The Visual Outcome After Cataract Surgery With Multifocal Intraocular Lenses And Monofocal Intraocular Lenses At Tertiary Care Hospital - A Prospective Observational Study

Abstract

BACKGROUND: The crystalline lens is part of the optical system of the eye that focuses rays of light on the retina. Apart from contributing to the optical power of the eye as a whole, the crystalline lens is able to dynamically change the optical power of the system by the process of accommodation for younger eyes. During life the ability of the crystalline lens to change in shape decreases, leading to presbyopia. For optimal visual performance crystalline lens should be transparent. Cataract describes the pathological opacification of the crystalline lens. Removal of the crystalline lens followed by implantation of an artificial intraocular lens (IOL) in the capsular bag of the eye, as practiced in cataract surgery, offers an opportunity to address refractive anomalies in patients who are ametropic due to removal of cataract. Implantation of an IOL with a fixed focal point (Monofocal IOL) will render a patient at best emmetropic for a single fixed working distance only, leading to a postoperative result comparable to presbyopia in an emmetropic subject; pseudo-accommodation can play a role in increasing the depth of field but spectacle independence for a range of working distances is not to be expected after implantation of a Monofocal IOL. To restore the missing accommodation we can implant Multifocal IOLs. Multifocal IOLs on the other hand, are designed to have two or more fixed focal points, thus facilitating a sharp retinal image of objects at multiple working distances resulting in increased spectacle independence, but these lenses can cause reduction in contrast sensitivity and higher incidence of photic phenomena such as halos, flare and glare. AIM OF THE STUDY The study was carried out with the aim of comparing the visual outcome after cataract surgery with Multifocal Intraocular Lenses and Monofocal Intraocular Lenses in respect to distant visual acuity, near visual acuity, contrast sensitivity, subjective symptoms and to assess functional status and quality of life. MATERIALS AND METHODS: A Prospective observational study was conducted in the Department of Ophthalmology, KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belagavi on patients undergoing cataract surgery during the period of 1st January 2015 – 31st December 2015. The study was approved by the Ethical and Research Committee of Jawaharlal Nehru Medical College, Belagavi. 40 eyes of 40 patients underwent phacoemulsification surgery with IOL implantation under LA. Choice of IOL inserted given according to their desire for spectacle independence. Monofocal group was taken as control. Both the groups were evaluated post operatively after 3 weeks and 6 weeks for distant vision, near vision, contrast sensitivity for distance, subjective satisfaction by standard questionnaire method and subjective symptoms like glare and halos and difficulty with night driving. Data was analyzed by chi-square test (p < 0.05%). RESULTS: Distant visual acuity 6/6 – 6/9 in 80% and 75% of the patients of Multifocal and Monofocal groups respectively, remaining patients had 6/12 – 6/18 vision. 85% of Multifocal group had N6 – N8 vision (p < 0.0001). High contrast sensitivity for distance was almost similar in both the groups, but low contrast was significantly reduced in Multifocal group as compared to Monofocal group (p = 0.0023). 15% of multifocal group had complained of glare and halos compared to Monofocal group who never had these visual sensations. 5% of patients in Multifocal group had difficulty with nighttime driving. 80% of patients in Multifocal group and 40% of patients in Monofocal group had become spectacles independent. INTERPRETATION AND CONCLUSION: The Multifocal IOL group experienced reduced spectacle dependency for near vision and a high level of patient satisfaction despite some reports of halos, glare and difficulty with night driving. The Monofocal IOL group experienced spectacle dependency for near vision. Overall, Multifocal IOLs offer best near vision acuity, good distant vision acuity, less limitation in visual function in selected and motivated individuals.