Applied Basic Science,made clinical.
The first exam in the NBEO series tests the biomedical and vision science you need for independent practice. Most items tie back to a clinical condition, directly or indirectly.
At a glance
Part I ABS
- Items
- 370
- Sessions
- 2 × 185
- Time
- 4 h
- Multiple response
- 10 to 15%
- Where
- Pearson
- When
- Mar · Aug
Next exam: Mar 15 to 18, 2027
Format
How the examis built.
One day, two sessions, 370 items. Here is what the items look like and how to pace them.
The numbers
- 370Items
- 350 scored and 20 unscored pretest items. You will not know which are which.
- 2 × 185Sessions
- Two sessions in one day, with an optional break of up to 45 minutes between them.
- 4 hTime
- Per session, about 78 seconds an item. Session one adds 15 minutes for the tutorial and agreement.
- 10 to 15%Multiple response
- Items that ask for 2, 3 or 4 answers. Every choice must be right: there is no partial credit.
- PearsonWhere
- Computer-based at Pearson test centers in the US, Puerto Rico and Canada.
- Mar · AugWhen
- Offered every March and August. You sit it on one day of the window.
01
Single best answer
Most items ask for the one best answer from a list of choices.
02
Multiple response
About 10 to 15% of items ask for 2, 3 or 4 answers and say how many. Every choice must be right to earn the point.
03
Condition-based
Most items tie basic science to a clinical condition, directly or indirectly. Expect a patient behind the physiology.
04
Generic drug names
Drugs appear by generic name only, so learn latanoprost rather than its brand name.
05
Pretest items
20 of the 370 items are unscored pretest questions mixed in with the rest. Treat every item as if it counts.
06
Pacing
185 items in 4 hours is about 78 seconds each. Flag a long item and come back rather than stalling on it.
Content
What Part Icovers.
NBEO publishes a content matrix and two outlines, one by condition and one by discipline. These are the areas our planner and question bank use, with the share of study time the planner gives each one.
Ocular disease and pathology
Lids, adnexa, cornea, uvea, lens, retina and optic nerve disease, from mechanism to clinical signs.
Planner share22%Ocular anatomy and physiology
Structure and function of the globe, adnexa and orbit, aqueous dynamics and phototransduction.
Planner share18%Optics and ametropia
Geometric, physical and ophthalmic optics: vergence, prism, lenses, coatings and refractive error.
Planner share16%Systemic health, microbiology and immunology
General anatomy and physiology, pathogens, hypersensitivity and the systemic diseases that reach the eye.
Planner share10%Pharmacology
Mechanisms, side effects and interactions of ocular and systemic drugs, always named by generic name.
Planner share10%Binocular vision and oculomotor function
Accommodation, vergence, AC/A ratio, fusional reserves, amblyopia and strabismus.
Planner share7%Neuroanatomy and the visual pathway
Cranial nerves, pupillary pathways and visual field defects by lesion site.
Planner share6%Contact lenses and low vision
Lens materials and fitting optics, vertex power, magnification and low vision devices.
Planner share6%Perception, color vision and development
Psychophysics, spectral sensitivity, color vision deficiencies and visual development.
Planner share5%
Strategy
How to preparefor Part I.
Five habits that make the most of the months before a March or August sitting.
- 1
Start with the heaviest areas
Ocular disease, anatomy and physiology, and optics carry the most weight. Build those first, then layer in the rest.
- 2
Make the formulas automatic
Vergence, Prentice's rule, effective power, critical angle and the AC/A ratio should take seconds, not minutes.
- 3
Study by condition, not by course
Items are condition-based, so connect each disease to its anatomy, physiology, microbiology and drugs in one sitting.
- 4
Practice multiple-response items on purpose
Check how many answers the stem wants and judge each option on its own. There is no partial credit.
- 5
Build stamina with full sessions
In the final weeks, sit at least one full 185-item session in 4 hours so exam day feels familiar.
Key dates
When to sitPart I.
Register through NBEO, then book your seat with Pearson as early as you can.
| Exam date | Register by | Scores released | Notes |
|---|---|---|---|
| Mar 15 to 18, 2027 | Mar 1, 2027 | May 7, 2027 | You test on one day of the window |
| Aug 18 or 19, 2027 | Aug 4, 2027 | Oct 8, 2027 | You test on one day of the window |
From NBEO's 2026 to 2027 exam calendar. NBEO notes that dates can change.
Check the official calendarPart I ABS question bank
24 questions with full explanations
Study notes
High-yield notes for Part I.Read, then practice.
Get started
Part I startswith one question.
Try ten Part I questions in tutor mode, with a full explanation after every answer.