Abstract
Purpose: :
Heidelberg Retinal Tomography is currently used routinely in the diagnosis and management of glaucoma. The purpose of this study was to prospectively compare the quality of HRT imaging between clear natural lenses, monofocal IOLs and newer multifocal (ReSTOR) IOLs. The ReSTOR lens utilizes apodized diffractive optics, which can be structurally visualized as multifocal rings on the surface of the lens. We hypothesized that the image quality, as measured by the mean pixel height standard deviation (MPHSD)number, will be degraded in the ReSTOR lens due to interference by its multifocal optics.
Methods: :
A prospective series of 32 control eyes with clear natural lenses, 9 eyes with monofocal IOLs, and 11 eyes with ReSTOR multifocal IOLs was selected for this study thus far (ultimately planning for at least 29 eyes in each group). Three HRT images were obtained from each eye in the study. The MPHSD, used to quantify image quality, was recorded for each image and averaged for each eye. The mean difference in MPHSD between each of the 3 groups of patients was then analyzed for statistical and clinical significance.
Results: :
The mean MPHSD calculated for the group of control eyes with clear natural lenes was 15.55, the mean MPHSD for the group of eyes with monofocal IOLs was 21.15, and the mean MPHSD for the group of eyes with ReSTOR multifocal IOLs was 25.91. The standard deviations for each of these groups were 3.97, 7.16, and 9.12 respectively. Analysis of the data thus far suggests that the differences in MPHSD between these groups are, or approach, clinical significance, with the ReStor multifocal group producing the highest MPHSD. The differences in standard deviation in the measurements between these groups suggests that the monofocal IOL and multifocal IOL groups produce more varying MPHSD numbers when compared to the clear natural lens population.
Conclusions: :
The results thus far suggest a trend toward a significant degradation in the quality and increased variability in quality of HRT images obtained in eyes with multifocal>monofocal IOLs vs those with clear natural lenses. It is unclear whether this finding can be completely attributed to the multifocal optics of the ReSTOR lens, as the monofocal group also showed some decrease in quality when compared to controls. While all of the images may be of sufficient quality to be used clinically, it is important that IOL choice be considered when HRT imaging may be required for glaucoma management. At this point, further data collection and analysis is required to more clearly confirm the results of this study.
Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • intraocular lens