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Influence of light filters in intraocular lenses on color perception and contrast acuity
ARTICLE
Influence of light filters in intraocular lenses on color perception and contrast acuity Elfriede Wissiak, MD, Navid Ardjomand, MD, Gernot Steinwender, MD, Martin Prskavec, MD, Ramin Baradaran-Dilmaghani, MD, Maria Kohl, MD, Matthias G. Wirtitsch, MD
PURPOSE: To compare contrast acuity at different illumination levels, color vision, and the subjective visual impression in patients after bilateral cataract surgery with mixed implantation of a yellowtinted intraocular lens (IOL) and an orange-tinted IOL. SETTING: Department of Ophthalmology, Hietzing Hospital, Vienna, Austria. DESIGN: Prospective case series. METHODS: Consecutive patients with age-related cataract had standardized small-incision cataract surgery with IOL implantation in the capsular bag. Patients were randomly assigned to receive a yellow Polylens Y30 in 1 eye and an Orange Series model PC 440Y in the contralateral eye. The main outcome measures were contrast acuity, color vision, and subjective visual impression. Contrast acuity was measured at illumination levels of 5.0 lux and 0.5 lux and contrast levels of 50.0%, 25.0%, and 12.5%. Color vision was assessed using the Heidelberg-multicolor anomaloscope, and the subjective visual impression was evaluated using a questionnaire. RESULTS: This study included 64 eyes of 32 patients. The intraindividual comparison showed no significant difference in contrast sensitivity at different contrast and illumination levels or in color vision. On questioning, 3 patients reported a difference in subjective color perception between the 2 IOL types. CONCLUSION: There were no differences in contrast sensitivity or color vision between yellowtinted IOLs and orange-tinted IOLs. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2015; -:-–- Q 2015 ASCRS and ESCRS
Blue light–filtering intraocular lenses (IOLs) were introduced in cataract surgery in the 1990s. At that time, large epidemiology studies described an increased risk for age-related macular degeneration (AMD) progression after cataract surgery and the increased light exposure at short wavelengths was proposed as the possible cause.1–3 As a consequence, IOLs that block not only the damaging ultraviolet (UV) radiation but also partially filter the visible blue light were developed. These IOLs combine the UV filter with a covalently bound chromophore that partly absorbs high-energy blue light in the spectral range of 400 to 500 nm.4 Based on those findings, in principle, the elderly natural lens through the physiologic Q 2015 ASCRS and ESCRS Published by Elsevier Inc.
yellowing process offers more protection than the young adult lens. At present, several manufacturers use yellow chromophores to mimic the absorption spectrum of the natural yellow cataract lens of a 60 year old.5 Recently, an IOL with orange chromophores was introduced with the intention of offering even higher photoprotection. Through filtering wavelengths between 400 nm and 600 nm, which include a larger part of visible blue light and parts of green and yellow light, this orange IOL proved to be a more powerful filter than yellow IOLs.5,6 However, yellow-tinted and orange-tinted IOLs are intended to protect an aging retina from visible highenergy light. However, they should not interfere
http://dx.doi.org/10.1016/j.jcrs.2014.09.048 0886-3350
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with the optical quality. Several studies have compared the visual performance in eyes with untinted IOLs and yellow-tinted IOLs, with the main focus on color vision and contrast acuity. Study results were controversial. Some studies found better performance7–9 and others worse performance10–12 with yellow-tinted IOLs. Yet other studies did not find statistically significant differences.13–21 To our knowledge, no study in the literature has compared the visual performance of yellow-tinted IOLs and orange-tinted IOLs intraindividually. Because the crucial wavelength spectrum for distinguishing luminance under scotopic conditions lies between 500 nm and 507 nm, the decreased light transmittance in this range in orange-tinted IOLs compared with the transmittance with yellow-tinted IOLs might have implications for color perception and scotopic vision6 (Figure 1). Therefore, the aim of the present study was to compare a yellow-tinted IOL and an orange-tinted IOL and their effect on contrast acuity, color vision, and subjective patient visual impression. To detect subtle changes between the 2 IOLs, we used strict inclusion criteria and the sensitive measuring methods outlined and used in our previously published study.22 PATIENTS AND METHODS This prospective randomized double-masked bilateral clinical trial with intraindividual comparison was performed at the Department of Ophthalmology, Hietzing Hospital, Vienna, Austria. The study followed the guidelines of the Declaration of Helsinki and was performed according to the European Union Good Clinical Practice guidelines. The study protocol was approved by the Ethics Committee of the City of Vienna, Austria, and was registered with the U.S. National Institutes of Health Clinical Trials.A After receiving an explanation of the nature and possible
Figure 1. Transmission characteristics of the blue–green light– filtering IOL (orange-tinted IOL) and the blue light–filtering IOL (yellow-tinted IOL) compared with those of a 53-year-old crystalline lens.
consequences of the study, all patients provided written informed consent.
Patient Recruitment Patients were recruited from a continuous cohort that presented with bilateral age-related cataract to the outpatient center of the Department of Ophthalmology, Hietzing Hospital, Vienna. Patients with amblyopia, pseudoexfoliation syndrome, primary or secondary glaucoma, ocular hypertension, uveitis, diabetic retinopathy, history of intraocular surgery, laser treatment, retinal pathology, or other relevant ophthalmic diseases were excluded. Furthermore, the systemic medications of patients being screened for the study were recorded and checked for possible ophthalmologic side effects. Patients using medications known to potentially cause such side effects were excluded from the study, as were patients with an expected postoperative corrected distance visual acuity (CDVA) worse than 1.0 (20/20). Patients with a congenital color vision anomaly, ocular surface disease, or ametropia of more than 3.0 diopters (D) were not included in this trial, nor were patients with nicotine or alcohol abuse.
Intraocular Lens Assignment Submitted: May 1, 2014. Final revision submitted: August 27, 2014. Accepted: September 1, 2014. From the Department of Ophthalmology (Wissiak, Ardjomand, Steinwender, Wirtitsch), Medical University Graz, Graz, the Department of Ophthalmology (Prskavec), Hietzing Hospital and the Center for Medical Statistics (Kohl), Informatics and Intelligent Systems, Medical University of Vienna, Vienna, and the Department of Ophthalmology (Baradaran-Dilmaghani), St. Josef Hospital, Braunau, Austria. Presented in part at the XXVIII Congress of the European Society of Cataract and Refractive Surgeons, Paris, France, September 2010. Corresponding author: Matthias G. Wirtitsch, MD, Department of Ophthalmology, Medical University Graz, Auenbruggerplatz 4, 8036 Graz, Austria. E-mail: [email protected].
