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

When there is bulbar enlargement, however slight it may be, the so-called diffuse sclerocorneal limbus is observed. This condition has been known since 1920, when Axenfeld [8] termed it anterior embryotoxon. It is present in all the cases with enlarged corneas and particularly in congenital glaucoma (Fig. 3.2). Its morphology is that of a pale crescent, mainly visible at the superior limbus, as the inferior limbus is generally poorly developed. This pallor is mainly attributable to its scarcity of vessels. The crescent’s edge near the cornea is definite and nacreous, and the edge near the conjunctiva gradually disappears. Inside the crescent, the vessels are fine, parallel, and enlarged. Sometimes there are whitish striae. This condition shows overall peripheral corneal thinning, offset by a greater development of episcleral and conjunctival tissue. Upon gonioscopic examination, the presence of the embryotoxon is evidenced by a white tissue, which shows through the cornea and goes beyond the level of the Schwalbe line. This condition occurs very frequently in congenital glaucoma, in the superior part of the limbus. Radial vessels are seen through this tissue. The image can be seen better using the 59° mirror of the Goldmann three-mirror lens. In 1967, Busacca [9] made a magnificent description of the anterior embryotoxon.

Chapter 15 explains the importance of studying this area, with transillumination or back illumination, in order to find the iris root behind the opacity and properly place the surgical incision.

The Optic Nerve

The optic nerve becomes rapidly cupped, which can be reversed if intraocular pressure is regulated in time. Chandler and Grant [10], stressed this phenomenon, and later, Shaffer [11–13] and Anderson [14] also covered this topic.

In many cases, it is difficult to examine the optic nerve because of the condition of the cornea. Moreover, it is important to bear in mind that this reversion does not occur in all cases because when the optic nerve fibers are damaged, optic disc and visual field damage is irreversible.

As regards optic nerve cupping in congenital glaucoma, it is important to summarize the studies conducted by Robin et al. [7]. He studied normal embryological development in embryos and fetuses of 5, 7, and 8 months of gestation, in infants aged 1 month, in children aged 12 years, and in adults aged 49 years, showing with microscopy, histochemistry, and electron microscopy that the development of the connective tissue of the lamina cribrosa is incomplete at birth (Fig. 3.6).

Robin et al. [7] also exposed the eyes of newborns and adults to intraocular pressures above 60 mmHg and found that disc cupping in newborns reacts with substantial increases, while in adults, it remains unchanged. Therefore, it is the lack of connective tissue at the level of the disc that allows disc cupping and its reversal in children.

The ophthalmologist also needs to know that after surgery for pediatric congenital glaucoma, postoperative hypotension can result in disc edema with swelling of the optic nerve vessels. This condition, which I have observed in several cases, can also be present in young adults, as demonstrated by Robin et al. [7]. Despite the congenital glaucoma, the pupil is hardly ever mydriatic, but generally miotic.

When measuring intraocular pressure, the pupil must never be dilated to see the fundus, because this might modify the intraocular pressure. The disc can be easily observed by means of an ophthalmoscope with a small-range diaphragm, with its illumination axis very close to the visual axis, or with a gonioscope. If pupil dilation is necessary, tropicamide, but only at 0.5%, must be used, because at 1% concentrations, it has cycloplegic effects. This examination can be performed on another occasion, without general anesthesia and with drug-induced pupil dilation.

At the beginning of congenital glaucoma, the disc is normal. If intraocular pressure is not regulated, the disc rapidly becomes cupped and it has the appearance of a glaucomatous disc. The main feature is that disc cupping is reversible if there is timely intraocular pressure regulation.

The appearance of papillary and retinal vessels should be carefully monitored after surgical operations intended to regulate intraocular pressure. In these cases, and to a greater extent, the younger the child, the more significant vessel dilation will be, and this dilation will lead to the consideration of the presence of aneurysms or congenital vascular diseases. But in a short time, they revert to their normal appearance.

