Cataract defined as clouding of the natural intraocular crystalline lens is one of the leading prevalences of global blindness almost about 62.6%.In today’s scenario where, economic and social expectations have risen to need near-perfect restoration of post cataract surgery vision, many novel techniques and improvements in optics quality of intraocular lenses (IOLs) have led to multiple newer advances attempting not only to improve patients vision but also to provide them with good visual quality. Multifocal lenses were designed to provide good distance, and near vision, (Werner L, 2021) (Javitt JC et al. 2000) in contrast to monofocal lenses which provided the clearest image at one fixed focal length (Werner L 2021). The appearance of multifocal lenses made a revolutionary change in cataract surgery, allowing spectacle independence on a daily basis(Mojzis P et al 2010) (Alio JL et al 2004) ,hence ensuring a good unaided distance and near visual acuity. In this study we compare the post operative results of monofocal vs multifocal lenses in our population operated at a tertiary eye hospital.

This study was undertaken in a tertiary eye care hospital, where patients above the age of 18 years were recruited after getting informed consent prospectively. All the patients enrolled in this study were informed about its nature and signed informed consent to undergo the clinical examination in accordance with the tenets of the Declaration of Helsinki. The study was approved by the hospital ethics committee. Based on the patient’s choice of IOL they were divided into Monofocal (Group A) vs Multifocal group (Group B). All patients with any preexisting ocular conditions, history of trauma, previous intraocular surgery, significant retinal pathology, glaucoma, conditions that can cause intraoperative complications like pseudoexfoliation, zonular break factors were excluded. The patients were examined detailed history, Anterior and posterior segment evaluations, slit lamp examination, and dilated fundoscopy was done (Sachdev et al ,2017). Biometry was performed using IOL master700, Barett suite formula was used for IOL power calculation. Preop vision assessment was done with Snellen chart for distance and near, contrast sensitivity with Pelli-robson chart at baseline visit and postoperative follow-up visits were scheduled on day 1, week 1, and week 8. All patients were operated by the same surgeon using the same technique of phacoemulsification lens with 2.8 mm incisions. The postoperative treatment included systemic antibiotics, lubricating eye drops, and tapering doses of topical antibiotic steroid combination for 8 weeks. During each visit outcome, a detailed slit lamp examination was done mandatorily, and all the patients were monitored for potential complications such as photophobia, photopsia, blepharospasm, ptosis, glaucoma and macular oedema. STASTICAL ANALYSIS: The collected data was analysed using SPSS software, ver.20.0 • Kolmogorov – Smirnov test and kurtosis, skewness was used to test the normality of the data (50 < n > 300) • Continuous variables are expressed in terms of Mean, Standard deviation (SD), Standard error (SE), Median and interquartile range (IQR) • Categorical variables are expressed in terms of frequency (n) and percentage (%) • Independent t test & Mann Whitney U test were used to compare means of continuous variables between two groups. • Chi-square test was used to compare categorical variables between two groups. • P < 0.05 was considered as statistically significant NORMALITY OF THE DATA Since the sample size was 60, normality was checked using Kolmogorov-Smirnov test, kurtosis and skewness. Kolmogorov-Smirnov test showed p > 0.05 and for few variables, and for few other variables it showed p < 0.05. kurtosis and skewness value for all parameters was between – 3.96 and + 3.96. Since the data has both normal and non-normally distributed variables, both parametric and non-parametric tests were used in the study.