Intraocular lens randomization was performed before patient recruitment. The patients and examiners were masked to the IOL assignment. No attempt was made to mask the surgeon to IOL assignment because both IOLs used in this study have a typical optic color and a typical design. However, the surgeon was unaware of the type of IOL to be used until the eye was prepared for IOL implantation. The first eye was randomly assigned to receive a multipiece foldable IOL, either a Polylens Y30 (Polytech Ophthalmologie GmbH), which filters blue light, or a Orange Series Model PC 440Y (Ophtec BV), which filters blue–green light, The contralateral eye received the other IOL. The Polylens Y30 is a UV light–filtering and blue light–filtering yellowtinted hydrophobic acrylic 3-piece IOL with an optic diameter of 6.0 mm. Angulation of the polyvinylidene fluoride haptics is 5 degrees and the overall diameter, 13.0 mm. The orange-tinted PC 440Y is a 3-piece IOL that has a 5.8 mm polysiloxane optic containing chromophores that filter UV light
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and blue–green light. The poly(methyl methacrylate) haptics have an angulation of 10 degrees; the overall diameter is 12.5 mm. Both IOLs are sharp-edged. The eye with the higher degree of cataract had surgery first. Surgery was performed between July 2008 and November 2009 by 1 of 3 surgeons (M.P., R.B.D., M.G.W.) using a standardized surgical technique. Both eyes of each patient had surgery performed on different days. The maximum time between the 2 surgeries was 4 days.
Surgical Technique Surgery was performed using topical anesthesia through a 2.6 mm temporal clear corneal incision. After exchange of the aqueous with an hyaluronic acid 5000 10 mg/mL (Healon), a well-centered 5.0 to 5.5 mm continuous curvilinear capsulorhexis was created with a bent needle or a capsulorhexis forceps. After phacoemulsification of the nucleus, the residual cortex was removed by coaxial irrigation/aspiration (I/A), which was followed by polishing the posterior capsule. The IOL was implanted after the anterior chamber and the capsular bag were filled with ophthalmic viscosurgical device (OVD). The residual OVD was aspirated with a coaxial I/A tip, the incision was hydrated, and the globe was filled with Ringer’s solution. Postoperative treatment consisted of a fixed tobramycin–dexamethasone combination (Tobradex) and diclofenac (Voltaren Ophtha) eyedrops 4 times a day for 1 month. The same experienced masked examiner performed testing in the second eye in a single session a mean of 90 days G 10 (SD) after surgery. The test duration was approximately 30 minutes. After the CDVA was measured, several color vision tests and contrast acuity tests were performed under standardized conditions as described in detail below. All tests were performed monocularly. The patients were allowed to relax between tests. The testing sequence of eyes was randomized using a table of random numbers to avoid bias. After the vision tests, the patient was interviewed using a patient questionnaire.
Color Vision Testing Blue–Green Color Vision Test The Heidelberg-multicolor anomaloscope MR (Oculus Optikger€ate GmbH) was used to test blue–green color vision. It uses the additive colormixing method and evaluates blue–green color vision using the Moreland 2 equation [blue (436 nm) C green (490 nm) Z cyan (480 nm) C yellow (589 nm)].20 After receiving an explanation of the testing procedure and after a trial run was performed, the patients were tested monocularly with best distance correction. The test was started with the presentation of a white fluorescent field, which is comparable to the standard light source C (6770 degrees Kelvin). This field was repeatedly presented every 3 seconds for a defined period to provide neutral adaptation throughout the test. The patient then looked at a circular, horizontally divided test field through an eyepiece with a viewing angle of 4 degrees. The upper half of the field of the testing device is a mixed field of green and blue, and the lower comparison field consists of cyan, which is desaturated by yellow. The upper mixed color field can be adjusted on a scale from 0 (turquoise free) to 100 (blue free). The brightness of the lower field can be adjusted on a scale from 0 to 100. The normal values range between 42 to 58 mixed color and 43 to 57 brightness. Starting with a mixed color of 100 and a brightness of 85, a stepwise reduction in mixed color was presented until the
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subjective matching point was passed. The patient was asked to make the 2 fields similar by adjusting the brightness of the lower comparison field. After this orientating testing procedure, a fine adjustment was performed, resulting in a lower and upper subjective matching point. The anomaloscope automatically calculates the tritanomaly quotient. The tritanomaly quotient represents an instantaneous observation of the blue-sensitive visual system and is subject to change during one’s lifetime. A tritanomaly quotient of 1 or lower is considered normal, whereas a tritanomaly quotient higher 1 shows a color error that increases with the value.
Contrast Sensitivity Test Near contrast sensitivity function was tested using the Holladay contrast acuity test (Stereo Optical Co., Inc.). Patients were positioned 40 cm from the reading chart with best distance correction plus a correction to set the reading point to 40 cm (C2.5 D). In all cases, 2 trial lenses were used for best correction to standardize light absorption. During testing, the 40 cm reading distance was checked several times using a measuring chain. Contrast sensitivity testing was performed with a 50.0% contrast chart and repeated at 25.0% and 12.5%. All contrast testing was performed at 2 illumination levels (ie, 5.0 lux for high-mesopic and 0.5 lux for low-mesopic conditions). The illumination level was checked using a light meter (Digital Luxmeter MS1500, Voltcraft, Conrad Electronic). The test was stopped when 3 or more errors were made in 1 line. The achieved line for each contrast plus the correct letters in the next line were recorded; each letter was given a value of 0.2. In the next step, the values recorded in lines were converted to logMAR notation for statistical analysis. After computation, data were reconverted for data presentation. A Light Source a Daylight Illuminator (Richmond Products, Inc.) was used for the contrast sensitivity testing. The bulb gives off 6280 degrees Kelvin light that closely matches the standards set by the International Commission of Illumination. The illuminator has been approved by the U.S. Food and Drug Administration and provides a color-rendering index of 94, as recommended in clinical studies. Daylight illumination and consistency of lightning have been found to be important in testing acquired color vision defects.23 The illumination level of the illuminator was set by a dimmer switch and controlled using a light meter. The luminance was set for high-mesopic and low-mesopic light conditions at 5.0 lux and 0.5 lux, respectively.
