Visual satisfaction and spectacle independence with monofocal intraocular lens with enhanced intermediate vision and trifocal intraocular lenses in the prepresbyopic age group patients with cataracts

Abstract

AIM:

This aims to study visual satisfaction and spectacle independence in prepresbyopic age patients with cataracts after the implantation of either monofocal intraocular lens (IOL) with enhanced intermediate vision or trifocal IOL.

SETTING:

Private practice.

MATERIALS AND METHODS:

This prospective, observational case study was conducted on patients in the prepresbyopic age group with cataracts. Patients were allocated to one of the two groups. Thirteen patients (26 eyes) received monofocal IOL with enhanced intermediate vision (intermediate vision group), and 12 patients (24 eyes) received diffractive multifocal IOLs (trifocal group). Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity, Uncorrected intermediate visual acuity (UIVA) and uncorrected near visual acuity (UNVA) values, defocus curves, and contrast sensitivities (CS) of the two groups were compared 3 months’ postsurgery. Their spectacle independence and visual satisfaction were also assessed.

RESULTS:

The study patients were aged 35–45 years and comprised 14 males and 11 females. No significant difference was observed in UDVA (intermediate vision group: 0.02 ± 0.01, trifocal group: 0.02 ± 0.01; P = 0.22) and UIVA (intermediate vision group: 0.20 ± 0.10, trifocal group: 0.19 ± 0.10; P = 0.12). However, a statistically significant difference was observed between the groups in terms of UNVA (intermediate vision group: 0.32 ± 0.10, trifocal group: 0.80 ± 0.10; P = 0.01). The mean CS in monofocal IOL with enhanced intermediate vision and trifocal groups were 1.577 ± 0.3 and 1.550 ± 0.2, respectively (P = 0.40). None of the patients experienced photic phenomena. In total, 10 of 13 patients in the monofocal IOL with enhanced intermediate vision group required spectacle correction for near visual acuity in the range of +1.00 to +2.00 D.

CONCLUSION:

This study found that there was no significant difference in distance and intermediate vision between the two groups. However, the trifocal group had better uncorrected near vision compared to the monofocal group that had enhanced intermediate vision. The conclusion is that using trifocal IOLs for both eyes provided complete independence from wearing glasses. In addition, no visual disturbances were observed after implanting the new-generation trifocal IOLs.

Introduction

Challenges involved in cataract surgery in young patients include correction of near and intermediate vision acuities after the implantation of monofocal intraocular lenses (IOLs). Strategies for correction of presbyopia postcataract surgery comprise prescribing spectacles or contact lenses. However, these modalities have their inherent disadvantages. Owing to the increase in the use of computers and mobile phones, the demand for intermediate-distance lenses has increased.

Due to excellent long-term outcomes for distance vision and low cost associated with monofocal IOLs, they are commonly implanted after cataract surgery. However, patients of the prepresbyopic age group with the implantation of monofocal IOLs may face difficulties adapting to postoperative presbyopia. Monofocal IOLs do not address intermediate vision. Therefore, spectacles may be needed for near and intermediate vision correction, which are cosmetically unacceptable.

Recent advances in the IOL technology have introduced trifocal and monofocal IOL with enhanced intermediate vision IOLs for the correction of intermediate vision. Multifocal IOLs provide excellent near and distance vision; however, they are associated with a reduction in contrast sensitivity and the formation of glare and halos. These photopic phenomena are responsible for patients’ dissatisfaction after cataract surgery.[1] Monofocal IOL with enhanced intermediate vision lenses was developed to overcome these difficulties and are similar to monofocal IOLs. These IOLs have a continuous change in power from the periphery to the center and have a modified aspheric anterior surface. These IOLs create a single-elongated focal point to enhance the vision range. Multifocal and monofocal IOL with enhanced intermediate vision lenses improve spectacle independence; however, the quality of vision is still debatable.[2]

Young patients are engaged in various activities such as driving, reading, writing, and using mobile phones and computers, which need near and intermediate vision. Therefore, their visual performance is better with trifocal and monofocal IOL with enhanced intermediate vision IOLs. Based on this assumption, we performed a comparison of these two IOLs in prepresbyopic age patients undergoing cataract surgery. The literature search did not reveal any study on these IOLs in prepresbyopic age patients with cataracts. We compared visual acuity, contrast sensitivity, spectacle independence, and photic phenomena in patients implanted with these IOLs.

