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

Krukenberg Spindle

This was described for the first time by Krukenberg in 1899 [51] in a mother and daughter. It is formed from the accumulation of pigment on the posterior face of the cornea. Its dimensions are approximately 6 mm in height by 3 mm in width. The pigment is phagocytosed by the endothelial cells covering the Descemet membrane.

We will not spend time studying the Krukenberg spindle since there are publications [30] that have investigated 202 cases in the United States. Hansen [52] shows a very good histological preparation of the Krukenberg spindle. Possibly the formation of the Krukenberg spindle is caused by the thermal flow that occurs in the anterior chamber. Of all our patients, 68.6% showed a Krukenberg spindle and 31.4% did not. However, these are pigmentary glaucomas (Fig. 20.28).

Pigmentation on the Surface of the Lens

In pigmentary glaucoma, we have also found pigment deposited on the lens, on the anterior and posterior capsule, in the zonular fibers, and in the anterior border of the vitreous body, anterior (zonular) hyaloids at the zonular fibers. The most important of these pigmentations is found on the posterior face of the lens, deposited toward the periphery on the capsule. This

pigmentation on the peripheral surface of the lens is irregular in shape: a half-ring, ring, or double ring.

We believe this ring is almost constant in advanced pigmentary glaucoma (Fig. 20.29a,b). In the group of patients studied, 93.4% presented pigmented rings in the posterior face of the lens, 60.6% presented two pigmented rings, one of them sometimes more complete, 30.3% presented a pigmented ring, sometimes incomplete, and 9.1% presented a half-ring.

Pigmentary Ring in the Chamber Angle

This characteristic pigmentation is found in all our patients. It presents as a very clearly defined band, dark brown in color, almost black, homogeneous and thick in the region of the scleral trabecular meshwork corresponding to the Schlemm canal. In some eyes, this pigmentation extends to all the filtering trabecular meshwork and even beyond it in the form of fine granules, some passing the Schwalbe line and others on the surface of the iris.

When the pigment dispersion is extensive, the trabecular meshwork is also pigmented up to the Schwalbe line and sometimes the pigment passes over this line and deposits on the posterior face of the cornea in a random way. It can accumulate in the steepest part of the angle. This pigment ring in the chamber angle is the clearest, most constant sign that permits a diagnosis of pigmentary glaucoma, once ocular hypertension has been found. Gonioscopy has diagnostic value (Fig. 20.30).

Figure 20.31 sketches the biomicroscope study findings. Figure 20.31a, with maximum, almost limbic, pupil dilation, shows the lens equator and two concentric pigment rings. The inner one is thicker and is made up of rectangular pieces. The outer one is thinner, and, with great magnification, a structure can be seen made up of overlapping granules of pigment.

A careful study locates these two rings accurately. Figure 20.31b corresponds to a section of the anterior segment, in which the cornea, sclera, iris, ciliary body, periphery of the lens, zonular fibers, and anterior hyaloids can be seen. In Fig. 20.31c, Z indicates the insertion of the posterior zonular fibers and W marks where the anterior hyaloids meet the posterior face of the lens, a structure known anatomically as the Wieger capsulohyaloid ligament. The zonular fibers and the posterior capsule of the lens form an acute angle open toward the periphery. The anterior hyaloids and the posterior capsule of the lens form another acute angle open toward the periphery. The latter is called the capsulohyaloid angle. The section of both spaces is triangular in shape.

Following up patients over the years, we have been able to observe that, in general, the pigment stops first in the angle that the zonular fibers form with the lens and so constitutes the first pigment ring. The pigment then passes to the Petit perilenticular space (which is formed by the anterior and posterior zonular bundles), passing through the posterior zonular fibers to the Hannover space, which in these diseases is real, not virtual, and this reaches the capsulohyaloid angle, where it forms the second pigment ring, at the capsulolenticular ligament of Wieger. In normal persons, this Hannover space is commonly virtual, but it is real in cases of pigmentary glaucoma.

In Fig. 20.31b, a section of the lens can be seen, obtained by placing the slit horizontally and at an angle. The precise location can be seen of the accumulations of

pigment that start the formation of the rings. Looking with greater magnification, it can be clearly observed that in the section the pigment has the same triangular shape corresponding to the capsulohyaloid angle and the zonular angle. As well as these rings, granules of pigment may be observed sticking to the zonular fibers, which are more numerous nearer their insertion, where they form macroscopically the first ring.

Having followed up these patients for years and observed how these rings slowly form, in addition to what has just been described, has convinced us that this sign is an acquired formation.