Patient Questionnaire After completing the visual tests, patients were asked whether they noticed a difference in color vision, contrast vision, or vision under poor light conditions between their 2 eyes. If not, the survey was stopped. If yes, patients were asked which eye they thought had the orange IOL, to describe their vision, and whether they were disturbed by the difference.
Statistical Analysis and Data Presentation All patients and eyes in this study were included in the statistical analysis. During study preparation, the sample size was calculated. The following assumptions for contrast sensitivity and color vision were made at the time of study planning: a clinically relevant difference of 10.0%, a within-
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group standard deviation of 12.5%, (contrast sensitivity) or 15.6% (color vision), a 2-sided experiment-wise significance level a of 5.0% (2.5% for each test, divided by 6 comparisons in the contrast sensitivity test), and a power of 85%. A suspected study subject dropout rate of 15% recommended a sample size of 32 patients. After all data had been crosschecked and entered into the database, the seal of the envelope with the randomization list was broken and the IOL implantation sequences of the patients were unmasked. The contrast sensitivity test was analyzed using a general linear mixed model, including the fixed within-block factors of contrast (the levels were 50.0%, 25.0%, and 12.5%), illumination level (5.0 lux, 0.5 lux), and type of IOL (yellow tinted or orange tinted) and the random factor of patient. Interactions between the fixed factors were hierarchically tested and dropped from the model if not significant. The blue–green color vision test was analyzed using paired t tests. This analysis yielded a P value for the comparison of the yellow-tinted IOL and orange-tinted IOL. Test results are presented as the mean G SD under each type of IOL and as the mean difference (95% confidence interval [CI]) of the 2 IOL types. Visual acuity data are presented as decimal fractions. For statistical purposes, the visual acuities were converted to logMAR notation and then reconverted for data presentation. To correct for multiple testing, the 2-sided significance level for each color vision and contrast sensitivity test was set at 2.5%. Statistical analysis was performed using SAS software (version 9.2, SAS, Inc.).
RESULTS Thirty-two patients (64 eyes) were part of the study screening, and all were included in the study. The mean age of the 20 women and 12 men was 70 G 8.7 years (range 51 to 90 years). All patients completed the scheduled vision tests and questionnaire. Visual Function Figure 2 shows the absolute values of the contrast sensitivity tests. Contrast level and illumination had statistically significant effects on contrast acuity (both P ! .0001). Intraindividual comparison showed no statistically significant difference in visual acuity (Figure 3) (geometric mean ratio of yellow-tinted IOL versus orange-tinted IOL, 0.996; 95% CI, 0.973-1.020; P Z .751). No significant interaction of the type of IOL with the contrast level or illumination was detected. The tritanomaly quotient in the anomaloscope testing showed no statistically significant difference between the yellow-tinted IOLs and the orangetinted IOLs (mean difference 0.004; 95% CI, 0.074 to 0.066; P Z .91) (Figure 4). Patient Questionnaire Twenty-nine of the 32 patients did not notice any difference between their 2 eyes. Three patients reported noticing a difference, and all 3 correctly
Figure 2. Absolute postoperatively.
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sensitivity
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identified the eye with orange-tinted IOL. One of these patients described a subtle gray tone in the eye with the orange-tinted IOL. The second patient noticed poorer vision in the dark in the eye with the orangetinted IOL than in the contralateral eye. The third patient said that colors appeared more matte with the orange-tinted IOL. All 3 patients said that their binocular vision was not disturbed. These 3 patients had or previously had jobs dealing with colors. One of them was a retired florist. The second patient worked in a boutique selling clothes. The third patient worked in a kindergarten, painting and doing handicrafts with children. Statistical evaluation of the questionnaire
Figure 3. Visual acuity: absolute values 3 months postoperatively.
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Figure 4. Blue–green color vision: tritanomaly quotient (anomaloscope) 3 months postoperatively.
did not reach the level of significance (P Z .08; 95% CI, 0.03 to 0.31). DISCUSSION This prospective randomized double-masked study with intraindividual comparison evaluated the clinical relevance of in vitro data comparing the visual performance of patients with a yellow-tinted IOL in 1 eye and an orange-tinted IOL in the contralateral eye. We found no statistically significant difference in CDVA, contrast sensitivity at different contrast levels and illuminations, or color perception between the eyes. The development of blue light–filtering IOLs to protect the retina and reduce the risk for the development or progression of AMD24–26 has led to an extensive discussion of the pros and cons of blocking blue light.13,27–31 Theoretically, filtering blue light can decrease scotopic vision and color perception by interfering with the excitation frequencies of rods and bluesensitive cones. Several studies have compared the optical performance between yellow-tinted blue light–filtering IOLs and clear IOLs that filter UV light only. The majority of clinical trials report comparable results for yellow-tinted and UV light–filtering IOLs regarding visual acuity data3,12,14,30,32,33 as well as contrast sensitivity values.15,31,34–36 Color perception testing mostly showed higher error scores with yellowtinted IOLs than with UV light–filtering IOLs, whereas in color discrimination, yellow-tinted IOLs usually performed better than UV–light filtering IOLs.8,14,15,30,34,36 These findings are in accordance with those in a previous study by our group22 that found a significantly lower blue–yellow foveal threshold in patients with a yellow-tinted IOL.
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The Orange Series Model PC 440Y orange-tinted IOL showed greater protection against blue-light damage than a yellow-tinted IOL (not the same IOL evaluated in current study) in a model of van de Kraats and van Norren5 On the other hand, the orange-tinted IOL provided substantially less signaling of the retinal sensory systems than the yellow-tinted IOL. However, Schmack et al.37 reported similar results after implantation of an orange-tinted IOL and a clear UV light– filtering IOL. They report comparable postoperative visual function except for color perception, which was slightly better in eyes with a clear IOL. In our cohort, 3 patients noticed a difference between the eye with a yellow-tinted IOL and the eye with an orange-tinted IOL. All 3 patients described reduced color perception. Al of them had or previously had jobs dealing with colors. Similar observations have been made in a recently published study comparing yellow-tinted IOLs and UV light–filtering IOLs.22 In conclusion, we did not find a statistically significant difference in contrast sensitivity at different contrast and illumination levels and color vision between the 2 IOL types. Nevertheless, mixed implantation of an orange-tinted IOL and yellow-tinted IOL should be avoided in patients having cataract surgery because approximately 10% of the enrolled patients in this study noticed a difference between the IOLs.
