Background: Due to high prevalence myopia has gained importance in epidemiological studies. Children with early onset are at particular risk of complications associated with myopia, as progression over time might result in high myopia and myopic macular degeneration. Both genetic and environmental factors play a role in the increasing prevalence of myopia. The aim of this study is to review the current literature on epidemiology and risk factors for myopia in school children (aged 6–19 years) around the world. Main body: PubMed and Medline were searched for the following keywords: prevalence, incidence, myopia, refractive error, risk factors, children and visual impairment. English language articles published between Jan 2013 and Mar 2019 were included in the study. Studies were critically reviewed for study methodology and robustness of data. Eighty studies were included in this literature review. Myopia prevalence remains higher in Asia (60%) compared with Europe (40%) using cycloplegic refraction examinations. Studies reporting on non-cycloplegic measurements show exceptionally high myopia prevalence rates in school children in East Asia (73%), and high rates in North America (42%). Low prevalence under 10% was described in African and South American children. In recent studies, risk factors for myopia in schoolchildren included low outdoor time and near work, dim light exposure, the use of LED lamps for homework, low sleeping hours, reading distance less than 25 cm and living in an urban environment. Conclusion: Low levels of outdoor activity and near work are well-established risk factors for myopia; this review provides evidence on additional environmental risk factors. New epidemiological studies should be carried out on implementation of public health strategies to tackle and avoid myopia. As the myopia prevalence rates in non-cycloplegic studies are overestimated, we recommend considering only cycloplegic measurements.

Glaucoma is one of the leading causes of blindness worldwide, and as the proportion of those over age 40 increases, so will the prevalence of glaucoma. The pathogenesis of primary open angle glaucoma (POAG) is unclear and multiple ocular risk factors have been proposed, including intraocular pressure, ocular perfusion pressure, ocular blood flow, myopia, central corneal thickness, and optic disc hemorrhages. The purpose of this review was to analyze the association between systemic vascular risk factors (including hypertension, diabetes, age, and migraine) and POAG, based on major epidemiological studies. Reports presenting the association between POAG and systemic vascular risk factors included a total of over 50,000 patients. Several epidemiological studies confirmed the importance of vascular risk factors, particularly hypertension and blood pressure dipping, in the pathogenesis and progression of glaucomatous optic neuropathy. We found that diabetes mellitus is associated with elevated intraocular pressure, but has no clear association with POAG. No significant correlation between migraine and POAG was found, however, the definition of migraine varied between studies.

Introduction: Accurate assessment of the corneal shape is important in cataract and refractive surgery, both in screening of candidates as well as for analyzing postoperative outcomes. Although corneal topography and tomography are widely used, it is common that these technologies are confused. The aim of this study was to present the current developments of these technologies and particularly distinguish between corneal topography and tomography. Methods: The PubMed, Web of Science and Embase databases were the main resources used to investigate the medical literature. The following keywords were used in various combinations: cornea, corneal, topography, tomography, Scheimpflug, Pentacam, optical coherence tomography. Results: Topography is the study of the shape of the corneal surface, while tomography allows a three-dimensional section of the cornea to be presented. Corneal topographers can be divided into large- and small-cone Placido-based devices, as well as devices with color-LEDs. For corneal tomography, scanning slit or Scheimpflug imaging and optical coherence tomography may be employed. In several devices, corneal topography and tomography have been successfully combined with tear-film analysis, aberrometry, optical biometry and anterior/posterior segment optical coherence tomography. Conclusion: There is a wide variety of imaging techniques to obtain corneal power maps. As different technologies are used, it is imperative that doctors involved in corneal surgery understand the science and clinical application of devices for corneal evaluation in depth.

Diabetes mellitus is one of the most prevalent chronic diseases worldwide. Diabetic patients are at risk of developing cataract and present for surgery at an earlier age than non-diabetics. The aim of this study was to review the problems associated with cataract surgery in a diabetic patient. Corneal complications in diabetic patients include delayed wound healing, risk of developing epithelial defects or recurrent erosions due to the impairment of epithelial basement membranes and epithelial–stromal interactions. Diabetic patients present lower endothelial cell density and their endothelium is more susceptible to trauma associated with cataract surgery. A small pupil is common in diabetic patients making cataract surgery technically challenging. Finally diabetic patients have an increased risk for developing postoperative pseudophakic cystoid macular edema, posterior capsule opacification or endophthalmitis. In patients with pre-proliferative or proliferative diabetic retinopathy, diabetic macular edema or iris neovascularization adjunctive therapy such as an intravitreal anti-vascular endothelial growth factor injection, can inhibit exacerbation related to cataract surgery.

Intraocular gases have been used in vitreoretinal surgery for over 40 years. The aim of this study was to review the complications related to the use of expandable gases in vitrectomy and their management. A PubMed, Cochrane Library, and Embase search was conducted using the terms “intraocular gas” and “vitrectomy for retinal detachment.” Of the articles retrieved by this method, all publications in English and abstracts of non-English publications were reviewed. Intraocular pressure elevation was reported in up to 58.9% patients after vitrectomy with expandable gas administration for retinal detachment. Vitreoretinal surgery is known to induce cataract development. With that, cataract progression is associated with lens exposure to intraocular gas, the duration of such exposure, patient’s age, and the magnitude of vitreous removal. With intraocular gas, the posterior surface of the lens becomes a strongly refractive factor, resulting in high myopia and temporary vision impairment. Other complications related to the use of expandable gases include anterior chamber and subconjunctival gas displacement. Single reports on subretinal and cranial gas migration were published. In vitrectomy for uncomplicated retinal detachments, attempts to shift from expandable gases towards air are observed. Nevertheless, gas tamponade remains a reasonable choice for patients suffering from retinal detachment.

Since the introduction, femtosecond laser-assisted cataract surgery was believed to revolutionize cataract surgery. However, the judgment of clinical benefit was found to be far more complex than initially might have been thought. The aim of this review was to analyze the benefits and drawbacks of femtosecond laser-assisted cataract surgery compared with traditional phacoemulsification cataract surgery. PubMed and the Web of Science were used to search the medical literature. The following keywords were searched in various combinations: femtosecond laser, femtosecond laser-assisted cataract surgery, phacoemulsification cataract surgery, FLACS. The benefits of femtosecond laser-assisted cataract surgery include lower cumulated phacoemulsification time and endothelial cell loss, perfect centration of the capsulotomy, and opportunity to perform precise femtosecond-assisted arcuate keratotomy incisions. The major disadvantages of femtosecond laser-assisted cataract surgery are high cost of the laser and the disposables for surgery, femtosecond laser-assisted cataract surgery–specific intraoperative capsular complications, as well as the risk of intraoperative miosis and the learning curve. Femtosecond laser-assisted cataract surgery seems to be beneficial in some groups of patients, that is, with low baseline endothelial cell count, or those planning to receive multifocal intraocular lens. Nevertheless, having considered that the advantages of femtosecond laser-assisted cataract surgery might not be clear in every routine case, it cannot be considered as cost-effective.