Materials and Methods

This prospective, observational, comparative, and nonrandomized study was conducted in a tertiary eye care center in Central India after obtaining approval from the institutional review board. The study followed the tenets of the Declaration of Helsinki and was conducted between December 2017 and March 2019.

The patients were divided into two groups based on the IOL type implanted after cataract surgery. The intermediate vision group received TECNIS Eyhance lenses (ICB00, Johnson and Johnson Vision, USA), and the trifocal group received multifocal IOL lenses (PanOptix, Alcon Laboratories, Fort Worth, TX, USA).

The inclusion criteria were prepresbyopic age (35–45 years), bilateral cataracts, corneal astigmatism <0.75 D, axial length 22.0–25 mm, and preoperative pupillary size ≤6 mm.

The exclusion criteria were subluxated cataracts, distorted pupil, retinal or macular pathology, prior retinal surgery or laser treatment, high myopia or hypermetropia, operated for glaucoma or on antiglaucoma drugs, amblyopia, previous refractive surgery, other eye operated for cataract and implanted with monofocal IOLs, and monocular patients. The intraoperative exclusion criteria were extended capsulorhexis, posterior capsular rent, zonular dehiscence, vitreous loss, and trauma to the pupil leading to irregular pupil. None of the patients had any systemic diseases or had undergone any major surgical procedures.

All patients underwent a thorough informed consent procedure that included a discussion of the risks and benefits of the implants.

Preoperatively, all patients underwent a thorough ocular examination that included the measurement of distance and near visual acuity with an Early Treatment Diabetic Retinopathy Study chart, slit-lamp biomicroscopy, cataract grading (according to Lens Opacities Classification System III), intraocular pressure measurement using applanation tonometer, and dilated retinal examination. Optical biometry (Lenstar LS 900, Haag-Streit, USA) was performed for IOL power calculation. Emmetropic power was considered in both the groups. Barrett's total keratometry formula was used in all cases.

Intraocular lens

PanOptix intraocular lens

The PanOptix IOL (TFNT00 model) is an acrylic, hydrophobic, single piece, foldable, and posterior chamber lens with a total diameter of 13 mm and a central optic of 6 mm. The posterior lens surface is spherical, and the anterior lens surface is aspheric, with a diffractive surface on the central 4.5-mm portion of the optic zone. The optic has an intermediate vision of +2.17 D at 60 cm and near vision of +3.25 D at 40 cm. The optic zone allows high-light utilization, transmitting 88% of the light to the retina at 3.0-mm pupil size. For intermediate and near vision each, 25% of the light is used, and 50% of the light is used for distance vision.

TECNIS Eyhance intraocular lens

The TECNIS Eyhance IOL (ICB00 model) is a monofocal, single-piece hydrophobic acrylic IOL having a 360° square edge, overall diameter of 13 mm, and a central optic of 6 mm. It has a modified aspheric anterior surface for distance vision and a continuous increase in power from the periphery to the center that enhances intermediate vision at 66 cm. The lens compensates for corneal spherical aberrations.

Surgical technique

A single-experienced surgeon performed all cataract surgeries under topical anesthesia. All patients underwent a 2.8-mm clear corneal temporal incision. A 5.5-mm capsulorhexis was created to cover a 6-mm optic of the IOL. The phacoemulsification settings were as follows: vacuum, 250 cc; flow rate, 30 cc; and power, 30%–50% in a pulse mode (Swisstech, Oertli phacoemulsification System, Switzerland). A thorough cortical wash and vacuum polishing of the posterior capsule were performed. After completion of the procedure, patients received either PanOptix or TECNIS Eyhance IOL in the capsular bag. All the operations were uneventful.

