Clareon Intraocular Lens: Results of Cataract Surgery. Exilaser Cuenca Ophthalmological

Objective : To analyze visual acuity, refractive cylinder, refractive sphere and complications in cataract surgery by phacoemulsification with Clareon intraocular lens. Methodology : A descriptive-observational, longitudinal study based on the review of medical records of the Exilaser Ophthalmology Clinic of 114 patients who underwent cataract surgery by phacoemulsification with a Clareon intraocular lens was carried out. Descriptive statistical techniques such as frequencies, measured percentages were used on those cases of central tendency and comparative analysis with T Student. Results: The most frequent pre-surgical visual acuity on the Snellen scale was 20/CD with 27.2%, the most frequent corrected pre-surgical visual acuity was 20/CD with 14.0%, the most frequent pre-surgical refractive cylinder value was 0 with 50.9%, the most frequent pre-surgical refractive sphere value was 0 with 28.9%. Post-surgical visual acuity was 20/30 with 20.2%, Corrected Post-surgical Visual Acuity was 20/20 with 53.5%, the most frequent post-surgical refractive sphere value was 0 with 40.4%, the most frequent Post-surgical Refractive Cylinder value was 0 with 14.0%. 99.1% did not present trans-surgical complications and 91.2% did not present post-surgical complications. Conclusions: Cataract surgery by phacoemulsification with CLAREON intraocular lens improves Visual Acuity and the Refractive Sphere, with statistically significant results, with minimal intra-surgical and post-surgical complications. Abbreviations: Visual acuity (VA), Visual acuity without correction (AVSC), Visual acuity with correction (AVCC), Refractive sphere (ER), Refractive cylinder (CR), Intraocular lens (IOL), Dioptres (D).


INTRODUCTION
According to WHO data in 2019 there are around 65.2 million people with visual impairment due to cataract.In Ecuador, with the data obtained by the National Institute of Statistics and Census (INEC), the prevalence of visual impairment is 1.3% due to life expectancy has been increasing, the prevalence of cataract is expected to increase.How García, R. and collaborators in their study carried out in Cuba in 2017, reported that the prevalence of cataracts predominated in patients between the ages of 70-79 years, being women the most affected.In the studies carried out by Garg, P et al, the importance of cholesterol and antioxidant levels as causes of cataracts in advanced ages is pointed out.(1)(2)(3)(4)(5)(6) Despite being a disease that can drastically affect a person's quality of life due to decreased vision, this is a reversible pathology through surgical treatment: the extraction of the affected crystalline lens being replaced with an intraocular artificial lens (MESS).The implementation of new surgical methods has been revolutionary, as in the case of phacoemulsification, where the lens is extracted through a small incision, becoming the technique of choice to treat cataracts.(7,8) Various authors worldwide such as He L, Cui Y. and collaborators; Ibanez I; Toyama et al.; Lujan P et al; Among others, they obtained positive results with the use of phacoemulsification surgery, improving short-term vision, taking into account different variables such as visual acuity (VA), refractive sphere (RE), refractive cylinder (CR), personal and ophthalmological history, among others.The study mentions that postoperative corneal edema, a history of glaucoma, very old age or a very long surgery are independent risk factors for having a visual complication; it is worth mentioning that these complications are rare.(9)(10)(11)(12)(13) It is clear that IOLs and phacoemulsification surgery have changed the lives of millions of patients since their invention, so we consider it important to study the results of different IOLs to compare how much they improve visual acuity, their possible complications, their interaction with the comorbidities, among other variables.
The focus of this study, the Clareon intraocular lens, is a monofocal IOL that is made of a new acrylic hydrophobic material, based on the characteristics of the AcrySof platform (previous model from the same commercial house).Stephen Lane et al in a study compared the Clareon IOL with AcrySof, enVista, TECNIS and Vivinex iSert IOLs.Tested in 35 °C deionized water for axial displacement, pág.3999 optical tilt, and decentering with the effect of compression, Clareon and AcrySof showed significantly less (P < 0.001) axial displacement at 10 mm compression compared to all.other models.Clareon's mean optical run out was found to be 0.04 ± 0.02 mm, which is less than the maximum of 0.6 mm specified by the International Organization for Standardization (ISO; 23).Optical tilt was also below the ISO-specified maximum value of 5° optical tilt, with a mean value of 0.5 ± 0.2°.(14)(15)(16) Gerd Auffarth compared results of in vitro evaluations of the Clareon IOL and the TECNIS, EnVista and Vivinex lenses, subjected to an accelerated aging process to induce glare formation, Clareon had a mean number of 4.09 bright microvacuoles/mm2, a number that characterizes it as Grade 0 on the Miyata flash scale.This concludes that it has a low probability of flashing over time.(14,15) To assess how the biomaterial interacts with the eye, comparative studies were performed between Clareon and AcrySof IOLs, with a viscosurgical ophthalmic device (VOD) and silicone oil was evaluated.The silicone oil adhesion study revealed comparable results between both lenses, the percentage coverages obtained are much lower than in silicone IOLs and hydrophobic material, likewise the authors of the investigation indicate that with these results there would be no problems with these lenses if the patient needs retinal surgery in the future.(14,15) The one referred to by the manufacturer Alcon as "AutonoMe" is the mechanism responsible for the delivery of the Clareon IOL.It is an automated, disposable, preloaded and easy-to-use system.It consists of a piston which moves downward to deliver the IOL, the same one that is driven by a cartridge The IOL is delivered folded and directly into the lens capsule.The IOL is delivered folded and directly into the lens capsule.The entire mechanism can be operated with one hand for ease of use.It is possible to insert the lens with incisions between 2.2 -3.2 mm and provides full visibility of the IOL during the procedure.The use of the injectors reduces damage to the IOL during insertion and decreases bacterial contamination (14)(15)(16).
The present study analyzes preoperative and post operative variables of patients undergoing phacoemulsification surgery with the Clareon IOL, and also analyzes the results taking into account the age, comorbidities or ophthalmologic history of the patients in search of possible variations in the visual acuity results.pág.4000