The pigment epithelial layer of the iris is destroyed and not in the region next to the pupil but in the peripheral part; the pigment, carried by the flow of the aqueous humor, enters through the anterior zonular fibers into the Petit perilenticular space, from there passes to the Hannover space and deposits on the posterior face of the lens. Moreover, the structure just described definitely does not represent a contact of the ciliary processes with the lens in the embryo stage that might leave pigment impressions. Sometimes the pigment reaches the ora serrata, and at other times passes it and deposits at those levels.

Chamber Angle in Pigmentary Glaucoma

As stated earlier, pigmentary glaucoma is a type of goniodysgenesis, a late congenital glaucoma. Figure 20.32a shows a scheme in which the most important point is the brown triangle (Fig. 20.32a, 1), showing the pathological tissue remnants that can, to a greater or lesser extent, reach the Schwalbe line, as in the congenital glaucomas. The notable pigmentation of the Schlemm canal (Fig. 20.32, 3) marks the diagnosis of pigmentary glaucoma.

Fig. 20.31a–c Zones of pigment accumulation in pigmentary glaucoma. In a, 1 wide internal pigment ring; 2 thinner external pigment ring, corresponding to the insertion of the posterior zonular fibers; 3 posterior zonular fibers; 4 dilated iris; 5 lens equator. b Optical section with oblique horizontal slit: 6 profile line of the anterior face of the lens; 7 profile line of the posterior face of the lens; 8 profile line of the posterior

zonular fibers; 9 profile line of the anterior hyaloids. c Z indicates the insertion of the posterior zonular fibers and W marks where the anterior hyaloids meet the posterior face of the lens, a structure known anatomically as the Wieger capsulohyaloid ligament. The two letters P mark the section of the pigment rings

Figure 20.33 shows the goniophotograph of another pigmentary glaucoma; Fig. 20.33b is a diagram distinguishing the different elements of this pathology corresponding to another case. In Fig. 20.33a, the Schlemm canal can be seen as a thick, absolutely black line, which is what in most cases provides the diagnosis when performing gonioscopy. Here the zone should be noted

that runs from the last roll of the iris to the following roll of the iris (vertical black line), because this zone presents iris atrophy, another feature of goniodysgenesis. Above the last fold of the iris, the strings forming the pathological mesodermal remnants can be clearly seen, and below they are blurred.

Apparent High Insertion of the Iris

in Pigmentary Glaucoma

Just as in a congenital glaucoma with type I and type II angles, the apparent high insertion of the iris can be at different levels: the ciliary body band, scleral spur, the Schlemm canal, the Schwalbe line or above it. In pigmentary glaucoma, the height of the apparent insertion of the iris can also vary. Figure 20.34 shows a pigmentary glaucoma with its apparently high insertion of the iris occurring at the level of the scleral spur. In Fig. 20.35, we have reproduced the angle of a refractory

congenital glaucoma (type II) with an apparently high insertion of the iris at the level of the Schwalbe line, to compare it with the chamber angle of pigmentary glaucoma, which in some cases resembles the type II chamber angle. Figure 20.36 is another example of the same situation. Figure 20.37 is what we consider an extraordinary example of the angle of a pigmentary glaucoma, taken, like the other goniophotographs, with the Roussell and Fankhauser lens, which enables us to see the atrophy of iris tissue at the periphery and through it, the pathological mesodermal remnants, and the pigment accumulated among them.

Congenital Anomalies of the Chamber

Angle (Frequency)

Of the 107 cases studied in our statistics, 77% presented a congenital anomaly of the chamber angle and 23% did not. In the latter cases, then, these were pigment dispersion syndromes with ocular hypertension and, sometimes, visual field defects.

The pictures of those presenting chamber angle anomalies could be different types: in the first type, the three forms presented together (pathological mesodermal remnants, absence of the ciliary body band, and inferior nasal depression), and accounted for 43% of anomalies. A second type showed only two of the forms in combination, either pathological mesodermal remnants and absence of the ciliary body band, or pathological mesodermal remnants and inferior nasal depression: this accounted for 4%. The other presented any of three completely isolated forms: pathological mesodermal remnants (36.4%), absence of the ciliary body band (10.2%), and inferior nasal depression (6%) (Table 20.2).

Refraction

In the group in which we made the statistics, 73.5% presented myopia between sph. −1 and sph. −27 D distributed as follows: 25%, between −1 and –2.5 D; 18%, between −3 and −5 D; 21.9%, between −6 and −13 Ds; 7%, between −14 and −18 D and two eyes, one −25 D and the other −27 D. In total, 19.5% were emmetropic and 7% hypermetropic, between +1 and +6 diopters (Table 20.3).

Table 20.2 Congenital anomalies of the chamber angle, in pigmentary glaucoma (107 cases) (frequency)

Forms

Cong congenital, RMP pathological mesodermal remnants, ABCC absence of the ciliary body band, DNI inferior nasal depression