RESUMO
Laser-assisted in situ keratomileusis (LASIK) is the most commonly performed laser refractive surgical technique worldwide for the treatment of myopia and myopic astigmatism. In recent years, small incision lenticule extraction (SMILE) has emerged as a promising alternative to LASIK, requiring only a single femtosecond laser to create an intrastromal lenticule, which is then removed via a small incision. The technique obviates the need for a corneal flap. A number of published studies have compared the two techniques in terms of visual, refractive and ocular surface outcomes. This review compares the clinical outcomes between LASIK and SMILE in treating myopia and myopic astigmatism based on studies published in the last 5 years. Twenty-two studies were included, all of which were observational in nature. Results suggest that the two techniques have comparable visual outcomes in terms of safety, efficacy and predictability, although recovery in visual acuity may be slower in SMILE-treated than LASIK-treated eyes. SMILE is found to result in less severe postoperative dry eye symptoms and faster recovery of corneal sensitivity than LASIK. It is important to note, however, that the SMILE technique is limited by the lack of a cyclotorsion-compensation system and option for customized treatment profile. The heterogeneity of results in this review may be attributable to the use of different LASIK platforms in different studies. Few studies compared the outcomes regarding severity of myopia. Future prospective randomized controlled trials with a larger sample size and longer follow-up period will be highly beneficial for progress in this field.
RESUMO
Recent advances in corneal imaging have allowed for more objective diagnosis and disease monitoring, as well as provided valuable guidance for treatment progress. However, there has been limited literature providing comprehensive insight into advances across different imaging modalities. The aim of this review was to provide a brief summary of significant advances in the field of corneal imaging over the past 5 years. A literature search in PubMed was performed on December 11, 2018, using the following key words in various and/or logic combinations: "cornea", "development", "advances", "topography", "Scheimpflug tomography", "ultra-high-speed Scheimpflug", "Corvis ST", "densitometry", "optical coherence tomography", "UHR-OCT", and "intraoperative OCT". The initial search showed a total of 2910 articles. Filters were then applied to select original research studies on humans published in the last 5 years which are available in full text and written in English. A final 55 studies were included for analysis. This review looks into 5 key imaging modalities: topography, tomography, confocal microscopy, densitometry, and angiography. For each imaging modality, the underlying scientific principles and current applications are outlined. Existing limitations and potential future applications for each of them are also discussed in this review. Recent advances in the imaging modalities show immense potential in providing objective, high-resolution, and comprehensive visualization of corneal structures and pathologies. Application to different fields in the future is highly probable but technical, economic, and skill-based limitations must first be overcome. Any attempt to replace traditional imaging techniques with these newer techniques must also be supported with evidence from robust clinical studies.