Methodology
A descriptive-observational, lengthwise study was performed at the "Centro Oftalmológico Exilaser", in the city of Cuenca, province of Azuay, Ecuador.We worked with the universe of clinical records, constituted by 114 patients with senile cataract who underwent phacoemulsification surgery with Clareon intraocular lens implantation, between June 2020 and July 2021.The surgeries were performed by 2 ophthalmologists trained in the phacoemulsification technique with minimal variability in the surgeon factor.
Inclusion criteria: Patients undergoing surgery by phacoemulsification with Clareon intraocular lens, with complete data in the clinical history before surgery and medical control one month later.
Exclusion criteria: Medical records with incomplete data, patients with simultaneous cataract and retina or cataract and glaucoma surgeries.

Statistical analysis:
The following variables were studied: age, personal pathologic history, surgical history, ophthalmologic history, trans-surgical complications and post-surgical complications.The following variables AVSC, AVCC, Cylinder and refractive sphere were analyzed preoperatively and analyzed again one month after surgery.Descriptive statistics of frequency and percentage were obtained for all variables.For the analysis of the pre-surgical and post-surgical results, Student's t-test was performed for paired samples; and for the analysis of the variables age, personal history and ophthalmologic surgical history together with the pre and post-surgical results, Student's t-test was used for independent samples, verified with Levene's test for equal variances and with a 95% confidence interval.It is clarified that the authors of the research have no conflicts of interest and the research is self-financed.

Table 1. Summary of qualitative variables
The distribution of patients is close to 50% in both age groups, with a slight majority of patients older than 70 years.More than half of the patients had no comorbidities, type 2 diabetes mellitus and arterial hypertension were both 21.9% of frequency.More than 80% of the patients had no ophthalmologic surgical history.There was only one trans-surgical complication (posterior capsule rupture).
Postoperative complications had a low frequency, the most relevant was corneal edema with 6.1%.The normality statistics were: Mean -0.59 D and SD: 0.76, Median: 0.00 Mode: 0.00.No difference was found between the pre-surgical CR and post-surgical CR.

Variable
pág. 4004 There is a difference in ER Pre-surgical and ER Post-surgical, with results much closer to a refraction of 0 after surgery.Patients under 70 years showed lower visual acuity in pre-surgical variables.But there is no significant difference between the two groups after surgery.No significant difference was found between patients with and without a personal history in their pre-and postoperative VA results.

