Parkinson disease (PD) is a neurodegenerative process that leads to a selective loss of dopaminergic neurons, mainly in the basal ganglia of the brain. Numerous studies have analyzed the ability of optical coherence tomography (OCT) to detect retinal nerve fiber layer (RNFL) thickness abnormalities and changes in PD, but the results have not always been consistent. Therefore, we carried out a meta-analysis to evaluate the RNFL thickness measured with OCT in PD. Case-control studies were selected through an electronic search of the Cochrane Controlled Trials Register, PUBMED and EMBASE. For the continuous outcomes, we calculated the weighted mean difference (WMD) and 95% confidence interval (CI). The statistical analysis was performed by RevMan 5.0 software. Thirteen case-control studies were included in the present meta-analysis, containing a total of 644 eyes in PD patients and 604 eyes in healthy controls. The results of our study showed that there was a significant reduction in average RNFL thickness in patients with PD compared to healthy controls (WMD = −5.76, 95% CI: −8.99 to −2.53, P = 0.0005). Additionally, differences of RNFL thickness in superior quadrant (WMD = −4.44, 95% CI: −6.93 to −1.94, P = 0.0005), inferior quadrant (WMD = −7.56, 95% CI: −11.33 to −3.78, P<0.0001), nasal quadrant (WMD = −3.12, 95% CI: −5.63 to −0.61, P = 0.01) and temporal quadrant (WMD = −4.63, 95% CI: −7.20 to −2.06, P = 0.0004) were all significant between the two groups. In view of these results and the noninvasive nature of OCT technology, we surmise that OCT could be a useful tool for evaluating the progression of the Parkinson disease. ClinicalTrials.gov NCT01928212

To comprehensively assess the precision and agreement of anterior corneal power measurements using 8 different devices. Thirty-five eyes from 35 healthy subjects were included in the prospective study. In the first session, a single examiner performed on each subject randomly measurements with the RC-5000 (Tomey Corp., Japan), KR-8000 (Topcon, Japan), IOLMaster (Carl Zeiss Meditec, Germany), E300 (Medmont International, Australia), Allegro Topolyzer (Wavelight AG, Germany), Vista (EyeSys, TX), Pentacam (Oculus, Germany) and Sirius (CSO, Italy). Measurements were repeated in the second session (1 to 2 weeks later). Repeatability and reproducibility of corneal power measurements were assessed based on the intrasession and intersession within-subject standard deviation (Sw), repeatability (2.77Sw), coefficient of variation (COV), and intraclass correlation coefficient (ICC). Agreement was evaluated by 95% limits of agreement (LoA). All devices demonstrated high repeatability and reproducibility of the keratometric values (2.77Sw<0.36D, COV0.98). Repeated-measures analysis of variance with Bonferroni post test showed statistically significant differences (P<0.01) among mean keratometric values of most instruments; the largest differences were observed between the EyeSys Vista and Medmont E300. Good agreement (i.e., 95%LoA within ±0.5D) was found between most instruments for flat, steep and mean keratometry, except for EyeSys and Medmont. Repeatability and reproducibility of vectors J₀ and J₄₅ was good, as the ICCs were higher than 0.9, except J₄₅ of Medmont and Pentacam. For the 95% LoAs of J₀ and J₄₅, they were all ≤ ±0.31 among any two paired devices. The 8 devices showed excellent repeatability and reproducibility. The results obtained using the RC-5000, KR-8000, IOLMaster, Allegro Topolyzer, Pentacam and Sirius were comparable, suggesting that they could be used interchangeably in most clinical settings. Caution is warranted with the measurements of the EyeSys Vista and Medmont E300, which should not be used interchangeably with other devices due to lower agreement. ClinicalTrials.gov NCT01587287

: Purpose:  To compare the repeatability and reproducibility of central corneal thickness (CCT) measurements by high‐resolution (HR) rotating Scheimpflug imaging and Fourier‐domain optical coherence tomography (FD‐OCT). CCT measurements were compared to those determined by ultrasound pachymetry (UP).Methods:  In 35 healthy eyes, intra‐observer repeatability for HR Scheimpflug (Pentacam) and FD‐OCT (RTVue) systems was determined in consecutive images taken by an observer in the shortest time possible. Imaging was repeated again by a second observer to evaluate inter‐observer reproducibility. The CCT measurements were compared among Scheimpflug, FD‐OCT and UP images.Results:  Mean coefficients of repeatability were 0.48% for Scheimpflug and 0.26% for FD‐OCT. For Scheimpflug, the coefficient of inter‐operator reproducibility was 0.87%. For FD‐OCT, the coefficient of inter‐operator reproducibility was 0.45%. The CCT measurements by Scheimpflug, OCT and UP images were (mean ± standard deviation) 521.7 ± 27.6 μm, 510.8 ± 28.6 μm and 516.5 ± 27.6 μm, respectively. The differences between instruments were statistically significant. The 95% limits of agreement in CCT were −0.7 to 22.5 μm for Pentacam‐OCT, −13.4 to 24.0 μm for Pentacam‐UP and −26.7 to 15.4 μm for OCT‐UP. There was a high degree of correlation between CCT measured by all 3 methods.Conclusion:  Noncontact measurements of CCT with HR Scheimpflug and FD‐OCT systems yielded excellent repeatability and reproducibility and can be used interchangeably. Although both devices were comparable with UP; in clinical practice, the measurements acquired by optical modalities are not directly interchangeable with UP measurements.