Prediction of the small aperture intraocular lens on visual acuity in patients with keratoconus.

PURPOSE: To investigate the impact of corneal higher-order aberrations (HOAs) on predicted corrected distance visual acuity (CDVA) in patients with keratoconus at varying simulated pupil apertures. SETTING: Ophthalmology clinics, Medical University of South Carolina, USA. DESIGN: Retrospective chart review study. METHODS: 56 eyes with keratoconus were examined using Scheimpflug tomography during routine examinations prior to medical intervention. The severity of keratoconus was graded using the Amsler-Krumeich classification. Zernike analysis was used to obtain corneal aberrations using simulated pupil diameters of 6-, 4-, and 2 mm. These data were extrapolated to obtain the total RMS HOAs for a 1.6 mm simulated pupil to evaluate the potential effect of a small aperture intraocular lens. Correlation analysis was used to study the impact and relative contributions of HOAs on CDVA. Convolution of HOAs from OPD-Scan III (NIDEK) provided a clinical method to predict CDVA with different simulated pupil sizes in corneas with irregular astigmatism. RESULTS: There were statistically significant positive correlations between photopic CDVA and the magnitude of total and individual (coma, spherical aberration and trefoil) HOAs in this cohort of keratoconus subjects. A keratoconus case with the small aperture IOL confirms the improvement in vision due to the pinhole effect. CONCLUSIONS: The small aperture IOL is expected to markedly reduce aberrations in keratoconus patients up to Amsler-Krumeich class 4 severity to levels consistent with the levels seen in healthy patients. Convolution of corneal HO aberrations with the ETDRS chart provides a useful simulation of the impact of pinhole optics in aberrated eyes.

Settling of buoyant microplastic in estuaries: The importance of flocculation.

Rivers and estuaries are regarded as major pathways of microplastic (MP) transport from terrestrial areas to marine ecosystems. Despite this knowledge on the transport dynamics and fate of MP in freshwater riverine and brackish estuarine waters is limited. Via ex situ settling experiments emulating the Msimbazi River and Estuary in Dar es-Salaam, Tanzania, we demonstrate that flocculation and subsequent settling of positively buoyant MP and fine-grained suspended sediment in riverine and estuarine waters are important for the environmental fate of the plastic particles. Our results show that settling velocities of MP and fine-grained sediment in estuarine water were between five and 21 times larger than in freshwater, explained by the increase in ionic strength that occurs when particles enter saline water. This confirms the concept of increased flocculation and settling of fine-grained particles as they are transported from freshwater to estuarine and marine waters. The implication is that land-based sources of small positively buoyant high-density polyethylene (HDPE) MP transported by rivers will tend to settle and accumulate in estuarine environments and thereby lead to a decrease in the overall load of MPs delivered to the wider marine environment. Thereby our results support the notion of estuaries as MP traps and that flocculation explains the trapping of large quantities of MP debris. Based on these findings we recommend that the interaction of MP with fine-grained sediment should be taken into account when transport models of this pollutant are established.

Tolerance to Induced Astigmatism With a Monofocal Intraocular Lens Designed to Extend the Depth of Focus.

PURPOSE: To determine tolerance to residual astigmatism and visual performance in eyes implanted with a monofocal intraocular lens (IOL) designed to extend the depth of focus (Tecnis Eyhance, DIB00; Johnson & Johnson Vision) compared to eyes implanted with a standard monofocal IOL (Tecnis ZCB00; Johnson & Johnson Vision). METHODS: This prospective, observational study enrolled consecutive patients who underwent routine cataract surgery and implantation of either the DIB00 (n = 20) or ZCB00 (n = 20) IOL. Astigmatic defocus was induced with a plus cylinder from +0.50 to +2.00 diopters (D) in 0.50-D steps for each astigmatic orientation (against-the-rule [ATR], with-the-rule [WTR], and oblique). Outcome measures included the comparison of mean visual acuity at each step of defocus, astigmatic defocus curves, and near and intermediate visual acuity. RESULTS: Eyes implanted with the DIB00 demonstrated greater astigmatic tolerance and were more likely to maintain 20/40 or better visual acuity with up to +2.00 D of induced ATR and oblique astigmatism than the ZCB00 IOLs. The DIB00 group showed 1.3 lines better visual acuity at 2.00 D of ATR astigmatic defocus and 1 line better than the ZCB00 group at 1.50 D of oblique astigmatic defocus. Although the distance visual acuity was comparable, near and intermediate visual acuities (both distance-corrected and uncorrected) were better for the DIB00 IOL than for the standard ZCB00 IOL. CONCLUSIONS: The monofocal IOL designed to extend the depth of focus (DIB00 group) showed greater tolerance to induced astigmatism in ATR and oblique orientations and superior uncorrected and distance-corrected near and intermediate visual acuity than the standard monofocal IOL of the same IOL platform. [J Refract Surg. 2023;39(4):222-228.].

Scheimpflug-Derived Corneal Lower and Higher Order Aberrations Post Intrastromal Corneal Ring Segments for Keratoconus.

Intrastromal corneal ring segments (ICRS) improve corneal topographic symmetry and reduce corneal aberrations through regularization of the corneal surface, thereby functioning as a viable surgical intervention for patients with keratoconus. This study aims to evaluate changes in lower- (LOAs) and higher-order aberrations (HOAs) amongst varying pupil sizes pre- and post- ICRS implantation in keratoconus patients. We specifically investigate the impact of pupil size on total corneal HOAs up to the 6th order. Twenty-one eyes that underwent ICRS implantation were included in this prospective interventional study. LOAs and HOAs measurements at the 6 mm, 4 mm, and 2 mm pupil diameters were collected preoperatively and at 6 months postoperatively using the Zernicke analysis function on a Scheimpflug device. ICRS implantation demonstrated a statistically significant effect in vertical coma with a −0.23 reduction (p = 0.015) for a 4 mm pupil size and a −1.384 reduction (p < 0.001) for 6 mm, with no significant effect at 2 mm. Horizontal coma, astigmatism 0°, astigmatism 45°, trefoil 5th order 30°, and RMS HOA demonstrated significant reductions at 4 mm or 6 mm pupil sizes but not at 2 mm. Our analysis demonstrates a favorable effect of ICRS implantation on larger pupil sizes, suggesting the importance of pupil size as it correlates with HOAs reduction.

SARS coronavirus protein nsp1 disrupts localization of Nup93 from the nuclear pore complex.

Severe acute respiratory syndrome coronavirus nonstructural protein 1 (nsp1) is a key factor in virus-induced down-regulation of host gene expression. In infected cells, nsp1 engages in a multipronged mechanism to inhibit host gene expression by binding to the 40S ribosome to block the assembly of translationally competent ribosome, and then inducing endonucleolytic cleavage and the degradation of host mRNAs. Here, we report a previously undetected mechanism by which nsp1 exploits the nuclear pore complex and disrupts the nuclear-cytoplasmic transport of biomolecules. We identified members of the nuclear pore complex from the nsp1-associated protein assembly and found that the expression of nsp1 in HEK cells disrupts Nup93 localization around the nuclear envelope without triggering proteolytic degradation, while the nuclear lamina remains unperturbed. Consistent with its role in host shutoff, nsp1 alters the nuclear-cytoplasmic distribution of an RNA binding protein, nucleolin. Our results suggest that nsp1, alone, can regulate multiple steps of gene expression including nuclear-cytoplasmic transport.