13 Congenital Glaucoma

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CHAPTER 12

THE OPTIC DISC IN CONGENITAL GLAUCOMA

12.1 Introduction

My research in primary congenital glaucoma was divided into four periods:

1960 - 1970: Intraocular pressure: normal and pathological.

1970 - 1980: Echometry in the diagnosis and in the follow-up.

1980 - 1990: Functional results in congenital glaucomas: computerized perimetry

(Octopus and high-pass resolution perimetry).

1991 - 1996: Study of the optic disc on the same patients with confocal tomography.

12.2 Intraocular Pressure

In 1967 I showed for the first time that intraocular pressure in the newborn up to 6

years of age, has a mean of 10 mmHg, instead of 15 mmHg like the adult [1] (Sampaolesi

1967).

In America, in 1969 Carvalho and Calixto [2] were the first authors to confirm thisfinding, followed by Radtke and Cohan in the USA in 1975 [3]. Tucker and coworkers

confirmed our results as well in 1992. In Europe, Tarkkanen, Reibaldi, Fledelius, Gold-

mann, Dominguez and others also confirmed the same values.

The results we obtained are summarized in figures 12.1 and 12.2. Figure 12.1 shows

a normal range band for intraocular pressure between birth and 6 years of age. The intra-

ocular pressure increases with age. Figure 12.2 displays the intraocular pressure values

obtained in different age groups.

12.3 Diagnosis by echometry

In 1970 I started to measure the axial length with echometry, initially in the eyes of

healthy children. In 1971 I started performing echometry in eyes with congenital glau-coma and I found that when the intraocular pressure values were doubtful because they

were at the top limit of the normal range, echometry was a very helpful new parameter.

This led us to undertake a systematic study of echometry in normal children with the

purpose of obtaining the mean values and their scatter according to age.

Conversely to what occurs in intraocular pressure readings, the axial length is not af-

fected by general anesthetics.

In 1974, at the Glaucoma Symposium held in Wrzburg, I drew the attention for the

first time to the extraordinary value of echometry for the diagnosis of congenital glau-


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12.4 Surgery

Until 1968 we performed Barkans goniotomy [18] with which we were successful in

65% of the cases. Since then, we have been performing trabeculectomy according to

Harms [19, 20, 21] or Paufiques technique [22], which have been successful in regulating

intraocular pressure in 98% of the cases.

There are two types of pathological chamber angles in children: type 1 and type 2.

The angle belonging to type 1 has thin pathological mesodermal remnants, while type 2

angles have thick mesodermal remnants (apparent high insertion of the iris). It is impos-

sible to distinguish the ciliary body band in both types of chamber angle.

Faced with type 1 chamber angles in eyes with an axial length not larger than 23 mm

within the first month of age, we decide to perform trabeculotomy and in type 2 chamber

angles with an axial length above 23 mm, the decision is combined surgery (trabeculot-

omy plus trabeculectomy). During the last 25 years most of the centers specialized in

children have left goniotomy aside and turned to trabeculotomy because this technique is

simpler and its results is better. It is also easier to learn by residents.

12.5 Echometry in the follow-up

Buschmann and Bluth, in 1974 [23, 24], were the first who conducted a follow-up of

congenital glaucomas with echometric measurements.

Echometry is very useful in the follow-up of congenital glaucomas, specially if it is

necessary to indicate a new surgery (reoperation).

There are four different types of evolution after surgery (figure 12.5):

1) When the axial length does not increase and, with time, falls within the normal range

of evolution. It is a satisfactory result and the best evolution one can expect.

Fig. 12.3 Fig. 12.4


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2) When the axial length continues to increase as revealed by subsequent checkups and

it deviates even further from the normal range. This is the worst type of evolution.

Reoperation is always necessary.

3) The axial length continues to increase parallel to the normal range. In these cases

reoperation is almost always necessary. The decision depends on the other parame-

ters.

4) There is a fourth type of evolution which was described by Massim and Pellat [25].The axial length remains for some time at pathological levels running parallel to the

normal range band, then increasing and, finally, back parallel to the normal band.

In these cases it is also necessary to perform a reoperation but the other parameters

should also be taken into consideration.

When the axial length continues to grow and the intraocular pressure rises to patho-

logical level, the indication for surgery is very simple. But when the intraocular pressure

is high but stays within the normal range, echometry is of great value to indicate a new

surgery. Carvalho and coworkers in 1979 [26] also studied the results of goniotomy and

trabeculotomy.

12.6 Material

We have studied three different populations which had pediatric glaucomas during

childhood [6, 7, 8, 9]. The first group (19 eyes), consisted of primary congenital glauco-

mas operated only once. The intraocular pressure was regulated and the axial length of

the eye stopped its enlargement after surgery. Surgery was successful.

The second group (12 eyes) consisted of children with primary glaucomas in which

the intraocular pressure was regulated and the axial length of the eye stopped its enlarge-

ment after 2 to 6 reoperations.