The Eyelids

In large eyes, with or without hypertension, there is a venous remora shown by the dilation of upper eyelid veins. This is a typical sign, illustrated in Fig. 3.7.

Chronology of Symptoms

In bilateral congenital glaucomas, the symptoms and signs mentioned above do not occur with the same se-

Fig. 3.6a–f Variation of the optic nerve structure between the 5th month of gestation and 49 years of age (Courtesy of H.A. Quigley). These microphotographs show preparations of the area of the lamina cribrosa and the optic nerve head, stained according to Mallory’s trichromic technique. The connective tissue is stained with blue, the nerve fibres and astrocytes with red. The sclera can be seen on the left in all cases, except in e and f. The photographs are arranged according to age, so the youngest (fetal) eye is on the top left-hand side and the oldest (adult) eye is on the bottom right-hand side: a 5 months of

gestation; b 7 months of gestation; c 8 months of gestation; d 1 month of age; e 12 years of age; f 49 years of age. In the two first photographs taken from fetal life, there is no connective tissue stained with blue in the optic nerve head; in the newborn (d) some blue coloration is starting to appear, but much less than in the optic nerve of the 12-year-old patient (e). The connective tissue is very dense at 49 years of age (×250). This accounts for the fact that optic disc cupping in children with congenital glaucoma is generally reversible when IOP is regulated with surgery

Fig. 3.7 Dilation of upper eyelid veins

verity in both eyes. They are stronger in the eye with more anatomical and functional disorders.

Signs and symptoms combine in a different way, but as Costenbader and Kwitko [15] showed, when glaucoma has its onset at birth, the signs appear in the following chronological order: hazy cornea, photophobia, eye enlargement, and epiphora. When the onset is between the 6th and 12th month of age, the order changes to eye enlargement, hazy cornea, photophobia, and epiphora. In glaucomas with an onset after the 1st year of age, photophobia is rare. As a symptom of congenital glaucoma, photophobia presumably originates in the stimulation of the sensory trigeminal branches by corneal alterations [16].

Hypertension can cause eye enlargement when it appears within the first 4 or 5 years. After this age, late diagnosis of congenital glaucoma is only possible by means of gonioscopy. This topic has been discussed by Cardia and Reibaldi [17].

References

1.Kaiser B, cited by Kluyskens J (1950) Le glaucome congénital. Rapport présenté à la Societé Belge d’Ophtalmologie

2.Horven I (1961) Tonometry in infants. Acta Ophthalmol Kbh, 39:911–918

3.Carvalho CA, Calixto N (1969) Semiología do glaucoma congenito. XV Cong Bras Oftal Porto Alegre, pp 105–174

4.Shaffer RN, Weiss DI (1973) Congenital and pediatric glaucomas. Mosby, St. Louis

5.Angell LK, Robb RM, Berson FG (1981) Visual prognosis in patients with ruptures in Descemet’s membrane due to forceps injuries. Arch Ophthalmol 99:2137–2139

6.Cibis GW, Tripathi RC (1982) The differential diagnosis of Descemet’s tears (Haab’s striae) and posterior polymorphous dystrophy bands. A clinicopathologic study. Ophthalmology 89:614–620

7.Robin AL, Quigley HA, Pollack IP, Maumenee IH (1979) An analysis of visual acuity, visual fields and disk cupping in childhood glaucoma. Am J Ophthalmol 88:847–858

8.Axenfeld T (1920) Embryotoxon corneal posterior. Ber Dtsch Ophthal Ges 38:301–302

9.Busacca A (1967) Le tableau biomicroscopique de l’embryotoxon. Ophthalmologica 153:1–5.