DISCUSSION
The age range most frequently subjected to phacoemulsification surgery with Clareon IOLs was the highest at 70 years, representing more than half of the universe.Almost the entire universe is older than pág.4006 50 years, which is why it is considered a diagnosis of senile cataract.The Isabel Ibáñez study at the Ircovisión Clinic in Murcia, which evaluates the visual acuity results of phacoemulsification cataract surgery with another intraocular lens (Tecnis Symfony), finds that the most frequent age range is from 42 years to 78 years (10).Talavero P. reports in his research an average age of between 60 and 63 years (11).
Regarding the personal pathological history, more than half of the patients did not present a pathological history, while the rest presented arterial hypertension and diabetes mellitus at the same frequency.
Similarly, in the study carried out by Luján Paredes et al. reports that the most frequent pathological history is arterial hypertension with more than a third of the cases (12).This frequent appearance of chronic degenerative diseases is once again explained by the advanced age in which the senile cataract occurs.
Regarding ophthalmological surgical history, it was observed that almost the entire universe did not present a history.This is in contrast to the research carried out by Luján Paredes S et al.where they found that 37.5% had previous surgery (12).
The results of the present investigation show that there is an improvement in VA, highlighting that both pre-surgical BCVA and pre-surgical BCVA had a higher frequency of 20/CD, and after phacoemulsification surgery with the Clareon IOL the most common post-surgical BCVA passed to be 20/30 and the post-surgical BCVA 20/20, that is, a very notable improvement in visual acuity, statistically verified when applying the T-Student test, with p<0.05.This agrees with the study carried out by Ibañez I., which evaluates the VA results of phacoemulsification cataract surgery with another IOL (Tecnis Symfony), the study shows that uncorrected distance visual acuity was 0.1 Log MAR, and the BCVA of about 0.07 Log MAR concluding that they improve both the quality of life and patient satisfaction (10).In the same way, it is similar to the results obtained by Luján P. et al. who evaluated the VA variation after phacoemulsification surgery with other types of intraocular lens, presenting a variation from pre-surgical to post-surgical visual acuity of 0.29 to 0.43 (1 equals a VA of 20/20), which would be expressed as an increase in its VA (12).
On the other hand, the study showed a statistically significant difference between pre-surgical and postsurgical RE, decreasing the mean diopters recorded in patients after surgery.No statistically significant pág.4007 difference was found for preoperative and postoperative CR.When comparing with the study by Asena B, who analyzes the results of 2 intraocular lenses (AcrySof PanOptix and AT LISA tri 839MP), we find similarity with their results, since it shows that preoperatively, refraction was similar in both groups, after the operation., mean CR values were similar between the 2 diffractive IOL groups, however, there were statistically significant differences between groups in ER (15).In the same way, we found similarity in the results of the refractive sphere and discrepancy with the results of the refractive cylinder with the study by Isabel I, which mentions that the refractive values after IOL implantation are notably improved with respect to the preoperative values.the mean value of the ER improved to -0.38 D and for the CR a mean of -1.06 D (17).
These results can be explained by the surgical technique used, which is phacoemulsification, in which a small incision is made in the sclerocorneal limbus of between 2.2 and 3.2 mm to introduce the intraocular lens, for which, according to the bibliography, an effect common is to cause mild astigmatism due to irregularities caused in the cornea that alter the refractive cylinder, therefore the results do not show improvement in the pre-surgical and post-surgical refractive cylinder, while the refractive sphere is significantly improved by the characteristics of the IOL, which prior to its placement it is chosen according to the refractive characteristics, which in the Clareon IOL range from +6.0 +30.0 D in 0.5 D increments with the possibility of adapting to the needs of any patient.
Regarding confirming that there are low rates of trans-surgical complications (13).
The Clareon IOL has the AutonoMe system, the mechanism responsible for delivering the IOL, which reduces traumatic processes and facilitates one-hand placement for the surgeon, thereby reducing the risk of trans-surgical complications.
Regarding post-surgical complications, almost all the patients did not present complications and in the patients who did present them, they were mostly mild complications such as corneal edema and uveitis that subside with medical treatment, although in one case retinal detachment was reported due to having suffered eye trauma prior to surgery.Comparing with the study by Isabel I. that analyzes the results of the Tecnis Symfony intraocular lens, it was observed that two patients had to undergo a capsulotomy due to opacification of the posterior capsule secondary to surgery.On the other hand, the study by Toyama T. et al, who found that in group 1, there was an IOP elevation in 2.2%, corneal epithelial damage in 2.2% and cystoid macular edema in 0.72 %, in group 2, IOP elevation occurred in 4.6% and corneal epithelial damage in 0.66%, these complications required complementary medical treatment in most cases.(13) In comparison with our study, similar frequencies of post-surgical complications were observed, although of less medical severity in the case of the Clareon IOL.Corneal edema and uveitis are common complications due to tissue manipulation typical of surgery; in the case of the phacoemulsification pág.4009 technique, it is due to the incision made for lens placement, although the use of increasingly smaller cuts and the delivery of the Folded 6mm IOLs have decreased the frequency of complications as evidenced in studies (17).
If we analyze the most relevant post-surgical complications caused by the IOL described in the bibliography, intraocular lens decentrations and dislocations, uveitis-glaucoma-hyphema syndrome, opacifications, IOL flashes and refractive problems stand out; these complications appear due to errors committed in surgery and intraocular lens defects, some may appear months to years after surgery.As it is a modern surgical technique and an intraocular lens with new technology, complications have been reduced.According to the studies carried out by the manufacturer (Alcon), this is explained by the hydrophobic acrylic material of the Clareon IOL, which is resistant to the appearance of flashes (grade 0 on the Miyata scale), due to its optical decentration of 0.04, which is less than maximum specified by the International Organization for Standardization and optical inclination of 0.5 which is below that specified by ISO standards, for which reason it is considered a long-term resistant lens and no complications of this type were found in our study (18,17).

