Comparison of the accuracy of six intraocular lens power calculation formulas for eyes of axial length exceeding 25.0 mm

Intraocular Lens Power Calculation Formulas—A Systematic Review

“…The Barrett Universal II formula has a unique theoretical model to predict the ELP which differs quite significantly from the other ones. As a theoretical formula, it uses traditional mathematics for IOL power calculation based on obligatory data (lens factor or A-constant, AL, K, ACD, target refraction) and optional data such LT and WTW; however, it was demonstrated that Barrett could be calculated even without ACD [ 2 , 5 , 36 ] The formula is available online, https://calc.apacrs.org/barrett_universal2105/ .…”

“…Using this concept, from the peer-reviewed literature, the best sections identified for each of the abovementioned IOL formulas were chosen, and an IOL super surface was developed [ 37 ]. Retrospective analyses showed that SRK/T tends to be better for longer eyes [ 5 ], while the Hoffer Q is more accurate for very short eyes [ 38 ]. In addition, due to AL or corneal power, some eyes require further optimization; for example, hyperopic eyes are difficult to calculate, as the smallest of changes in ELP can alter the lens power calculations significantly.…”

“…The third- and fourth-generation formulas are being replaced by more accurate ones. The Barrett Universal II [ 5 , 14 , 16 , 17 , 28 , 31 , 48 , 51 – 55 ] among vergence formulas and Kane [ 1 , 15 , 20 , 34 , 36 , 42 , 45 , 56 , 57 ] and PEARL-DGS [ 18 , 24 , 40 , 58 ] among AI-based formulas are currently most often reported as the most precise. Overall, IOL power calculation formulas based on machine learning are very promising and can have a positive effect on the outcomes of postoperative refraction; additionally, machine learning methods can also be incorporated into a variety of existing IOL power formulas to refine their accuracy [ 59 ].…”

“…Over the years, many IOL power calculation formulas have been introduced in efforts to obtain the most precise postoperative refractive results. Traditionally they were classified by generations, as shown in Table 1 [ 5 ]. However, categorizing formulas based on a logical approach is much more useful (Table 2 ).…”

“…The accuracy of IOL power calculation formulas for eyes shorter than 22.0 mm and longer than 25.0 mm is less precise [ 11 – 14 ]. So far, the Barrett Universal 2 formula has appeared to be the most accurate in calculating IOL power for myopic eyes [ 5 , 14 – 17 ], and Kane for hyperopic eyes [ 18 – 21 ]. But the newly developed methods have very promising results as well [ 22 – 24 ].…”