During biometry using partial coherence interferometry (IOLMaster 700), the signal-to-noise ratio (SNR) is found to be low, affecting measurement accuracy. Which of the following is the most likely cause of low SNR in this patient?
- A Corneal edema
- B Dense posterior subcapsular cataract ✓
- C Vitreous hemorrhage
- D Epiretinal membrane
Correct answer: B. Dense posterior subcapsular cataract
Explanation
Low SNR in partial coherence interferometry is most commonly caused by dense cataracts (especially posterior subcapsular), which scatter the infrared beam. Corneal edema, vitreous hemorrhage, and epiretinal membrane can also reduce SNR, but dense cataract is the most frequent and clinically significant cause affecting biometry accuracy.
Reference: Ophthalmic Surgical Procedures, 3rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.