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After instilling proparacaine, how long until anesthetic effect typically begins?
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Key Facts: ROUB Exam
180
MCQ Items
IJCAHPO ROUB
22-25 mm
Normal AL
Adult phakic eye
1550 m/s
Phakic Velocity
A-scan calibration
Pearson VUE
Delivery
IJCAHPO
IJCAHPO ROUB is the A-scan biometry + IOL power calculation credential. ~170-180 MCQ via Pearson VUE. Master normal axial length 22-25 mm, immersion > contact A-scan accuracy, IOL formula selection (Hoffer Q short, SRK/T long, Barrett Universal II all-comers), post-LASIK formulas (Haigis-L, Barrett True K), and silicone oil velocity (~980 m/s).
Sample ROUB Practice Questions
Try these sample questions to test your ROUB exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1What is the normal axial length range for an adult human eye?
2An axial length less than 22 mm is classified as which type of eye?
3Which structure does the A-scan ultrasound beam encounter FIRST when measuring axial length via contact technique?
4What is the typical anterior chamber depth (ACD) range in an adult phakic eye?
5What is the typical thickness range of the adult crystalline lens?
6What is the average corneal power (K reading) in a normal eye?
7How many distinct layers does the human cornea contain?
8Which spike on an A-scan represents the boundary between the vitreous and the retina?
9What is the approximate axial length of a newborn human eye?
10An axial length greater than 26 mm indicates which clinical condition risk?
About the ROUB Exam
IJCAHPO specialty credential for ophthalmic ultrasound biometrists — A-scan biometry and IOL power calculation for cataract surgery planning. Covers ocular anatomy, A-scan techniques (contact applanation vs immersion), IOL power formulas (SRK/T, Holladay, Hoffer Q, Haigis, Barrett Universal II), interpretation of biometry results, patient care/equipment calibration, and special situations (post-refractive surgery, silicone oil eyes, staphyloma, pediatrics).
Questions
180 scored questions
Time Limit
Per IJCAHPO
Passing Score
Scaled (IJCAHPO-set)
Exam Fee
~$350-525 (IJCAHPO via Pearson VUE)
ROUB Exam Content Outline
IOL Power Calculation
SRK/T, Holladay 1/2, Hoffer Q, Haigis, Barrett Universal II, Hill-RBF, Kane formulas; A-constant optimization
A-scan Techniques
Contact applanation vs immersion, gain, probe alignment, spike interpretation
Ocular Anatomy
Globe, axial length, lens, cornea, vitreous, choroid
Patient Care & Equipment
Patient prep, anesthesia (proparacaine), probe sterilization, calibration with test block
Interpretation of Results
A-scan spike pattern, axial length variants, dense cataracts, between-eye comparison
Special Situations
Pediatric, post-refractive (Haigis-L, Barrett True K), silicone oil, staphyloma
How to Pass the ROUB Exam
What You Need to Know
- Passing score: Scaled (IJCAHPO-set)
- Exam length: 180 questions
- Time limit: Per IJCAHPO
- Exam fee: ~$350-525
Keys to Passing
- Complete 500+ practice questions
- Score 80%+ consistently before scheduling
- Focus on highest-weighted sections
- Use our AI tutor for tough concepts
ROUB Study Tips from Top Performers
Frequently Asked Questions
When should immersion A-scan be used over contact A-scan?
Immersion A-scan (probe in saline shell over open eye) is preferred for ALL cataract biometry — contact (applanation) A-scan compresses the cornea and may shorten axial length by 0.1-0.3 mm, causing IOL power errors. Immersion is mandatory in long eyes (AL >25 mm), short eyes (AL <22 mm), and post-refractive eyes where small AL errors translate to large IOL power errors. Optical biometry (IOLMaster/Lenstar) replaces ultrasound when media are clear.
Which IOL formula is best for short vs long eyes?
Short eyes (AL <22 mm): Hoffer Q has historically been the most accurate; Holladay 2 also good. Long eyes (AL >26 mm): SRK/T traditionally; Wang-Koch axial length adjustment improves accuracy further. All-comers across AL range: Barrett Universal II is now the most widely accepted high-accuracy formula; Hill-RBF (artificial intelligence) and Kane formulas competitive. The 3rd-generation formulas (SRK/T, Holladay 1, Hoffer Q) require accurate K + AL only; 4th/5th-gen formulas use additional inputs (ACD, lens thickness, white-to-white).
How are post-LASIK eyes calculated?
Post-refractive surgery eyes (LASIK, PRK) have artificially flattened keratometry that under-estimates true corneal power → IOL power miscalculation. Specialized formulas include: Haigis-L (uses AL + ACD, no K dependence), Barrett True K (with or without prior K data), Shammas-PL (no historical data needed), Maloney method, ASCRS Post-Refractive IOL Calculator (online — averages multiple methods). Always document refractive surgery history; aim slight myopic target.
How should I study for IJCAHPO ROUB?
Plan 60-100 hours over 8-12 weeks. Focus weighted study on IOL Power Calculation (25%) and A-scan Techniques (25%) — together half the exam. Master normal axial length and velocities, contact vs immersion technique, formula selection by AL range, post-refractive formulas, and silicone oil velocity adjustments. Hands-on biometry experience reinforces written content.