Graphical abstract
Abstract
Purpose
To assess visual performance and patient satisfaction of multifocal contact lenses in eyes having monofocal intraocular lens (IOL) implantation.
Methods
We prospectively assessed uncorrected visual acuity at all distances (0.3, 0.4, 0.5, 0.7, 1, and 5 m), higher-order aberrations (HOAs), objective scattering index (OSI), contrast sensitivity, and patient satisfaction, before and during multifocal contact lenses wear in IOL-implanted eyes.
Results
Visual acuity at 0.3, 0.4, 0.5, 0.7, 1, and 5 m during wearing multifocal contact lenses was 0.21 ± 0.08, 0.11 ± 0.06, 0.01 ± 0.08, -0.02 ± 0.10, -0.02 ± 0.08, and -0.01 ± 0.07, respectively. We found a significant improvement at near to intermediate distances (30, 40, and 50 cm), but no significant change at intermediate to far distances (70 cm, 1 m, and 5 m). Log contrast sensitivity significantly decreased at 6 and 12 cycles/degrees, but did not significantly change at 1.5, 3, and 18 cycles/degrees. Third-order aberrations significantly increased after CL treatment, but fourth-order aberrations or total higher-order aberrations did not significantly change during CL treatment. The OSI and log(s) did not significantly change during CL treatment. The patient satisfaction score for overall vision significantly improved during CL treatment.
Conclusions
Multifocal contact lenses significantly improved visual acuity at near to intermediate distances, and subsequent patient satisfaction, even though contrast sensitivity function slightly decreased, suggesting its viability of presbyopic correction in monofocal IOL-implanted eyes.
1
Introduction
Modern cataract surgery has been widely recognized not only as a refractive surgery, but also as a presbyopia-correcting surgery. Accordingly, it is of clinical importance to correct refractive errors as much as possible, and to obtain good near to distance visual acuity without spectacle correction, in order to further improve visual performance and subsequent patient satisfaction. The refractive accuracy of cataract surgery has been much improved by the introduction of both optical biometry, and the latest generation intraocular lens (IOL) power calculation formulas in recent years. However, some patients show dissatisfaction concerning their presbyopic vision, even after monofocal IOL implantation. Multifocal IOL implantation has shown to be effective for obtaining good near to far visual outcomes, and thus reducing spectacle dependence in cataract patients [ ]. However, some patients are dissatisfied with their vision, possibly due to glare, halo, and starburst, refractive errors, or neural adaptation failure [ ]. Actually, multifocal IOL explantation is sometimes required, especially when these complaints are severe and persistent [ ]. Multifocal contact lenses have shown to be helpful to obtaining good near to far visual outcomes, and thus reducing spectacle dependence in presbyopic subjects [ ]. Multifocal contact lenses have several advantages over multifocal IOL implantation, in terms of a preference of non-surgical procedures, the prevention of the possible risk of postoperative complications, the reversibility, and the variability of the lens power over time. Moreover, it can be applied a long time after cataract surgery was performed. However, to the best of our knowledge, the detailed visual performance and patient satisfaction of multifocal contact lens wear in eyes undergoing cataract surgery have so far been not fully elucidated. It may give us intrinsic insights on the clinical application of multifocal contact lenses in monofocal IOL-implanted eyes. The goal of the present study is to prospectively evaluate the detailed visual performance and patient satisfaction of multifocal contact lenses in eyes having monofocal IOL implantation.
2
Methods
2.1
Study population
The study protocol was registered with the University Hospital Medical Information Network Clinical Trial Registry (00,035,897). This prospective observational study comprised a total of 20 eyes of 10 consecutive patients (2 men and 8 women, mean age ± standard deviation: 57.9 ± 11.9 years), who underwent standard phacoemulsification with non-toric monofocal IOL implantation. Eyes with postoperative best corrected visual acuity of less than 0.1 logMAR, eyes with corneal astigmatism of 1 diopter (D) or more, eyes with any history of ocular surgery, ocular trauma, or other concomitant eye diseases, and eyes developing any intraoperative or postoperative complications, were excluded from the study.
We quantitatively assessed visual acuity at all distances (0.3, 0.4, 0.5, 0.7, 1, 3, and 5 m) using a Snellen chart (TMI-V5, TMI, Saitama, Japan), higher-order aberrations (HOAs), objective intraocular scattering metrics such as objective scattering index (OSI) and log(s), contrast sensitivity, and patient satisfaction, before and during multifocal contact lens (Dailies Total1(R) Multifocal, Alcon Laboratories, Fort Worth, TX) wear in the study population. This contact lens is a silicone hydrogel, daily disposable, aspheric, and progressive refractive lens, with 3 add profiles (+1.25 D, +2.0 D, and +2.5 D) for near vision in the center region, a base curve of 8.5 mm, and a lens diameter of 14.1 mm [ ]. During an initial trial, the lens power was targeted at emmetropia with the lowest add (+1.25 D). The spherical power and the add were adjusted with preliminary evaluation, and determined based on patient preferences of far and near binocular vision. Contact lens fitting was confirmed by an experienced ophthalmologist (K.I.). The subjects were instructed to use these contact lenses daily for one month.
