Technology, Techniques, and Clinical Applications

Taraprasad Das PremNandhini Satgunam Editors

PremNandhini Satgunam

Editors

Technology, Techniques, and Clinical Applications

Editors

Anant Bajaj Retina Institute, Srimati

Kanuri Santhamma Centre for

Vitreoretinal Diseases, Kallam Anji https://doi.org/10.1007/978-981-97-0138-4

Reddy Campus

L V Prasad Eye Institute

Hyderabad, Telangana, India

PremNandhini Satgunam

Brien Holden Institute of Optometry and

Vision Sciences and Prof. Brien Holden

Eye Research Centre

L V Prasad Eye Institute

Hyderabad, Telangana, India

ISBN 978-981-97-0137-7        ISBN 978-981-97-0138-4  (eBook)

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My patients who encouraged me to interpret the test reports in their clinical context.

Several teachers came together to make this book a reality. I dedicate this book to all these teachers, and to the future teachers.

The ocular system is highly intricate, complex and involves not only the globe of the eye itself, but also its neural connections with the brain and surrounding muscular tissue. In order to perceive visual information of the highest quality, all ocular components are required to function harmoni­ ously together. Consequently, examination approaches of the eye are required to meet an equivalent level of sophistication. Several sub-special­ ties have developed within ophthalmology; however, alongside some highly specific examination tools, key underlying examination techniques form the basis for standardized assessments of visual function and delivery of eye care. Thus, to provide an accurate diagnosis, clinicians must be well-versed in the fundamental techniques of ocular examination and be aware of any significant new and upcoming technologies within the field. While technological advancements allow for more detailed imaging and assessment of the eye as well as the opportunity to gain a deeper under­ standing of the underlying pathophysiology of disease states, these also present unique challenges as these additional tools must be integrated into standard practice.

This book, Ophthalmic Diagnostics: Technology, Techniques, and Clinical Applications by Taraprasad Das and PremNandhini Satgunam, contains 35 unique chapters, each contributed by expert authors, covering both basic and clinical aspects of ophthalmic diagnosis, as well as novel and recent investigational techniques. Cumulatively, the contents bring together a valuable collection of skills and techniques for accurately diag­ nosing pathologic conditions. This is a useful reference tool for all profes­ sionals involved in the eye care sector: medical, nursing, optometry, orthoptics, and vision science.

In modern clinical practice, virtually all parts of the eye can be examined from a functional, pathologic, or biometric perspective. These are highly interrelated and synergized; a suite of testing procedures and multimodal imaging techniques is often required to understand the patient thoroughly. Visual acuity has long been the standard parameter to measure visual func­ tion and indicate the presence of ocular pathology; however, visual acuity scores alone often have limited real-world applicability. Contrast sensitivity, visual fields, stereopsis, color vision, and ocular alignment also need to be considered for a broader assessment of the visual function of patients in the real world. Additionally, visual acuity will be significantly influenced by the optical state of the eye, and this requires accurate measures of refraction to be obtained. Aside from its clinical use, information from refraction can be translated into functional benefits for the patient by prescribing and ­dispensing corrective spectacles. While technological advancements tend toward elimi­ nating examiner bias through automated objective measures, examination via retinoscopy remains an invaluable skill, particularly for assessments in remote environments and in children and patients with intellectual disabilities.

To identify pathologies, slit lamp biomicroscopy is the core technique used to observe structures in the anterior segment of the eye. This has founded other viewing techniques, such as gonioscopy and fundoscopy. Since the advent of film and flash photography in the nineteenth century, numerous imaging modalities are now available to document pathologic conditions from the surface of the eye to the retina and optic nerve. Optical coherence tomography (OCT) is the fundamental modern-day imaging device which offers insights into almost every layer and tissue plane of the eye for both practitioners in the clinic and surgeons in the operating room. Further advancements in OCT capabilities have allowed finer segmentation on a cel­ lular level as well as non-invasive visualization of the array of blood vessel networks located between the retina and the choroid. Earlier compromises between imaging speed, resolution, and invasiveness are significantly less apparent, contributing to a more detailed investigation with less patient burden.

On a global scale, cataract formation has been the most significant con­ tributor to blindness, particularly in developed countries. In ophthalmic prac­ tice, cataract assessment is routine and a fundamental surgical indication for ophthalmologists. Biometry with current technologies and optimized lens formulas can now account for complex optics to provide accurate and conve­ nient measurements, minimizing errors across a broad range of eyes. However, ultrasound techniques remain a reliable technique in the clinic to overcome the challenges of dense cataract and ocular media opacity, which hinder standard optical-based measures.

While the identification of ocular diseases and improvement of visual function is often the main intent of conducting ocular examinations, deeper insights can be gained as ocular pathology, alignment, and function can be the manifestations of systemic diseases, including diabetes, trauma, inflamma­ tory and autoimmune conditions, as well as neurological defects. Testing pupillary responses is a core medical skill that assesses the optic nerve and higher neurological function. Electrophysiology has been able to differenti­ ate, diagnose, and understand several rare inherited retinal degenerations using the principles of neuronal activity.

Naturally, the culmination of technological advancements opens the door to future novel applications. Tele-ophthalmology is evolving to become a vital solution for delivering ophthalmic and optometric healthcare to remote areas. The development of smartphone-based ophthalmic imaging is one of the key drivers allowing this to be implemented more efficiently with mini­ mal economic burden; however, it requires a lot of support from healthcare systems.

A wide spectrum of eye care professionals in early and established careers will find this book a most valuable resource in the clinical care of patients.

Medical Director, Sydney Retina Clinic,

Andrew Chang

Sydney, NSW, Australia

Head of Ophthalmology, Sydney Eye Hospital,

Sydney, NSW, Australia

Clinical Associate Professor, Sydney University,

Sydney, NSW, Australia

Conjoint Professor, Discipline of Surgery, UNSW

Sydney, NSW, Australia