Improving refractive outcomes in cataract surgery: A global perspective

Table 1 Available intraocular lens power formulae

Name of formula	Variables required	Comments
SRK I and Binkhorst I 1st Generation	Keratometry, Axial Length	Obsolete High levels of error, should not be used
SRK II and Binkhorst II 2nd Generation	Keratometry, Axial Length	Obsolete High levels of error, should not be used
Holladay 1 3rd Generation	Keratometry, Axial Length	Trend toward better outcomes for eyes between 22.00 mm and 26.00 mm, compared to other 3rd generation[14]
SRK/T 3rd Generation	Keratometry, Axial Length	Better outcomes for eyes over 26.00 mm, compared to other 3rd generation formulae[14]
Hoffer Q 3rd Generation	Keratometry, Axial Length	Better outcomes for eyes under 22.00 mm, compared to other 3rd generation[14]
T2 3rd Generation	Keratometry, Axial Length	Very good outcomes for eyes over 22.00 mm[15] It corrects the cusp phenomenon, an error observed using the SRK/T on certain eyes[16]
Holladay 2 4th Generation	Keratometry, Axial Length, Anterior Chamber Depth, Lens Thickness, Horizontal White to White, Age, Pre operative refraction	No data has been reported showing an advantage over an appropriately selected 3rd generation formula
Olsen 4th Generation	Keratometry, Axial Length, Anterior Chamber Depth, Lens Thickness, Horizontal White to White	There is eidence suggestive of improved performance over 3rd generation formulae for eyes with axial length between 20.00 and 26.00 mm[17,18]
Haigis 5th Generation	Keratometry, Axial Length, Anterior Chamber Depth	Very good outcomes for eyes across the axial length range and best reported outcomes for eyes longer than 28.00 mm[19] For best results, three IOL constants need to be optimized requiring data from at least 500 eyes

IOL: Intraocular lens.