Accuracy Of Intraocular Lens Power Calculation Formulas In A Steep Cornea: A Case Report

There is no enough knowledge about the accuracy of intraocular lens (IOL) power calculationformulas in steep corneas. This study may be the first one that compares the accuracy of the SRK IIformula with Holladay1, Hoffer Q and Haigis formulas in steep corneas. We reported a case of a 60-year-old female, with a cataract in the left eye and with a steep cornea. We used the modern formulas;Holladay1, Hoffer Q and Haigis. The result (+7.0D) was unexpected compared to the manifestrefraction and to the IOL power calculated in the right eye using the same formulas which was(+17.0D). We implanted (+12.0D) Sensar 1-piece IOL depending on our clinical experience.

This study compares the accuracy of the SRK IIformula with Holladay1, Hoffer Q and Haigis formulas in steep corneas. We reported a case of a 60-year-old female, with a cataract in the left eye and with a steep cornea. We used the modern formulas;Holladay1, Hoffer Q and Haigis. The result (+7.0D) was unexpected . We implanted (+12.0D) Sensar 1-piece IOL.

A 60- year-old female was presented to ourhospital with cataract OS. She was (-1.5/ -2.25axis100 OD & - 5.75 OS). Axial length was(23.76 mm OS) but the K- readings were high;K1 = 50.88 and K 2 = 54.12 D. Hence, we haveperformed the modern third and fourthgeneration IOL calculation formulas; Holladay1, Hoffer Q, and Haigis using the Lenstar optical biometry. It was a surprise to us that the result of biometry was +7.0 D . Whenwe looked at the result of the right eye, in which we used the same formulas, we found the IOLpower was +17.0 D using Holladay1 and Haigisand it was +16.5 D with Hoffer Q. These resultsincreased our doubts about the accuracy of theresult of the left eye. The axial length of theright eye was 23.09mm, K1 46.69. K2 48.95OD. So the only obvious difference betweenboth eyes was the corneal power. We implanted+12.0 D Sensar Monofocal 1-piece IOLdepending on our clinical experience. The earlypostoperative refraction was (+0.00/-1.75axis106). Postoperatively, we used thepatient data to get the IOL power by the SRK IIformula. The surprise that it was the most accurate result (+11.5 D) using A118. Measurements were repeated for each formula three times. We found that the SRK II may be superior to the Holladay1, Hoffer Q and Haigis when the corneal power was more than
+ 49.0D. In the right eye where the average Kreading was less than 49.0D, there was no such difference between SRK II and the other formulas.

SRK II formula is easy and as accurate for eyes with average axial length as the modern formulas. When average corneal power is more than 49.0D this formula may be the best compared to Holladay1, Hoffer Q, and Haigis formulas. Further studies may be necessary to confirm our results.