Purpose. To compare the results of trifocal IOL calculation using various corneal topographic data (ring and zone). Methods. This retrospective study involved 35 patients (40 eyes), underwent cataract surgery (FLACS) with trifocal IOL implantation (AcrySof IQ PanOptix). The calculation was performed using IOL-Master 500 according to 4 formulas (Haigis, HofferQ, Holladay 1, SRK / T) and Tomey OA-2000 according to 2 formulas (Barrett II Universal, Olsen). Topographic values included Km collected from Pentacam HR Power Distribution Apex map with diameter of 3.0 and 5.0 mm on a ring and zone. Predicted and actual refraction were compared after surgery. Results. Mean Km value on 3 mm zone and ring was: 42.75±1,46 D and 42.91±1.43 D, respectively (p<0.0001). Mean Km value on 5 mm zone and ring was: 43.09±1.5 D and 43.55±1.48 D, respectively (p<0.0001). According to 6 formulas Mean Absolute Error (MAE) calculated using 3 mm zone data was significantly less then on 3mm ring: 0.3± 0.28; 0.48±0.3 and Median Absolute Error (MedAE) was 0.225 (0.3); 0.465 (0.397) respectively (p<0.01). The same data were obtained on 5mm zone and ring: MAE was 0.29±0.28; 0.35±0.29 and MedAE amounted to 0.225 (0.3); 0.29 (0.38) respectively (p=0.02). Conclusion. Mean Km value on Power Distribution Apex map according to ring is significantly greater then according to zone. 1) Predicted refraction using corneal topographic ring data deviates towards hyperopia relative to the actual postoperative refraction. 2) The use of topographic data on zone allows to obtain more accurate calculation of trifocal IOL than when using the data on the ring. Key words: IOL calculation, Trifocal IOL, corneal topography.
Purpose. To compare the results of trifocal IOL calculation using various corneal tomographic data (ring and zone). Methods. This retrospective study involved 46 patients (46 eyes), underwent cataract surgery with trifocal IOL implantation (AcrySof IQ PanOptix). The calculation was performed using Tomey OA-2000 according to 2 formulas (Barrett II Universal, Olsen). Keratometry values included Km (the average of two main meridians of a cornea) provided by Pentacam HR Power Distribution Apex map, which describes total corneal refractive power (TCRP) with diameter of 3.0, 4.0 and 5.0 mm on a ring and zone. Mean (MAE) and median (MedAE) predicted postoperative refraction errors were assessed after surgery. Results. Mean Km value on 3 mm zone and ring was: 42.75±1,46 D and 42,91±1,43 D, respectively (p<0,0001). Mean Km on 4 mm zone and ring was: 42.6±1.5 D and 43.3 ± 1.5 D, respectively (p <0.005). Mean Km value on 5 mm zone and ring was: 43,09±1,5 D and 43,55±1,48 D, respectively (p<0,0001). Calculations using the Barrett II Universal formula revealed significant difference between MAE and MedAE of the predicted postoperative refraction on 5mm zone and ring (p=0.045). When using the Olsen formula in the calculations, significant difference was revealed using the Km data with a diameter of 3 mm and 5 mm (p=0.001 и p=0.009, respectively). The calculation on 3 mm ring was more accurate than for 3 mm zone. With a 5 mm diameter, the calculation is more accurate according to the zone data. Conclusion. Mean Km value on Power Distribution Apex map according to ring is significantly greater then according to zone. 1) The calculation of the trifocal IOL based on the TCRP zone data is reliably more accurate than the ring data according to both formulas (Barrett II Universal and Olsen) with a diameter of 5 mm. 2) According to the Olsen formula with a diameter of 3 mm, the calculation of the optical power of trifocal IOL based on TCRP ring data is more accurate. Key words: IOL calculation, Trifocal IOL, corneal topography
Purpose. To compare keratometry data based on principles of Gaussian optics and ray tracing method. Material and methods. The study involved 60 patients (60 eyes). Comparative assessment of three groups of keratometric data obtained from optical biometer IOL Master 500 and Axial/Sagital and Total Corneal Refractive Power maps from Pentacam-HR was carried out. Results. When analyzing the obtained indicators, reliably significant results were revealed only when comparing the data of Total Corneal Refractive Power, based on the ray tracing, with classical keratometry IOL Master 500. A comparative assessment of the obtained keratometric data of two Pentacam-HR maps did not show a statistically significant difference, as well as the indicators of classical keratometry Pentacam-HR and IOL Master 500. Conclusion. 1. Evaluation of keratometry data in patients with uncomplicated cataract based on Gaussian optics showed comparable values for the Pentacam-HR and IOL Master 500. There was no significant difference in keratometric values in the comparative analysis of data from Pentacam-HR between classical keratometry and Total Corneal Refractive Power. 2. Total Cornea Refractive Power from Pentacam HR based on ray tracing determined significantly lower values in comparison with the classic keratometry IOL Master 500. Key words: keratometry, corneal refractive power, ray tracing, keratotomography.
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