Clinical study on visual outcomes with four different intraocular lens following cataract surgery

INTRODUCTION

Cataract surgery with intraocular lens (IOL) implantation is one of the most commonly performed surgical procedures worldwide.^[1] As the global population continues to age, the demand for cataract surgery has steadily increased. The selection of the appropriate IOL is a critical component of achieving optimal visual outcomes for patients. IOLs come in a variety of materials, designs, and optical properties to address different patient needs and preferences.^[2]

Accurate biometric measurements are essential for selecting the ideal IOL power and minimizing refractive errors after cataract surgery. The IOL Master 700, a swept-source optical coherence tomography-based biometry device, has become widely accepted for its precision and reliability in measuring key parameters such as axial length, keratometry, and anterior chamber depth. The integration of this advanced biometry technology has helped surgeons achieve even more predictable refractive results.^[3]

While many IOL brands have demonstrated excellent clinical results, it is valuable to directly compare the visual and refractive outcomes of different IOL options to help guide surgeon selection. There have been comparative evaluations between different types of monofocal lenses,^[4] monofocal versus multifocal,^[5] and lenses of different prices.^[2] This retrospective study aimed to evaluate and compare the visual acuity and refractive outcomes of four commonly used posterior chamber IOL brands implanted during routine cataract surgery, with consideration of the high-quality biometric data obtained using the IOL Master 700. All the lenses were monofocal, hydrophobic acrylic but belonged to a variable price range.

MATERIAL AND METHODS

RESULTS

We studied a total of 140 eyes of 125 patients. The eyes were divided into four groups, each having 35 eyes. Group A was implanted with Tecnis Eyhance, Group B with AcrySof IQ, Group C with Hoya iSert 150, and Group D with S lens. The mean age of patients in each group, sex distribution, mean axial length, and keratometry readings are given in Table 1. When we analyzed the pre-operative data, there was no statistically significant difference between the four IOL groups with respect to axial length, Keratometry values (K1, K2), and astigmatism (ΔK). Hence, the visual outcome following surgery is unlikely to be affected by these parameters. Surgically induced astigmatism for a 2.2 mm incision is 0.2, and for a 2.8 mm incision is 0.3.

Pre-operative vision in Group A ranged from perception of light (PL)+ to 6/12, in Group B from hand motion (HM)+ to 6/9., in Group C from HM+ to 6/9, and in Group D from PL+ to 6/9. The mean and SD of post-operative vision on days 1, 7, and 30 in logMAR are given in Table 2. A comparison of pre-operative and post-operative visual acuity (UCVA) in all the groups on days 1, 7, and day 30 is illustrated in Figure 1.

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Figure 1:

Pre- and post-operative visual outcomes among four groups.

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The post-operative status of the cornea was noted in all cases. Any eye having corneal stria was treated with 5% hypertonic saline. As this may serve as a confounding factor in early post-operative UCVA, so for the purpose of analysis the final (4^th week) UCVA and BCVA were considered. On average, 97.14% of patients in the study attained a BCVA of 6/12 or better at the final follow-up; 83.57% of patients attained UCVA of 6/6–6/12 at the final follow-up. On analyzing the different lenses, varied outcomes were observed after 4–6 weeks. The highest percentage of patients achieving good UCVA (6/6–6/12) was seen with AcrySof IQ (94.28%), followed by S-Lens (88.57%), Hoya iSert 150 (82.85%), and Eyhance (68.57%). This was not the same when BCVA was compared between the groups. Hoya iSert fared best in this parameter, where 100% of patients attained BCVA of 6/6–6/12, followed by AcrySof IQ (97.14%), S-Lens (97.14%), and Eyhance (94.28%).

Table 2 shows that log MAR UCVA in post-operative day (POD) 1 in the four groups did not show any difference statistically (P = 0.42). In POD 7, however, Group B (AcrySof IQ) had statistically significantly better UCVA as compared to the other three groups (P = 0.04). In POD 30, the UCVA in Groups B, C, and D were comparable, which was better than Group A (Eyhance), the difference being significant statistically (P = 0.01). The post-operative spherical equivalent in the four groups was comparable. The spherical equivalent required to achieve BCVA was lowest in Group B (0.15 ± 0.24) and highest in Group A (0.30 ± 0.28), though not a significant difference. This explains why 31.43% of patients in Group A did not have good UCVA (6/6–6/12). There were no intraoperative or post-operative complications in any of the study groups.

