![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 fo](/sites/g/files/rbvwei2691/files/styles/news_195_260/public/2024-05/Screenshot%202024-05-01%20at%201.15.12%E2%80%AFPM_0.png?h=93c0ba6c&itok=6EG4s_k_)
![](/sites/g/files/rbvwei2691/files/2024-05/Screenshot%202024-05-01%20at%201.15.12%E2%80%AFPM_0.png)
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