Clinical Application of Optical Coherence Tomography in the Corneal Degenerations

Anterior segment optical coherence tomography (AS-OCT) has become an essential tool in the diagnosis and management of corneal degenerations. AS-OCT optical findings and thickness measurements are useful for the proper evaluation of the ocular surface diseases. AS-OCT imaging provides noninvasive information necessary to decide clinical and surgical management. This device helps to achieve a correct pre-intervention investigation and will allow physicians to compare the corneal status after the surgical process. Thus, it is useful to evaluate the corneal thickness, areas of hyper-reflective material, and corneal fibrosis in certain disorders such as Salzmann’s nodular degeneration (SND) and Terrien’s marginal degeneration (TMD), before and following the surgical process

Two cases of accidental dislocation of the silicone sleeve of an extrusion cannula into the vitreous cavity

Background: fluid-air exchange during vitreoretinal surgery is often used as a tool for subretinal fluid endodrainage. Soft-tipped flexible extrusion cannulas are commonly used to aspirate the posterior subretinal fluid. Methods: this is an observational two-case series describing two patients who underwent 20-G pars plana vitrectomy complicated by the accidental fall of the silicone sleeve of a soft-tipped extrusion cannula into the vitreous cavity. In the first case, the cannula had inadvertently been subjected to sterilization process. Results: while withdrawing the soft-tipped extrusion cannula from the eye, following internal drainage of transvitreal and subretinal fluid, the loose silicone sleeve probably got entangled at the inner lip of the sclerotomy and finally fell on the retinal surface. In both cases, the silicone sleeve was held and removed with an intraocular forceps. Conclusions: this rare complication has been reported in the literature only once previously. Sterilization of disposable subretinal fluid cannulas is not advisable because of the risk of dislocation of the silicone sleeve into the eye. Besides this, it is important to check the integrity of the silicone sleeve before and after surgery

Computational simulation of scleral buckling surgery for rhegmatogenous retinal detachment: on the effect of the band size on the myopization

A finite element model (FE) of the eye including cornea, sclera, crystalline lens, and ciliary body was created to analyze the influence of the silicone encircling bandwidth and the tightness degree on the myopia induced by scleral buckling (SB) procedure for rhegmatogenous retinal detachment. Intraocular pressure (IOP) was applied to the reference geometry of the FE model and then SB surgery was simulated with encircling bandwidths of 1, 2, and 2.5 mm. Different levels of tightening and three values of IOP were applied.The anterior segment resulted as unaffected by the surgery. The highest value of Cauchy stress appeared in the surroundings of the implant, whereas no increment of stress was observed either in anterior segment or in the optic nerve head. The initial IOP did not appear to play any role in the induced myopia.The wider the band, the greater the induced myopia: 0.44, 0.88, and 1.07 diopters (D) for the 1, 2, and 2.5mm bandwidth, respectively.Therefore, patients become more myopic with a wider encircling element. The proposed simulations allow determining the effect of the bandwidth or the tightness degree on the axial lengthening, thus predicting the myopic increment caused by the encircling surgery.The authors wish to acknowledge the research support by the Spanish Ministry of Education and Science Research Project DPI2014-54981R, the CIBER initiative, Instituto de Salud Carlos III (ISCIII) Platformfor Biological Tissue Characterization of the Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBERBBN), and the Department of Industry and Innovation (Government of Aragón) through the research group Grant T88 (Fondo Social Europeo)

An Update on Corneal Biomechanics and Architecture in Diabetes

In the last decade, we have witnessed substantial progress in our understanding of corneal biomechanics and architecture. It is well known that diabetes is a systemic metabolic disease that causes chronic progressive damage in the main organs of the human body, including the eyeball. Although the main and most widely recognized ocular effect of diabetes is on the retina, the structure of the cornea (the outermost and transparent tissue of the eye) can also be affected by the poor glycemic control characterizing diabetes. e different corneal structures (epithelium, stroma, and endothelium) are affected by specific complications of diabetes. e development of new noninvasive diagnostic technologies has provided a better understanding of corneal tissue modifications. e objective of this review is to describe the advances in the knowledge of the corneal alterations that diabetes can induc

The Effect of Intraocular Pressure on the Outcome of Myopic Photorefractive Keratectomy: A Numerical Approach

Photorefractive Keratectomy (PRK) is a surgical procedure widely performed to correct myopia. In this work, the effect of the intraocular pressure (IOP) on the refractive correction achieved by the PRK surgery was analyzed using a numerical model. Simulations of PRK surgery at 10, 15 and 21 mmHg of IOP were performed and the post-surgical diopters were estimated. For low and medium values of IOP (10 and 15 mmHg), the computed results were close to those used by clinicians based on experience and defined without considering the IOP, while an undercorrection was predicted for the highest value of IOP (21 mmHg). From these results, we suggest that IOP should be considered in the determination of the depth of ablation, in addition to other factors such as the level of myopia or the corneal central thickness

Two Cases of Accidental Dislocation of the Silicone Sleeve of an Extrusion Cannula into the Vitreous Cavity

Background: Fluid-air exchange during vitreoretinal surgery is often used as a tool for subretinal fluid endodrainage. Soft-tipped flexible extrusion cannulas are commonly used to aspirate the posterior subretinal fluid. Methods: This is an observational two-case series describing two patients who underwent 20-G pars plana vitrectomy complicated by the accidental fall of the silicone sleeve of a soft-tipped extrusion cannula into the vitreous cavity. In the first case, the cannula had inadvertently been subjected to sterilization process. Results: While withdrawing the soft-tipped extrusion cannula from the eye, following internal drainage of transvitreal and subretinal fluid, the loose silicone sleeve probably got entangled at the inner lip of the sclerotomy and finally fell on the retinal surface. In both cases, the silicone sleeve was held and removed with an intraocular forceps. Conclusions: This rare complication has been reported in the literature only once previously. Sterilization of disposable subretinal fluid cannulas is not advisable because of the risk of dislocation of the silicone sleeve into the eye. Besides this, it is important to check the integrity of the silicone sleeve before and after surgery