Discussion
Cataract, cataracts, visual impairment, cataract, abnormal color vision, IOL, corneal irregular astigmatism
CATARACT, IOL, GROUP B, NEAR VISION, RECRUITMENT, CATARACT, LENS, CATARACTS
Cataract extraction combined with IOL implantation is the only effective method for the treatment of cataracts at present. Patients put forward higher requirements for the postoperative effect of cataracts to meet the needs and improve the quality of life. A previous studyTypically, doctors implanted monofocal IOL for patients during cataract surgery, which could provide good distance only. Thus, the patients required spectacles correction for intermediate and near vision postoperatively. The emergence of trifocal IOL makes it possible for patients to have spectacles independence after surgery. Trifocal IOL can converge parallel light into far, intermediate, and near focus and provide a good functional vision at all distances with high levels of spectacles independence and patient satisfaction. In the current study, group A (with 839MP) had better monocular UCVA in the distance, intermediate, and near vision, while BCVA had no difference.When different types of IOLs were implanted, statistically significant differences were detected in the area-of-focus metric between groups A and B in the distance area, intermediate area, and near area. The range from 0-4.34 mm diameter center is +1.66 D, +3.33 D, with additional medium and near vision trifocal design, and that for 4.34-6 mm is +3.33 D bifocal designed with additional near vision. This design results in wider and better vision after trifocal IOL implantation, which in turn, leads to better visual function, higher satisfaction, spectacles independence, and quality of life, especially in the intermediate and near distance. The study by Tarib et alAlthough the contrast sensitivity values of patients with scotopic and photopic vision after trifocal IOL implantation were within the normal range, Group B had significantly higher CSF under UCVA at 3 months after the operation in our study.Due to the diffraction design of this trifocal IOL, patients had more visual interference after implantation, especially glare and halos. However, no statistical difference was detected in the visual interference between the 2 groups. This may be related to the special design of the trifocal IOL, making it to have high light energy utilization. Interestingly, we found that 2 patients in group A had an abnormal color vision after implantation, and their vision was slightly bluish, while no patient reaction was noted in group B. This phenomenon could be attributed to the diffraction ring design of this trifocal IOL. The height of the diffraction step of IOL with different diopters determined the passage of specific diffracted light waves, while the wavelengths of light of different colors varied, resulting in abnormal color vision in some patients due to the diffraction of light waves after implantation. However, this part of the abnormality could be gradually alleviated after brain fusion and adaptation and did not affect the patient’s daily life. Nonetheless, this finding needs to be substantiated further. However, this study was limited by the sample size and the recruitment of patients from only one hospital.In conclusion, compared to monofocal intraocular lens, the trifocal intraocular lens provides a full range of clear vision for the majority of patients with simple cataracts and improves the rate of spectacle independence and patients’ satisfaction, but reduces the patients’ contrast sensitivity and cause visual impairment. However, the objective quality of vision did not show any difference and would not significantly affect the daily life of the patients. Despite visual interference, trifocal intraocular lenses are preferred by patients. By strictly controlling the indications of trifocal intraocular lenses implantation, such as spherical aberration, the total corneal irregular astigmatism in 4-mm area, and the kappa angle, this visual interference can be reduced to a minimum and would not affect the daily life of patients.