WHAT WAS KNOWN Compared with untinted IOLs, yellow-tinted IOLs and orange-tinted IOLs offer higher photoprotection by absorbing visible high-energy light. In vitro studies show differences in the absorption spectrum of yellow-tinted and orange-tinted IOLs. WHAT THIS PAPER ADDS After cataract surgery with implantation of a yellow-tinted IOL in 1 eye and an orange-tinted IOL in the other eye, no statistically significant differences in contrast acuity, color vision, or subjective visual impression were found between the 2 IOL types. Nevertheless, approximately 10% of the patients in this study noticed a difference between the IOLs; thus, mixed implantation of an orange-tinted IOL and a yellow-tinted IOL should be avoided in patients having cataract surgery.
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19. Espindle D, Crawford B, Maxwell A, Rajagopalan K, Barnes R, Harris B, Hileman K. Quality-of-life improvements in cataract patients with bilateral blue light-filtering intraocular lenses: clinical trial. J Cataract Refract Surg 2005; 31:1952–1959 20. Marshall J, Cionni RJ, Davison J, Ernest P, Lehmann R, Maxwell WA, Solomon K. Clinical results of the blue-light filtering AcrySof Natural foldable acrylic intraocular lens. J Cataract Refract Surg 2005; 31:2319–2323 21. Davison JA, Patel AS, Cunha JP, Schwiegerling J, Muftuoglu O. Recent studies provide an updated clinical perspective on blue light-filtering IOLs. Graefes Arch Clin Exp Ophthalmol 2011; 249:957–968. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3124647/pdf/417_2011_Article_1697.pdf. Accessed February 28, 2015 22. Wirtitsch MG, Schmidinger G, Prskavec M, Rubey M, Skorpik F, Heinze G, Findl O, Karnik N. Influence of blue-light-filtering intraocular lenses on color perception and contrast acuity. Ophthalmology 2009; 116:39–45 23. Dain SJ. Daylight simulators and colour vision tests. Ophthalmic Physiol Opt 1998; 18:540–544 24. Meyers SM, Ostrovsky MA, Bonner RF. A model of spectral filtering to reduce photochemical damage in age-related macular degeneration. Trans Am Ophthalmol Soc 2004; 102:83–93. discussion 93–95. Available at: http://www.aosonline.org/xactions/ 2004/1545-6110_v102_p083.pdf. Accessed February 28, 2015 25. Sparrow JR, Miller AS, Zhou J. Blue light-absorbing intraocular lens and retinal pigment epithelium protection in vitro. J Cataract Refract Surg 2004; 30:873–878 26. Tanito M, Kaidzu S, Anderson RE. Protective effects of soft acrylic yellow filter against blue light-induced retinal damage in rats. Exp Eye Res 2006; 83:1493–1504 27. Mainster MA, Turner PL. Blue-blocking IOLs vs. shortwavelength visible light: hypothesis-based vs. evidence-based medical practice [editorial]. Ophthalmology 2011; 118:1–2 28. Cuthbertson FM, Peirson SN, Wulff K, Foster RG, Downes SM. Blue light–filtering intraocular lenses: review of potential benefits and side effects. J Cataract Refract Surg 2009; 35:1281–1297 29. Algvere PV, Marshall J, Seregard S. Age-related maculopathy and the impact of blue light hazard. Acta Ophthalmol Scand 2006; 84:4– 15. Available at: http://www3.interscience.wiley.com/cgi-bin/fulltext/118606387/PDFSTART. Accessed February 29, 2015 30. Mester U, Holz F, Kohnen T, Lohmann C, Tetz M. Intraindividual comparison of a blue-light filter on visual function: AF-1 (UY) versus AF-1 (UV) intraocular lens. J Cataract Refract Surg 2008; 34:608–615 31. Mainster MA, Turner PL. Blue-blocking IOLs decrease photoreception without providing significant photoprotection. Surv Ophthalmol 2010; 55:272–283 32. Mainster MA. Violet and blue light blocking intraocular lenses: photoprotection versus photoreception. Br J Ophthalmol 2006; 90:784–792. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860240/pdf/784.pdf. Accessed February 29, 2015 33. Khokhar SK, Jindal A, Agarwal T, Panda A. Comparison of color perception after tinted blue light–filtering and clear ultraviolet– filtering intraocular lens implantation. J Cataract Refract Surg 2011; 37:1598–1604 34. Muftuoglu O, Karel F, Duman R. Effect of a yellow intraocular lens on scotopic vision, glare disability, and blue color perception. J Cataract Refract Surg 2007; 33:658–666 35. Neumaier-Ammerer B, Felke S, Hagen S, Haas P, Zeiler F, Mauler H, Binder S. Comparison of visual performance with blue light filtering and ultraviolet light filtering intraocular lenses. J Cataract Refract Surg 2010; 36:2073–2079 36. Wang H, Wang J, Fan W, Wang W. Comparison of photochromic, yellow, and clear intraocular lenses in human eyes
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under photopic and mesopic lighting conditions. J Cataract Refract Surg 2010; 36:2080–2086 37. Schmack I, Schimpf M, Stolzenberg A, Conrad-Hengerer I, Hengerer FH, Dick HB. Visual quality assessment in patients with orange-tinted blue light filtering and clear ultraviolet lightfiltering intraocular lenses. J Cataract Refract Surg 2012; 38:823–832
trials.gov/ct2/show/NCT00612729?termZ00612729&rankZ1. Accessed February 28, 2015
OTHER CITED MATERIAL A. U.S. National Institutes of Health Clinical Trials. Light Filters in Intraocular Lenses (IOLs) and Its Influence on Colour and Contrast Vision. NCT00612729. Available at: https://clinical
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First author: Elfriede Wissiak, MD Department of Ophthalmology, Medical University Graz, Graz, Austria
Influence of light filters in intraocular lenses on color perception and contrast acuity Elfriede Wissiak, MD, Navid Ardjomand, MD, Gernot Steinwender, MD, Martin Prskavec, MD, Ramin Baradaran-Dilmaghani, MD, Maria Kohl, MD, Matthias G. Wirtitsch, MD
