Preface

Imagination is the key to any discovery, and its presence in science to improve eyesight is no exception. The eyes are our windows to the brain and vision is the ability to interpret and understand the information that comes in through the eyes. The visual system utilizes brain pathways to process and understand what the eyes sense. The dynamic process of vision is to identify, interpret, and understand what the eyes see. An image is a sight that has been recreated and an appearance detached from the place and time in which it first appeared.

Blindness is an important symptom of many eye disorders. The estimated global cost of vision loss today is US\$3 trillion. Science and research have always been crucial to furthering our understanding of ophthalmic conditions and their treatment and prevention. Ophthalmology research has resulted in major advancements in medical science and ophthalmic practice. Discoveries made in various fields including genetics, immunology, and ocular biology have reshaped the foundations of ophthalmology and formed many new paradigms for the repair, regeneration, and rehabilitation of countless disorders. Scientific achievements in ophthalmology have produced fundamental insights and opened up possibilities for improving human health. A major challenge for the next decade will be to translate these advances into identifying the design and testing of novel approaches for disease treatments.

This book provides readers with a comprehensive overview of the latest and most advanced findings in several aspects of ophthalmic pathology, treatment, and surgical strategies, as well as in vision sciences and perception. Chapters cover such topics as acute hydrops, cataract treatments, keratoconus, surgical/non-surgical treatments in vision rehabilitation, and geometric analysis of ophthalmic lens. I thank all the contributors for their kind efforts in the preparation of this book.

> **Alireza Ziaei, MD** Harvard Medical School BCH, Boston, USA

**Michele Lanza** University of Campania "Luigi Vanvitelli", Italy

**1**

**Chapter 1**

**Abstract**

ocular allergy

**1. Introduction**

**1.1 Epidemiology**

according to an American study [5].

Management

Acute Hydrops and Its

*Praveen Subudhi, Sweta Patro and Nageswar Rao Subudhi*

early identification of progressive keratoconus and halting its progression.

**Keywords:** acute hydrops, keratoconus, compressive sutures, intracameral gas,

Acute hydrops is a well-known complication of progressive keratoconus. It has also been reported in other noninflammatory ectatic disorders such as pellucid marginal degeneration and keratoglobus. The incidence of acute hydrops is minimal but varies according to race. A 2011 UK census reported higher number of cases among the South Asian and Black ethnic groups, compared with that in the general population. The reported incidence rates among the white, South Asian, and black population are 0.07/100,000, 0.32 /100,000, and 0.37/100,000, respectively [1]. According to numerous studies, the trend in acute hydrops Incidence among patients with keratoconus has been shown to be decreasing; Tuft et al. and Amsler M et al. reported the prevalence of acute hydrops as 2.6% and 2.8%, respectively [2, 3]. Acute hydrops can occur at any age but is commonly reported in individuals aged between 20 and 30 years, whereas the broad age range is 10 to 47 years. It has a significant gender disparity; men are more susceptible to this condition compared with women, with a ratio of 1.2:1 according to the Auckland Keratoconus Study [4], 3:1 according to a UK prospective study [1], and 2.9:1

Acute hydrops is a well-known complication of keratoconus. It usually manifests as sudden onset loss of vision. Mostly presents in the pubertal age group. Allergic conjunctivitis associated with eye rubbing is the most substantial risk factor. Primary pathology being stromal lysis, which triggers the progression of cone, causing an undue stretch on Descemet Membrane, eventually resulting in its splitting and stromal imbibition of aqueous through these ruptures. Clinical signs are circumcillary congestion and thick/edematous cornea with obscuration of the anterior segment. Conservative therapy delays wound healing; hence early surgical intervention is recommended globally for faster resolution of stromal edema. Long-standing corneal edema mounts to corneal perforation and neovascularisation of cornea. Compressive suture, non expansile intracameral gas injection, Deep anterior lamellar keratoplasty, and mini Descemet membrane keratoplasty are various management modalities reported in literature. Acute hydrops could be well prevented with
