The advent of integrated intraoperative optical coherence tomography (i2OCT) has opened the door for safer and more complex surgeries in the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in pediatric cataract surgery in circumstances that are not traditionally considered for i2OCT use. The specific circumstances include: evaluation and treatment of a child following cataract extraction with lens implantation who has failed two attempts at YAG capsulotomy; lysis of post-trauma keratolenticular adhesion in an opaque cornea; surgical removal of secondary lens epithelial cell proliferation after pediatric cataract extraction with lens implantation, and identification of posterior capsular openings and defects. In each case the use of i2OCT allowed the procedure to be completed safely and successfully or informed the surgeon, allowing modification of the surgical decision tree.
The advent of integrated intraoperative optical coherence tomography (i2OCT) has opened the door for safer and more complex surgeries in the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in pediatric glaucoma surgery. It can be used to identify Schlemm's canal, Barkan's membrane, demonstrate the corneal pathology in Haab's striae, and iris hypoplasia in cases of Axenfeld-Rieger anomaly. It can help identify drainage blebs that are filtering and those that are not, and identify successful drainage tube flushing. It has also been used to identify a ligating suture effect on a drainage tube. We describe these scenarios in relation to training and augmenting surgical techniques.
The relationship between the anterior vitreous interface and the posterior capsule has received increasing attention in the past decade. The advent of integrated intraoperative optical coherence tomography has allowed a real-time opportunity to grasp this dynamic understanding. Here we describe the normal anatomy of this interface in children and then demonstrate the variation in this interface with different forms of pediatric cataract, namely a posterior plaque and posterior capsular opacity due to abnormal adherence to the vitreous face. The authors describe these changes using meticulous annotation. An understanding of these differences will aid the surgeon in managing pediatric cataracts in a more confident and safe manner.
The advent of integrated intraoperative ocular coherence tomography (i2OCT) has opened the door for safer more complex surgeries of the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in strabismus surgery. It can be used to identify extraocular muscles, especially in cases of strabismus reoperations, thereby augmenting the surgical technique. Its use to help train strabismus surgery is invaluable, allowing the trainee to understand the depth of the scleral pass during strabismus surgery. The authors describe these scenarios of training and augmenting the surgical technique.
The advent of integrated intraoperative optical coherence tomography (i2OCT) has opened the door for safer and more complex surgeries in the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in oculoplastic surgery. It can be used in cases of severe symblepharon where the cornea is heavily involved, so that the surgeon is aware of the depth of the pannus when trying to remove it. It can also be used when the corneal planes are difficult to identify. In oculoplastic surgery the technology allows for identification of tissue planes when en face visualization is difficult due to developmental abnormalities and repeated surgeries. Our experience reflects some of the many uses of iOCT in ophthalmic surgery, highlighting its added value in surgical precision.
This chapter describes the development of the infant in the seventh month of life. Now that her son is beginning to sit up on his own, he has begun to notice and watch screens whenever they are in use around him. Revisiting her initial promise to herself to keep her child away from screens for the first 2 years of life, the author reviews research on whether it is harmful for babies to look at screens and whether infants and young children can learn from these media. She concludes with some practical recommendations based on the research she reviews for deciding how much screen time is too much.
Drug delivery into the posterior segment of the eye is complicated by the existence of the blood-ocular barrier. Strategies for delivering drugs to the posterior segment include systemic administration, modification of the barrier, and local drug delivery (including transcorneal, transscleral, and intravitreal). The most commonly used method for drug delivery into the posterior segment is by intravitreal injection. Other routes that can be used to achieve therapeutic drug levels in the posterior segment include topical, iontophoretic, and juxtascleral delivery. Extended-release intravitreal drug delivery systems can achieve sustained therapeutic levels with the goal of providing a prolonged clinical benefit with significantly fewer interventions.
The coexistence of cataract and glaucoma represents a challenge for the ophthalmologist and the issue is still open to debate. The surgical management is based on both the visual field defect and the loss of visual acuity. The surgical options currently available are: (1) cataract extraction alone, (2) sequential glaucoma surgery and cataract extraction, and (3) combined surgery by 1 site or by 2 separate sites. Phacoemulsification alone is suggested when glaucoma can be controlled by medication and the visual field defect is moderate and nonprogressive. In case of a refractory glaucoma (3 or more types of medication required) with associated early-stage cataract, phacoemulsification could be postponed until after glaucoma surgery. The cataractogenous effect of the procedure should be considered in this situation. Moreover, cataract extraction performed after a filtering surgery may lead to a reduction of the bleb function. When both glaucoma and cataract are sight impairing, combined surgery is indicated since it allows a greater intraocular pressure decrease than phacoemulsification alone.
