When evaluating a patient who has been diagnosed with glaucoma, it’s important to perform a thorough evaluation of the optic nerve in order to monitor for progression of the disease. Evaluating for glaucoma starts by evaluating the cup to disk (C/D) ratio.
Full Answer
How does glaucoma affect the Cup to disc ratio?
Glaucoma increases the cup to disc ratio (CDR), affecting the peripheral vision loss. This paper addresses the various image processing techniques to diagnose the glaucoma based on the CDR evaluation of preprocessed fundus images.
What is a good C/D ratio for glaucoma?
There is not a specific C/D ratio that is diagnostic of glaucoma. However, a general rule of thumb is that ~0.6 or greater is suspicious. Only about 5% of individuals without glaucoma have a C/D ratio of >0.6. You also need to consider this in context of the overall size of the optic nerve.
How do you evaluate for glaucoma?
Evaluating for glaucoma starts by evaluating the cup to disk (C/D) ratio. However, this single measurement can be misleading if it’s not considered in relation to other features such as overall disc size, location of disc thinning, changes in the vasculature, color changes, peripapillary atrophy, and asymmetry between eyes.
What is the pathophysiology of glaucomatous cupping?
As glaucomatous cupping occurs, the blood vessels appear to shift nasally due to loss of the neuroretinal rim.
How do you evaluate cup to disc ratio?
2:085:27Cup-to-disc ratio: getting it right | OT Skills Guide - YouTubeYouTubeStart of suggested clipEnd of suggested clipNerve you can get an approximate measurement of the disc and cup using a slit lamp by a microscope.MoreNerve you can get an approximate measurement of the disc and cup using a slit lamp by a microscope.
How is glaucoma progression measured?
Loss of retinal nerve fiber layer can be observed in red-free photos and is quantified with OCT. The peripapillary RNFL thickness is by far the most popular OCT parameter used for glaucoma diagnosis and monitoring progression.
What is cup to disc ratio in glaucoma?
A C/D ratio between 0.4 and 0.8 can characterize a patient with a normal optic disc (i.e., physiologic cupping), a glaucoma suspect or someone with early to moderate glaucoma (depending on the optic disc size); If the C/D ratio is 0.8 or greater, consider the individual's disc as glaucomatous unless proven otherwise.
What is normal optic disc cupping?
As the rims become thinner, you will see cupping of the disc – an increased cup to disc (C/D) ratio. There is not a specific C/D ratio that is diagnostic of glaucoma. However, a general rule of thumb is that ~0.6 or greater is suspicious. Only about 5% of individuals without glaucoma have a C/D ratio of >0.6.
How do you read the OCT disk?
5:0617:21how to read an OCT report of glaucoma ? - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd the numbers are displayed here in hours or in sectors. And the same clue. If it's one percent ofMoreAnd the numbers are displayed here in hours or in sectors. And the same clue. If it's one percent of the population. It will be red if it occurs at five percent it will be yellow.
What rates of glaucoma progression are clinically significant?
The reported proportion of glaucomatous eyes progressing at faster than -1.5 dB/year have varied from 3 to 17% in some previous studies [16, 17, 19, 20, 30-35], while others found that 15-20% of eyes seem to progress at rates of VFI loss greater than 5% per year [21, 36].
What is vertical cup disc ratio?
The vertical cup to disc ratio (VCDR) is a simple, robust indicator of glaucomatous loss of the neuroretinal rim1 Unlike other measures of optic nerve morphology, such as rim area, clinical estimations of the VCDR are commonly made by most ophthalmologists and do not require multiple measurements or additional imaging ...
Does cup-to-disc ratio increase with age?
Vertical optic cup diameter and optic cup area increased with age. The mean cup/disc diameter ratio increased by about 0.1 between the ages of 30 and 70 years.
What does cupping mean in an eye exam?
The term cupping of the optic nerve describes the appearance of the optic nerve to the examining eye doctor. When the nerve is viewed through the pupil, it looks like a cup seen from above. The cup is really an empty space in the middle of the optic nerve surrounded by optic nerve fibers.
What does a small cup-to-disc ratio mean?
Abstract. Background: A small cup-to-disc (C:D) ratio is an established risk factor for nonarteritic anterior ischemic optic neuropathy. We sought to determine if a small C:D. ratio was present in patients with idiopathic intracranial hypertension (IIH) as a potential risk factor for visual loss in that disorder.
What is cup to disc asymmetry?
Abstract: : Cup to disc asymmetry is considered a characteristic risk factor in the diagnosis of primary open angle glaucoma.
Does optic nerve cupping always mean glaucoma?
Up to 20% of nonglaucomatous cupping has been misdiagnosed and treated as glaucoma. Young age, pallor of the disc, loss of visual acuity and color vision, and a poor correlation between optic nerve and visual field findings are suggestive of a condition other than glaucoma.
Lag Time Conundrum
Before OCT, ophthalmologists could make only a general estimate of glaucoma progression based on the appearance of the optic nerve, Dr. Asrani said. “We were looking for cupping that increases with loss of the retinal nerve fiber layer [RNFL]. With OCT, however, we can measure ganglion cell loss and RNFL thinning.”
Pearls for OCT Use
Dr. Asrani: OCT is difficult to interpret in high myopes (greater than –8 or –9 D) because the structures of the retina do not conform to the normative database.
OCT in Clinical Practice
When to image? Any type of structural assessment requires several tests in a short period of time to establish a baseline, Dr. Mansberger said. With OCT, you need 5 to 8 scans, depending on the frequency of imaging, slope of loss, and variability of results.
New Anatomical Insights
Perhaps a new paradigm proposed by Balwantray C. Chauhan, PhD, and Claude F. Burgoyne, MD, will help to increase diagnostic accuracy. 5 Using SD-OCT, they found that what the clinician interprets as the disc margin using conventional assessment methods doesn’t correspond to the anatomy.
Meet the Experts
BALWANTRAY C. CHAUHAN, PHD Professor of ophthalmology and research director at the Department of Ophthalmology and Visual Sciences at Dalhousie University in Halifax, Nova Scotia. Relevant financial disclosures: Allergan: C; Heidelberg Engineering: C,S.