DISTANCE VISUAL ACUITY BETWEEN TWO GROUPS VA Group A Group B n % n % 6/6 13 43.3 9 30.0 6/9 7 23.3 5 16.7 6/12 5 16.7 11 36.7 6/18 0 0 1 3.3 6/24 3 10.0 3 10.0 6/36 1 3.3 0 0 Total 30 100 30 100 POST-OPERATIVE DAY-1 VISUAL PERFORMANCE 1.On the first post operative day, 66% of the patients had UCVA of 6/18 or better with a monofocal lens and 70% of the patients had UVCA of 6/18 or better with a multifocal lens. striate keratopathy was the most common cause for decreased Visual acuity on 1st post operative day 2.NEAR VISION; On checking the near vision on 1st Post operative day in the monofocal group, 96.7% had near vision less than N18. In the Multifocal group, 36,7% had N6, 43.3% had N8, 13.3% had N10, 6.7% had N12 vision. There is significant difference in the post-op day-1 near vision between two groups (p < 0.0001) COMPARISON OF NEAR VISION BETWEEN TWO GROUPS Group A Group B n % n % N6 0 0 11 36.7 N8 0 0 13 43.3 N10 0 0 4 13.3 N12 1 3.3 2 6.7 N18 27 90.0 0 0 N36 2 6.7 0 0 Total 30 100.0 30 100.0 3.On post op Day-1 in the monofocal group, more than 96.7% of patients had contrast sensitivity 2.1 and in multifocal group,60% of the patients had contrast sensitivity 2.1 and 36.7% had 1.96. There is significant difference in the post-op day-1 contrast sensitivity between two groups (p = 0.001) POST-OPERATIVE DAY-7 VISUAL PERFORMANCE 1) On day 7, 86.6% patients had UCVA of 6/9 or better vision with a unifocal lens and 83.3 of the patients had UCVA of 6/9 or better vision with a multifocal lens. COMPARISON OF CONTRAST SENSITIVITY Group A Group B n % n % 1.1 1 3.3 1 3.3 1.96 0 0 11 36.7 2.1 29 96.7 18 60.0 TOTAL 30 100.0 30 100.0 DISTANCE VISUAL ACUITY BETWEEN TWO GROUPS VA Group A Group B n % n % 6/6 19 63.3 13 43.3 6/9 7 23.3 12 40 6/12 4 13.3 5 16.7 Total 30 100 30 100 2) VISUAL ACUITY : COMPARISON OF CONTRAST SENSITIVITY Group A Group B n % n % 0 0 8 26.7 30 100 22 73.3 30 100.0 30 100.0 VISUAL ACUITY (Mann-Whitney U test) Group A Group B Z-score p-value Number 30 30 -1.369 0.171 Minimum 0 0 Maximum 0.3 0.3 Mean 0.087 0.13 Median 0 0.2 IQR 0 – 0.2 0 – 0.2 Mean rank 27.72 33.28 3) NEAR VISION: On Day 7 in the monofocal group, 10% had N12, 90% had N18. In the Multifocal group, 53.3% had N6, 40% had N8 and 6.7% had N12. There is significant difference in the post-op day-7 near vision between two groups (p < 0.0001). Patients with multifocal IOLs were found to have better unaided near vision of N6 which could be attributed to the inbuilt near vision add and the zonal progressive design of IOL which offer the patients spectacle independence COMPARISON OF NEAR VISION BETWEEN TWO GROUPS Group A Group B n % n % N6 0 0 16 53.3 N8 0 0 12 40 N12 3 10 2 6.7 N18 27 90 0 0 Total 30 100.0 30 100.0 4) CONTRAST SENSITIVITY: On Day-7 in the unifocal group, 100% of patients had contra sensitivity 2.1 and in multifocal group, 73.3% of the patients had contrast sensitivity 2.1 and 26.7% had 1.96. There is significant difference in the post-op day-7 contrast sensitivity between two groups (p = 0.002). POST-OPERATIVE 8-WEEKS VISUAL PERFORMANCE 1) VISUAL ACUITY: At the end of eight week, 100% had UCVA of 6/9 or better with unifocal lens and 93.3% with multifocal lens . The rationale for this drop in vision was cystoid macular oedema. A maximum of +0.5 D sphere was noticed and the post operative residual spherical error was largely zero. Most of the patients had induced post operative Astigmatism less than 1 D. DISTANCE VISUAL ACUITY BETWEEN TWO GROUPS VA Group A Group B n % n % 6/6 23 76.7 21 70 6/9 7 23.3 7 23.3 6/12 0 0 2 6.7 Total 30 100 30 100 2) VISUAL ACUITY VISUAL ACUITY (Mann-Whitney U test) Group A Group B Z-score p-value N 30 30 -0.723 0.469 Minimum 0 0 Maximum 0.2 0.3 Mean 0.04 0.06 Median 0 0 IQR 0 0 – 0.2 Mean rank 29.3 31.7 2) NEAR VISION: At the end of week 8, in the monofocal group, 23.3% had N12, 76.7% had N18 and In the Multifocal group, 56.7% had N6, 43.3% had N8 and 6.7% had N12. There is significant difference in the post-op week-8 near vision between two groups (p < 0.0001). COMPARISON OF NEAR VISION BETWEEN TWO GROUPS Group A Group B n % n % N6 0 0 17 56.7 N8 0 0 13 43.3 N12 7 23.3 2 6.7 N18 23 76.7 0 0 Total 30 100.0 30 100.0 3) CONTRAST SENSITIVITY: At the end of week 8, in the monofocal group, 100% of patients had contra sensitivity 2.1 and in multifocal group, 73.3% of the patients had contrast sensitivity 2.1 and 26.7% had 1.96. There is significant difference in the post-op week-8 contrast sensitivity between two groups (p = 0.002). COMPARISON OF CONTRAST SENSITIVITY Group A Group B n % n % 1.96 0 0 8 26.7 2.1 30 100 22 73.3 TOTAL 30 100.0 30 100.0