Following the surgery, the patients were administered antibiotics and steroid drops four times per day for 1 month. All patients had a routine 1-day postoperative examination. All examinations were performed 3 months after surgery by a second examiner who was unaware of the study objective. The examination included the measurement of uncorrected distance visual acuity (UDVA), corrected distance visual acuity, uncorrected near visual acuity (UNVA) at 40 cm, corrected near visual acuity, uncorrected intermediate visual acuity (UIVA) at 60 cm, and corrected intermediate visual acuity. A spectacle independence questionnaire was used to determine spectacle independence.[3] The quality of vision was assessed using a Rasch-scored questionnaire.[4] Photopic lighting conditions were maintained for all visual acuity tests. Contrast sensitivity was assessed using the Pelli–Robson chart at 1-m distance.

Statistical analysis

Data were entered into an MS Excel sheet, and statistical analyses were performed using Statistical Package for the Social Sciences (SPSS) version 13.0 (SPSS Inc., Chicago, IL, USA). The data are expressed as the mean ± standard deviation or number and percentage. The between group comparison was performed using the unpaired t-test. Fisher's exact test was used for comparing categorical variables. P <0.05 was considered statistically significant.

Results

The study was conducted in 50 eyes of 25 patients, with 13 (26 eyes) patients implanted with Eyhance (ICB00) IOLs and 12 (24 eyes) patients implanted with PanOptix IOLs (TFNT00). Preoperative characteristics of the patients in the two groups are presented in Table 1. All patients underwent bilateral implantation of IOLs. The surgery was uneventful and successful in all patients. The capsulorhexis remained intact in all patients, with the IOLs well-centered inside the capsular bag. No case of posterior capsule rupture or vitreous loss was observed.

Table 1.

Preoperative characteristics of the two groups

Parameters	Monofocal IOLs with enhanced intermediate vision (n=13 patients, 26 eyes)	Trifocal group (n=12 patients, 24 eyes)	P
Age (years) (range)	42.22±3 (36–45)	43.22±2 (35–45)	0.13
Sex (male: female)	8:5	6:6	0.16
Preoperative UDVA (range)	0.5±0.20 (0.1–1.00)	0.45±0.20 (0.10–1.00)	0.22
Spherical equivalent (D) (range)	0.23±1.24 (0.50–1.50)	0.44±1.34 (0.50–1.50)	0.13
Corneal astigmatism (D) (range)	0.55±0.24 (0.11–1.00)	0.58±0.21 (0.10–1.00)	0.12
Axial length (mm) (range)	22.23±0.78 (22.01–24.12)	22.38±0.75 (22.12–24.01)	0.12
Anterior chamber depth (mm) (range)	2.99±0.78 (2.50–3.22)	3.00±0.99 (2.63–3.22)	0.22

UDVA: Uncorrected distance visual acuity, IOLs: Intraocular lens

The postoperative follow-up was uneventful in all patients. The IOLs remained well-centered in the capsular bag in all patients during follow-up visits. None of the patients in either group developed posterior capsular opacification. No signs of shrinkage of the rim of the anterior capsular margin were observed during the follow-up period. Both eyes were set for distance vision, and no postoperative refractive error was observed. Tables 2 and 3 present visual outcomes in the two groups with 3-month postoperative follow-up. All patients in both the groups had achieved high degrees of UDVA and UIVA. However, UNVA was statistically better in the trifocal group than in the monofocal IOL with enhanced intermediate vision group (P = 0.01).

Table 2.

