Performance of the SRK/T formula using A-Scan ultrasound biometry after phacoemulsification in eyes with short and long axial lengths

Abstract

BackgroundThe SRK/T formula is one of the third generation IOL calculation formulas. The purpose of this study was to evaluate the performance of the SRK/T formula in predicting a target refraction ±1.0D in short and long eyes using ultrasound biometry after phacoemulsification.MethodsThe present study was a retrospective analysis, which included 38 eyes with an AL < 22.0 mm (short AL), and 62 eyes ≥24.6 mm (long AL) that underwent uncomplicated phacoemulsification. Preoperative AL was measured by ultrasound biometry and SRK/T formula was used for IOL calculation. Three different IOLs were implanted in the capsular bag. The prediction error was defined as the difference between the achieved postoperative refraction, and attempted predicted target refraction. Statistical analysis was performed with SPSS V21.ResultsIn short ALs, the mean age was 65.13 ± 9.49 year, the mean AL was 21.55 ± 0.45 mm, the mean K1 and K2 were 45.76 ± 1.77D and 46.09 ± 1.61D, the mean IOL power was 23.96 ± 1.92D, the mean attempted (predicted) value was 0.07 ± 0.26D, the mean achieved value was 0.07 ± 0.63 D, the mean PE was 0.01 ± 0.60D, and the MAE was 0.51 ± 0.31D. A significant positive relationship with AL and K1, K2, IOL power and a strong negative relationship with PE and achieved postoperative was found. In long ALs, the mean age was 64.05 ± 7.31 year, the mean AL was 25.77 ± 1.64 mm, the mean K1 and K2 were 42.20 ± 1.57D and 42.17 ± 1.68D, the mean IOL power was 15.79 ± 5.17D, the mean attempted value was −0.434 ± 0.315D, the mean achieved value was −0.42 ± 0.96D, the mean PE was −0.004 ± 0.93D, the MAE was 0.68 ± 0.62D. A significant positive relationship with AL and K1, K2 and a significant positive relationship with PE and achieved value, otherwise a negative relationship with AL and IOL power was found. There was a little tendency towards hyperopic for short ALs and myopic for long ALs. The majority of eyes (94.74 %) for short ALs and (70.97 %) for long ALs were within ±1 D of the predicted refractive error. No significant relationship with PE and IOL types, AL, K1, K2, IOL power, and attempted value, besides with MAE and AL, K1, K2, age, attempted, achieved value were found in both groups.ConclusionThe SRK/T formula performs well and shows good predictability in eyes with short and long axial lengths.

Fakoemülsi̇fi̇kasyon Cerrahi̇si̇ Yapilan Hastalarda Hedef Refrakti̇f Değer İle Sonuç Refrakti̇f Değeri̇n Karşilaştirilmasi

“…Thanks to the developing biometric devices and formulas, it has become possible to reach the targeted refractive results after phacoemulsification surgery (9). Today, one of the most important goals of cataract surgery is to achieve the desired refractive result (10)(11)(12). Kaya et al evaluated the SRK-T and SRK-2 biometric formulas in eyes with a short axial length in their study.…”

“…The mean IOP before surgery was 14.9±1.8[10][11][12][13][14][15][16][17][18][19][20] mm Hg in the SRK-T group and 14.5±1.7[11][12][13][14][15][16][17][18] mm Hg in the SRK-2 group. The average IOP at 3 months after surgery was 13.5±1.67[10][11][12][13][14][15][16][17] mm in the SRK-T group and 13.8±1.86[11][12][13][14][15][16][17][18][19] mm Hg in the SRK-2 group. There was no difference between the two groups in terms of IOP values before and after surgery.…”

The Accuracy of Different Generation Intraocular Lens Power Formulas in Eyes with Axial Length Lower than 22 millimeter

“…Narvaez et al have reported equal refractive results when compared the effectiveness of Hoffer Q, Holladay 1, Holladay 2 and SRK/T formulas in short, medium and long eyes [17]. Karabela et al have obtained good outcomes in both short and long eyes by using SRK/T formula [18]. In contrast to these studies, Aristodemou et al have demonstrated the superiority of SRK/T and Hoffer Q in eyes with AL greater than 26 mm, and less than 21.5 mm respectively in their comprehensive study [11].…”

Comparison of Axial Ocular Measurements with Contact and Non-contact Biometry

“…However, the ultrasound technique requires physical direct or indirect (immersion technique) contact of transducer with the cornea. Both ultrasound (US) A-scan biometry and non-contact PCI based devices are used for calculating IOL power 6,8 . AL in ultrasound method is measured from corneal vertex to the internal limiting membrane (ILM) 9 .…”