Clinical Outcomes with a New Model of Extended Depth of Focus Intraocular Lens

Purpose: To evaluate the early clinical outcomes of a new diffractive extended depth-of-focus (EDOF) intraocular lens (IOL). Methods: Prospective case series enrolling patients undergoing cataract surgery with implantation of the EDOF IOL AT LARA (Carl Zeiss Meditec, Jena, Germany). Distance, intermediate and near visual acuity were evaluated during a follow-up of 1 month. Likewise, defocus curve, binocular mesopic contrast sensitivity, perception of photic phenomena, patient satisfaction and spectacle independence were assessed. Results: The study enrolled 38 eyes of 19 patients with a mean age of 69.5 years. A significant reduction of manifest refraction and improvement in corrected distance visual acuity (CDVA) was observed with surgery (p < 0.001). All eyes achieved a 1-month postoperative binocular CDVA of 20/20 or better. Likewise, all eyes achieved a DCIVA of 20/30 or better at 1 month postoperatively, and a total of 92.1% achieved DCNVA of 20/40 or better. Concerning refractive predictability, 97.4% of eyes had a 1-month postoperative spherical equivalent within ±0.50 D. The level of patient satisfaction with distance, intermediate and near vision was high, with 95% of patients reporting that they would have the same surgical procedure with the same IOL again. Difficulties in night driving or associated to halos were low. A total of 89% of patients reported to be spectacle independent postoperatively. Conclusions: The EDOF IOL AT LARA is able to provide a functional restoration of the visual function across distances after cataract surgery, with very high levels of patient satisfaction and minimal incidence of photic phenomena.

(IOLs) has been developed and widely expanded in clinical practice, the extended depth of focus (EDOF) IOL technology [1].This type of implants is aimed at providing functional vision at different distances while minimizing the incidence of photic phenomena [1], as the presence of secondary out-of-focus images corresponding to different foci is avoided due to the presence of a continuous range of focus [2].In other words, no clearly differentiated foci are generated by EDOF IOLs as it is the case with multifocal IOLs [3].It should be considered that photic phenomena are one of the main causes of dissatisfaction after cataract surgery with implantation of multifocal IOLs [4] and one of the main reasons leading surgeons to multifocal IOL explantation [5].
The main basis of EDOF technology is the use of an optical design providing a more reduced near addition of the IOL while maintaining a continuous range of functional vision across intermediate and near distances.This can be achieved by means of a diffractive [6] [7] or a refractive platform [6] [8] aimed at controlling the level of spherical or coma aberration.Different studies have shown the clinical performance of EDOF IOLs, reporting good visual and contrast sensitivity outcomes, with high levels of patient satisfaction [9]- [14].Concerning photic phenomena outcomes, whereas some comparative trials have found no significant differences between multifocal and EDOF IOLs [9] [11] [12], others have found a lower incidence of photic phenomena with EDOF designs compared to trifocal IOLs [13].The aim of the current study was to evaluate the clinical outcomes of a new model of diffractive EDOF IOL in terms of visual acuity across different distances, contrast sensitivity, photic phenomena and patient satisfaction.

Examinations
All patients underwent a comprehensive preoperative ophthalmological examination including measurement of uncorrected and corrected distance visual acuity (UDVA and CDVA), keratometry, optical biometry (IOLMaster, Carl Zeiss Meditec AG, Germany), manifest refraction, biomicroscopy, Goldmann applanation tonometry, and dilated fundoscopy.Postoperatively, patients were evaluated the day after surgery, and at 1 week and 1 month after surgery.At these two postoperative visits, the following clinical tests were performed: measurement of monocular UDVA and CDVA, measurement of monocular distance-corrected near (DCNVA, 40 cm) and intermediate visual acuity (DCIVA) (80 cm), and manifest refraction.Likewise, at 1 month postoperatively, a monocular distance-corrected defocus curve was obtained in all cases, including levels of defocus from +2 to −4 D in steps of 0.50 D as well as a measurement of binocular contrast sensitivity under mesopic conditions with Functional Acuity Contrast Test charts (CST 1800 system, Vision Science Research).Patient satisfaction and quality of life were determined by means of a questionnaire, which was completed by the patients at the last follow-up visit.Questions included satisfaction about: adaption between photopic and mesopic conditions, ability to find the correct distance, night driving, vision during the day, halos, adaption between far and near vision and vice versa, as well as general satisfaction for distance, intermediate and near vision, and overall satisfaction.Patients were also asked whether they would perform the same surgery again and whether they need to wear glasses for the daily tasks.Each subscale score was converted to a score between 0 and 5, with higher scores indicating better results.Finally, halometry was also measured at this visit.

Surgical Technique
An experienced surgeon (FP) performed all surgeries using a standard technique of sutureless phacoemulsification.Topical anaesthesia was initially administered, and pharmacologic mydriasis was induced.Once pupillary dilation was achieved, the surgical procedure was initiated with a clear cornea microincision of around 2.2 mm with a diamond knife and a paracentes is 60˚ -90˚ clockwise from the main incision.The IOL was implanted through the main incision using a specific injector.Postoperative pharmacological treatment consisted of a combination of antibiotic and steroidal anti-inflammatory drops.Likewise, non-steroidal anti-inflammatory drops were prescribed to prevent macular edema.

Statistical Analysis
Data analysis was performed using the software SPSS for Windows version 19.0 Open Journal of Ophthalmolog (IBM, Armonk, NY, USA).Normality of data samples was evaluated by means of the Kolmogorov-Smirnov test.When parametric analysis was possible, the Student t test for paired data was used to compare the results between consecutive visits.When parametric analysis was not possible, the Wilcoxon test was used to compare the analyzed parameters between visits.For all statistical tests, a p-value of less than 0.05 was considered as statistically significant.

