Ординатура / Офтальмология / Английские материалы / The Glaucomas Volume 1 Pediatric Glaucomas_Sampaolesi, Zarate_2009

IIb. Optic Disc Colobomas

Ocular manifestations can show an abnormal coaptation of the proximal area of the optic vesicle slit. The optic disc is enlarged, with sharp borders and a bright white color with a deep cup. The cup is decentered toward the bottom, making the neuroretinal rim disappear there. This defect generally presents a choroidal coloboma at the deepest part of the optic disc, and it is sometimes associated with a coloboma of the iris.

Ultrasonography and computerized tomography show a posterior pole cup of the eye as in morning glory syndrome and, contrary to this syndrome, it is generally bilateral.

Visual acuity depends on the integrity of the papillomacular bundle. The retinal vessels are normal. They are sometimes accompanied by a macular serous detachment.

Systemic manifestations include optic disc colobomas may be accompanied by Charge’s syndrome [53, 54], Walker-Warburg’s syndrome [55], Aicardi’s syndrome [56, 57], or the linear Nevus sebaceous syndrome [58]. Sometimes the coloboma has an atypical connection with an orbital cyst [59].

In optic disc colobomas, as already said, a choroidal coloboma equal or larger in size than the optic disc in its inferior part is usually present. Sometimes there is no optic disc coloboma but this small inferior coloboma is present. One of these cases is shown on the vertical section of both depressions at the bottom of the optic disc, as well as on a tridimensional representation, the measurement of the optic disc area and of the area of the coloboma (Fig. 17.36). The main features are described in Fig. 17.37.

IIc. Peripapillary Staphyloma

This is a very infrequent condition, which is unilateral and is manifested by a deep cup surrounding the optic disc, especially in its inferior part. The cup is surrounded by a pigmentary halo and, conversely to what occurs in morning glory syndrome, there is no central glial white veil. The visual acuity may be normal or reduced, and in the visual field there is a centrocecal scotoma. It is often associated with a coloboma of the iris,

Fig. 17.38 Peripapillary staphyloma

the retina, and the ciliary body, and only very rarely does a basal encephalocele appear, as a manifestation of the CNS [60].

In a highly myopic case combined with glaucoma, we have observed a staphylomatous depression around the optic disc in the center of which there was a flat glaucomatous optic disc. Figure 17.38 shows the pertinent confocal tomographies. Figure 17.39 shows the main characteristics.

III. Megalopapilla

When the optic disc surface is greater than 2.5 mm2, megalopapilla is diagnosed. There are two types of megalopapilla:

1.Type I: the optic disc bears a normal configuration and the condition is bilateral. The cup/disc ratio is high, which must be kept in mind when making the differential diagnosis with low-tension glaucoma (cup/disc ratio: mean, 0.16 + 2 SD = 0.6 mm maximum). The whole optic disc surface is pale, and the cup is either round or oval.

2.Type II: this is characterized by a cup decentered toward the top of the optic disc, i.e., the contrary to what occurs in optic nerve colobomas, where the cup is decentered toward the bottom. The cilioreti-

nal arteries are more common in megalopapilla [61]. The neuroretinal rim is reduced or has almost completely disappeared in the top part. It usually occurs unilaterally. Many megalopapillas appear in normal subjects with a normal visual field. It is one of the wide range of optic discs [62].

It should be kept in mind that megalopapilla may develop in congenital glaucomas, mainly in reoperated cases. This megalopapilla is acquired because as the sclera distends, with the consequent axial length and ocular volume increase, the Elschnig ring enlarges, and therefore so does the whole optic disc surface. Figure 17.38 shows the images, and their characteristics are shown in Fig. 17.40.

IV. Optic Disc Pits

On ophthalmoscopy, the optic disc manifests as a round or oval, gray, white, or yellow depression, usually located in the temporal area. It is accompanied by peripapillary pigmentary changes and in 50% of cases, one or two cilioretinal arteries come from the pit [63]. It is generally unilateral.

The visual field defects correlate with the position of the pit, depending on the fibers crossing the area. There is a blind spot enlargement and arcuate scotomas are the most common defects. We have sometimes found central scotomas.

As for the retina, in 25%–75% of cases macular serous edema [64, 65] leading to macular detachment occurs. Lincoff et al. [66] have studied this subject in

depth and proved that the retinal separation is similar to a retinoschisis and that a retinal hole of the external layers of the macula leading to a central scotoma may develop. The retina around the macular hole is detached. Gas injections and laser photocoagulation are recommended in these cases.

Retinofluoresceinography shows that an early hypofluorescence and a late hyperfluorescence of the pit usually take place. There is no fluorescein passage to the vitreous or to the macula.

The pathological anatomy reveals that the dysplastic retina is herniated inside a pocket or cavity that extends toward the back, frequently inside the subarachnoid space through a defect of the lamina cribrosa [67, 68] (Figs. 17.41, 17.42).

V. Tilted Disc Syndrome

Tilted disc syndrome is a bilateral condition where the superior temporal part of the optic nerve is elevated and the inferior nasal part is shifted in a posterior direction. This gives the optic disc an oval shape with its greater axis in an oblique position.

On ophthalmoscopy, the optic disc has its greater axis in an oblique position. There is a situs inversus of the optic disc vessels with an inferonasal congenital conus and retinal epithelium and choroid thinning in the inferonasal area that may be accompanied by inferonasal albinism.

The visual field presents a bitemporal hemianopsia or a superior quadrantanopsia. This visual field defect is a refractive scotoma secondary to a localized regional myopia in the inferotemporal retina. If a −4-D lens is used, the scotoma disappears and in this way its refractive nature is confirmed. Consequently, there is a myopic astigmatism with the greater axis parallel to the ectasia [69]. In my opinion, tilted optic disc syndrome is related to nasal ectasia of the fundus. This syndrome was described by Riise [70]. See the article by Argento and Mayorga [71] (Figs. 17.43, 17.44).

VI. Optic Nerve Dysplasia

VII. Congenital Optic Nerve Pigmentation

This is gray in albinism due to late myelinization.

VIII. Aicardi Syndrome

There is depigmented lacunae around the optic disc with pathological anatomy: lack of choroid and of pigmentary epithelium in the lacunae. Sometimes, congenital optic disc alteration. Lethal in males.

Systemic Manifestation (CNS)

Corpus Callosum Agenesia

Other ocular manifestations include microphthalmos, retrobulbar cyst, pseudoglioma, bifid spine, detachment of the macular retina, pupillary membrane, iris synechiae, and iris colobomas.

Other general manifestations include spina bifida; scoliosis, microcephalia, muscular hypotonia, and mental retardation.