Blood-retinal barrier breakdown with macular edema is caused by many diseases, which modulate--via different growth factors--the integrity of the tight junctions. Starling's law predicts furthermore that macular edema will develop if the hydrostatic pressure gradient between capillary and retinal tissue is increased, for example in the presence of elevated blood pressure, or if the osmotic pressure gradient is decreased, for example when protein accumulates excessively in the extracellular space within the retina. The rationale for clinical treatment of macular edema is based on the understanding and the inhibition of these pathophysiological mechanisms. On the medical side, nonsteroidal anti-inflammatory drugs inhibit the production of prostaglandins and leukotrienes, and modulate fluid movement coupled to chloride movement. Corticosteroids block cyclooxygenase and interleukin, downregulate vascular endothelial growth factor (VEGF) and decrease the phosphorylation of occludin, thereby increasing the tightness of the blood-retinal barrier. Carbonic anhydrase inhibitors are thought to modulate the polarized distribution of carbonic anhydrase at the level of the retinal pigment epithelium via extracellular pH gradients and thus the fluid resorption from the retina into the choroid. Anti-VEGF agents restore occludin proteins in the blood-retinal barrier and reduce protein kinase C activation. On the surgical side, the beneficial effect of vitrectomy with release of traction on the macula is explained by an increase in tissue pressure and a lowering of the hydrostatic pressure gradient, reducing the water flux from blood vessels into retinal tissue. The therapeutic action of vitrectomy in nontractional edema is thought to be based on two mechanisms: increased oxygen transport between the anterior and posterior segments of the eye and the removal of growth factors which are secreted in large amounts into the vitreous during proliferative vasculopathies.
Trabeculectomy with anti-fibrotic treatment is still the most popular incisional procedure for glaucoma filtration surgery (GFS) worldwide. The advent of anti-fibrotic agents reduced failure due to scarring but resulted in increased complications. Advances in trabeculectomy surgery have been driven by the need to minimise the risk of: (1) complications and (2) surgical failure. This chapter covers preoperative, intraoperative and postoperative strategies, which improve the outcome of GFS. Strategies to reduce the risk of complications centre on the prevention of postoperative hypotony by minimising the risk of overdrainage, postoperative wound leaks and poor bleb morphology. Surgical techniques to reduce the risk of postoperative fibrosis by the use of anti-fibrotic agents (including mitomycin C) are discussed in detail. These techniques are based on a combination of considerable clinical experience, observation and laboratory research. The need to address pre-, intra- and postoperative issues in each individual patient is emphasised. These changes are embodied in the system we call the 'Moorfields Safer Surgery System'. The use of these strategies has considerably reduced the incidence of major complications including hypotony, cystic blebs and endophthalmitis in practices around the world. Most of these techniques are simple, require minimal equipment and can be easily mastered. They are associated with an improvement in overall outcome and it is hoped that this chapter will help the reader benefit from these advances.
Vitreomacular traction (VMT) is one of many possible factors involved in the etiology of diabetic macular edema (DME). Pharmacologic vitreoretinal separation is a potential alternative to vitrectomy for VMT in diabetic retinopathy. Small case series have been published on the use of enzymatic vitreolysis in tractional DME, and demonstrate that the enzymatic release of the posterior vitreous cortex is more likely following the injection of plasmin enzyme. Further prospective and randomized clinical trials are necessary to evaluate the clinical relevance of ocriplasmin for vitreomacular traction in diabetic retinopathy, and additional studies are needed to determine more accurately which patients might benefit most from this treatment and how often and at what concentration ocriplasmin should be administered.
Technical advancements have substantially extended the indications for surgery in diabetic retinopathy (DR) during the last 40 years, from the traditional indications including non-clearing vitreous hemorrhage, traction retinal detachment (RD), and traction-rhegmatogenous RD, to epiretinal membrane (ERM), vitreomacular traction, diffuse macular edema, neovascular glaucoma, and anterior hyaloid fibrovascular proliferation. The goals of vitreoretinal surgery in DR are multiple: clearing media opacities, release of traction (anteroposterior and/or tangential), segmentation and/or removal of traction bands, peeling of ERMs, hemostasis, laser photocoagulation, and tamponade of retinal breaks with gas or silicone oil. The best management is achieved with integrated care provided by physicians with expertise in medical management of diabetes and surgical care of DR. In this chapter, the indications for surgery, preoperative considerations, surgical techniques, and complications, together with their management, will be discussed.
