We thank Dr Ho for the insightful comments regarding our article, “Effect of Yellow-Tinted Intraocular Lenses on Short-Wavelength Automated Perimetry.” Our study found that short-wavelength automated perimetry (SWAP) shows significantly decreased sensitivity in eyes with yellow-tinted intraocular lenses (IOLs) compared with eyes with clear IOLs, whereas standard automated perimetry failed to show the difference.
SWAP is not easy to perform, especially for older patients. We agree that the Swedish interactive threshold algorithm (SITA) with SWAP may be a better choice than the full-threshold strategy with SWAP because of its advantages with regard to shorter test duration. However, we could not perform SWAP with SITA because the SWAP with SITA mode was not available at our institution. Although we agree with Dr Ho’s comment, we do not believe that use of the full-threshold strategy with SWAP could affect the study results significantly, because we did not assess serial SWAP changes in the same location and we attempted to obtain the best result of SWAP to overcome patients’ poor performances or long-term variability problems. Furthermore, a recent study demonstrated that sensitivities did not differ between SITA and full-threshold algorithms, despite several advantages associated with SWAP using SITA.
As suggested by Dr Ho, analysis of the intertest variability in SWAP could be another option. In several patients whose visual field results were serially reliable, we found that the intertest difference of the results tended to be greater in eyes with yellow-tinted IOLs. In our study, however, we used several strategies to overcome variability problems. First, we performed standard automated perimetry before SWAP for all subjects with the expectation that the patient would become more familiar with the visual field test through a learning effect. Second, we attempted to obtain the most reliable result through repeated testing.
We also agree with Dr Ho’s comment that the statistical significance may not always retain a clinically meaningful difference, especially when the extent or magnitude of mean deviation and pattern standard deviation variability is not documented fully. However, we added the glaucoma hemifield test score as a measured outcome, which has not been attempted previously. Glaucoma hemifield test reports from SWAP also showed significant differences between eyes with yellow-tinted and clear IOLs, whereas those from standard automated perimetry did not. A recent study by Wirtitsch and associates demonstrated that foveal threshold was significantly lower in eyes with yellow-tinted IOLs in SWAP. Comparisons using several different types of indices could support and reinforce the result that yellow IOLs may affect SWAP.
Further evaluation regarding the effect of yellow-tinted IOLs on the variability of SWAP may be valuable. We thank Dr Ho for his insightful suggestions, which we had not considered.