Section 3 OCT in Glaucoma

**121**

**Chapter 8**

**Abstract**

**1. Introduction**

**2. Why optic nerve?**

Role of Optical Coherence

Management of Glaucoma

the progression of this sight threatening disease called glaucoma.

tomography, time domain optical coherence tomography

**Keywords:** optical coherence tomography, pre perimetric glaucoma,

ganglion cell complex, retinal nerve fiber layer, spectral domain optical coherence

From the early days until the turn of the twentieth century, glaucoma was defined as "pressure within the eye higher than the statistical normal of the population." It was thought that this rise in pressure caused damage to the optic nerve that was irreversible. It is not until the end of twentieth century, when newer concepts such as the ocular hypertension and the normal tension glaucoma emerged, which led people to challenge this definition [1]. Glaucoma then was redefined by the American Academy of Ophthalmology as an optic neuropathy with characteristic structural damage to optic nerve, associated with progressive retinal ganglion cell death, loss of nerve fibers, and visual field loss. However, the intraocular pressure was considered as the strongest risk factor and possibly the only modifiable one [2].

Optic nerve evaluation is the cornerstone of management of glaucoma. It remains the most crucial step in the early diagnosis of glaucoma and monitoring progressive nerve damage. Stereoscopic changes in the optic nerve head and retinal nerve fiber layer, which are seen clinically, are actually the manifestations of loss

*Baswati Sahoo and Julie Pegu*

Tomography in the Evaluation and

Glaucoma is the leading cause of irreversible, yet preventable, blindness throughout the world. Since it is a disease which can be treated but not cured, it is crucial for the treating ophthalmologist to catch the disease as early as possible. The diagnosis of glaucoma is currently based on the appearance of the optic disc and standard achromatic perimetry. However, to detect glaucoma in its early stages, there are various diagnostic modalities of which optical coherence tomography serves as a novel tool. Optical coherence tomography has emerged over the years with the ability to detect changes in the optic nerve head, retinal nerve fiber layer, and currently the ganglion cell layer much earlier than the defects manifest functionally. Thus, optical coherence tomography acts as an important diagnostic aid to diagnose and monitor
