The IOL Consultant Software has the Holladay 1, Holladay 2, Hoffer Q and SRK/T. The H2 is better than the Haigis and is comparable to the Barrett when the Long Axial Length Adjustment is used. More importantly, the Software has many other functions such as Silicone in Vitreous, Retinal Detachment, Post Refractive Surgery, Piggy Back Lenses, Secondary Piggy Back Lenses, the Most Accurate Toric Calculations and Back Toric Calculations to determine the necessary rotation of a Toric IOL for optimum placement, just to mention a few.
HICSOAP does not use or support the Barrett formula. The BARRETT Universal Formula is proprietary and we do not have it in the IOL Consultant Software. Koch first found this and reported the Wang/Koch adjustment and we then published the Non-Linear Long Eye Adjustment in 2018. The recent article by Melles and Holladay in Ophthalmology shows a difference in the Holladay 2 and the Barrett in LONG EYES. The article explains that the H1 and H2 formulas are less accurate in long eyes because the optical axial length measurement is wrong. We have added a Holladay Non Linear Regression which is superior to the WANG/Koch and any other formula.
In the Study with Melles (Melles RB, MD, Holladay JT, Chang WJ. Accuracy of Intraocular Lens Calculation Formulas. Ophthalmology 2018 Feb;125(2):169-178) we found that if you use the Holladay Non Linear Regression in Long Eyes and used the REFRACTION before affected by the cataract (if not know leave blank) the results were 80% within +/- 0.50 D.
The Holladay Toric Calculator is the most accurate and better than the Barrett as we reported in the JCRS.
You should be using the Holladay 2 formula with the Holladay Non-Linear Regression option checked.
These formulas are proprietary and have never been published. Large studies, like the one by Melles (1), demonstrate that the Holladay 2 is within 2% of the newer formulas. In addition, the Barrett uses post op K's in their studies, which reduces the accuracy of the H2, but helps the Barrett. Also, the Holladay Toric Calculator is the most accurate of all of the formulas (2). The SIA is adjusted for the incision location, axis and magnitude of the preoperative astigmatism for every patient. There are many other features such as piggy back IOLs, silicone in vitreous, etc.
1. Melles RB, MD, Holladay JT, Chang WJ. Accuracy of Intraocular Lens Calculation Formulas. Ophthalmology 2018 Feb;125(2):169-178
2. Holladay JT, Pettit G. Improving Toric Intraocular Lens Calculations Using Total Surgically Induced Astigmatism for 2.5 mm Temporal Incision. J Cataract Refract Surg March 2019; 45: 272-83