DISCUSSION

The WHO advises that at least 90% of patients undergoing cataract surgery should achieve satisfactory visual outcomes (6/6–6/18), with no more than 5% experiencing poor vision (<6/60) after the procedure in any service setting.^[7] This study compared the visual outcomes of four lenses with similar qualities but varying prices.

Since the development of the ancient “couching” technique in the 5^th century BC, cataract surgery has continuously evolved.^[8] One key consumable in phacoemulsification cataract surgery is IOLs. Unfortunately, due to the increased branding of IOLs, current economic instability, and rising inflation, the cost of surgery continues to escalate. The issue of IOL cost has been addressed by producing low-cost lenses, making the technology more accessible to those who cannot afford expensive options. However, an ethical question arises: are these low-cost IOLs as effective and safe as their branded, more expensive counterparts? This study aimed to address that concern, and it demonstrates that branding is not a significant factor in terms of visual acuity when surgical variables are controlled. Such studies comparing multiple lens options have been conducted in the past. However, there are yet no reports on the comparison of post-operative visual acuity of patients implanted with Hoya iSert 150 and S Lens, which, though belong to the imported segment, are economically viable. Moreover, these two lenses have additionally been compared with two immensely popular and well-accepted branded lenses. This is the strength of our study.

Goslings et al.^[9] studied outcomes of aspheric monofocal (Vivinex iSert) with Tecnis Eyhance, a modified monofocal IOL designed to slightly extend the depth of focus. He concluded that Eyhance offers improved intermediate vision compared to standard aspheric monofocal IOLs. The benefit of this improvement on patients’ self-perceived vision after surgery appears to be limited. In terms of distance vision rehabilitation, no significant differences were found between the modified and standard monofocal IOLs.

Singh et al.^[10] compared Technis Eyhance ICB00 and one-piece ZCB00 monofocal IOL and concluded that the uncorrected distant visual acuity was comparable in both the ICB00 and ZCB00 groups at the 6-week and 3-month follow-up periods, with no significant differences observed. The uncorrected intermediate and near vision were significantly better in ICB00 versus ZCB00 at 6 weeks and 3 months postoperatively. This finding is mirrored in the study by Kang et al.,^[11] who concluded that there was no significant difference in uncorrected distant visual acuity (UDVA) values postoperatively between the ICB00 and ZCB00 in the Asian population. But when it comes to uncorrected intermediate (P < 0.001) and near vision (P < 0.05), ICB00 fared better than ZCB00 at 3 months postoperatively.

Memon et al.^[2] compared three monofocal IOLs of varying cost and reported that branding is not a significant factor regarding visual acuity when surgical variables are controlled. In their large study population (n = 3237), 88.2% attained BCVA between 6/6 and 6/12. In the third follow-up, no significant difference was found in BCVA of the three IOL groups, which were operated by senior surgeons. But when the rest of the surgeons’ results were compared, the difference was statistically significant at the third follow-up. The median BCVA for the economical lens was 0.3 log MAR, for the moderately priced lens was 0.2 log MAR, and for the expensive lens was 0.2 log MAR (P = 0.036).

Shetty et al.^[4] compared three different types of monofocal IOL (Matrix Aurium, AcrySof single piece, and AcrySof IQ lens) and found that 69% of the eyes implanted with Matrix Aurium group had good UDVA post-surgery; the proportion was 48% and 57% in the AcrySof single piece and AcrySof IQ group (P = 0.09), respectively. The mean age (SD) in these groups was 58.9 ± 10.4, 60.4 ± 11.3, and 57.4 ± 14.9 years for Group A, B, and C, respectively.

In the present study on POD 30, Group B (Acrysof Alcon IQ) gave the best results of good visual acuity (6/6–6/12) with a proportion of 94.28%, followed by Group D (S-Lens) (88.57%), Group C (Hoya iSert 150) (82.85%), and Group A (Eyhance) (68.57%), respectively, with clinically significant difference in P-value for POD 7 and POD 30.

CONCLUSION

This study evaluated the visual outcomes of four different monofocal IOLs and found not much of significant differences in performance, regardless of price. All four IOLs produced comparable post-operative visual acuity and refractive outcomes. This suggests that the cost of the lens does not play a major role in surgical success. These findings are particularly relevant in settings where cost is a concern. Surgeons can confidently select more affordable monofocal IOLs without compromising the quality of care, considering both the percentage of patients achieving the optimal vision and the consistency of the outcomes across different lens types. Any of the four monofocal IOLs studied can be effectively used in cataract surgery, with the success of the procedure depending more on the surgeon’s skill than the cost or brand of the IOL.