Ophthalmology · Ophthalmic Imaging and Investigations (OCT, FFA, B-scan, Perimetry, Biometry, Topography)

Which IOL power calculation formula uses three constants (a0, a1, a2) and is particularly useful for both extremely short and extremely long axial lengths?

  • A SRK/T
  • B Haigis
  • C Holladay 1
  • D Hoffer Q
Correct answer: B. Haigis

Explanation

The Haigis formula uses three constants (a0, a1, a2) where a1 is linked to axial length and a2 to anterior chamber depth, making it versatile across a wide range of axial lengths including extremes. SRK/T, Holladay 1, and Hoffer Q each use a single surgeon factor or A-constant and are less accurate at extremes of axial length.

Reference: Intraocular Lens Power Calculations, Haigis, 1st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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