Factors affecting central corneal thickness measurement agreement between Scheimpflug imaging and ultrasound pachymetry in keratoconus

A comparative study of pupil offset measurement using Pentacam and Keratron Scout in myopic young adults

CLINICAL RELEVANCE

Assessing the consistency of pupil offset measurements between the Pentacam and Keratron Scout is essential for the refractive surgery design of young myopic patients.

BACKGROUND

Accurate preoperative measurement of pupil offset is critical to achieving a better quality of vision after refractive surgery. The Pentacam and Keratron Scout are commonly used in hospitals, and evaluating their consistency is essential for accurate measurement of pupil offset.

METHODS

Six hundred eyes (600 subjects) were included in this study. Pupil offset and its X, Y-component were measured by Pentacam and Keratron Scout, respectively. Agreement and repeatability between the two devices were identified by intraclass correlation coefficient and Bland-Altman plots with 95% limits of agreement. Paired t-tests and Pearson analysis were used to compare the differences and correlations between the two devices.

RESULTS

The mean age of all subjects was 23 ± 5 years. The mean pupil offset magnitude obtained from Pentacam and Keratron Scout was 0.16 ± 0.08 mm and 0.15 ± 0.07 mm. The 95% limits of agreement (-0.11-0.13, -0.09-0.11, and -0.11-0.12) and intraclass correlation coefficient (0.82, 0.84, and 0.81) demonstrated good agreement and repeatability of the two devices in measuring pupil offset and its X, Y-component. A significant correlation between the two devices was found (r = 0.71, 0.73, and 0.70). The direction of pupil offset measured by the devices was both predominately towards the superonasal quadrant.

CONCLUSION

Pentacam and Keratron Scout showed good agreement in measuring pupil offset and its X, Y-component, which can be used interchangeably in clinical practice.

Corneal thickness measurements with the RTVue, Casia-2, and Pentacam devices in patients with mild-to-moderate keratoconus: a comparative study

BACKGROUND

To compare the characteristics of corneal thickness measurements among the RTVue, Casia-2, and Pentacam in patients with mild-to-moderate keratoconus.

METHODS

We recruited 46 eyes of 46 patients diagnosed with mild-to-moderate keratoconus at our hospital between January and March 2022. The central corneal thickness (CCT) and thinnest corneal thickness (TCT) were measured using two optical coherence tomography (OCT) instruments (RTVue and Casia-2) and the more conventional Pentacam. Differences and correlations between the CCTs and TCTs, based on the device and influencing factors, were explored.

RESULTS

The CCTs were highly consistent among the groups (p = 0.434) and correlated with one another (p < 0.001). The TCTs measured by OCTs were thinner than those measured by the Pentacam (p < 0.001); however, all three devices were highly correlated (p < 0.001). The thinnest point location measurements with RTVue and Casia-2 differed significantly from the measurements with the Pentacam. Bland-Altman plots demonstrated a significant agreement between Pentacam and OCTs in TCT measurement (p < 0.001); the 95% limits of agreement were - 3.1 μm to + 33.1 μm for Pentacam and RTVue and - 8.6 μm to + 36.5 μm for Pentacam and Casia-2. RTVue and Casia-2 showed no difference in corneal thickness (p = 0.633) and thinnest point location measurement (p > 0.05). Multivariate analysis identified that the TCT measurement difference between the RTVue and Pentacam was related to the difference between the CCT and TCT (b = 0.490, 95% confidence interval [CI]: 0.033 to 0.948, p = 0.036), whereas the difference between the Casia-2 and Pentacam was related to the anterior radius for curvature (A) grade (b = 3.9, 95% CI: 1.753 to 6.074, p = 0.001), corneal pachymetry at the thinnest (C) grade (b = - 7.875, 95% CI: - 11.404 to - 4.346, p < 0.001), and the difference between the CCT and TCT (b = 0.425, 95% CI: 0.1 to 0.751, p = 0.012).

CONCLUSIONS

CCTs in patients with mild-to-moderate keratoconus were similar among all three devices, but the TCTs and the thinnest point locations were not. Furthermore, the TCT measurement differences between the OCT devices and the Pentacam were more pronounced in keratoconus cases with a steeper anterior surface, thicker TCTs, and a larger difference between the CCT and TCT.

TRIAL REGISTRATION

Number: 2021118-1. Retrospectively registered: September 01, 2021.

The diagnostic value of 123I-IMP SPECT in ocular adnexal lymphoma

BACKGROUND

N-isopropyl- (¹²³I) p-iodoamphetamine (¹²³I-IMP) is specifically accumulated in primary central nervous system lymphoma (PCNSL) during single-photon emission tomography (SPECT) and contributes to its diagnostic imaging. However, whether ¹²³I-IMP is accumulated in ocular adnexal lymphoma (OAL), one of the malignant intraorbital tumors, remains unclear. This study aimed to evaluate the diagnostic value of ¹²³I-IMP SPECT in OAL.

METHODS

Between August 2005 and June 2020, 26 patients with intraorbital tumors underwent neurosurgery at the tertiary care center. Of these, 15 patients who underwent ¹²³I-IMPSPECT before surgery were retrospectively examined. The region of interest was set in the cerebellum ipsilateral to the intraorbital tumor on ¹²³I-IMP SPECT, and the tumor-to-cerebellum ratio (T/C ratio) was calculated using the following formula: T/C ratio = [accumulation of tumor (count/pixel)]/[accumulation of ipsilateral normal cerebellar hemisphere (count/pixel)].

RESULTS

Six patients were included in the OAL group, who were pathologically diagnosed with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), diffuse large B-cell lymphoma (DLBCL), and plasmacytoma. The T/C ratio in the OAL group was statistically higher than that in the non-OAL group (p < 0.01). The optimal cutoff values for both groups were between 0.76 and < 0.93. The sensitivity and specificity were 1.00, respectively.

CONCLUSIONS

¹²³I-IMP SPECT is useful as one of the examinations in the differential diagnoses of OAL, because it showed a significantly higher accumulation in OAL group than in non-OAL group.