Barrett GD. True-K formula: new approach to biometry after LASIK. Presented at ASCRS 2009.

Barrett GD.  Approaches to biometry in patients who have had corneal refractive surgery. Presented at WOC 2008.

Modified from the formula in:

Barrett GD. An improved universal theoretical formula for intraocular lens power prediction. J Cataract Refract Surg, 19 (1993), 713–720

Barrett GD. Intraocular lens calculation formulas for new intraocular lens implants. J Cataract Refract Surg, 13 (1987), 389–396

Barrett True K No History Formula does not use any historical data.