The routine tests required for examination of the ophthalmic patients include recording of visual acuity, color vision and color defects, slit-lamp examination, tonometry, gonioscopy, optic disc assessment, ophthalmoscopy, and perimetry. In the present edition, the chapter on perimetry is updated and both Octopus and Humphrey perimetry are described.

Fundus fluorescence angiography and Indocyanine green angiography are invaluable tools in the diagnosis, documentation and follow-up of chorioretinal disorders. Both types of angiography help in monitoring treatment of the macular diseases. A-scan and B-scan ultrasonography are well-established and essential procedures. A-scan is largely used for biometry and supplementing findings of B-scan. Three-dimensional ultrasound tomography has improved visualization of the posterior segment pathology. It can measure the volume, surface and boundaries of the intraocular tumors. Ultrasound biomicroscopy (UBM) can imagine the anatomy and pathology of the anterior segment of the eye both qualitatively and quantitatively. The images are helpful in understanding the mechanism of different types of glaucoma and identifying lesions of the ciliary body.

Confocal microscopy is an advanced imaging technology that facilitates examination of microstructure of the cornea for identifying diseases like keratoconus, corneal dystrophies and corneal degeneration. Corneal topography is a useful tool for the diagnosis of corneal curvature pathologies. However, it is more often applied in planning appropriate refractive surgery.

Separate chapters have been devoted for the diagnosis of infective keratitis, uveitis, retinopathy of prematurity, localization of intraocular foreign body, concomitant and incomitant strabismus, dry eye disease, epiphora and proptosis.

Like other branches of medicine, ophthalmology is an ever-expanding discipline. With inroads of technology, new diagnostic tools have been introduced in the ophthalmology. New chapters based on recent development include Imaging in Glaucoma, Spectrum Domain Optical Coherence Topography, Anterior Segment Optic Coherence Topography, Pentacam, and IOL Power Calculation. Additionally, Diagnostic Procedures for Genetically Transmitted Eye Diseases, Diagnostic Modalities of Intraocular Malignancies, Ptosis Evaluation, and Ocular Motor Nerve Palsies have been included.

Optic coherence tomography (OCT) has emerged to the forefront of ocular imaging as it can measure the thickness of retina, RNFL, optic cup depth and can produce the maps of internal limiting membrane and retinal pigment epithelium. It has significant utility in the diagnosis of glaucoma and retinal diseases. Earlier, time domain OCT was used in ophthalmic clinics. It is now being replaced by the Spectrum domain OCT because it provides a superior image quality with larger field and reduced motion artifacts, faster acquisition of images and higher detection rate of ocular disorders.

Pentacam and anterior segment optical coherence tomography (ASOCT) are used for imaging of cornea and anterior chamber. Pentacam can produce anterior and posterior corneal curvature maps and diagnose forme fruste keratoconus. It measures corneal power and thus guides in refractive surgery. It can assess grades of cataract and IOL power and facilitates refractive cataract surgery.

Anterior segment optical coherence tomography (ASOCT) is a relatively new modality to directly visualize cornea, anterior chamber and measures anterior chamber depth, angle width, and can imagine scleral spur, ciliary body, ciliary sulcus and canal of Schlemm. Application of ASOCT has improved the results of refractive surgery, phakic IOL implantation, and glaucoma surgery.

With the completion of Human Genome Project in 2003, data, devices and molecular techniques have progressed remarkably. It has been reported that out of 4,000 genetic disorders, about one-third are ocular diseases. Cytogenetics provides the broad overview of genetic landscapes. It detects abnormalities in the number, and structure of chromosomes. Several methods for detection of mutation of genes are comprehensively described in the chapter on Diagnostic Procedures for Genetically Transmitted Eye Diseases. Early diagnosis of gene defect is likely to open possibilities of the gene therapy in some ophthalmic disorders.

Three chapters—Electrophysiological Tests for Visual Function Assessment, Pupil and Ocular Nerve Palsies included in this edition of the book are likely to assist readers in the diagnosis of neuro-ophthalmic problems. Electrophysiological tests can assess the functional integrity of visual pathway. They not only help in detecting the cause of visual loss but also the site 12of the lesion. A detailed chapter has been devoted to cover the EOG, ERG, Pattern ERG, Multifocal ERG, VEP and Multifocal VEP, and their utility in the diagnosis of neurological and retinal disorders and drug toxicity. Similarly, testing of ocular motor nerves may localize lesions of the central nervous system. Proper examination of pupil and its reflexes cannot be overemphasized as they reveal a wealth of information on the diseases of the nervous system.

Newer investigative procedures in ophthalmology have revolutionized the diagnosis of the eye diseases. The early diagnosis is a key to early treatment, better prognosis and ultimate improved quality of the life of the eye patients. We hope that residents and ophthalmic practitioners will continue to find the 3rd edition of the book more useful in the investigations of eye patients in their clinical practices.

The main aim of the book—Diagnostic Procedures in Ophthalmology is to provide useful information on diagnostic tests, which an ophthalmologist intends to perform or order during his clinical practice. Some of the procedures described in the book, assessment of visual acuity, slit-lamp examination, tonometry, gonioscopy, perimetry, and ophthalmoscopy, are routine examinations. However, the technique of proper examination and interpretation of findings to arrive at a correct diagnosis must be known to the practicing ophthalmologist or optometrist.

Procedures such as ophthalmic photography, evaluation of optic nerve head, fundus fluorescein angiography, and indocyanine green angiography are invaluable because they not only help in the diagnosis and documentation but also help in monitoring the management of eye disease. Corneal topography gives useful data about corneal surface and curvature and contributes to the success of Lasik surgery to a great extent. The role of A-scan ultrasonography in the measurement of axial length of the eye and biometry cannot be overemphasized. B-scan ultrasonography is needed to explore the posterior segment of the eye when media are opaque or an orbital mass is suspected. Ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT) are relatively new noninvasive tools to screen the eye at the microscopic level. UBM helps in understanding the pathogenesis of various forms of glaucoma and their management. OCT obtains a tomograph of the retina showing its microstructure incredibly similar to a histological section. It helps in the diagnosis and management of the macular and retinal diseases. Electrophysiological tests allow objective evaluation of visual system. They are used in determination of visual acuity in infants and in the diagnosis of the macular and optic nerve disorders. What diagnostic tests should be ordered in the evaluation of the patients with infective keratitis or uveitis? Chapters on Diagnostic Procedures in Infective Keratitis and Diagnostic Procedures in Uveitis provide an answer.

The experts who have credibility in their fields have contributed chapters to the book. Not only the procedures of diagnostic tests are described but to make the reader conversant, characteristic findings in the normal and the diseased eye are also highlighted with the help of illustrations.

The book should be of great help to the practicing ophthalmologists, resident ophthal-mologists, optometrists and technicians as it provides instant access to the diagnostic procedures in ophthalmology.

We are indebted to all contributors for their excellent contributions in short time in spite of their busy schedule. Mr JP Vij deserves our sincere thanks for nice publication of the book.

Our special appreciation goes to Dr R Ramakrisnan, Dr P Vijayalakshmi, Dr Rajul Parikh, Dr S Honavar, Dr Jayamuruga Pandian and Dr Rajeev Pappuru for submitting their write-up on a short notice and enabling us to maintain the schedule of publication.

Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Managing Director) and Mr Tarun Duneja (Director Publishing) of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, deserve our sincere thanks for their cooperation and meticulous publication of the third edition of the Diagnostic Procedures in Ophthalmology.