SUBJECTIVE AND OBJECTIVE REFRACTION AFTER CATARACT SURGERY: THREE TYPES OF LENSES (MONOFOCAL, EDOF AND MULTIFOCAL) AND THEIR COMPLIANCE WITH THE TARGET REFRACTION

Accurate prediction of the postop-refraction is crucial in refractive surgery.The refractive prediction error (PE) is important indicator and is calculated as the difference between the postoperative refraction and the preoperatively predicted target refraction.The PE is compared for the implantation of 3 intraocular lenses (IOLs): Vivity, PanOptix and SN6ATx.

Opthalmological department, Goethe University Frankfurt

The study included a total of 43 patients, of which 15 received the Vivity IOL(EDOF IOL, Alcon), 14 the PanOptix IOL (Multifocal IOL, Alcon) and a further 14 the SN6ATx IOL (Monofocal toric, Alcon).The PE was calculated in spherical equivalent (SE) and followed the formula: PE = postoperative refraction - predicted target refraction.Positive PE values indicated undercorrection,while negative PE values indicated overcorrection.The mean PE was calculated for each IOL.In addition an Alpins vector analysis was performed to evaluate the efficiency of the refractive correction for each IOL.This included the determination of the SIA(Surgically Induced Astigmatism) of the subjective refraction(SR) and the consideration of the preoperative visual acuity.The results of the vector analysis showed that the difference vector (DV),which represents the deviation between the SIA of the SR and the preoperative visual acuity,should be minimised in order to achieve optimal refractive correction.

The results of the comparison of the PE in SE for the different IOLs are as follows: Vivity: PE in SE: -0.04D PanOptix: PE in SE: -0.06D SN6ATx: PE in SE: 0.19.The vector analysis (Alpins) resulted: Vivity: DV=0.31 D @ 66° and correction index (CI)=1.63. Panoptix:DV=0.02 D @ 60° and CI=1.07 SN6ATx(toric):DV=0,01 D @ 81° and CI=1,15

The PE in the SE from the target refraction comparison indicates how well the actual postoperative refraction corresponds to the intended target refraction.The vector analysis considers not only the magnitude of the error, but also its direction and the efficiency of the correction. The results show that there are differences in the refractive PE between the different intraocular IOLs.The Vivity had the lowest PE on average, followed by SN6ATx and PanOptix.However,the results of the vector analysis indicate that the Vivity has the highest DV, followed by the SN6ATx and PanOptix.The deviation between the SIA of the subjective refraction and the preoperative visual acuity is greatest with the Vivity. A direct comparison between the two analyses shows that the results are not always parallel, as Vivity has the best PE value in the target refraction comparison, but the highest DV value in the vector analysis according to Alpins.This could indicate that the Alpins vector analysis provides additional information about the direction and degree of astigmatism that is not contained in the PE alone.