Comparative study of corneal thickness and thinnest point position of keratoconus measured by Pentacam HR and RTVue OCT / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the difference, correlation, and consistency of corneal thickness and the thinnest point position detected by Pentacam HR corneal topography map and RTVue optical coherence tomography(OCT)in patients with keratoconus.METHODS: Cross-sectional comparative study. The corneal curvature map, corneal thickness map, thinnest point position, and thinnest point thickness were detected by Pentacam HR and RTVue OCT. Paired sample t-test was used for data consistent with normal distribution, and paired sample rank sum test was used for data inconsistent with normal distribution. Spearman correlation analysis and Bland-Altman analysis were used for the correlation and consistency of the two measurement methods.RESULTS: A total of 63 patients(105 eyes)with keratoconus were included in this study, including 49 males(77.8%)and 14 females(22.2%), aged 22.24±6.19 years; among them, relevant data of Pentacam HR topographic map: Km was 47.85±4.73D and Kmax was 55.43±8.72D. In measuring central corneal thickness and the thinnest point thickness of keratoconus, the Pentacam HR was 4.70μm and 19.46μm thicker than the mean value measured by RTVue OCT(P<0.05). There was no significant difference between the horizontal and vertical coordinates of the thinnest points measured by the two devices(P>0.05). The central corneal thickness and the thinnest point thickness measured by the two devices were highly correlated, the horizontal coordinate of the thinnest point was moderately correlated, and the vertical coordinate of the thinnest point was weakly correlated. Bland-Altman analysis showed that the central corneal thickness, the thinnest point thickness, the horizontal coordinate of the thinnest point, and the vertical coordinate of the thinnest point were 95.2%(100/105)and 93.3%(98/105), 95.2%(100/105), 95.2%(100/105)respectively, which were within the 95% consistency limit, while the consistency ranges were -36.00～+26.62μm, -42.27～+3.36μm, -0.80～+0.84mm, and -1.95～+1.06mm, respectively.CONCLUSION: In keratoconus, the central corneal thickness and the thinnest point thickness measured by Pentacam HR were higher than those measured by RTVue OCT. It is not recommended that the central corneal thickness and the thinnest point thickness measured by the two instruments be interchangeable in clinical use because of the wide range of consistency between the two instruments' results. The position of the thinnest corneal point measured by the two instruments is similar and consistent, so it could be considered to replace the measured values of the two instruments in clinical use.

Optical quality assessment in patients with macular edema using optical quality analysis system / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To evaluate optical quality, intraocular scatter, and determine the impact of retinopathy on optical quality in macular edema(ME)patient by using the Optical Quality Analysis System(OQAS^TMⅡ).<p>METHODS: This was a prospective case-control study. Fifty-eight eyes of 49 macular edema patients who were confirmed by ophthalmic examination in our hospital from August 2019 to January 2020 were selected as the ME group, and 30 eyes of 30 healthy volunteers who were matched with gender and age range for the study were selected for the normal control group. The clinical data of the two groups of patients were recorded. Under the same test conditions, the same operator used OQAS^TMⅡ to check the visual quality of the study object, including the cutoff of the modulation transfer function(MTF cutoff), strehl ratio(SR), OQAS^TMⅡ values(100%, 20%, 9%)and contrast levels(OV100%, OV20%, OV9%). The difference of data between the two groups were analyzed, and the correlation between the visual quality and the thickness and volume of the macular fovea in the ME group were analyzed.<p>RESULTS: The average best corrected visual acuity in the macular edema group was significantly lower than the control group, and the thickness and volume of macular fovea were significantly higher than the control group(<i>P</i><0.001). Compared with the control group, the OSI of the macular edema group was significantly higher, and MTF cutoff, SR value, OV(100%, 20%, 9%)significantly decreased(<i>P</i><0.001). In the macular disease group, the thickness of macular fovea was positively correlated with OSI(<i>r</i>=0.566, <i>P</i><0.001), while MTF cutoff(<i>r</i>=-0.336, <i>P</i>=0.010), OV100%(<i>r</i>=-0.326, <i>P</i>=0.013), OV20%(<i>r</i>=-0.349, <i>P</i>=0.007)and OV9%(<i>r</i>=-0.321, <i>P</i>=0.014)were negative correlation, but it had no correlation with SR. In the macular edema group, the volume of macular fovea was positively correlated with OSI(<i>r</i>=0.574, <i>P</i><0.001). It was negatively correlated with MTF cutoff(<i>r</i>=-0.367, <i>P</i>=0.005), SR(<i>r</i>=-0.265, <i>P</i>=0.045), OV100%(<i>r</i>=-0.351, <i>P</i>=0.007), OV20%(<i>r</i>=-0.385, <i>P</i>=0.003)and OV9%(<i>r</i>=-0.375, <i>P</i>=0.004).<p>CONCLUSION: The optical quality of patients with macular edema is lower than the normal population, and the changes in macular retina morphology and thickness could affect the optical quality and intraocular scattering. The optical quality parameters measured by OQAS^TMⅡ may provide new clinical reference for macular function evaluation.