The third group (29 eyes) consisted of late congenital glaucomas, goniodysgenesis

and juvenile open angle glaucoma. As these diseases manifested later, generally between

Fig. 12.5


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4 and 6 years of age, the axial length of the eyes did not grow despite the ocular hyper-

tension because the sclera was no longer elastic. The intraocular pressure was regulated

with medical therapy or surgery (table 12.1).

Material Cases Follow- Male Female

up (yrs.)

Group 1: Primary congenital 19 12-28 13 6

glaucomas operated once

Group 2: Reoperated primary 12 7-22 10 2

congenital glaucomas

Group 3: Goniodysgenesis 29 11-23 15 14Total: 60 7-24 38 22

Control group: Normal individuals [25] 110 50 60

(age: 5-25 yrs.)

Table 12.1

The follow-up of the three groups was performed with echometry and applanation

tonometry. Ten to 28 years after surgery, the results were assessed by means of the analy-

sis of the following parameters: axial length, myopia, visual acuity, visual field and optic

disc appearance (scanning laser tomography). The optic disc was studied with the Hei-

delberg Retina Tomograph HRT (software version 1.11).

The axial length is different in the three groups. After surgery, group 1 remained at

the values reached before surgery; in group 2 (reoperated cases), the axial length wasbigger, and in group 3 it fell within the normal range because the sclera does not enlarge

after 5 years of age.

The myopia is also different in the three groups. Group 2 was highly myopic, group

1 mildly myopic and the group 3 was almost emmetropic.

The best visual acuity was found in group 3, the worst in group 2; in group 1, it was

considerably good.

The only visual field damage that can be found in children is diffuse sensitivity de-

pression, i.e. pathological MD values (figure 12.6).

Fig. 12.6


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12.8 Study of the optic nerve in congenital glaucomas

12.8.1 Method

We studied the optic discs in the three groups with the Heidelberg Retina Tomo-

graph (HRT). Three images were acquired for each eye and the mean topography was

obtained. The standard deviation of the mean topography must always be lower than 30

m. The HRT was developed by Heidelberg Engineering GmbH (Heidelberg, Germany)

and uses the principle of confocal laser scanning microscopy [30]. The basic clinical

work with this device was performed by Burk and coworkers at Heidelberg University,

Germany [27, 28, 29].

In addition to the study of the optic disc parameters, the profiles of the optic discs of

each group were studied to a scale.

12.8.2 ParametersWe will now explain the alterations found in each parameter for each group, com-

pared to the parameters of a group of 110 normals, ranging from 5 to 25 years of age

[31].

One way analysis of variance (ANOVA) was used for overall comparison among the

four groups and post hoc comparisons were done with Tukey's test. Data was considered

as statistically significant if p < 0.05. All tests were performed with the software Graph-

Pad InStat (version 2.05).

In tables 12.2 and 12.3, "p" represents the results obtained with the ANOVA, in-

cluding normals. Table 12.2 shows the differences between groups 1, 2 and 3, while table

12.3 shows the differences of each group with the control (normal group). In both tables,

*, ** and *** indicate p < 0.05; < 0.01 and < 0.001, respectively. NS indicates there was

no significance.

Figures 12.7a and 12.7b show the analysis of the parameters disc area and cup/disc

area ratio. Figures 12.8a-d show the analysis of the parameters related to the disc cup-

ping: mean cup depth, maximum cup depth, cup area and cup volume. Figures 12.9a and

12.9b analyze the parameters rim volume and rim area. Figures 12.10a and 12.10b show

the cup shape measure and contour line height variation.

In each parameter, the difference between the three groups (table 12.2) and the dif-

ference between each group and the normal group (table 12.3) were analyzed.

Disc area (figure 12.7a)

In the three groups, statistically significant differences were found between groups 1

and 2 (p < 0.05) and between groups 2 and 3 (p < 0.01). No significant difference was

found between groups 1 and 3. Compared to the normal group, significant difference wasfound only for group 2 (p < 0.001).

Cup/disc area ratio (figure 12.7b)


and 2 (p < 0.001) and between groups 1 and 3 (p < 0.01). No significant difference was

found between groups 2 and 3. Compared to the normal group, significant differences

were found for groups 2 and 3 (p < 0.0001).


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Mean cup depth (figure 12.8a)

The difference between the three groups was statistically significant only between

groups 1 and 2 and between groups 2 and 3 (p < 0.001). Compared to the normal group,

all three groups were significantly different (p < 0.001).

Maximum cup depth (figure 12.8b)

As with the previous parameter, the differences were statistically significant only

between groups 1 and 2 and between groups 2 and 3 (p < 0.001). All three groups were

significantly different from the normal group (p < 0.001).

Cup area (figure 12.8c)


and 2 (p < 0.001), between groups 1 and 3 (p < 0.05), and between groups 2 and 3 (p

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