To view this page ensure that Adobe Flash Player version 11.1.0 or greater is installed.
Pearls for Correct Assessment of Optic
Disc at Glaucoma Diagnosis
Department of Ophthalmology, Faculty of Medicine, Yuksek Ihtisas University, Ankara, Turkey
T he correct evaluation of the optic disc, and related structures in ophthalmoscopy, is critical for the diagnosis of open angle glaucoma
because usually glaucomatous optic nerve damage firstly occurs in the optic disc before detectable visual field defects become apparent;
however, some studies have demonstrated that visual field defects can also be found without any glaucomatous changes in the optic disc.
The purpose of this review is to provide a guide to clinicians for the evaluation of the optic disc in glaucoma suspects and patients. This guide can
facilitate the diagnosis and exclusion of glaucoma in these subjects.
Keywords Glaucoma, diagnosis, optic nerve head, optic
disc, correct evaluation
Disclosure: Burak Turgut has nothing to declare in
relation to this article. No funding was received in the
publication of this article.
Compliance with Ethics: This study involves a review of
the literature and did not involve any studies with human
or animal subjects performed by any of the authors.
Authorship: All named authors meet the International
Committee of Medical Journal Editors (ICMJE) criteria
for authorship of this manuscript, take responsibility
for the integrity of the work as a whole, and have
given final approval to the version to be published.
Open Access: This article is published under the Creative
Commons Attribution Noncommercial License, which
permits any non-commercial use, distribution, adaptation
and reproduction provided the original author(s) and
source are given appropriate credit.
Received: 21 April 2017
Accepted: 21 August 2017
Citation: US Ophthalmic Review, 2017;10(2):104–10
Corresponding Author: Burak Turgut, Yuksek Ihtisas
University, Faculty of Medicine, Department of
Ophthalmology, Street 1377, No.21, 06520, Ankara, Turkey.
The optic nerve head (ONH) is the region where retinal ganglion cells (RGCs) leave the eyeball via the
scleral canal. It also consists of blood vessels, glial, and connective tissue. Glaucoma is a progressive
optic neuropathy characterized by the loss of retinal nerve fibres and the axons of RGCs at the level
of the ONH. The primary site for glaucomatous damage is the ONH. 1–3 Although the ONH and the optic
disc are often used to mean the same thing, in fact the optic disc is the part of the ONH which is
observed in ophthalmoscopy. Although there are no clear lines demarcating the histologic layers of
ONH, the ONH consists of the surface retinal nerve fibre layer (RNFL), and pre-laminar, laminar (lamina
cribrosa [LC]), and retrolaminar layers. 1–6 Therefore, we actually observe the superficial RNFL and the
optic cup in the ONH.
Glaucomatous optic nerve damage usually occurs in the ONH before there are any detectable
visual field (VF) defects; however, some studies have demonstrated that VF defects can also be
found without any glaucomatous changes in the optic disc. 7–9 It is understood that glaucomatous
VF defects can be detected on standard automated perimetry when 20–40% of RGCs are lost. 10,11
Thus, the correct and careful evaluation of the optic disc and tissues immediately surrounding
the disc are very important for detecting early glaucomatous damage. However, firstly it is crucial
to know what the features and appearance of a healthy optic disc should be. In the examination
of the ONH, the size and shape of the optic disc should be correctly evaluated, as should:
• the size, color, and integrity of the neuroretinal rim (NRR);
the size and shape of the optic cup;
the cup-to-disc ratio (CDR);
the shape and configuration of the vessels in the ONH;
the presence of the laminar dot sign in the cup;
the changes in peripapillary region (ONH hemorrhages, peripapillary atrophy [PPA]); and
the loss of lines belong to RNFL in red-free illumination (Figures 1A and B, and 2A–F). 1–6,12
The main techniques for clinical examination of the ONH include direct ophthalmoscopy, indirect
ophthalmoscopy, and slit-lamp biomicroscopy with a contact lens or non-contact handheld lens
(+66, +78, +90 diopter [D]) or a Hruby lens. The use of a slit lamp with a handheld lens is the
preferred method because it provides good stereopsis and magnification for the physician and also
convenience for the patient. 13–19
Although retinal tomography and optical coherence tomography (OCT) are useful methods to perform
some measurements such as optic disc diameter, CDR, NRR thickness and optic disc area, direct
evaluation of the optic disc by the physician is necessary.
104 TOUCH ME D ICA L ME D IA