PURPOSE: To compare contrast acuity at different illumination levels, color vision, and the subjective visual impression in patients after bilateral cataract surgery with mixed implantation of a yellowtinted intraocular lens (IOL) and an orange-tinted IOL. SETTING: Department of Ophthalmology, Hietzing Hospital, Vienna, Austria. DESIGN: Prospective case series. METHODS: Consecutive patients with age-related cataract had standardized small-incision cataract surgery with IOL implantation in the capsular bag. Patients were randomly assigned to receive a yellow Polylens Y30 in 1 eye and an Orange Series model PC 440Y in the contralateral eye. The main outcome measures were contrast acuity, color vision, and subjective visual impression. Contrast acuity was measured at illumination levels of 5.0 lux and 0.5 lux and contrast levels of 50.0%, 25.0%, and 12.5%. Color vision was assessed using the Heidelberg-multicolor anomaloscope, and the subjective visual impression was evaluated using a questionnaire. RESULTS: This study included 64 eyes of 32 patients. The intraindividual comparison showed no significant difference in contrast sensitivity at different contrast and illumination levels or in color vision. On questioning, 3 patients reported a difference in subjective color perception between the 2 IOL types. CONCLUSION: There were no differences in contrast sensitivity or color vision between yellowtinted IOLs and orange-tinted IOLs. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2015; -:-–- Q 2015 ASCRS and ESCRS
Blue light–filtering intraocular lenses (IOLs) were introduced in cataract surgery in the 1990s. At that time, large epidemiology studies described an increased risk for age-related macular degeneration (AMD) progression after cataract surgery and the increased light exposure at short wavelengths was proposed as the possible cause.1–3 As a consequence, IOLs that block not only the damaging ultraviolet (UV) radiation but also partially filter the visible blue light were developed. These IOLs combine the UV filter with a covalently bound chromophore that partly absorbs high-energy blue light in the spectral range of 400 to 500 nm.4 Based on those findings, in principle, the elderly natural lens through the physiologic Q 2015 ASCRS and ESCRS Published by Elsevier Inc.
yellowing process offers more protection than the young adult lens. At present, several manufacturers use yellow chromophores to mimic the absorption spectrum of the natural yellow cataract lens of a 60 year old.5 Recently, an IOL with orange chromophores was introduced with the intention of offering even higher photoprotection. Through filtering wavelengths between 400 nm and 600 nm, which include a larger part of visible blue light and parts of green and yellow light, this orange IOL proved to be a more powerful filter than yellow IOLs.5,6 However, yellow-tinted and orange-tinted IOLs are intended to protect an aging retina from visible highenergy light. However, they should not interfere
http://dx.doi.org/10.1016/j.jcrs.2014.09.048 0886-3350
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with the optical quality. Several studies have compared the visual performance in eyes with untinted IOLs and yellow-tinted IOLs, with the main focus on color vision and contrast acuity. Study results were controversial. Some studies found better performance7–9 and others worse performance10–12 with yellow-tinted IOLs. Yet other studies did not find statistically significant differences.13–21 To our knowledge, no study in the literature has compared the visual performance of yellow-tinted IOLs and orange-tinted IOLs intraindividually. Because the crucial wavelength spectrum for distinguishing luminance under scotopic conditions lies between 500 nm and 507 nm, the decreased light transmittance in this range in orange-tinted IOLs compared with the transmittance with yellow-tinted IOLs might have implications for color perception and scotopic vision6 (Figure 1). Therefore, the aim of the present study was to compare a yellow-tinted IOL and an orange-tinted IOL and their effect on contrast acuity, color vision, and subjective patient visual impression. To detect subtle changes between the 2 IOLs, we used strict inclusion criteria and the sensitive measuring methods outlined and used in our previously published study.22 PATIENTS AND METHODS This prospective randomized double-masked bilateral clinical trial with intraindividual comparison was performed at the Department of Ophthalmology, Hietzing Hospital, Vienna, Austria. The study followed the guidelines of the Declaration of Helsinki and was performed according to the European Union Good Clinical Practice guidelines. The study protocol was approved by the Ethics Committee of the City of Vienna, Austria, and was registered with the U.S. National Institutes of Health Clinical Trials.A After receiving an explanation of the nature and possible
Figure 1. Transmission characteristics of the blue–green light– filtering IOL (orange-tinted IOL) and the blue light–filtering IOL (yellow-tinted IOL) compared with those of a 53-year-old crystalline lens.
consequences of the study, all patients provided written informed consent.
Patient Recruitment Patients were recruited from a continuous cohort that presented with bilateral age-related cataract to the outpatient center of the Department of Ophthalmology, Hietzing Hospital, Vienna. Patients with amblyopia, pseudoexfoliation syndrome, primary or secondary glaucoma, ocular hypertension, uveitis, diabetic retinopathy, history of intraocular surgery, laser treatment, retinal pathology, or other relevant ophthalmic diseases were excluded. Furthermore, the systemic medications of patients being screened for the study were recorded and checked for possible ophthalmologic side effects. Patients using medications known to potentially cause such side effects were excluded from the study, as were patients with an expected postoperative corrected distance visual acuity (CDVA) worse than 1.0 (20/20). Patients with a congenital color vision anomaly, ocular surface disease, or ametropia of more than 3.0 diopters (D) were not included in this trial, nor were patients with nicotine or alcohol abuse.
Intraocular Lens Assignment Submitted: May 1, 2014. Final revision submitted: August 27, 2014. Accepted: September 1, 2014. From the Department of Ophthalmology (Wissiak, Ardjomand, Steinwender, Wirtitsch), Medical University Graz, Graz, the Department of Ophthalmology (Prskavec), Hietzing Hospital and the Center for Medical Statistics (Kohl), Informatics and Intelligent Systems, Medical University of Vienna, Vienna, and the Department of Ophthalmology (Baradaran-Dilmaghani), St. Josef Hospital, Braunau, Austria. Presented in part at the XXVIII Congress of the European Society of Cataract and Refractive Surgeons, Paris, France, September 2010. Corresponding author: Matthias G. Wirtitsch, MD, Department of Ophthalmology, Medical University Graz, Auenbruggerplatz 4, 8036 Graz, Austria. E-mail: [email protected].
