The OAT exam — the Optometry Admission Test — is the standardized, multiple-choice test US optometry schools use in admissions.
It has four sections: Survey of the Natural Sciences (biology, general chemistry and organic chemistry), Reading Comprehension, Physics and Quantitative Reasoning.
You take it at a Prometric test center, and the full appointment runs five hours and five minutes.
Scores range from 200 to 400, and every US optometry school accepts OAT results.
What is the OAT?
The OAT — the Optometry Admission Test — is the standardized, multiple-choice admission exam for US optometry schools.
The Association of Schools and Colleges of Optometry (ASCO) is its governing body, and the ADA's Department of Testing Services runs the testing program.
Prospective optometry students take it at a Prometric test center as part of applying to Doctor of Optometry programs.
Results are reported as scale scores from 200 to 400 in 10-point increments.
It is the admissions exam for optometry school, not a licensing exam.
Licensing comes later — every state requires optometrists to be licensed — and the OAT does not itself complete that step.
What sections and how many questions?
The OAT has four multiple-choice sections, defined in the OAT program's 2026 Candidate Guide.
The Survey of the Natural Sciences is the largest section at 100 items, split into 40 biology, 30 general chemistry and 30 organic chemistry questions.
Reading Comprehension runs 50 items, Physics 40 and Quantitative Reasoning 40.
| Section | Questions | Time |
|---|---|---|
| Survey of the Natural Sciences | 100 (40 biology, 30 general chemistry, 30 organic chemistry) | 90 minutes. |
| Reading Comprehension | 50 | 60 minutes. |
| Physics | 40 | 50 minutes. |
| Quantitative Reasoning | 40 | 45 minutes. |
Specifications do get updated: the 2026 Candidate Guide anticipated updated Organic Chemistry test specifications in June 2026, which the ADA described as mainly renaming topics and expanding subtopic lists rather than changing content.
Check the current guide for the live specifications before you build a study plan.
How long is the test?
The timed sections run 90 minutes for the Survey of the Natural Sciences, 60 for Reading Comprehension, 50 for Physics and 45 for Quantitative Reasoning.
Around the sections, the appointment includes an optional 15-minute tutorial, an optional 30-minute scheduled break and an optional 15-minute post-test survey.
With all three optional pieces, the total administration time is five hours and five minutes.
You sit the whole appointment at a Prometric test center, so plan the day around it.
The optional pieces can shorten the session, but the section times are fixed.
How hard is the OAT?
There is no official answer, because there is no official passing score: the OAT program leaves it to each optometry program to decide what score it accepts.
The difficulty is structural.
A single sitting spans biology, general chemistry, organic chemistry, reading comprehension, physics and quantitative reasoning, and the pacing is tight — the Survey of the Natural Sciences alone is 100 questions in 90 minutes.
The retake rules also make every attempt count.
Candidates must wait 60 days between attempts and may test at most four times in any 12-month period.
After three attempts you need permission to test again, with proof of an optometry school application, and after a fifth attempt retesting is limited to once per 12 months.
Because the Candidate Guide sets no passing score, treat any single "good score" figure you see elsewhere as one school's expectation, not a national threshold.
Retake rules change
When should you take it?
The OAT program's own advice: take it in the second semester of your junior year of college, or in the summer between junior and senior year, after you have completed the subjects the test covers.
The logic is sequencing rather than a date.
The test assumes you have finished the coursework it covers, and the program's advice names organic chemistry in particular.
Build in retake room, too.
With a 60-day wait between attempts, a second sitting needs space on the calendar before your application deadlines.
Not every accepted applicant is a traditional-age student.
Of the 2,099 applicants accepted through OptomCAS in 2024-25, 152 were aged 26-30, 31 were 31-35, 12 were 36-40, 3 were 41-45 and 4 were 46 or older.
Older applicants are in the accepted pool too, and the sequencing advice translates directly: finish the coursework, then schedule the exam.
How do schools use it?
OAT results are accepted by every optometry school in the US and by select schools in Canada.
What each school does with the score is its own call — there is no official passing score, and each program decides what it accepts.
Scores are not the only door in.
For the 2026-27 cycle, OptomCAS's school table shows most optometry schools accepting the MCAT and/or DAT, and many accepting the GRE, in place of the OAT.
The alternatives vary by program.
SUNY lists GRE, MCAT, DAT and PCAT, while Southern College of Optometry accepts the GRE and MCAT only case by case.
Some classes have even arrived with little or no admission testing.
ASCO's profile of the 2025 entering class shows all 92 Indiana University School of Optometry matriculants entering with no admission test, and UC Berkeley admitted 24 of its 69 matriculants with no exam.
Policies move between cycles, though.
OptomCAS's 2026-27 table now lists Indiana University as strongly preferring the OAT and accepting the MCAT and DAT, so a school's test policy in one cycle is not a promise for the next.
Check each target school's current admissions page before you choose which exam to sit.
Career information for future optometry students — not medical, licensing, billing or legal advice. Test rules are the OAT program's and admissions requirements are each school's; confirm current details with both before you register or apply.