CONCLUSIONS
More than half of the patients did not present additional comorbidities, more than three quarters suffered from senile cataract as the only ophthalmological pathology and had not had previous ophthalmological surgeries.
Phacoemulsification cataract surgery with Clareon intraocular lens shows statistically significant improvement in post-surgical VA and post-surgical corrected VA, observing that most patients have 20/20 visual acuity.
Regarding refraction, ER is statistically lower after surgery.There is no statistically significant difference between pre-surgical and post-surgical CR.
Patients under 70 years of age have lower pre-surgical VA and pre-surgical AVC than those over 70 years of age.After surgery this difference is no longer statistically significant.
The comparison of patients with a pathological history does not show a statistically significant difference in the pre-surgical or post-surgical measurements.
pág. 4010 The comparison of patients with an ophthalmological surgical history does not show a statistically significant difference in the pre-surgical measurements, but after surgery the patients without a surgical history show better visual acuity.
There is evidence of minimal frequency of trans-surgical complications.The frequency of post-surgical complications is very low, highlighting that most of the complications presented are mild and do not require secondary medical interventions.
Phacoemulsification surgery with Clareon IOL is beneficial by improving visual acuity, reducing the refractive sphere, with minimal intra-surgical and post-surgical complications.

Table 8 .
Correlations of paired samples of preoperative and postoperative results, T Student 95% confidence interval.
The T-Student test shows that both the BCVA and BCVA showed improvement after surgery, a statistically significant result.The mode for postoperative BCVA and BCVA were 20/30 and 20/20, respectively.

Table 9 .
Correlations of Independent samples results according to age, T Student confidence interval 95%.

Table 10 .
Correlations of Independent samples according to Personal history, T Student confidence interval 95%.

Table 11 .
Correlations of Independent samples according to ophthalmological surgical history, T Student 95% confidence interval.
the comparative tests according to age, it was found that patients under 70 years of age 20/200 for BCVA in both groups), while there is a difference Significant for postsurgical VA, on the one hand, patients with a history presented mean BCVA and BCVA of 20/200; and the patients with no history presented means of BCVA and BCVA of 20/60 and 20/40 respectively (p<0.05).Regarding trans-surgical complications, almost all the patients did not present them, the only complication presented was rupture of the posterior capsule in one patient.When compared with the study by Toyama T. et al. carried out at the Tokyo Metropolitan Geriatric Hospital, where 2 groups of patients (over 90 years and over 80 years) who underwent intraocular lens phacoemulsification surgery of various sizes were analyzed.models it was found that in group 1, anterior capsular rupture occurred in 2.9%, posterior capsule rupture in 0.72% and Zinn zonular dialysis in 1.4%.In group 2, anterior capsular tear occurred in 2%, Zinn zonular dialysis in 0.66%, and a very large wound in 0.66%,