcards to manage the volume of terms and concepts. Our biology study guide provides a topic-level breakdown.
General Chemistry: Focus on equilibrium, acids and bases, thermodynamics, solutions, electrochemistry, and gas laws. Practice quantitative problem-solving under timed conditions. See our general chemistry study guide.
Organic Chemistry: Master the major reaction types (substitution, elimination, addition, oxidation/reduction, carbonyl chemistry) and be comfortable with stereochemistry, nomenclature, and spectroscopy basics. See our organic chemistry study guide.
Physics: Cover all topics in the content outline, but spend extra time on optics (lenses, mirrors, refraction, thin lens equation, magnification), as this is particularly relevant to optometry and is tested heavily. Our physics study guide covers the full range.
Reading Comprehension: Practice reading dense scientific passages under timed conditions. Focus on identifying the main idea, supporting details, and the author’s purpose. Skills developed here transfer to your academic coursework as well.
Quantitative Reasoning: Review basic algebra, probability, statistics, and geometry. Practice with timed problem sets to build speed. This section is typically approachable for students who have completed college-level math.
Next Steps After the OAT
Your OAT® scores are sent to optometry schools through OptomCAS®. If you need to retake the exam, wait the required 90 days, carefully analyze your section scores, adjust your study plan based on what the data shows, and retake. For detailed information on the optometry school application process, see our OptomCAS® application guide and the optometrist career profile.
References
Association of Schools and Colleges of Optometry (ASCO). “Optometry Admission Test (OAT).” ASCO, 2025. https://www.opted.org/oat/. Accessed March 2026.
Khan Academy. “Science.” Khan Academy, 2025. https://www.khanacademy.org/science. Accessed March 2026.
OpenStax. “Free Textbooks.” Rice University, 2025. https://openstax.org/. Accessed March 2026.