NOBC 2025 SESSION C - OPTICAL BIOMETRY

1. Regarding the steps in performing optical biometry

• A. Machines should be calibrated daily

• B. Ensure patient sight is fixed

• C. Patients no need to open their eyes widely

• D. Measurement of AXL in both eyes need to be repeated if the difference between IOL power is greater than 1.0D

2. 2. Regarding advantages of optical biometry

• A. It is an invasive, automated method using the infrared laser light

• B. It is suitable in case of dense cataract

• C. It produces axial length and keratometry reading in single device

• D. Real time 2D images from cornea to retina ensure correct alignment

Answer explanation

A. False: It is an invasive, automated method using the infrared laser light (F) – noninvasive

B. False : Not suitable for dense cataract

3. Which parameters are included in the optical biometry print-out

• A. Axial length

• B. Anterior chamber depth

• C. Lens thickness

• D. Spike pattern

4. These are included in White-To-White/Pupilometry/Central Corneal Thickness section

• A. WTW diameter

• B. Offset of cornea vertex to Iris

• C. Pachymetry

• D. Offset of cornea vertex to pupil centre

5. 5. Choose the correct match

• Swept Source -

  Argos

• OLCR -

  Lenstar 900

• Swept Source -

  IOL Master 700

• PCI -

  Pentacam AXL

6. 6. Choose the correct statement

• A. Optical axis is an imaginary line perpendicular to the cornea that intersects the center of pupil

• B. Visual axis is an imaginary line that connects the object in space, the center of pupil and the center of fovea

• C. Ultrasound biometer measures the AXL from corneal vertex to inner limiting membrane

• Optical biometer measures the AXL from corneal vertex to retinal pigment epithelium

Regarding the ocular refractive structures

• It made up of cornea, aqueous humour, lens and vitreous humour

• Lens has the strongest refractive power

• Refractive index of cornea is 1.376

• Lens contribute 1/3 of total refractive eye power

Answer explanation

B. False. Cornea has the strongest refractive power, about 40D