Intraocular lens randomization was performed before patient recruitment. The patients and examiners were masked to the IOL assignment. No attempt was made to mask the surgeon to IOL assignment because both IOLs used in this study have a typical optic color and a typical design. However, the surgeon was unaware of the type of IOL to be used until the eye was prepared for IOL implantation. The first eye was randomly assigned to receive a multipiece foldable IOL, either a Polylens Y30 (Polytech Ophthalmologie GmbH), which filters blue light, or a Orange Series Model PC 440Y (Ophtec BV), which filters blue–green light, The contralateral eye received the other IOL. The Polylens Y30 is a UV light–filtering and blue light–filtering yellowtinted hydrophobic acrylic 3-piece IOL with an optic diameter of 6.0 mm. Angulation of the polyvinylidene fluoride haptics is 5 degrees and the overall diameter, 13.0 mm. The orange-tinted PC 440Y is a 3-piece IOL that has a 5.8 mm polysiloxane optic containing chromophores that filter UV light
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and blue–green light. The poly(methyl methacrylate) haptics have an angulation of 10 degrees; the overall diameter is 12.5 mm. Both IOLs are sharp-edged. The eye with the higher degree of cataract had surgery first. Surgery was performed between July 2008 and November 2009 by 1 of 3 surgeons (M.P., R.B.D., M.G.W.) using a standardized surgical technique. Both eyes of each patient had surgery performed on different days. The maximum time between the 2 surgeries was 4 days.
Surgical Technique Surgery was performed using topical anesthesia through a 2.6 mm temporal clear corneal incision. After exchange of the aqueous with an hyaluronic acid 5000 10 mg/mL (Healon), a well-centered 5.0 to 5.5 mm continuous curvilinear capsulorhexis was created with a bent needle or a capsulorhexis forceps. After phacoemulsification of the nucleus, the residual cortex was removed by coaxial irrigation/aspiration (I/A), which was followed by polishing the posterior capsule. The IOL was implanted after the anterior chamber and the capsular bag were filled with ophthalmic viscosurgical device (OVD). The residual OVD was aspirated with a coaxial I/A tip, the incision was hydrated, and the globe was filled with Ringer’s solution. Postoperative treatment consisted of a fixed tobramycin–dexamethasone combination (Tobradex) and diclofenac (Voltaren Ophtha) eyedrops 4 times a day for 1 month. The same experienced masked examiner performed testing in the second eye in a single session a mean of 90 days G 10 (SD) after surgery. The test duration was approximately 30 minutes. After the CDVA was measured, several color vision tests and contrast acuity tests were performed under standardized conditions as described in detail below. All tests were performed monocularly. The patients were allowed to relax between tests. The testing sequence of eyes was randomized using a table of random numbers to avoid bias. After the vision tests, the patient was interviewed using a patient questionnaire.
Color Vision Testing Blue–Green Color Vision Test The Heidelberg-multicolor anomaloscope MR (Oculus Optikger€ate GmbH) was used to test blue–green color vision. It uses the additive colormixing method and evaluates blue–green color vision using the Moreland 2 equation [blue (436 nm) C green (490 nm) Z cyan (480 nm) C yellow (589 nm)].20 After receiving an explanation of the testing procedure and after a trial run was performed, the patients were tested monocularly with best distance correction. The test was started with the presentation of a white fluorescent field, which is comparable to the standard light source C (6770 degrees Kelvin). This field was repeatedly presented every 3 seconds for a defined period to provide neutral adaptation throughout the test. The patient then looked at a circular, horizontally divided test field through an eyepiece with a viewing angle of 4 degrees. The upper half of the field of the testing device is a mixed field of green and blue, and the lower comparison field consists of cyan, which is desaturated by yellow. The upper mixed color field can be adjusted on a scale from 0 (turquoise free) to 100 (blue free). The brightness of the lower field can be adjusted on a scale from 0 to 100. The normal values range between 42 to 58 mixed color and 43 to 57 brightness. Starting with a mixed color of 100 and a brightness of 85, a stepwise reduction in mixed color was presented until the
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subjective matching point was passed. The patient was asked to make the 2 fields similar by adjusting the brightness of the lower comparison field. After this orientating testing procedure, a fine adjustment was performed, resulting in a lower and upper subjective matching point. The anomaloscope automatically calculates the tritanomaly quotient. The tritanomaly quotient represents an instantaneous observation of the blue-sensitive visual system and is subject to change during one’s lifetime. A tritanomaly quotient of 1 or lower is considered normal, whereas a tritanomaly quotient higher 1 shows a color error that increases with the value.
Contrast Sensitivity Test Near contrast sensitivity function was tested using the Holladay contrast acuity test (Stereo Optical Co., Inc.). Patients were positioned 40 cm from the reading chart with best distance correction plus a correction to set the reading point to 40 cm (C2.5 D). In all cases, 2 trial lenses were used for best correction to standardize light absorption. During testing, the 40 cm reading distance was checked several times using a measuring chain. Contrast sensitivity testing was performed with a 50.0% contrast chart and repeated at 25.0% and 12.5%. All contrast testing was performed at 2 illumination levels (ie, 5.0 lux for high-mesopic and 0.5 lux for low-mesopic conditions). The illumination level was checked using a light meter (Digital Luxmeter MS1500, Voltcraft, Conrad Electronic). The test was stopped when 3 or more errors were made in 1 line. The achieved line for each contrast plus the correct letters in the next line were recorded; each letter was given a value of 0.2. In the next step, the values recorded in lines were converted to logMAR notation for statistical analysis. After computation, data were reconverted for data presentation. A Light Source a Daylight Illuminator (Richmond Products, Inc.) was used for the contrast sensitivity testing. The bulb gives off 6280 degrees Kelvin light that closely matches the standards set by the International Commission of Illumination. The illuminator has been approved by the U.S. Food and Drug Administration and provides a color-rendering index of 94, as recommended in clinical studies. Daylight illumination and consistency of lightning have been found to be important in testing acquired color vision defects.23 The illumination level of the illuminator was set by a dimmer switch and controlled using a light meter. The luminance was set for high-mesopic and low-mesopic light conditions at 5.0 lux and 0.5 lux, respectively.
