ABO Glaucoma Diagnosis and Management 2 — Questions and Answers
Question 1: A highly myopic patient with a tilted optic disc shows borderline RNFL thinning flagged 'red' on OCT but has full visual fields and a stable disc. What best explains this finding?
- Early normal-tension glaucoma requiring immediate treatment
- A false-positive ('red disease') from comparison to a normative database that excludes high myopes (Correct answer)
- Segmentation failure caused by posterior vitreous detachment
- Compressive optic neuropathy from a pituitary lesion
Correct answer: A false-positive ('red disease') from comparison to a normative database that excludes high myopes
Normative databases usually exclude high myopes, so tilted discs and shifted RNFL peaks often produce false-positive 'red' flags.
Question 2: After myopic LASIK, how does Goldmann applanation tonometry most likely misreport a patient's true IOP?
- It overestimates IOP because of increased corneal rigidity
- It is accurate because LASIK spares Bowman layer
- It underestimates IOP because of the thinner, weaker central cornea (Correct answer)
- It overestimates IOP because of epithelial hyperplasia
Correct answer: It underestimates IOP because of the thinner, weaker central cornea
Central corneal thinning and changed biomechanics after LASIK cause GAT to underestimate true IOP.
Question 3: On gonioscopy, a narrow angle shows no visible structures. What technique best tells appositional closure apart from peripheral anterior synechiae?
- Dynamic indentation gonioscopy with a Zeiss-type four-mirror lens (Correct answer)
- Goldmann three-mirror gonioscopy in bright light
- Van Herick slit-lamp estimation
- Anterior segment OCT in the dark only
Correct answer: Dynamic indentation gonioscopy with a Zeiss-type four-mirror lens
Indentation pushes aqueous peripherally and opens appositionally closed angles; synechial areas stay closed.
Question 4: A glaucoma patient has a disc hemorrhage and a dense superior arcuate defect close to fixation. Which visual field test best defines central involvement?
- Humphrey 30-2 SITA Standard
- Goldmann kinetic perimetry with the V4e target
- Humphrey 10-2 (Correct answer)
- Frequency-doubling screening C-20
Correct answer: Humphrey 10-2
The 24-2 grid (6° spacing) can miss paracentral damage, which the 10-2 (2° spacing) shows much better.
Question 5: In the Ocular Hypertension Treatment Study (OHTS), which baseline factor was a strong independent predictor of conversion to POAG?
- Thicker central corneal thickness
- Thinner central corneal thickness (Correct answer)
- Female sex
- Myopia under 1 diopter
Correct answer: Thinner central corneal thickness
OHTS found that thinner CCT, older age, higher IOP, larger cup-to-disc ratio, and higher PSD predicted conversion.
Question 6: According to the ISNT rule for a healthy optic disc, which neuroretinal rim is normally thickest?
- Superior
- Nasal
- Temporal
- Inferior (Correct answer)
Correct answer: Inferior
Normal rim thickness usually runs Inferior ≥ Superior ≥ Nasal ≥ Temporal.
Question 7: A young myopic man has midperipheral radial iris transillumination defects, a Krukenberg spindle, and a very open angle with concave peripheral iris. What is the proposed mechanism of his condition?
- Reverse pupillary block with iris-zonule rubbing that releases pigment (Correct answer)
- Exfoliative material deposited on the lens capsule
- Anterior rotation of the ciliary body
- Endothelial migration across the trabecular meshwork
Correct answer: Reverse pupillary block with iris-zonule rubbing that releases pigment
In pigment dispersion syndrome, posterior iris bowing (reverse pupillary block) rubs the iris pigment epithelium against the zonules.
ABO Glaucoma Diagnosis and Management 2
A highly myopic patient with a tilted optic disc shows borderline RNFL thinning flagged 'red' on OCT but has full visual fields and a stable disc.
What best explains this finding?