Purpose
To investigate the effect of yellow-tinted intraocular lenses (IOLs) on short-wavelength automated perimetry (SWAP).
Design
Cross-sectional observation study.
Methods
Twenty-two patients who had implantation of yellow-tinted IOLs (AcrySof SN60AT or SN60WF; Alcon Laboratories) in 1 eye and nontinted IOLs (AcrySof SA60AT) in the other eye were included in the study. Standard automated perimetry (SAP) and SWAP were performed. The results for the mean deviation (MD), pattern standard deviation (PSD), and glaucoma hemifield test results were compared intra-individually.
Results
There was no statistically significant difference between the IOLs on the SAP (MD, PSD; P = .851, P = .388, respectively). However, a significant difference was observed between the IOLs on the SWAP (MD, PSD; P = .033, P = .033, respectively). The glaucoma hemifield test did not show significant differences in the SAP ( P = .083). However, the SWAP showed significant differences ( P = .003).
Conclusions
The yellow-tinted IOLs may affect the results of the SWAP; therefore, caution is needed in interpreting the results of the SWAP in eyes with implanted yellow-tinted IOLs.
The human crystalline lens has a protective effect on the retina against the short wavelength of light; it becomes yellowish with age. However, after cataract extraction, it has been reported that the ocular transmission of light energy is dramatically increased in pseudophakic or aphakic eyes. As a result of exposure to ultraviolet-A (UVA, 315–400 nm) and blue light (400–480 nm), the risk of development or progression of age-related macular degeneration is known to be increased.
The conventional clear intraocular lens (IOL) was designed so that ultraviolet rays with wavelengths less than 400 nm can be blocked, but blue light (400–480 nm) cannot be blocked. The yellow-tinted IOL, which has a blue light–filtering chromophore, was designed with the expectation that blue light may be blocked and the retina may be protected from the potential damage caused by the short wavelength of light. The yellow IOL reduces transmission of blue light from 71% at 400 nm to 22% at 475 nm. However, concern that a blue light–absorbing polymer contained in the yellow IOL affects color perception has emerged, and has been reported as an issue in some cases. Blue-yellow perimetry, short-wavelength automated perimetry (SWAP), differs from standard automated perimetry (SAP) in that the yellow light is used as a background and the blue light is used as a stimulus.
This study was performed to assess the effects of yellow IOL on the performance of blue-yellow perimetry. Because the yellow IOLs are broadly used today, it is important to determine whether yellow IOLs have an adverse effect on SWAP in the screening of patients with glaucoma who have implanted yellow IOLs.
Methods
Among the patients who underwent cataract extraction and IOL implantation in both eyes from June 2007 until August 2009 at our institution, 22 patients (44 eyes) that had implantation of yellow-tinted IOLs (AcrySof SN60AT or SN60WF; Alcon Laboratories, Fort Worth, Texas, USA) in 1 eye and nontinted IOLs (AcrySof SA60AT; Alcon Laboratories) in the other eye were the subjects of this study. Subjects were excluded if they had any coexisting ocular disease known to affect the visual field, such as optic nerve disease, glaucoma, or diabetic retinopathy. The optic discs were evaluated and the retinal nerve fiber layers (RNFL) were examined by Cirrus optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, California, USA) and RNFL fundus photography.
After confirming that no abnormality of the disc was present, SAP (central 30-2 SITA-standard strategy) and SWAP (central 24-2 full-threshold strategy) were measured with Humphrey Field Analyzer II (Carl Zeiss Meditec, Zeiss-Humphrey, San Leandro, California, USA). The data were obtained at least twice to enhance reliability of the data in the period 1 to 6 months after surgery. All visual fields used for analysis satisfied the following reliability criteria: fixation loss less than 10% and false-positive or false-negative rates of less than 20%. When the reliability index was met with repetitive testing, the mean values of mean deviation (MD) and pattern standard deviation (PSD) were used for the analysis. Normality of data distribution of the MD and PSD was tested using the Kolmogorov-Smirnov test. An intra-individual comparison of the MD and PSD value was achieved by using a paired t test.