Results
The sociodemographic and clinical characteristics of the patients is shown in Table 1.Concerning refractive predictability, a total of 97.4% of eyes had a 1-month postoperative spherical equivalent within ±0.50 D. Figure 1 shows the mean binocular defocus curve at 1 month after surgery.As shown, a distance-corrected visual acuity over 0.2 logMAR was achieved for defocus levels up to −2 D.

Quality of Vision and Patient Satisfaction Outcomes
Figure 2 shows the mean mesopic monocular contrast sensitivity function evaluated at 1 month after surgery.The mean halo score obtained by halometry was 0.81 (SD: 0.11; median: 0.85; range: 0.56 to 0.97).Table 3 shows the mean scores of different aspects of quality of vision and patient satisfaction using the subjective questionnaire.Good scores were obtained for all aspects, with the lowest scores associated to night driving and halos.A total of 95% (18) of the patients reported that would have the same surgical procedure with the same IOL again.Likewise, and 89% (17) of the patients reported to be spectacle independent postoperatively.

Discussion
This is one of the first clinical studies reporting the clinical outcomes obtained with the EDOF IOL AT LARA, which is based on a diffractive platform.Distance visual acuity is excellent with this EDOF IOL, with a 1-month postoperative UDVA and CDVA of 0.08 ± 0.10 and 0.00 ± 0.02, respectively.Therefore,  tient satisfaction score of 9.0 (scale, 0 to 10) [19].Pedrotti and colleagues [20] compared the results of the same Symfony EDOF IOL with those obtained with a monofocal aspheric IOL, obtaining significantly better monocular and binocular UDVA with the EDOF IOL.However, these authors did not find significant differences among EDOF and monofocal groups in terms of contrast sensitivity  [18], allowing the patient to perform daily activities without difficulties.This is reflected in the high level of patient satisfaction for near vision.Ruiz-Mesa and coauthors [12] [18] found in two comparative studies that the defocus curves were significantly better for defocus levels be-tween −2.50 and −4.00 D with trifocal IOLs than with an EDOF IOL.Pedrotti and colleagues [9] reported as well a more limited near visual outcome in eyes implanted with an EDOF IOL compared to those implanted with a high addition multifocal IOL.However, in all these previous comparative series, the general level of patient satisfaction was high, similar as in our study.Indeed, a total of 95% of patients reported that they would have the same surgical procedure with the same IOL again, with only 11% of patients reporting the occasional use of glasses for near, especially for prolonged tasks.Similarly, in the Concerto multicentre study, more than 91% of patients implanted with a diffractive EDOF IOL reported that they would recommend the same procedure to their friends and family.
The incidence of photic phenomena was minimal, with a median value of 4.0 each (scale, 0-worst situation to 5-best situation) in the patients' evaluation of postoperative night driving and difficulties associated to halos.Likewise, a median value of 5.0(with the same scale) was obtained for the subjective patient evaluation of the postoperative adaption between photopic and mesopic conditions.This confirms one of the potential advantages of EDOF IOLs, the generation of less disturbing photic phenomena.Hamid and Sokwala [13] reported in a comparative study that the perception of halos with a trifocal IOL was more disturbing compared to EDOF IOLs.However, other authors such as Escandón-García et al. [22] found in a prospective case series that objective dysphotopsia measured with a light distortion analyzer was not reduced in eyes implanted with EDOF IOLs compared to trifocal IOLs.Possibly, in some patients with specific characteristics, the tolerance to the double halo generated by trifocal IOLs [23] is similar to that associated to the halos of lower magnitude generated by EDOF IOLs.Future studies should investigate this further.

Conclusion
The EDOF IOL AT LARA is able to provide a restoration of the visual function across distances after cataract surgery, with very high levels of patient satisfaction.The near visual performance obtained with this IOL is more limited than that obtained with multifocal IOLs, but it is within a functional range allowing the patient to perform most of the daily activities without the need for glasses.
As expected according to the design of the IOL, the incidence of photic phenomena was minimal, with low impact on night driving.Future studies should confirm all these outcomes in larger samples over a longer follow-up period.

Financial Disclosure
The study was supported by a research grant of Carl Zeiss Meditec.

Figure 2 .
Figure 2. Mean mesopic binocular contrast sensitivity function at 1 month after surgery.

Table 2
summarizes the postoperative visual and refractive outcomes in the analysed sample.As shown, a significant reduction of manifest refraction and a significant improvement in CDVA was observed with surgery (p < 0.001).All eyes achieved a 1-month postoperative binocular CDVA of 20/20 or better (Figure1).Likewise, all eyes achieved a DCIVA of 20/30 or better at 1 month postoperatively, and a total of 92.1% (35) achieved DCNVA of 20/40 or better.

Table 1 .
Sociodemographic and clinical characteristics of the patients.

Table 2 .
Postoperative visual acuity and subjective refraction in the analyzed sample.

Table 3 .
Quality of vision and patient satisfaction outcomes obtained using a subjective questionnaire at 1 month after surgery (score from 0 = worst score to 5 = best score).
0.156) or ocular optical quality parameters (P ≥ 0.084).The excellent distance visual outcomes obtained with the EDOF IOL evaluated in our series are also consistent with the good level of refractive predictability, with almost all eyes having a postoperative spherical equivalent within ±0.50 D.