Postoperative binocular visual outcome in the two groups after 3 months

Parameters	Monofocal IOLs with enhanced intermediate vision group (n=26 eyes)	Trifocal group (n=24 eyes)	P
UDVA	0.02±0.01 (0.00–0.63)	0.02±0.01 (0.00–0.6)	0.22
UIVA	0.20±0.10 (0.01–0.12)	0.19±0.10 (0.01–0.13)	0.12
UNVA	0.32±0.10 (0.25–0.5)	0.80±0.10 (0.00–0.80)	0.01
CDVA	0.01±0.01 (0.00–0.63)	0.01±0.01 (0.00–0.63)	0.24
CIVA	0.05±0.01 (0.00–0.63)	0.05±0.01 (0.00–0.63)	0.34
CNVA	0.01±0.01 (0.00–0.03)	0.01±0.01 (0.00–0.02)	0.33

CDVA: Corrected distance visual acuity, CIVA: Corrected intermediate visual acuity, CNVA: Corrected near visual acuity, UDVA: Un CDVA, UIVA: Un CIVA, UNVA: Un CNVA, IOLs: Intraocular lens

Table 3.

Postoperative binocular visual outcome in the two groups after 3 months

Parameters	Monofocal IOLs with enhanced intermediate vision group (n=26 eyes)	Trifocal group (n=24 eyes)	P
UDVA	0.01±0.02 (0.00–0.22)	0.01±0.02 (0.00–0.22)	0.22
UIVA	0.05±0.02 (0.00–0.10)	0.01±0.02 (0.00–0.22)	0.22
UNVA	0.50±0.20 (0.2–0.30)	0.60±0.10 (0.00–0.80)	0.03
CDVA	0.01±0.01 (0.00–0.55)	0.01±0.01 (0.00–0.50)	0.34
CIVA	0.05±0.01 (0.00–0.63)	0.05±0.01 (0.00–0.60)	0.33
CNVA	0.01±0.01 (0.00–0.02)	0.01±0.01 (0.00–0.01)	0.23

CDVA: Corrected distance visual acuity, CIVA: Corrected intermediate visual acuity, CNVA: Corrected near visual acuity, UDVA: Un CDVA, UIVA: Un CIVA, UNVA: Un CNVA, IOLs: Intraocular lens

The mean contrast sensitivities (CS) in monofocal IOL with enhanced intermediate vision and trifocal groups were 1.577 ± 0.3 and 1.550 ± 0.2, respectively (P = 0.40).

The binocular defocus curves of both the IOLs are presented in Figure 1. Both the IOLs showed a peak at defocus 0.0 D and a reduction in visual acuity with increased negative spherical spectacle power from 1.0 D. Eyes implanted with PanOptix IOLs had a smoother profile than those implanted with Eyhance IOLs. Table 4 presents patient-reported spectacle independence in the two groups. One patient in both the groups needed spectacles for distance vision. Two patients in the intermediate vision group required spectacles for intermediate vision, whereas none of the patients in the trifocal group required spectacles for near and intermediate vision. In total, 10 patients in the intermediate vision group required spectacles for near vision in the range of +1.00 to +2.00 D. Complete satisfaction was reported by 91.7% of the patients in the trifocal group in terms of distance vision.

Figure 1.

Binocular defocus curves of both the intraocular lens. Blue curve indicate Eyhance and orange indicate trifocal intraocular lens. Both the intraocular lens showed a peak at defocus 0.0 D and a reduction in visual acuity with increased negative spherical spectacle power from 1.0 D. Eyes implanted with PanOptix intraocular lens had a smoother profile than those implanted with Eyhance intraocular lens

Table 4.

