Evaluation of topographic, tomographic, topometric, densitometric, and aberrometric features of cornea with pentacam HR system in subclinical keratoconus.

PURPOSE: To investigate topographic, tomographic, topometric, densitometric, and aberrometric parameters in subclinical keratoconus with the Pentacam HR imaging system. METHODS: Data of 3128 patients were evaluated, finding in 108 patients clinical keratoconus in one eye and subclinical keratoconus in the other. Corneal topographic, tomographic, topometric, densitometric, and aberrometric values obtained using the Pentacam HR imaging system were compared between clinical keratoconus, subclinical keratoconus, and normal eyes. RESULTS: Comparing eyes with subclinical keratoconus and the control group, while flat K, horizontal coma, horizontal trefoil, and vertical trefoil values were similar (p > 0.05 for each), all other parameters were significantly different (p < 0.05 for each). Densitometry values of eyes with subclinical keratoconus were significantly higher in all layers of the 0-2 mm annular area and in the anterior and central layers of the 2-6 mm annular area compared to the control group (p < 0.05 for each). According to the receiver operating characteristic curve analysis, the densitometry region with the largest area under the curve was the anterior layer of the 0-2 mm annular area. The sensitivity in this region was 79.4% and the specificity 73.2% in distinguishing eyes with subclinical keratoconus from normal eyes when 19.3 GSU was considered the threshold. CONCLUSION: Corneal densitometry values in the 0-2 and 2-6 mm annular areas, especially in the anterior layers, are parameters that can be used to predict and distinguish subclinical keratoconus from normal eyes.

Could Corneal Densitometry be a Progression Criterion for Subclinical Keratoconus?

Objectives: The objective of this study is to investigate the changes in topometry, tomography, and corneal densitometry in subclinical keratoconus (SK) at the 6-month interval. Methods: The clinical keratoconus and SK groups included 25 eyes; the control group included 22 eyes from 22 patients. Corneal topographic, tomographic, topometric, and densitometric values obtained using the Pentacam HR imaging system were analyzed. Results: Posterior elevation (PE), Keratoconus index (KI), index of height asymmetry (IHA), index of height decentration (IHD), Dp, Da, Final D, maximum pachymetric progression index (PPImax), and maximum Ambrósio relational thickness parameters showed significant changes between the baseline and the 6th-month follow-up in SK group (p<0.05 for all values). There were significant changes in all zones except a central layer of 6-10 zone, anterior, and central layer of 10-12 zone between the baseline and the 6th-month follow-up in the SK group (p<0.05, for all values). The changes in mean±standard deviation of KI, IHA, IHD, PPImax parameters, and corneal densitometry values of the posterior layer of 0-2 mm and 2-6 mm zones were significant in the SK group compared to the controls (p<0.05, for all values). Conclusion: PE, KI, IHA, IHD, and PPImax parameters as well as increasing corneal light backscatter of the posterior central layer might be useful for follow-up of progression of SK. New multimeric parameters created by combinations of topometric, tomographic, and corneal densitometry parameters could be the future of SK follow-up.

Topometric and Tomographic Evaluation of Subclinical Keratoconus.

PURPOSE: To investigate the corneal topometric and tomographic findings that can be used in the diagnosis of subclinical keratoconus. METHODS: A retrospective cohort study. The study group was selected from patients with clinically evident keratoconus in one eye and subclinical keratoconus without evident topographic findings in fellow eye. The age-matched control group was selected from patients who were candidates for laser in situ keratomileusis (LASIK) and did not develop ectasia after LASIK surgery at least 1-year follow-up. All subjects underwent topographic, topometric and tomographic (Belin-Ambrósio Enhanced Ectasia Display III) analyses via a Pentacam HR rotating Scheimpflug camera (Oculus, Germany, version 1.20r.98) before LASIK surgery. RESULTS: The study group consisted of 151 patients (69 male and 82 female, mean age of 24.8 ± 7.2 years) and the control group also consisted of 150 patients (70 male and 80 female, mean age of 26.0 ± 6.3 years). There were statistically significant differences in all measured topometric (p˂.05) and tomographic (p˂.001) parameters between the eyes with subclinical keratoconus and those of the control group. In discriminating eyes with subclinical keratoconus from normal eyes, final D showed the highest area under curve value (0.858, sensitivity 85.2%, specificity 66.7%), followed by maximum pachymetric progression index (0.809, sensitivity 81.9%, specificity 69.4%) and average pachymetric progression index (0.796, sensitivity 81.9%, specificity 68.1%) in receiver operating characteristic analysis. CONCLUSION: Topometric and tomographic parameters might be useful for early detection of keratoconus, but the sensitivity and specificity of any parameter are not high enough to be used alone.