10.Chandler PA, Grant MW (1965) Lectures on glaucoma. Lea and Febiger, Philadelphia

11.Shaffer RN, Hetherington J Jr (1960) The glaucomatous disc in infants. A suggested hypothesis for disc cupping. Trans Am Acad Ophthalmol Otol 73:929–935

12.Shaffer RN (1967) New concepts in infantile glaucoma. Can J Ophthal 2:243–248

13.Shaffer RN (1955) Pathogenesis of congenital glaucoma, gonioscopic and microscopic anatomy. Trans Am Acad Ophth 59:297–308

14.Anderson DR (1975) Pathogenesis of glaucomatous cupping. A new hypothesis. In: Symposium on glaucoma. Transactions of the New Orleans Academy of Ophthalmology. Mosby, St. Louis, pp 81–94

15.Costenbader FD, Kwitko ML (1967) Congenital glaucoma. An analysis of seventy seven consecutive eyes. J Pediat

Ophthamol 4:9–15

16 Offret G (1960) La photophobie et son traitement. L’Année Thérapeutique et Clinique en Ophtalmologie. XI:303–317

17.Cardia LE, Reibaldi A (1985) Sulla diagnosi e trattamento del glaucoma congenito. Malattie congenite dell’apparato oculare. Verduci, Roma, pp 225–254

Fig. 4.1 Fluoromethyl-2,2,2- trifluoro-1-(trifluoromethyl) ethyl ether

Like all inhalatory agents, it reduces intraocular pressure, relaxing extraocular muscle tone, depressing the CNS, encouraging the outflow of aqueous humor, and diminishing venous and arterial blood pressure. With controlled ventilation and normocapnia, it reduces the IOP in proportion to the depth of anaesthesia. Given that it is well-accepted on inhalation, its rapid induction, the precise control of alveolar concentration, its hemodynamic stability, and the rapid recovery, Sevoflurane is the nearest we currently have to an ideal inhalatory agent for anesthesia in children.

In all cases, when we have given general anesthesia to children, we have used an oximeter, a device for determining oxygen saturation in the blood (Fig. 4.2).

Sevorane (sevoflurane) is applied either on a gauze covering the mouth or on a mask through which the drug is administered drop by drop (Fig. 4.3).

Macroscopic examination is carried out by opening the eyelids as much as possible (Fig. 4.4a). Funduscopy with the ophthalmoscope follows (Fig. 4.4b).

Once general anaesthesia has been induced, the examination continues as follows:

1.Two drops of a local anesthetic (Novesine, Anestalcon, etc.) are instilled in each eye so that they fall

directly on the cornea, to produce the best effect (Fig. 4.5a).

2.Fluorescein paper strips are applied on the eyes (these are paper strips with dry fluorescein on the edge, which is dissolved by the tears, manufactured by Haag Streit) (Fig. 4.5b).

Since the head of newborns up to 2 years of age is much smaller than that of adults, a wooden supplement (Fig. 4.6a) covered with disposable paper towels is put on the chin holder of the slit lamp so that the infant’s eyes are suitably positioned, at the level of the horizontal black strip of the slit lamp (Fig. 4.6b). Of course, the sleeping child is seated on the lap of the nurse or anesthetist, who holds the child’s head (Fig. 4.6b).

An important advantage of Halothane and Sevorane is that they keep the eye looking straight forward, which helps make an accurate examination with applanation tonometry and gonioscopy (Fig. 4.7).

Biomicroscopy of the anterior segment is performed, with special emphasis on the presence of tears in the Descemet membrane (Haab striae) on the cornea, and their location is illustrated in a cir-

cle with the pupil drawn in it. Tears in the Descemet membrane located at the level of the pupil produce amblyopia and strabismus. In these cases, perforating corneal grafts have been required. These procedures have a good prognosis if performed properly (see Chap. 18, clinical history no. 238).

3.At this stage in the examination, the pupil should be thoroughly examined to find any pigment ectropion and to check whether there is hypoplasia of the superficial mesenchymal layer of the iris or if it is still under development. Special attention should also be given to the presence of anomalies characteristic of secondary congenital glaucomas at the posterior corneal surface, such as posterior embryotoxon, Rieger syndrome, etc.