Patient-reported spectacle independence

Spectacles needed	Trifocal group (n=12), n (%)		Monofocal IOLs with enhanced intermediate vision group (n=13), n (%)
Distance	1 (8.3)		1 (7.7)
Intermediate	0		2 (15.4)
Near	0		10 (76.9)
Satisfaction with spectacle independence	CS, n (%)	NS, n (%)	CS, n (%)	NS, n (%)
Distance	11 (91.7)	1 (8.3)	12 (92.3)	1 (7.7)
Intermediate	12 (100)	0	9 (69.2)	4 (30.8)
Near	12 (100)	0	2 (15.4)	11 (84.6)

CS: Completely satisfied, NS: Not satisfied, IOLs: Intraocular lens

None of the patients complained of glare and halos at night and difficulty with driving in photopic and scotopic conditions.

Discussion

A major concern after monofocal IOL implantation in a young patient is intermediate and near vision acuity. With advanced technologies, intermediate and near vision acuity can be corrected during cataract surgery with the implantation of extended-depth-of-focus (EDOF), trifocal, bifocal, or multifocal IOLs. The daily use of mobile phones and computers has led to an increase in the demand for EDOF and trifocal IOLs for intermediate vision. Studies have compared these two IOLs in senile cataracts.[2,3,5,6,7,8] We believe that patients in the prepresbyopic age group with uncomplicated cataracts who require intermediate vision are suitable candidates for the implantation of trifocal IOLs and monofocal IOLs with enhanced intermediate vision, which provide an extended range of vision. Therefore, the present study was conducted.

Trifocal IOLs offer a range of vision from near to distance. However, glare and halos can occur, particularly during nighttime. Hence, monofocal IOLs with the intention of improving intermediate vision must be developed.

In this study, excellent uncorrected distance and intermediate visual outcomes were observed in monofocal IOLs with enhanced intermediate vision and trifocal IOLs. However, one patient in each group required distance vision correction, and two patients implanted with monofocal IOLs with enhanced intermediate vision required correction for intermediate vision. Lee et al. in their study on the comparison of EDOF and monofocal IOLs with enhanced intermediate vision have shown excellent UNVA in both the groups after bilateral implantation. However, spectacle independence was higher in the EDOF group than in the trifocal group.[6] Zein et al. objectively and subjectively evaluated trifocal IOL implantation and demonstrated that it provides complete spectacle independence.[7] The UIVA in both the groups at 6 months of follow-up in our study (Eyhance = 0.05 ± 0.02 and PanOptix = 0.01 ± 0.02) was better than that in the studies by Zein et al.[7] (0.82 ± 0.31 decimal Snellen) and Cochener et al.(0.57 ± 0.20 decimal Snellen).[2] This difference may be due to differences in the examination distance between studies. We used 60 cm as an intermediate distance of the standard arm length for working on a laptop, using a mobile phone, cooking, and driving a car while checking the speedometer.

In this study, binocular UNVA was better with trifocal IOLs (0.60 ± 0.10) than with monofocal IOLs with enhanced intermediate vision (0.50 ± 0.20, P = 0.03). A similar observation was reported in the study by Jeon et al., where trifocal IOLs had better near vision than monofocal IOLs with enhanced intermediate vision.[9] Imburgia et al. in their study on the comparison of trifocal IOLs with monofocal IOLs showed good visual outcomes at all distances with trifocal IOLs compared with monofocal IOLs.[10]

However, certain studies have shown no significant difference in near-visual acuity between monofocal IOLs with enhanced intermediate vision and monofocal IOLs.[11,12,13] Lee et al. in their study on the comparison of Eyhance and Symphony IOLs concluded that binocular near visual acuity did not differ significantly between the groups.[6] This inconsistency in the results of various studies may be due to variability in the sample size between the studies. Another reason could be the binocular summation effect that is stronger in monofocal IOLs with enhanced intermediate vision than in trifocal IOLs.[14] Whether increasing the sample size will improve the result needs to be studied.