Long-Distance and Trans-Generational Stomatal Patterning by CO2 Across Arabidopsis Organs.

Stomata control water loss and carbon dioxide uptake by both altering pore aperture and developmental patterning. Stomatal patterning is regulated by environmental factors including atmospheric carbon dioxide (p[CO2]), which is increasing globally at an unprecedented rate. Mature leaves are known to convey developmental cues to immature leaves in response to p[CO2], but the developmental mechanisms are unknown. To characterize changes in stomatal patterning resulting from signals moving from mature to developing leaves, we constructed a dual-chamber growth system in which rosette and cauline leaves of Arabidopsis thaliana were subjected to differing p[CO2]. Young rosette tissue was found to adjust stomatal index (SI, the proportion of stomata to total cell number) in response to both the current environment and the environment experienced by mature rosette tissue, whereas cauline leaves appear to be insensitive to p[CO2] treatment. It is likely that cauline leaves and cotyledons deploy mechanisms for controlling stomatal development that share common but also deploy distinctive mechanisms to that operating in rosette leaves. The effect of p[CO2] on stomatal development is retained in cotyledons of the next generation, however, this effect does not occur in pre-germination stomatal lineage cells but only after germination. Finally, these data suggest that p[CO2] affects regulation of stomatal development specifically through the development of satellite stomata (stomata induced by signals from a neighboring stomate) during spacing divisions and not the basal pathway. To our knowledge, this is the first report identifying developmental steps responsible for altered stomatal patterning to p[CO2] and its trans-generational inheritance.

Early orthopaedic challenges in haemophilia patients and therapeutic approach.

INTRODUCTION: There is growing evidence that subclinical joint bleeding early in life may lead to subtle changes in joint function, gait, and muscle development in young children with haemophilia. The early identification of such changes provides an opportunity for clinicians to intervene before irreversible structural changes occur. MATERIALS AND METHODS: We have undertaken motion analysis of the knee in 273 children (mean age 9.8 years) with haemophilia A, haemophilia B, or von Willebrand disease and compared the results with those from 200 healthy age- and sex-matched controls (mean age 10.3 years). We have also completed detailed orthopaedic assessments and evaluated overall fitness in most of these children. RESULTS: There was a clear correlation between total motion score and age: r(2)=0.47 for the healthy children and r(2)=0.69 for the haemophilic children. The differences were most striking in children aged 3-4 years. Significant between-group differences were also observed in the comparison of knee bends, gait scores, and rhythmicity. Orthopaedic examinations revealed previously clinically silent pressure pains in the ligaments of the knee joints of 38% of children and in the ligaments and capsule of the ankle joints of 60% of children. The five-item fitness check showed significant deficits relative to controls in overall fitness, endurance, coordination, and flexibility. CONCLUSIONS: Children and adolescents with haemophilia show significant functional impairments relative to normal controls. Early comprehensive assessments of the musculoskeletal system should be made so that individualized physical, physiotherapy, and sports therapy programmes can be developed.

Common solutions to resolve different dietary challenges in the ruminant dentition: the functionality of bovid postcanine teeth as a masticatory unit.

Plasticity of tooth shape in mammals is of great adaptive value for the efficient exploitation of specific feeding niches and is a crucial mechanism for ecological diversification. In this study, we aimed to infer chewing effectiveness from the functional shape of different postcanine teeth within bovids, the most diverse extant group of large herbivorous mammals. We consider the postcanine dentition as a masticatory unit and test for differences related to food biomechanical properties, dietary abrasiveness, and chewing dynamics. We compare functional properties of the postcanine tooth row among species with well-known dietary strategies by integrating digitalization of high-resolution occlusal surface 3D-models of upper postcanine dentitions and quantification of the indentation index (D), a structural parameter representing enamel complexity. We test for differences in the occlusal shape among tooth positions in the postcanine dentition using robust, heteroscedastic tests in a one-way analysis of variance. Our results show three distinct patterns of enamel complexity along the tooth row: (1) D is more homogeneously distributed among tooth positions; (2) D increases gradually in the mesiodistal axis along the tooth row; and (3) D increases abruptly only at the transition between premolars and molars. We interpreted these patterns as different adaptive configurations of the postcanine tooth row relating to diet. Grass- and fruit-eating bovids show the same abrupt increase in enamel complexity at the transition from premolars to molars. Intermediate feeding and leaf-browsing species show the same gradual, mesiodistal increase in complexity along the tooth row. The absolute physical dietary resistance (biomechanical properties plus abrasiveness) and its relation to mechanical constraints of the chewing stroke are the likely selective factors leading to convergence of enamel complexity patterns along the tooth row among taxa with different diets.