Patient Questionnaire After completing the visual tests, patients were asked whether they noticed a difference in color vision, contrast vision, or vision under poor light conditions between their 2 eyes. If not, the survey was stopped. If yes, patients were asked which eye they thought had the orange IOL, to describe their vision, and whether they were disturbed by the difference.
Statistical Analysis and Data Presentation All patients and eyes in this study were included in the statistical analysis. During study preparation, the sample size was calculated. The following assumptions for contrast sensitivity and color vision were made at the time of study planning: a clinically relevant difference of 10.0%, a within-
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group standard deviation of 12.5%, (contrast sensitivity) or 15.6% (color vision), a 2-sided experiment-wise significance level a of 5.0% (2.5% for each test, divided by 6 comparisons in the contrast sensitivity test), and a power of 85%. A suspected study subject dropout rate of 15% recommended a sample size of 32 patients. After all data had been crosschecked and entered into the database, the seal of the envelope with the randomization list was broken and the IOL implantation sequences of the patients were unmasked. The contrast sensitivity test was analyzed using a general linear mixed model, including the fixed within-block factors of contrast (the levels were 50.0%, 25.0%, and 12.5%), illumination level (5.0 lux, 0.5 lux), and type of IOL (yellow tinted or orange tinted) and the random factor of patient. Interactions between the fixed factors were hierarchically tested and dropped from the model if not significant. The blue–green color vision test was analyzed using paired t tests. This analysis yielded a P value for the comparison of the yellow-tinted IOL and orange-tinted IOL. Test results are presented as the mean G SD under each type of IOL and as the mean difference (95% confidence interval [CI]) of the 2 IOL types. Visual acuity data are presented as decimal fractions. For statistical purposes, the visual acuities were converted to logMAR notation and then reconverted for data presentation. To correct for multiple testing, the 2-sided significance level for each color vision and contrast sensitivity test was set at 2.5%. Statistical analysis was performed using SAS software (version 9.2, SAS, Inc.).
RESULTS Thirty-two patients (64 eyes) were part of the study screening, and all were included in the study. The mean age of the 20 women and 12 men was 70 G 8.7 years (range 51 to 90 years). All patients completed the scheduled vision tests and questionnaire. Visual Function Figure 2 shows the absolute values of the contrast sensitivity tests. Contrast level and illumination had statistically significant effects on contrast acuity (both P ! .0001). Intraindividual comparison showed no statistically significant difference in visual acuity (Figure 3) (geometric mean ratio of yellow-tinted IOL versus orange-tinted IOL, 0.996; 95% CI, 0.973-1.020; P Z .751). No significant interaction of the type of IOL with the contrast level or illumination was detected. The tritanomaly quotient in the anomaloscope testing showed no statistically significant difference between the yellow-tinted IOLs and the orangetinted IOLs (mean difference 0.004; 95% CI, 0.074 to 0.066; P Z .91) (Figure 4). Patient Questionnaire Twenty-nine of the 32 patients did not notice any difference between their 2 eyes. Three patients reported noticing a difference, and all 3 correctly
Figure 2. Absolute postoperatively.
contrast
sensitivity
values
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months
identified the eye with orange-tinted IOL. One of these patients described a subtle gray tone in the eye with the orange-tinted IOL. The second patient noticed poorer vision in the dark in the eye with the orangetinted IOL than in the contralateral eye. The third patient said that colors appeared more matte with the orange-tinted IOL. All 3 patients said that their binocular vision was not disturbed. These 3 patients had or previously had jobs dealing with colors. One of them was a retired florist. The second patient worked in a boutique selling clothes. The third patient worked in a kindergarten, painting and doing handicrafts with children. Statistical evaluation of the questionnaire
Figure 3. Visual acuity: absolute values 3 months postoperatively.
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Figure 4. Blue–green color vision: tritanomaly quotient (anomaloscope) 3 months postoperatively.
did not reach the level of significance (P Z .08; 95% CI, 0.03 to 0.31). DISCUSSION This prospective randomized double-masked study with intraindividual comparison evaluated the clinical relevance of in vitro data comparing the visual performance of patients with a yellow-tinted IOL in 1 eye and an orange-tinted IOL in the contralateral eye. We found no statistically significant difference in CDVA, contrast sensitivity at different contrast levels and illuminations, or color perception between the eyes. The development of blue light–filtering IOLs to protect the retina and reduce the risk for the development or progression of AMD24–26 has led to an extensive discussion of the pros and cons of blocking blue light.13,27–31 Theoretically, filtering blue light can decrease scotopic vision and color perception by interfering with the excitation frequencies of rods and bluesensitive cones. Several studies have compared the optical performance between yellow-tinted blue light–filtering IOLs and clear IOLs that filter UV light only. The majority of clinical trials report comparable results for yellow-tinted and UV light–filtering IOLs regarding visual acuity data3,12,14,30,32,33 as well as contrast sensitivity values.15,31,34–36 Color perception testing mostly showed higher error scores with yellowtinted IOLs than with UV light–filtering IOLs, whereas in color discrimination, yellow-tinted IOLs usually performed better than UV–light filtering IOLs.8,14,15,30,34,36 These findings are in accordance with those in a previous study by our group22 that found a significantly lower blue–yellow foveal threshold in patients with a yellow-tinted IOL.
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The Orange Series Model PC 440Y orange-tinted IOL showed greater protection against blue-light damage than a yellow-tinted IOL (not the same IOL evaluated in current study) in a model of van de Kraats and van Norren5 On the other hand, the orange-tinted IOL provided substantially less signaling of the retinal sensory systems than the yellow-tinted IOL. However, Schmack et al.37 reported similar results after implantation of an orange-tinted IOL and a clear UV light– filtering IOL. They report comparable postoperative visual function except for color perception, which was slightly better in eyes with a clear IOL. In our cohort, 3 patients noticed a difference between the eye with a yellow-tinted IOL and the eye with an orange-tinted IOL. All 3 patients described reduced color perception. Al of them had or previously had jobs dealing with colors. Similar observations have been made in a recently published study comparing yellow-tinted IOLs and UV light–filtering IOLs.22 In conclusion, we did not find a statistically significant difference in contrast sensitivity at different contrast and illumination levels and color vision between the 2 IOL types. Nevertheless, mixed implantation of an orange-tinted IOL and yellow-tinted IOL should be avoided in patients having cataract surgery because approximately 10% of the enrolled patients in this study noticed a difference between the IOLs.