Because none of the visual fields showed a generalized depression of sensitivity on the glaucoma hemifield test, the results were divided into 3 groups: “within normal limits,” “borderline,” and “outside normal limits,” which were scored as 2, 1, and 0, respectively. An intra-individual comparison was performed to determine whether there was a difference between the yellow IOL and clear IOL on the glaucoma hemifield test comment using a marginal homogeneity test. The glaucoma hemifield test comments from SAP and SWAP were also compared among the same eyes.
All statistical analysis was performed using Statistical Package for Social Science software version 15.0 (SPSS, Inc, Chicago, Illinois, USA) and a P value less than .05 was considered statistically significant.
Results
The patient demographics are shown in Table 1 . The mean age of the 13 men and 9 women was 64.8 ± 10.3 (SD) years. There were no statistically significant differences between the 2 types of IOLs with respect to the postoperative logMAR (logarithm of minimal angle of resolution) best-corrected visual acuity (BCVA) and spherical equivalent ( Table 1 ). The ratios of the right and left eyes were 13 to 9 and 9 to 13 in the 2 IOL groups respectively, and no significant difference was observed ( P = .058, χ 2 test).
| Parameter | All Patients | Yellow-Tinted IOL | Nontinted IOL | P Value |
|---|---|---|---|---|
| No. of eyes | 44 | 22 | 22 | |
| Age (years) | 64.8 ± 10.3 | |||
| Sex (M/F) | 11/9 | |||
| Eye (OD/OS) | 13/9 | 9/13 | .058 a | |
| logMAR BCVA | 0.04 ± 0.07 | 0.01 ± 0.03 | .138 b | |
| SE (D) | −0.01 ± 0.57 | −0.33 ± 0.60 | .06 b |
The average MDs of the eyes with yellow IOLs and clear IOLs were −3.21 ± 4.1 and −3.10 ± 2.92 respectively in the SAP ( P = .853). The average PSDs for each of the IOL groups were 3.46 ± 1.75 and 3.17 ± 1.76 respectively for the SAP ( P = .388) ( Table 2 ). For the SWAP, the average MDs of the yellow IOL and clear IOL were −6.54 ± 4.25 and −4.93 ± 4.56, and the means of the PSD were 4.39 ± 1.30 and 3.91 ± 1.17, respectively. These differences in the SWAP were statistically significant ( P = .033, P = .033) ( Table 3 ).
| Yellow-Tinted IOL | Nontinted IOL | P Value a | |
|---|---|---|---|
| Mean deviation (MD) | .853 | ||
| Mean (SD) | −3.21 (4.10) | −3.10 (2.92) | |
| Range | −18.45∼0.77 | −9.90∼1.10 | |
| Pattern standard deviation (PSD) | .388 | ||
| Mean (SD) | 3.46 (1.75) | 3.17 (1.76) | |
| Range | 1.0∼9.15 | 2.36∼6.18 | |
| Yellow-Tinted IOL | Nontinted IOL | P Value a | |
|---|---|---|---|
| Mean deviation (MD) | |||
| Mean (SD) | −6.54 (4.25) | −4.93 (4.56) | .033 |
| Range | −18.74∼−1.42 | −13.09∼3.73 | |
| Pattern standard deviation (PSD) | |||
| Mean (SD) | 4.39 (1.30) | 3.91 (1.17) | .033 |
| Range | 3.09∼7.86 | 2.36∼6.18 | |
For the glaucoma hemifield test comment, there was no significant difference between the SAP and SWAP testing in the eyes with clear inserted IOLs ( P = .083), whereas they significantly differed for the eyes with the yellow inserted IOLs ( P = .049) ( Table 4 ). The intra-individual comparison showed that the SAP did not show significant differences. However, the SWAP showed significant differences between 2 IOLs ( P = .287, P = .002, respectively) ( Table 5 ).
| Glaucoma Hemifield Test Scores a in the Same Eye | Clear IOL | Yellow IOL |
|---|---|---|
| SAP=SWAP | 11 | 8 |
| SAP<SWAP | 5 | 4 |
| SAP>SWAP | 6 | 10 |
| P value b | .083 | .049 |
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