Scleral lens prescription and management practices: Emerging consensus

PURPOSE

To describe international scleral lens prescription and management practices across multiple practice types.

METHODS

For this cross-sectional study, scleral lens practitioners were asked to complete an electronic survey that requested information about a single scleral lens patient. Data collected included practitioner demographics (practice type, country, years of experience) and patient indications for scleral lens wear, fitting process, lens design, and care products.

RESULTS

Data were collected for 259 patients (419 eyes). Most participants (60%) practiced in the US, 75% worked primarily in community practice, and 58% claimed more than 5 years' experience fitting scleral lenses. Indications for scleral lens wear were corneal irregularity (87%), ocular surface disease (9%), and uncomplicated refractive error (4%). During the fitting process, the mean (SD) number of lenses ordered was 2.4 (1.6) (range, 1-16 lenses) during 3.8 (2.4) visits (range, 1-18 visits). Of patients, 62% used a daily surfactant cleaner, 47% used hydrogen peroxide disinfection, and 67% used single-use vials of nonpreserved saline. Mean lens diameter was 16.2 (1.1) mm (range, 11.8-23.0 mm). The landing zones were spherical (64%), toric (26%), quadrant-specific (7%), and custom (3%) designs. Optical power was spherical in 70%, toric in 27%, and higher-order aberration correcting in 3% of lenses. Only 5 lenses had multifocal optics.

CONCLUSIONS

General consensus regarding prescribing patterns (lens design, wearing schedules, care products) between US vs non-US, community vs academic, and new vs established providers is reported in this study. Relatively low percentages of patients wearing lenses with advanced landing zones or optical designs suggest that these new options have not been widely adopted.

Is the pacing site closer to the left ventricular septal endocardium in left bundle branch pacing or in left ventricular septal pacing?

PURPOSE

Distinguishing between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) is challenging. This study aimed to compare the echocardiographic distance from the pacing lead tip to the left ventricular (LV) septal endocardium between patients who underwent LBBP and those who underwent LVSP successfully.

METHODS

Fifty-nine consecutive patients (age 71.9 ± 12.0 years, 35.6% male) with traditional indications for permanent cardiac pacing were included (LBBP group, n = 46; LVSP group, n = 13). Unipolar pacing from the final pacing sites generated narrow QRS complexes with a right bundle branch block pattern in all patients. After the procedure, a physician blinded to the group allocation performed echocardiographic measurements of the distance between the lead tip and the LV septal endocardium.

RESULTS

The mean paced QRS duration was comparable between the LBBP group and the LVSP group (105.3 ± 15.6 ms vs. 109.2 ± 9.6 ms, P = 0.287). In the LBBP group, the interval from the left bundle branch potential to QRS onset was 28.7 ± 9.0 ms. During diastole, the mean distance between the lead tip and the LV septal endocardium was 0.6 ± 0.9 mm in the LBBP group and 3.0 ± 1.6 mm in the LVSP group (P < 0.001). During systole, the distance was 1.5 ± 1.4 mm in the LBBP group and 4.3 ± 2.6 mm in the LVSP group (P < 0.001).

CONCLUSIONS

The landing zone of the lead tip was closer to the LV septal endocardium in the patients who underwent LBBP. There is a need for real-time intraprocedural monitoring of the distance between the lead tip and the LV septal endocardium when performing LBBP.

Landing Zone Remodelling after Endovascular Repair of Dissected Descending Aorta

OBJECTIVE

The aim of this study was to determine geometric changes in the proximal and distal aortic landing zones after thoracic endovascular aortic repair (TEVAR) for acute descending aortic dissection.

METHODS

This was a retrospective analysis of clinical and radiological data. Included are patients who underwent TEVAR for acute descending aortic dissection between 2004 and 2018. Analysed are the proximal and distal landing zones' initial geometries and their change at follow up. Median follow up time was 2.3 (first quartile 0.9, third quartile 4.5) years.

RESULTS

One hundred and one patients were included (93 type B and 8 non-A non-B dissections, aged 65 (57, 74) years old, and 29% female). Dissection extended down to the abdominal aorta in 69% patients. The proximal landing zone was non-dissected in 92 patients. The diameters of non-dissected proximal landing zones increased by 3 (-1, 5; p < .001) mm at follow up. The distal landing zone was dissected in 84% of patients. The diameters of dissected distal landing zones had increased at follow up by 7 (3, 12) mm and 4 (1, 10; both p < .001) mm measured in true lumen and total aorta, respectively, observed one year after TEVAR. Stent grafts reached their nominal diameter at follow up in 22% and 17% of proximal and distal landing zones, respectively. There were seven proximal and 10 distal stent graft induced new entries at follow up. Aortic re-intervention was necessary in 23 patients entailing 19 TEVAR extensions and four open aortic repairs.

CONCLUSION

The distal landing zone in patients undergoing TEVAR for descending aortic dissection is frequently dissected and is associated with the risk of d-SINE at follow up and the need for re-interventions after TEVAR - factors that emphasise the importance of long term follow up.

The landing zone - Ground for model transfer in chemistry

This essay proposes a new notion - the landing zone - in order to identify conceptual features that allow modelers to transfer mathematical tools across disciplinary borders. This discussion refers to the transferable models as 'templates'. Templates are functions, equations, or computational methods that are capable of being generalized from a particular subject matter. There are formal and conceptual prerequisites for the transfer of a template to a new domain. A landing zone is an ontology that contributes to the satisfaction of these conditions for successful transfer. This paper presents a case study on a model in chemistry - the Quantum Theory of Atoms in Molecules (QTAIM) - that makes use of transferred templates from physics - the virial theorem and the wave function. The landing zone in this case is a new ontological notion, that of the topological atom, which prepares ground for the use of the virial theorem and the wave function in chemistry. The virial theorem requires that there exists in-principle stability to the system that it represents, and the wave function requires transformation in its representation that is justified. The ontology of QTAIM - the landing zone for these templates - grounds the scientific use of these templates in the context of chemistry.