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Purpose: We compared the characteristics of subtle morphological changes in subclinical keratoconus (KC) and normal corneas using Scheimpflug tomography (Pentacam®) and assessed the efficacy of these parameters for distinguishing KC or subclinical KC from normal eyes. Patients and Methods: In this multicenter comparative study at Dhahran Eye Specialist Hospital and Al Kahhal Medical Complex in the Eastern Province of Saudi Arabia, we analyzed the Scheimpflug tomography charts of patients with topographically normal eyes and those with unilateral KC. Patients were divided into the normal (NL: patients considered for refractive surgery and with normal topographic/tomographic features, 129 eyes), KC (30 patients with manifest KC in one eye based on biomicroscopy and topographical findings), and forme fruste KC (FFKC: fellow eyes of patients in the KC group that met the NL group criteria) groups. Corneal morphological parameters were analyzed using the area under the receiver operating characteristic (ROC) curves (AUCs). Results: For distinguishing NL and KC groups, all measured corneal morphological parameters, except for flat keratometry, maximum Ambrósio relational thickness index, and minimum sagittal curvature, had AUCs >0.75. The surface variance index yielded the largest AUC (0.999). For distinguishing NL and FFKC groups, all corneal morphological parameters had AUCs <0.8. Total higher-order aberrations (RMS HOA) yielded the highest AUC, followed by Belin/Ambrosio Enhanced Ectasia total deviation (BAD-D), back elevation at the thinnest location, average pachymetric progression index (PPIave), and deviation of Ambrosio relational thickness (Da) (AUC 0.74-0.78). Conclusion: The diagnostic performance of all tested topographic and tomographic parameters measured using Scheimpflug tomography for discriminating subclinical KC was fair at best, with the top parameters being RMS HOA, BAD-D, back elevation at the thinnest location, PPIave, and Da. Distinguishing between subclinical KC and healthy eyes remains challenging. Multimodal imaging techniques may be required for optimal early detection of subtle morphological changes.
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BACKGROUND: The coronavirus disease 2019 (COVID-19) has spread worldwide, and the vaccine remains the ultimate cornerstone to overcoming its long-term impact. Vaccine hesitancy might obstruct the effort to achieve herd immunity and eradicate the virus. We assessed Saudi Arabian individuals' willingness, beliefs, and barriers regarding the COVID-19 vaccine and their adherence to preventive measures during and after the pandemic. METHODS: A self-administered electronic validated questionnaire was distributed among the five major regions in Saudi Arabia between November and December 2020. The questionnaire addressed the sociodemographic data, beliefs, potential barriers, parents' acceptance of COVID-19 vaccination for their children, and adherence to protective measures during and after the pandemic. RESULTS: Of 8,056 participants, 4,218 (52.4%) of a non-representative sample were willing to be vaccinated against COVID-19. Being a young adult, male, having less than a high school degree, being a smoker, having a chronic disease, and having a history of seasonal influenza vaccine uptake were positive predictors of COVID-19 vaccine acceptance. Hesitant participants reported concerns about vaccine side effects and safety as the main barriers to accepting the COVID-19 vaccine. Some refusers (26.1%) declared that they would reconsider vaccination only if the safety and effectiveness of the vaccine were reported by more studies. CONCLUSIONS: Our study revealed a promising willingness to accept the vaccine among the population, with positive beliefs and attitudes toward COVID-19 vaccination. However, a considerable proportion of the population was reluctant to accept the vaccine. Thus, publicly providing information about vaccine safety and implementing health education programs is crucial for increasing the public's confidence in the vaccine.