Macular edema is the swelling of the central portion of the human retina and it is associated with increased retinal thickness. It can be simply defined as an excess of fluid within the retinal tissue. It must be realized that the normal retina possesses a functional extracellular space. With regard to the extracellular volume of the retina, there have been few physiologic studies, but there are reported values of 24.8% for the cerebrum and 23.6% for the cerebellum. It is accepted that the retinal extracellular space is similar to the brain. It is generally agreed that the proximate cause of macular edema and retinal fluid accumulation is a breakdown of the blood-retinal barrier (BRB). When there is a breakdown of the BRB, retinal edema can be interpreted in terms of basic principles of capillary filtration (Starling's law). Therefore, the main factors influencing retinal edema formation are BRB permeability, capillary hydrostatic pressure, tissue hydrostatic pressure, tissue osmotic pressure, and plasma osmotic pressure. Active transport by the retinal pigment epithelium is necessary to remove water that percolates through the retina from intraocular pressure and is also as a safety mechanism against fluid accumulation in disease. Clinical evaluation of the BRB and retinal edema can be performed noninvasively by using an OCT-based method designated OCT-Leakage, which is capable of identifying and quantifying sites of alteration of the BRB, and by mapping sites of low optical reflectivity, i.e., changes in the retinal extracellular fluid.
Mini glaucoma devices for external filtration may be implanted with an ab externo procedure (Ex-PRESS and InnFocus Microshunt) or with an ab interno procedure (XEN Gel stent). The Ex-PRESS is an FDA-approved mini glaucoma device that has been developed in order to simplify anterior guarded filtering procedures, making them faster, safer and easier. It is positioned under a scleral flap and it is introduced in the anterior chamber through a needle hole, avoiding the excision of the corneal-scleral button and the iridectomy. Like other anterior filtering guarded procedures, it may be associated with releasable sutures and with an everting suture (the safe Ex-PRESS procedure) in order to increase safety and efficacy. The InnFocus Microshunt is a new ab externo filtering device currently under investigation; it is very easy to implant and highly promising in terms of safety and efficacy. The XEN Gel stent is an ab interno implanted soft, collagen tube that makes a permanent bypass between the anterior chamber and the subconjunctival space. It is a smart, quick, effective and simple procedure that recently gained FDA approval.
This chapter provides the reader with practical information to be applied to the various remaining causes of macular edema. Some clinical cases of macular edema linked to ocular diseases like postradiotherapy for ocular melanomas remained of poor functional prognosis due to the primary disease. On the contrary, macular edema occurring after retinal detachment or after diverse systemic or local treatment use is often temporary. Macular edema associated with epiretinal membranes or vitreomacular traction is the main cause of poor functional recovery. In other cases, as in tractional myopic vitreoschisis, the delay to observe a significant improvement of the vision after surgery should be long. Finally, macular edema associated with hemangiomas or macroaneurysms should be treated, if symptomatic, using the same current treatment as in diabetic macular edema or exudative macular degeneration. The miscellaneous chapter is always a challenging one, laden with two serious caveats: being too exhaustive or forgetting common circumstances. The author has attempted to provide the reader with useful, practical information that can be applied to the various causes of macular edema.
The macula is predisposed to edema in various retinal conditions, even when the insult is remote from the macula. The various factors that may predispose the macula to edema include high metabolic activity, radial arrangement of the Henle's layer, lack of inner layers at the fovea, and lack of blood supply at the fovea. The edema is most pronounced in the outer plexiform layer (Henle's layer). Alteration in the blood-retinal barrier and ischemia cause disturbances in vascular permeability as well as with the function of Müller cells. K+ ions and aquaporin-4 play an important role in maintaining the dryness of the macula in physiological conditions. Intracellular edema of Müller cells contributes significantly to macular edema. Steroids and anti-VEGF agents reduce intracellular edema, apart from extracellular edema. Therapeutic targets for improving Müller cell function could play a key role in the development of new molecules.
Diabetic retinopathy (DR), a major microvascular complication of diabetes, has a significant impact on the world's health systems. Globally, the number of people with DR will grow from 126.6 million in 2010 to 191.0 million by 2030, and it is estimated that the number with vision-threatening diabetic retinopathy will increase from 37.3 million to 56.3 million if prompt action is not taken. Lack of early diagnosis and management is the leading cause of blindness in working-age populations The gap between demand and annual eye examinations has been a big challenge. Furthermore lack of availability of cost effective simplified retinal imaging tools has limited the diabetic retinopathy screening program in many parts of the world in last few decades. This has led to the development of innovative ideas and availability of cost effective simplified retinal imaging tools. In this chapter we will be describing some of the well known commercially available emerging simplified (Non Tabletop, Hand Held, Portable) retinal imaging tools that have potential to help in screening diabetic retinopathy with ease and without increasing financial burden.