Multifocality aims at the concept of restoring patient to near normal vision helping to retain good distance, intermediate and near vision. There is bound to be a reduction in contrast in a multifocal IOL because at any given distance 100% of light is not focused on the retina. According to our study, distance visual acuity is comparable in both the groups, with no significant statistical difference. According to Leyland M et al (2003), Altemir-Gomez et al, (2020) also distance acuity was similar in multifocal and monofocal IOLs. Unaided near vision tended to improve with multifocal IOLs, , in the monofocal group, 23.3% had N12, 76.7% had N18 and In the Multifocal group, 56.7% had N6, 43.3% had N8 and 6.7% had N12. There is significant difference in the post-op week-8 near vision between two groups (p < 0.0001). similar results were seen by Leyland M et al (2003), multifocal IOLs were designed to avoid the need for glasses by providing two or more points of focus. Javitt JC et al (2000) also concluded that patients with multifocal IOLs had better near visual acuity and reported better overall vision. Steinert RF et al (1992) concluded that patients with multifocal IOL achieved significantly better uncorrected near vision than monofocal IOL. According to our study, adverse effects of multifocal IOLs was reduced contrast sensitivity and experience of halos around lights. Ravalico G et al(1994) had similar finding that there was a significant drop in contrast in patients with multifocal IOL despite the good visual acuity and this can affect the quality of vision. One of the strengths of this study is the corelation and comparison of multifocal intraocular lens with monofocal intraocular lens. However, the conclusion of this study cannot be generalised to the population at large considering that it was conducted on a smaller sample size should be taken into consideration. Further prospective studies in a larger population could be needed.

Our prospective interventional study shows that the visual performance of monofocal and multifocal intraocular lenses (IOLs) depends on various factors, such as patient age, lifestyle, and visual demands. Monofocal IOLs typically provide clear distance vision, but patients may still require glasses for reading or other near vision tasks. Multifocal IOLs, on the other hand, aim to reduce or eliminate the need for glasses by providing both distance and near vision correction, but may result in decreased visual acuity or contrast sensitivity compared to monofocal IOLs. Ultimately, the choice between monofocal and multifocal IOLs depends on the patient's individual needs and expectations

1. Werner, L. (2021). Intraocular Lenses: Overview of Designs, Materials, and Pathophysiologic Features. Ophthalmology, 128(11), e74-e93. 2. Javitt JC et al. (2000), cataract extraction with multifocal intraocular lens (IOL) implantation; a multinational clinical trial evaluating clinical, functional, and quality-of-life outcomes. journal Ophthalmology 2000 (Vol. 107, Pages 2040-2048). 3. Aliño JL, Plaza-Puche AB, Javaloy J, Ayala MJ. Comparison of the visual and intraocular optical performance of a refractive multifocal IOL with rotational asymmetry and an apodized diffractive multifocal IOL. J Refract Surg 2012; 28:100–105. 4. Sachdev, Gitansha Shreyas; Sachdev, Mahipal, (December 2017). Optimizing outcomes with multifocal intraocular lenses. Indian Journal of Ophthalmology 65(12): p 1294-1300. | DOI: 10.4103/ijo.IJO_1072_17 5. Altemir-Gomez I, Millan MS, Vega F, et al. Comparison of visual and optical quality of monofocal versus multifocal intraocular lenses. European Journal of Ophthalmology. 2020;30(2):299-306. doi:10.1177/1120672119827858 6. Canovic, S., Konjevoda, S., Pavicic, A. D., & Stanic, R. (2019). Intraocular Lens (IOL) Materials 7. Yamuchi, T., Tabuchi, H., Takase, K., Ohsugi, H., Ohara, Z., & Kiuchi, Y. (n.d.). Comparison of Visual Performance of Multifocal Intraocular Lenses with Same Material Monofocal Intraocular Lenses 8. Preethi, S., & Gnanadurai, J. S. C. (n.d.). Comparison of Performance Standards Between Unifocal and Multifocal Intraocular Lenses Following Cataract Surgery. 9. Jorge, A., Pilar, Y., Canlo, M., Plaza, A. B., & Vega, A. (n.d.). Clinical Outcomes with a New Design in Multifocal Intraocular Lens: A Pilot Study. 10. Aliño JL, Piñero DP, Plaza-Puche AB, Rodriguez Chan MJ. Visual outcomes and optical performance of a monofocal intraocular lens and a new-generation multifocal intraocular lens. J Cataract Refract Surg 2011; 37:241–250. 11. McNeely RN, Threshold limit of multifocal IOL to residual astigmatism. J Cataract Refract Surg 2016; 42:1134. 12. Leyland and Zinicola conducted a systematic review to compare multifocal and monofocal IOLs in cataract surgery. The study was published in the journal Ophthalmology in 2003 (Vol. 110, Pages 1789-1798). 13. Steinert RF et al. conducted a prospective, randomized, double-masked comparison of a zonal progressive multifocal IOL and a monofocal IOL. The study was published in the journal Ophthalmology in 1992 (Vol. 99, Pages 853-860). 14. Hayashi K et al. conducted a study to examine the correlation between pupillary size, IOL decentration, and visual acuity of a zonal progressive multifocal lens and a monofocal lens. The study was conducted at Hayashi Eye Hospital in Japan. 15. Ravalico G et al. conducted a study to evaluate the functional outcomes of a new type of intraocular lens called Domilens type Progress1. The study was published in the journal J Fr Ophthalmol in 1994 (Vol. 17, Pages 175-181).