24.1 Timed Practice Strategy
Key Takeaways
- The COA exam gives 180 minutes for roughly 200 scored items, so budget about 50 seconds per question and protect a 15-minute review buffer.
- Answer every item: there is no penalty for guessing, so a flagged-but-answered question always beats a blank one.
- Review missed items by cause (recall gap, misread, calculation, sequence) using an error log, not just by raw score.
- Full-length timed sets are only useful when you study the rationale for every miss and every guessed correct answer.
24.1 Timed Practice Strategy
The Certified Ophthalmic Assistant (COA) exam is delivered by IJCAHPO (International Joint Commission on Allied Health Personnel in Ophthalmology) through Pearson VUE test centers or OnVUE remote proctoring. You answer about 200 scored multiple-choice questions plus a small block of unscored pretest items (you may see roughly 210-225 total) within a 180-minute window. The passing standard is a scaled score of 72, set by a modified-Angoff criterion-referenced method, so you are measured against a fixed competency bar, not against other candidates.
Pace math you must internalize
Divide time by items to get a hard target. With 180 minutes and ~200 scored questions, you have roughly 54 seconds per item. Build in a buffer for review, and your working pace is closer to 45-50 seconds. Set physical checkpoints so you never drift:
| Clock elapsed | You should be at or past | Notes |
|---|---|---|
| 45 min | Question 50 | First quarter; calibrate pace |
| 90 min | Question 100 | Halfway in time and items |
| 135 min | Question 150 | Last quarter begins |
| 165 min | All items answered | 15 min reserved for flagged review |
If at 90 minutes you are only on question 80, you are behind: pick up speed by answering more on first read and flagging less.
No-penalty guessing rule
IJCAHPO scoring gives no deduction for wrong answers, so a blank is strictly worse than a guess. Never leave the building with an unanswered item. The disciplined move is: commit a best answer on first pass, flag it if uncertain, and only return if time remains.
Three-pass method
A repeatable structure beats reading every stem twice in random order.
- Pass 1 (fast): Answer everything you know in under 30 seconds. Flag anything that needs calculation, lensometry, optics, or a long clinical vignette. Do not let one keratometry or vertex-distance calculation eat five minutes.
- Pass 2 (work): Return to flagged items. These are your tonometry conversions, prism diopter problems, retinoscopy/refraction logic, and contact-lens base-curve questions. Now you have time to do the arithmetic carefully.
- Pass 3 (review): With the reserve buffer, recheck flagged items and any stem where you changed your mind. Only change an answer if you can name the specific rule that proves your first choice wrong.
Distractor discipline on a knowledge exam
The COA exam is heavily fact and procedure based: ocular anatomy, visual acuity testing, pupil assessment, tonometry, lensometry, basic pharmacology, microbiology and sterilization, and patient services. Distractors are usually plausible because they are real concepts placed in the wrong context. A classic trap pairs a correct procedure with the wrong unit (for example, prism in diopters versus centrads, or intraocular pressure in mmHg). Read what is actually being asked before scanning options.
Build an error log
After each timed block, log every miss and every lucky guess. For each, write the cause in one of these buckets: recall gap, misread stem, calculation error, wrong sequence/order of testing, or unit/terminology confusion. Then repair the pattern before your next large set. A score on a practice test is data; the error log is the lesson.
- Use the real 180-minute clock for full sets.
- Answer every item; never leave a blank.
- Flag rather than stall on calculations.
- Track pace against the 45/90/135-minute checkpoints.
- Convert every miss into a one-line error-log rule.
Worked calculation examples to rehearse under time
The items that consume the most clock are the ones with arithmetic, so practice them until they are mechanical. A few recur often:
- Vertex-distance compensation: Moving a strong lens closer to or farther from the eye changes its effective power. As a rule of thumb, lenses above about +/-4.00 diopters need compensation when the vertex distance shifts by even 2-3 mm. Know that a plus lens moved farther from the eye acts stronger, and a minus lens moved farther acts weaker. You will not derive Newton's equation under time; you memorize the direction and the threshold.
- Prism by Prentice's rule: Prism (in prism diopters) equals the lens power in diopters multiplied by the decentration in centimeters. A patient with a +5.00 D lens decentered 0.5 cm experiences 2.5 prism diopters of induced prism. Drill this until it is one step.
- Transposition: Convert plus-cylinder to minus-cylinder form by adding the cylinder to the sphere, flipping the cylinder sign, and rotating the axis 90 degrees. Example: +2.00 +1.00 x 090 becomes +3.00 -1.00 x 180.
- Snellen and visual acuity: Recall that 20/40 means the patient sees at 20 feet what a normal eye sees at 40 feet, and be ready to convert to LogMAR or count-fingers/hand-motion notation.
Timing pitfalls specific to this exam
The single biggest scored-point loss is not difficulty; it is abandoning easy points late because earlier items ran the clock down. Protect the back third of the exam. A second pitfall is changing correct answers during review out of anxiety: data shows considered first instincts on factual recall items are usually right, so only overturn an answer when you can cite the exact rule that disproves it. Treat your practice exams as rehearsals for both the clock and your own nerves, and log timing failures alongside content failures.
During a full-length timed COA practice exam, you reach question 80 when the on-screen clock shows 90 minutes elapsed. What is the best adjustment?