Paso 3. Evaluación de los criterios objetivos de la oferta: la mesa de con-
5.1.1.8 Facturación y Cobro
In addition to glaucoma, other abnormalities can cause excavation and or pallor of the optic disk
Fig. 8.17: Myopic disk with primary open-angle glaucoma
and it is, therefore, important to rule out these possibilities before making the diagnosis of glaucoma.
Physiological Cupping
Assessment of the size of the optic disk, careful examination of the neuroretinal rim and the retinal nerve fiber layer can help distinguish physiological cupping from glaucomatous damage in most cases.
Optic Nerve Coloboma
Optic nerve colobomas typically demonstrate enlargement of the papillary region, partial or complete excavation, blood vessels entering and exiting from the border of the defect and a glistening white surface. The visual field defects can be in the form of generalized constriction, centrocecal scotomas, altitudinal defects, arcuate scotomas, enlargement of the blind spot and ring scotomas that can mimic those found in glaucomatous eyes.
Morning glory syndrome is a variant of optic disc coloboma and is characterized by a large excavated disk, central core of white or gray glial tissue surrounded by an elevated annulus of variably pigmented subretinal tissue (Fig. 8.18). The retinal vessels appear to enter and exit from the margins of the disk, are straightened and often sheathed.
in about one-third. Involvement is usually unilateral in about 80% cases and the optic disk is larger on the involved side. Approximately 55-60% of the eyes have a field defect in the form of arcuate scotomas, paracentral scotoma, altitudinal defect, generalized constriction and nasal or temporal steps.24
In the absence of other indicators of congenital anomaly (like associated fundus coloboma, the differential diagnosis may be difficult and the absence of progression on follow-up may be the only indicator that the patient has a congenital anomaly and not glaucoma.
Anterior Ischemic Optic Neuropathy A history of acute visual loss, initial swelling of the optic disk, absence of marked cupping, rise in ESR, presence of centrocecal scotoma or altitudinal defects can help differentiate it from glaucoma (Fig. 8.20). In the late stages the cupping in some cases may be exactly the same as is seen in glaucoma.
Fig. 8.18: Optic disk photograph showing characteristic morning glory syndrome
Congenital Optic Disk Pit
Congenital optic disk pits appear gray or yellowish-white, round or oval, localized depression within the optic nerve (Fig. 8. 19). They are located within the temporal aspect of the disk in over half of the cases and centrally
Fig. 8.19: Optic disk photograph showing congenital optic disk pits
Fig. 8.20: Anterior ischemic optic neuropathy. The right-sided optic disk photograph is from patients with long- standing AION showing typical glaucomatous cupping
Figs 8.21A and B: A Optic disk photograph showing significant cupping, but with out of proportion pallor.
B Visual field defect showing a temporal hemianopia suggestive of pituitary tumor
A
Neurological Causes
Pallor disproportionate to cupping, normal intraocular pressure or unusual history of onset, progression and age should arouse suspicion of a neurological disorder causing optic disk damage (Fig. 8.21).
Presence of visual field defects that respect vertical midline and the pattern of the field defects should be able to suggest the possible site of the intracranial lesion.
Summary
In summary, the optic disk evaluation in glaucoma is best done stereoscopically at the slit- lamp with a dilated pupil using one of the 60D, 78D or 90D lenses. Changes in the neuro- retinal rim, optic disk hemorrhages, peripapillary atrophy and nerve fiber layer defects are more important features than the cup-disk ratio. The cup-disk ratio is to be documented and interpreted along with the disk size and not in isolation. The diagnosis of glaucoma will depend on the presence of a visual field defect that correlates with the anatomic changes on the optic nerve head and the peripapillary retina.
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