Astigmatism evaluation prior to cataract surgery.

PURPOSE OF REVIEW: To evaluate and summarize literature from the past 18 months reporting advancements and issues in astigmatism assessment prior to cataract surgery. RECENT FINDINGS: New and updated toric calculators and regression formulas offer the opportunity for more accurate lens selection for our patients. Concurrently, improvements in topographic evaluation of corneal keratometry have allowed for a decrease in unplanned residual corneal astigmatism. Measuring posterior corneal astigmatism is especially valuable in eyes with keratoconus when planning to implant toric intraocular lens (IOL) and now allows access to this patient population. SUMMARY: Improved accuracy of astigmatism evaluation now occurs with point reflections on the corneal surface along with the latest generation toric lens formulas which integrated posterior corneal astigmatism, predicted lens position, and intended spherical power of the IOL. These improvements can allow for incorporation of toric lenses in keratoconus patients.

Asymptomatic Leukemic Optic Nerve Infiltration as Presentation of Acute Lymphoblastic Leukemia Relapse.

The authors report a case of asymptomatic leukemic optic neuropathy as the first sign of acute lymphoblastic leukemia relapse in a 4-year-old boy. Routine ophthalmologic examination showed normal visual acuity and pupillary function in the presence of a tumoral mass covering the left optic disc. The mass resolved with preservation of vision after intrathecal chemotherapy. A routine ophthalmological examination is recommended for all patients with a history of acute lymphoblastic leukemia to exclude optic nerve involvement without systemic symptoms or signs. Vision can be preserved and radiation avoided by using targeted chemotherapy. [J Pediatr Ophthalmol Strabismus. 2017;54:e60-e62.].

Reduced Glutathione Level Promotes Epithelial-Mesenchymal Transition in Lens Epithelial Cells via a Wnt/ß-Catenin-Mediated Pathway: Relevance for Cataract Therapy.

The epithelial-mesenchymal transition (EMT) process plays a pivotal role in the pathogenesis of posterior capsular opacification because of remnant lens epithelial cell proliferation, migration, and transformation after cataract surgery. The latter, we hypothesize, may result in posterior capsule wrinkling and opacification because of a profound change in the lens growth environment via a 1000-fold reduction of extracellular glutathione (GSH) levels. To test this hypothesis, we investigated the EMT process in cell culture and GSH biosynthesis deficiency mouse models. Our data indicate a dramatic increase of pro-EMT markers, such as type I collagen, α-smooth muscle actin, vimentin, and fibronectin, under conditions of lens GSH depletion. Further study suggests that decreased GSH triggers the Wnt/ß-catenin signal transduction pathway, independent of transforming growth factor-ß. Equally important, the antioxidants N-acetyl cysteine and GSH ethyl ester could significantly attenuate the EMT signaling stimulated by decreased GSH levels. These findings were further confirmed by mock cataract surgery in both gamma glutamyl-cysteine ligase, catalytic subunit, and gamma glutamyl-cysteine ligase, modifier subunit, knockout mouse models. Remarkably, increased EMT marker expression, ß-catenin activation, and translocation into the nucleus were found in both knockout mice compared with the wild type, and such increased expression could be significantly attenuated by N-acetyl cysteine or GSH ethyl ester treatment. This study, for the first time we believe, links oxidative stress to lens fibrosis and posterior capsular opacification formation via EMT-mediated mechanisms.