SS-OCT Biometers Using the SOS versus Mean Group Refractive Index to Measure Axial Length

KEY TAKE-AWAYS 

• Today’s SS-OCT Biometers employ two methods to measure the axial length: Sum-of Segments using individual refractive indices or a Mean Group Refractive Index 

• The differences in axial length measurement between the two methods are statistically significant and most noticeable in long and short eyes 

• Axial length determined with the Mean Group Refractive Index is slightly shorter in short eyes and longer in long eyes 

• Depending on the length of the eye, some newer IOL power calculation formulas may provide better outcomes with the Sum-of-Segment method