Ocular HOAs for a 4-mm pupil were obtained with a Hartmann-Shack aberrometer (KR-1W, Topcon, Tokyo, Japan). Total ocular HOAs were calculated as the root-mean-square of the third- and fourth-order coefficients.
The objective scattering index (OSI), as a measure of objective forward scattering, was obtained with an Optical Quality Analysis System II™ (OQAS II; Visiometrics, Terrassa, Spain), which is designed on the basis of the double-pass technique, for a 4-mm pupil [ ]. This index is calculated by evaluating the amount of light outside the double-pass retinal intensity point spread function image in relation to the amount of light on the center. With this instrument, the central area selected was a circle of a radius of 1 min of arc, while the peripheral zone was a ring set between 12 and 20 min of arc [ ].
The retinal straylight value, as a measure of subjective forward scattering, was obtained with the C-Quant straylight meter (Oculus Optikgeräte, GmbH, Wetzlar, Germany) [ ]. In brief, the subjects are asked to choose which semicircle is flickering more strongly, and to press a button on the left or the right side of the device. The straylight meter will change the luminance of the stimulus and counter-phase modulating light until the two halves are balanced. To obtain the straylight value, this process is repeated 3 times with different levels of compensation light, resulting in a logarithmic straylight value, which is abbreviated as log(s). The measurement was accepted only when the estimated standard deviation was lower than 0.08 and the quality factor was higher than 1.00 [ ].
The contrast sensitivity function was obtained with a contrast sensitivity unit (VCTS-6500, Vistech) under photopic conditions (500 lx). The test was performed with best spectacle correction at 2.5 m. The area under the log contrast sensitivity function (AULCSF) was calculated from the obtained data of contrast sensitivity, as described previously [ ]. In brief, the log of contrast sensitivity was plotted as a function of log spatial frequency, and third-order polynomials were fitted to the data. The fitted function was integrated, and the resultant value was defined as the AULCSF. Overall vision satisfaction was assessed using visual analogue scale (VAS) symptom intensity scores on a scale of 0 (no satisfaction) to 100 (maximum satisfaction). All examinations were performed by experienced ophthalmic technicians.
This observational study was approved by the Institutional Review Board at Kitasato University (B18-171), and followed the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients after explanation of the of the nature and possible consequences of the study.
2.2
Statistical analysis
We conducted statistical analyses by using a commercially available statistical software (Bellcurve for Excel, Social Survey Research Information Co, Ltd., Tokyo, Japan). Since all data did not fulfill the criteria for normal distribution by the Kolmogorov-Smirnov test, the Wilcoxon signed-rank test was used to compare the biometric data between the two groups. The results are expressed as mean ± standard deviation, and a value of p < 0.05 was considered statistically significant.
3
Results
Table 1 shows the demographics of the study population. Eyes fitted with add designation of +1.25, +2.00, and +2.50 D were 0, 14 (70%), and 6 eyes (30%), respectively. No contact lens-related complications were observed during the 1-month observation period. Distance-corrected binocular visual acuity at 0.3, 0.4, 0.5, 0.7, 1, and 5 m during multifocal contact lens wear was 0.21 ± 0.08, 0.11 ± 0.06, 0.01 ± 0.08, -0.02 ± 0.10, -0.02 ± 0.08, and -0.01 ± 0.07, respectively. We found a significant improvement at near to intermediate distances (30, 40, and 50 cm)(Wilcoxon signed-rank test, p = 0.008, p = 0.005, and p = 0.011), but no significant change at intermediate to far distances (70 cm, 1 m, and 5 m)(p = 0.161, p = 1.000, and p = 0.263)( Fig. 1 ). Log contrast sensitivity was significantly decreased at 6 and 12 cycles/degrees (p = 0.028, p = 0.046), but not significantly changed at 1.5, 3, and 18 cycles/degrees (p = 0.590, p = 0.317, and p = 0.185)( Fig. 2 ). Table 2 summarizes higher-order aberrations, intraocular scattering, contrast sensitivity, and patient satisfaction before and during multifocal contact lens wear. Third-order aberrations significantly increased during contact lens wear (p = 0.008), but fourth-order aberrations or total higher-order aberrations did not significantly change during contact lens wear (p = 0.101, and p = 0.057). The OSI and log(s) did not significantly change during contact lens wear (p = 0.135, and p = 0.076). The AULCSF significantly decreased during contact lens wear (p = 0.013). The patient satisfaction score for overall vision significantly improved during contact lens wear (p = 0.025).
