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To verify the influence of axial length (AL) variations after cataract surgery in IOL power calculation. Patients underwent ophthalmic evaluation before surgery, including optical biometry with IOLMaster 500. Same exams were repeated 2 months after surgery: AL of operated eye was evaluated using two modes (pseudophakic/aphakic options). Mean Keratometry and AL changes were analyzed. Furthermore, refractive prediction error (PE) was back-calculated with Barrett Universal-II, Hoffer-Q, Holladay-1 and SRK/T formulas. To eliminate any systematic error, the mean error (ME) was zeroed-out for each formula. MEs and median absolute errors (MedAEs) of PEs were analyzed. Two-hundred-one operated eyes of 201 patients and 201 opposite eyes were evaluated. In operated eyes, mean AL difference was - 0.11 ± 0.07 mm (p < 0.001) with pseudophakic option and 0.00 ± 0.07 mm (p = 0.922) with aphakic option. There were not-statistically significant differences between MedAE of PEs calculated after zeroing-out the ME with different ALs (p > 0.05). Instead, only MEs of PEs obtained with postoperative ALs-pseudophakic option were not-statistically different from zero (p > 0.05). AL measurement change after cataract surgery is probably due to a systematic error in optical biometer in case of phakic eyes. A correction factor applied to preoperative AL could eliminate any systematic error in IOL power calculation without modifying the lens constant., (© 2022. The Author(s).)

Purpose: To describe the different formulas that try to overcome the problem of calculating the intraocular lens (IOL) power in patients that underwent corneal refractive surgery (CRS)., Methods: A Pubmed literature search review of all published articles, on keyword associated with IOL power calculation and corneal refractive surgery, as well as the reference lists of retrieved articles, was performed., Results: A total of 33 peer reviewed articles dealing with methods that try to overcome the problem of calculating the IOL power in patients that underwent CRS were found. According to the information needed to try to overcome this problem, the methods were divided in two main categories: 18 methods were based on the knowledge of the patient clinical history and 15 methods that do not require such knowledge. The first group was further divided into five subgroups based on the parameters needed to make such calculation., Conclusion: In the light of our findings, to avoid postoperative nasty surprises, we suggest using only those methods that have shown good results in a large number of patients, possibly by averaging the results obtained with these methods.

Purpose: To describe the clinical results of a corneal radius correcting factor (CRCF), which is based on the axial length and independent of knowledge from the previous surgical procedure, in calculating intraocular lens (IOL) power in eyes that developed cataract after corneal refractive surgery., Methods: Intraocular lens power for 62 eyes that previously underwent corneal refractive surgery was calculated with the SRK/T and SRK II formulas using an axial length-related CRCF, and the expected refractive errors were compared with the actual postoperative refractive errors., Results: Using the CRCF, the refractive outcomes ranged between -3.25 and +1.00 diopters (D) (mean -0.41+/-0.75 D), with 37 (60%) eyes within +/-0.50 D and 53 (85%) eyes within +/-1.00 D of the intended refraction. Using the raw data, without the correcting factor, the refractive outcomes would have ranged between -2.00 and +5.00 D (mean +2.17+/-1.45 D) with 7 (11%) eyes within +/-0.50 D and 15 (24%) eyes within +/- 1.00 D of the intended refraction., Conclusions: Pending further validation through a larger prospective evaluation, the CRCF combined with the SRK/T formula is recommended in eyes with an axial length up to 30 mm and the average IOL power calculated with the SRK/T and SRK II formulas when the axial length is >30 mm.

Purpose: To test the reliability of a corneal radius correcting factor (R factor) in calculating intraocular lens (IOL) power in eyes that developed cataract after refractive surgery and compare it with the clinical history (CHM) and double-K (DKM) methods., Setting: Department of Ophthalmology, Second University of Naples, Naples, Italy., Methods: Nineteen eyes from the literature that underwent cataract extraction and IOL implantation after refractive surgery were used to compare actual postoperative and expected refractive errors utilizing the R factor, CHM, and DKM. Intraocular lens powers were calculated with 3 formulas: SRK/T, Hoffer Q and Holladay 1. The differences were evaluated with the Wilcoxon test and Spearman correlation., Results: With the R factor SRK/T and Holladay 1 formulas gave the best results; 16 (84.2%) and 17 (89.5%) eyes were within +/-2 diopters (D) of emmetropia. With CHM, the best results were obtained using the SRK/T and Holladay 1 formulas; with both formulas 12 (63.2%) eyes were within +/-2 D of emmetropia. With DKM, the best results were obtained using SRK/T and Holladay 1 formulas; with both formulas 10 eyes (52.63%) were in the range of +/-2 D from emmetropia., Conclusions: The R factor can be used with the SRK/T or Holladay 1 formula because this method seems comparable or superior to DKM and CHM.

Purpose: To find a method of calculating intraocular lens (IOL) power that may be independent of preoperative data, in eyes that have developed a cataract after refractive surgery., Methods: Prior to and 1 month after PRK, the SRK/T formula was used to calculate IOL power in 88 eyes of 65 patients with a preoperative spherical equivalent refraction between -16.25 to +0.25 D (mean -5.39 +/- 3.19 D). IOL power was calculated by utilizing the spherical equivalent refraction as target both before and after PRK. Utilizing the postoperative corneal radius measurement (R2), an underestimation of the IOL power was found. For this reason, the mean postoperative corneal radius (R3) that gave the same IOL power found before surgery was calculated for each patient. The R3/R2 ratios were plotted against the axial eye length and a linear regression formula was used to calculate R2 correcting factors that gave the new corneal radius (R4). Patients were divided into classes according to axial eye length, and the mean R3/R2 ratios for each class were calculated and used to recalculate the new mean radius (R5). IOL power for emmetropia was calculated in all patients by utilization of R3, R4, R5, the historical method, and the "true corneal power" method., Results: Within +/-0.50 D from the IOL power calculated with R3, R4 gave 35 (39.3%) IOLs, while R5 gave 40 (45.5%) IOLs; the clinical history method gave 24 (27.3%) IOLs and "true corneal power" gave 23 (26.1%) IOLs, with a statistically significant difference P<.001)., Conclusions: Our theoretical method, based on correlation between axial eye length and corneal radius correcting factors, may represent an effective method of calculating IOL power after PRK, especially if the history of the patient is unknown.