Geographic atrophy growth

About this calculator

Enter the total lesion area from two imaging visits to see how fast geographic atrophy grew, both as area per year and as the square-root rate used in research.

What you need

• The date and total lesion area (mm²) from each image, measured by your eye doctor
• The imaging used and whether the fovea is involved

How it is calculated

Years = days ÷ 365.25. Area growth = (later area − earlier area) ÷ years. Square-root growth = (√later area − √earlier area) ÷ years.

What the result can and cannot tell you

The square-root figure is a transformed measure that research studies use to compare lesions of different sizes; it is not a measured spread of the lesion edge. Where the lesion is, especially whether the fovea is involved, matters as much as how fast it grows. An apparent decrease usually reflects measurement differences.

References

1. Progression of geographic atrophy in age-related macular degeneration. AREDS2 Report Number 16
2. The rate of progression of geographic atrophy decreases with increasing baseline lesion size even after the square root transformation
3. Netra Eye Institute: Dry AMD

Related

• OCT macular thickness change
• Amsler grid self-check
• Ellipsoid zone width change
• Dry AMD guide
• All eye calculators

For information only. These tools explain numbers and do not replace an eye examination or your eye doctor’s advice. Values you enter stay in your browser.