SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Cataract

271

To determine the heritability of nuclear cataract progression and to explore prospectively the effect of dietary micronutrients on the progression of nuclear cataract.

Concepts: Genetics, Nutrition, Cataract

168

We present an overview of currently available toric intraocular lenses (IOLs) and multifocal toric IOLs. Relevant patient selection criteria, IOL calculation issues, and surgical techniques for IOL implantation are discussed. Clinical outcomes including uncorrected visual acuity, residual refractive astigmatism, and spectacle independency, which have been reported for both toric IOLs and multifocal toric IOLs, are reviewed. The incidence of misalignment, the most important complication of toric IOLs, is determined. Finally, future developments in the field of toric IOLs are discussed. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Concepts: Ophthalmology, Lens, Presbyopia, Contact lens, Refractive error, Intraocular lens, Cataract, Toric lens

167

PURPOSE: To compare the visual outcomes of additional multifocal intraocular lenses (IOLs) for sulcus fixation with those of standard multifocal IOLs in the capsular bag. SETTING: Department of Ophthalmology, Rudolf-Virchow-Klinikum Glauchau, Glauchau, Germany. DESIGN: Prospective controlled clinical trial. METHODS: Eyes had phacoemulsification and implantation of a monofocal IOL in the capsular bag and an additional aberration-free diffractive IOL in the ciliary sulcus (multifocal add-on IOL group). Measurements of uncorrected and distance-corrected distance, intermediate, and near visual acuities; contrast sensitivity; and defocus curve were performed 3 months postoperatively. Results were compared with those in eyes with an aberration-correcting diffractive posterior chamber IOL (multifocal PC IOL group). RESULTS: The multifocal add-on IOL group comprised 34 eyes of 20 patients and the multifocal PC IOL group, 31 eyes of 17 patients. Cataract surgery, IOL implantation, and the postoperative course were uneventful in all cases. There were no statistically significant differences in uncorrected and distance-corrected distance, intermediate, or near visual acuities between the 2 groups. The median uncorrected distance visual acuity was 0.00 logMAR in both groups, and the median uncorrected near visual acuity was 0.10 logMAR in both groups. Contrast sensitivity testing yielded significantly better results in the multifocal add-on IOL group, especially at spatial frequencies over 1.5 cycles per degree. Defocus curves were similar in the 2 groups. CONCLUSION: Visual performance with a multifocal diffractive add-on IOL was equivalent to that achieved with a commonly used multifocal diffractive PC IOL. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Concepts: Statistical significance, Visual acuity, Ophthalmology, Lens, Contact lens, Intraocular lens, Eye surgery, Cataract

151

We performed a systematic review and meta-analysis to evaluate the benefit and harms associated with implantation of toric intraocular lenses (IOLs) during cataract surgery. Outcomes were postoperative uncorrected distance visual acuity (UCDVA) and distance spectacle independence. Harms were evaluated as surgical complications and residual astigmatism.

Concepts: Medicine, Surgery, Visual acuity, Ophthalmology, Presbyopia, Intraocular lens, Cataract, Toric lens

40

The repair and regeneration of tissues using endogenous stem cells represents an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has not yet been demonstrated. Currently, the only treatment for cataracts, the leading cause of blindness worldwide, is to extract the cataractous lens and implant an artificial intraocular lens. However, this procedure poses notable risks of complications. Here we isolate lens epithelial stem/progenitor cells (LECs) in mammals and show that Pax6 and Bmi1 are required for LEC renewal. We design a surgical method of cataract removal that preserves endogenous LECs and achieves functional lens regeneration in rabbits and macaques, as well as in human infants with cataracts. Our method differs conceptually from current practice, as it preserves endogenous LECs and their natural environment maximally, and regenerates lenses with visual function. Our approach demonstrates a novel treatment strategy for cataracts and provides a new paradigm for tissue regeneration using endogenous stem cells.

Concepts: Human, Developmental biology, Cellular differentiation, Regeneration, Object-oriented programming, Intraocular lens, Cataract

37

Cataracts reduce vision in 50% of individuals over 70 years of age and are a common form of blindness worldwide. Cataracts are caused when damage to the major lens crystallin proteins causes their misfolding and aggregation into insoluble amyloids. Using a thermal stability assay, we identified a class of molecules that bind α-crystallins (cryAA and cryAB) and reversed their aggregation in vitro. The most promising compound improved lens transparency in the R49C cryAA and R120G cryAB mouse models of hereditary cataract. It also partially restored protein solubility in the lenses of aged mice in vivo and in human lenses ex vivo. These findings suggest an approach to treating cataracts by stabilizing α-crystallins.

Concepts: Protein folding, In vivo, Chemical substance, In vitro, Blindness, Cataract, Ex vivo

31

The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

Concepts: Protein, Gene, Mutation, Amino acid, Acid, In vitro, Cataract, Conserved sequence

28

This literature review looks at the current status of multifocal intraocular lenses (IOLs) in cataract surgery. The results of implantation of multifocal IOLs of diffractive, refractive, and hybrid diffractive-refractive design are described with regard to uncorrected near and distance visual acuity and spectacle independence. The occurrence of photic phenomena and contrast sensitivity loss with multifocal IOLs are also addressed. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

Concepts: Visual acuity, Ophthalmology, The Current, Contact lens, Intraocular lens, Eye surgery, Cataract, Corrective lenses

28

Traumatic eye injuries are associated with significant visual impairment and are a major cause of monocular blindness. Rapid assessment and examination following trauma to the eye is crucial. A thorough knowledge of potential injuries is imperative to ensure rapid diagnosis, to prevent further damage to the eye, and to preserve visual capacity. One consequence of ocular trauma is cataract formation. We report a case and image of a 5-year-old boy who presented after sustaining a blunt head trauma. CT scan of the head revealed a markedly hypodense left eye lens.

Concepts: Eye, Visual perception, English-language films, Ophthalmology, Lens, Blindness, Cataract, Eye injury

28

To describe the differences in treatment costs for infants randomized to contact lens correction versus primary intraocular lens (IOL) implantation after unilateral cataract surgery in the Infant Aphakia Treatment Study (IATS).

Concepts: Cornea, Ophthalmology, Lens, Contact lens, Intraocular lens, Phacoemulsification, Cataract, Aphakia