WHAT WAS KNOWN Compared with untinted IOLs, yellow-tinted IOLs and orange-tinted IOLs offer higher photoprotection by absorbing visible high-energy light. In vitro studies show differences in the absorption spectrum of yellow-tinted and orange-tinted IOLs. WHAT THIS PAPER ADDS After cataract surgery with implantation of a yellow-tinted IOL in 1 eye and an orange-tinted IOL in the other eye, no statistically significant differences in contrast acuity, color vision, or subjective visual impression were found between the 2 IOL types. Nevertheless, approximately 10% of the patients in this study noticed a difference between the IOLs; thus, mixed implantation of an orange-tinted IOL and a yellow-tinted IOL should be avoided in patients having cataract surgery.
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19. Espindle D, Crawford B, Maxwell A, Rajagopalan K, Barnes R, Harris B, Hileman K. Quality-of-life improvements in cataract patients with bilateral blue light-filtering intraocular lenses: clinical trial. J Cataract Refract Surg 2005; 31:1952–1959 20. Marshall J, Cionni RJ, Davison J, Ernest P, Lehmann R, Maxwell WA, Solomon K. Clinical results of the blue-light filtering AcrySof Natural foldable acrylic intraocular lens. J Cataract Refract Surg 2005; 31:2319–2323 21. Davison JA, Patel AS, Cunha JP, Schwiegerling J, Muftuoglu O. Recent studies provide an updated clinical perspective on blue light-filtering IOLs. Graefes Arch Clin Exp Ophthalmol 2011; 249:957–968. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3124647/pdf/417_2011_Article_1697.pdf. Accessed February 28, 2015 22. Wirtitsch MG, Schmidinger G, Prskavec M, Rubey M, Skorpik F, Heinze G, Findl O, Karnik N. Influence of blue-light-filtering intraocular lenses on color perception and contrast acuity. Ophthalmology 2009; 116:39–45 23. Dain SJ. Daylight simulators and colour vision tests. Ophthalmic Physiol Opt 1998; 18:540–544 24. Meyers SM, Ostrovsky MA, Bonner RF. A model of spectral filtering to reduce photochemical damage in age-related macular degeneration. Trans Am Ophthalmol Soc 2004; 102:83–93. discussion 93–95. Available at: http://www.aosonline.org/xactions/ 2004/1545-6110_v102_p083.pdf. Accessed February 28, 2015 25. Sparrow JR, Miller AS, Zhou J. Blue light-absorbing intraocular lens and retinal pigment epithelium protection in vitro. J Cataract Refract Surg 2004; 30:873–878 26. Tanito M, Kaidzu S, Anderson RE. Protective effects of soft acrylic yellow filter against blue light-induced retinal damage in rats. Exp Eye Res 2006; 83:1493–1504 27. Mainster MA, Turner PL. Blue-blocking IOLs vs. shortwavelength visible light: hypothesis-based vs. evidence-based medical practice [editorial]. Ophthalmology 2011; 118:1–2 28. Cuthbertson FM, Peirson SN, Wulff K, Foster RG, Downes SM. Blue light–filtering intraocular lenses: review of potential benefits and side effects. J Cataract Refract Surg 2009; 35:1281–1297 29. Algvere PV, Marshall J, Seregard S. Age-related maculopathy and the impact of blue light hazard. Acta Ophthalmol Scand 2006; 84:4– 15. Available at: http://www3.interscience.wiley.com/cgi-bin/fulltext/118606387/PDFSTART. Accessed February 29, 2015 30. Mester U, Holz F, Kohnen T, Lohmann C, Tetz M. Intraindividual comparison of a blue-light filter on visual function: AF-1 (UY) versus AF-1 (UV) intraocular lens. J Cataract Refract Surg 2008; 34:608–615 31. Mainster MA, Turner PL. Blue-blocking IOLs decrease photoreception without providing significant photoprotection. Surv Ophthalmol 2010; 55:272–283 32. Mainster MA. Violet and blue light blocking intraocular lenses: photoprotection versus photoreception. Br J Ophthalmol 2006; 90:784–792. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860240/pdf/784.pdf. Accessed February 29, 2015 33. Khokhar SK, Jindal A, Agarwal T, Panda A. Comparison of color perception after tinted blue light–filtering and clear ultraviolet– filtering intraocular lens implantation. J Cataract Refract Surg 2011; 37:1598–1604 34. Muftuoglu O, Karel F, Duman R. Effect of a yellow intraocular lens on scotopic vision, glare disability, and blue color perception. J Cataract Refract Surg 2007; 33:658–666 35. Neumaier-Ammerer B, Felke S, Hagen S, Haas P, Zeiler F, Mauler H, Binder S. Comparison of visual performance with blue light filtering and ultraviolet light filtering intraocular lenses. J Cataract Refract Surg 2010; 36:2073–2079 36. Wang H, Wang J, Fan W, Wang W. Comparison of photochromic, yellow, and clear intraocular lenses in human eyes
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under photopic and mesopic lighting conditions. J Cataract Refract Surg 2010; 36:2080–2086 37. Schmack I, Schimpf M, Stolzenberg A, Conrad-Hengerer I, Hengerer FH, Dick HB. Visual quality assessment in patients with orange-tinted blue light filtering and clear ultraviolet lightfiltering intraocular lenses. J Cataract Refract Surg 2012; 38:823–832
trials.gov/ct2/show/NCT00612729?termZ00612729&rankZ1. Accessed February 28, 2015
OTHER CITED MATERIAL A. U.S. National Institutes of Health Clinical Trials. Light Filters in Intraocular Lenses (IOLs) and Its Influence on Colour and Contrast Vision. NCT00612729. Available at: https://clinical
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First author: Elfriede Wissiak, MD Department of Ophthalmology, Medical University Graz, Graz, Austria