Defocus curves help in choosing an appropriate IOL depending on the patients’ needs. The trifocal IOL curve showed a smoother profile along the entire curve than the Eyhance IOL. This correlates with the result by Lee et al.[6] Thus, both trifocal IOLs and monofocal IOLs with enhanced intermediate vision are viable options for spectacle-free vision for intermediate distance. This also signifies spectacle independence in the two groups. None of the patients in the trifocal group required spectacle correction for near and intermediate vision. However, the Eyhance group required spectacle correction in the range of +1 to +2.00 D sphere for near vision. Monofocal IOLs required near vision correction in the range of 2.25–3.0 D. Furthermore, analogs observations were noted in other studies.[6,9]

Studies have reported reduced contrast sensitivity after the implantation of multifocal IOLs compared with that after monofocal IOL implantation.[15] This occurs due to the division of light energy through different focal points produced by multifocal IOLs. In our study, no significant difference was observed in the contrast sensitivity values between the two groups (intermediate vision group: 1.577 ± 0.3 and trifocal group: 1.550 ± 0.2, P = 0.40). This finding is in agreement with those of various studies.[5,6,11] Joshi in his study on a comparative evaluation of diffractive multifocal with accommodative IOL observed lower contrast sensitivity values with multifocal IOLs than with accommodative IOLs.[16] However, contrast sensitivity is better with present-generation trifocal IOLs than with bifocal and multifocal IOLs.[17,18,19] Improved contrast sensitivity improves vision quality. None of the patients in either group had glare and halos at night and difficulty in driving during the day or night. This could be due to the small sample size of the study. Eyhance is a monofocal refractive IOL with induced spherical aberrations. This leads to negligible glare and halos. Multifocal IOLs due to diffractive optical principles represent an increased risk of glare and halos.[20,21] Studies have shown high incidences of glare and halos after the implantation of PanOptix IOL. However, the comparative difference between the groups was not significant.[10,22,23]

Spectacle independence after IOL implantation depends on the type of tasks performed by and the personality traits of the individual. We used a questionnaire designed by Morlock et al. as patients find it easy to understand.[3] In this study, spectacle independence was equal for distance and intermediate vision in both groups. However, for near-vision patients, spectacles were not required after trifocal IOL implantation. Patients in our study were in the prepresbyopic age group and actively involved in activities requiring a vision for all distances. Several studies have shown that spectacle independence is higher with trifocal IOLs than with monofocal IOLs, with enhanced intermediate vision.[2,6,7,19,24,25] The satisfaction level has been reported to be equal in both the groups in some studies.[23,26] The satisfaction level depends on proper preoperative counseling regarding the need for spectacles postoperatively for some fine work.

This study had certain limitations, including a small size and a short-term follow-up of 3 months. It is easy to recruit many patients with senile cataracts than in a younger age group patients having cataracts. Furthermore, to study bilateral implantation of IOLs, patients should have bilateral cataracts and be willing to undergo a surgery in a short duration. We could not compare various study parameters in our study because studies on monofocal IOL with enhanced intermediate vision and trifocal IOLs implanted in patients of the prepresbyopic age group are unavailable in the literature. However, all patients were operated by a single surgeon with the same technique to minimize confounding factors. Another notable limitation was the nonrandomized nature of the study. Nonetheless, the purpose of this study was to provide crucial information to cataract surgeons by comparing IOLs used for spectacle-free vision in prepresbyopic age patients. The evaluation performed was related to the binocular impanation of IOLs. Consequently, no monocular data for either lens were collected.

Conclusion

Bilateral implantation of either trifocal IOL or monofocal IOL enhanced for intermediate vision provides a good visual outcome. Prepresbyopic age patients having cataracts and seeking spectacle independence may benefit from trifocal IOLs. Satisfaction levels were higher with trifocal IOLs than with monofocal IOL with enhanced intermediate vision IOLs. With the new generation of trifocal IOLs, contrast sensitivity, and photic phenomena can be overcome. We recommend a randomized, comparative evaluation of these lenses in a large number of prepresbyopic age patients having cataract with a long-term follow-up.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.