4.The presence of cataract, and, finally, the presence of an anterior embryotoxon, which is typical in children with congenital glaucoma, are ruled out. It should be kept in mind that this embryotoxon influences corneal diameter measurements at the vertical axis. Therefore, as is explained later, the corneal diameter should be measured at the horizontal meridian.

5.IOP measurement is performed with Goldmann applanation tonometry (Fig. 4.8). The position of

the eye is crucial for this measurement. At present, before this measurement, the IOP is measured with Pascal’s tonometry (Fig. 4.9) to avoid the influence of corneal thickness on IOP values.

Gonioscopy is performed with a Goldmann three-mirror lens specially manufactured by Haag Streit for children. Unlike the one designed by Goldmann for adults, there is a 10-mm lens and an 11-mm lens designed for children (Fig. 4.10)

Gonioscopic examination is more accurate with the use of the lens designed by Fankhauser and Roussell, (Fig. 4.11), since this provides a perfectly defined greatly magnified image. In addition, with this lens, a perfect evaluation of the two types of congenital glaucomas is possible (type 1, primary congenital glaucoma, and type 2, refractory congenital glaucoma), as well as the identification of congenital anomalies of the chamber angle in secondary congenital glaucoma.

6.In goniophotography, photographs are taken with the highest illumination of the slit lamp, with a Tungsten 160 ASA film for night lighting. A Nikon camera was adapted to perfectly fit the eyepiece of the slit-lamp by means of a ring specially manufactured by Pfortner Laboratories (Fig. 4.12a,b).

In the last 5 years, we have obtained complete images or slit images by means of movie camera 1, connected to a monitor which is, in turn, connected to camera 2. Camera 1 works as a video camera. Camera 2 works as a digital video recorder (Fig. 4.13).

7.Echometry is used to obtain the axial length. Firstly, the eyelids are separated by means of an Ossoinig shell (Fig. 4.14). A drop of methylcellulose is administered inside the shell to seal off the scleral contact area (Fig. 4.15a), so that the saline solution with which the cylinder is filled does not leak through the contact area between the shell and the eye (Fig. 4.15b). The probe of the echometer can thus be placed in the saline solution with no contact with the cornea (Fig. 4.16a) (noncontact echometry). An echogram is obtained, which not only provides the axial length measure, but also offers more details on the configuration of the anterior chamber, as well as of the lens and corneal thickness. Figure 4.16b shows that the peaks representing the anterior and posterior corneal surfaces are well apart from each other (thereby reflecting the great thickness of the cornea) due to the corneal edema caused by ocular hypertension.

8.The last step involves the measurement of the corneal diameter with a strabismus caliper, at the horizontal meridian (Fig. 4.17a, b).

Once the examination has been completed, as the anesthesia is very superficial, the anesthesiologist

squeezes the ear lobe of the infant to wake him up (Fig. 4.18a–c). This is very important, since one of the parents, who has been present in the office during the entire examination, can see how short this examination is and leave with the baby awake. The parents will then be willing to attend the subsequent follow-up visits, during which general anesthesia is used again.

Even though I have been working in a University Hospital for 54 years, during which we have examined more than 4,000 infants under general anesthesia as described, with the method taught to all the residents, at present the examination under general anesthesia is performed in the operating room, with the infant in the supine position and the IOP measured with hand-held applanation tonometry. This failure to apply the method described is all the more surprising since it is taught thoroughly and is extensively used worldwide. These ophthalmologists even fail to use the method they have been taught by Dr. Manzitti. He made the child lie in a supine position, with the chin-holder removed from the slit-lamp, and measured the IOP and performed gonioscopy correctly by placing the slit-lamp at different heights.

9.The chamber angle can be examined with the SLOCT (Heidelberg Engineering, Heidelberg, Germany) (Fig. 4.19), a very important new device for the study of congenital glaucoma.