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| ARTICLE |
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| Year : 1969 | Volume
: 17
| Issue : 5 | Page : 208-215 |
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The relation of myopia with congenital glaucoma
GR Patel, SN Cooper
Ophthalmic Department, Lokmanya Tilak Municipal General Hospital, Sion, Bombay-22, India
| Date of Web Publication | 11-Jan-2008 |
Correspondence Address:
G R Patel
Ophthalmic Department, Lokmanya Tilak Municipal General Hospital, Sion, Bombay-22
India
 Source of Support: None, Conflict of Interest: None  | Check |
How to cite this article:
Patel G R, Cooper S N. The relation of myopia with congenital glaucoma. Indian J Ophthalmol 1969;17:208-15 |
The association of glaucoma with high myopia is by no means a new observation, Fuchs [3] having drawn attention to myopia in young subjects with deep anterior chambers and increased intra-ocular pressure. In this study we have tried to equate such myopia with the congenital variety of glaucoma.
As can be seen from [Table - 1] there is a kind of myopia (Group - I) which is quite distinct from the degenerative type (Group - II) and the physiological type (Group - III) which is associated with body-growth. Groups - II and III are frequently come across, whereas Group - I is not so frequent and can be missed if not searched for. In the small number belonging to this group that we have been able to investigate during the last year, let us point out the distinguishing features : (i) a comparatively high incidence in males (8 Males to 2 Females), (ii) average tension 28.6 mm Hg corrected against scleral rigidity, (ii) comparatively good vision, (iv) with unaffected chorioretina, (v) atrophic changes in the disc in some, with or without cupping and (vi) changes in the filtration angle.
However, there is another group (Group - la) which resembles Group -1 in every respect, except that the tension is within the normal range. We are. therefore, concerned with groups I and I-a, for our observations today. The importance of such cases lies in the fact that they offer themselves to treatment by some kind of decompression operation which not only normalises the tension but also prevents further increase in the degree of myopia.
We do not wish only to draw attention to this clinical anomaly, but to offer an explanation for the mechanics that may be operating in such cases.
| Materials and Methods | |  |
Cases of high myopia were collected from the refraction department of our Hospital and groups I and I-a cases were picked after noting the age, refraction, fundus changes, slit lamp examination, gonioscopy, tonometery with scleral rigidity and provocative
test for glaucoma. The selection of cases for group-II for the sake of comparison was limited only to the last 3 months of our study.
Records of three cases operated by Dr. S. N. Cooper have been included in this study as they have been followed for some years.
| Observations | | |
It may be mentioned at the outset that [Table - 1] does not indicate the relative incidence in Groups I and II. The incidence in Group-II should be much higher since we have selected only 15 cases for the sake of comparison only with Group-I.
It will be seen from [Table - 1] that the sex incidence in Group I is 4:1, whereas in Group II, it is about equal. The significance of sex incidence we shall deal with later.
From [Table - 2] it can be seen that the average visual acuity is definitely better in Group I and I-a.
In [Table - 3]the tension differences speak for themselves. In evaluating the tension we have made allowance for scleral rigidity which is well known to be lower in myopia. It was noted that the difference in scleral rigidity between the 2 groups was not much, 0.013 in Group-I, which is actually lower than in Group II which is 0.015 but the differences in intra-ocular pressure they make are significant.
[Figure - 1] shows the typical angle changes as seen by a gonioscope in Group-I, with a deep anterior chamber.
As regards the histories of those cases that had been operated by Dr. S. N. Cooper and followed up for from 5-20 years, they have been appended at the end. Briefly, the cases were in young subjects of 18-22 years with myopia progressing even after the age of 20 when ordinarily physiological myopia ceases to increase.
Stabilization of myopia with normalisation of tension followed trephining operations on both eyes.
| Discussion | | |
We have come to regard these cases as a variant of congenital glaucoma from the following facts.
1. Phyletogenetically tracing the development of the angle of the anterior chamber to primates, Troncoso [8] has shown, as can be seen from the comparative figures in [Figure - 2], that during development the intrascleral vascular plexus with the trabeculum lining its inner side moves forwards. Ttt attachment of the pectinate ligament from the top of the trabeculum from which the iris used to hang like a curtain in rodentia (rabbits), gradually moves forwards. It now lines the angle of the chamber with atrophied fibres which were thick and stout in the ungulate (Pig). In primates the remnants of these ligaments can be seen standing out quite prominently [Figure - 3],[Figure - 4],[Figure - 5] in some sections of the anterior chamber. Busacca. [2]
Secondly, during development as shown by Mann [5] and can be seen from this picture of the anterior chamber of a 48 mm (l0 weeks) embryo [Figure - 6] the portion between the angle-base and the edge of the optic cup is filled with undifferentiated mesodermal tissue which differentiates into the different parts forming the anterior chamber in adults, viz. the iris stroma on one side and the trabculae, the scleral spur and the ciliary muscle on the other [Figure - 7]. This section (Mann [5] ) is of the angle of a 5 months' human embryo. Some undifferentiated mesodermal tissue is seen lying in the angle which eventually atrophies. The amount of atrophy of these remnants of the mesoderm determines the gonioscopic appearance and the functional efficiency of this important region. Persistence of this meshwork at the angle can easily obstruct the filtration passage of the aqueous.
Coming to the question of congenital glaucoma, buphthalmos of congenital origin is the result of an extreme degree of obstruction to the outflow of aqueous. The nature of this obstruction is still disputed. Barkan [1] has described an ill-defined membranous tissue covering the trabecular zone.
Maumenee [6] attributes it to an insufficient cleavage between the anlage that forms the trabeculae and the sclera on one hand and that which forms the iris stroma on the other [Figure - 8].
When we talk of buphthalmos we are dealing with extreme degrees of obstruction involving the whole circumference of the angle, whatever be the nature of the obstruction. It is quite possible that lesser degrees of obstruction involving lesser area of the angle may prevail. On such an assumption we base our concept of those cases of myopia in the young where the intraocular tension is raised and some pathology of the angle is observed by gonioscopy. Even it is not necessary to have visual evidence of obstruction to filtration as seen by the goniscope. The obstruction may lie in the trabecula, where there is no goniscopic evidence of obstruction.
Assuming that initially there is a partial obstruction to the passage out of aqueous which is of a congenital nature, there should be a slight rise of I.O.P. in the tender eye of the infant.
The scleral envelop resists this initial distensile pressure as in the case of a rubber balloon which needs a much stronger pressure initially to distend the balloon, after which the resistance to distension is reduced. The effects of such ballooning of the eye-ball are not appreciated till the child is of school going age. The later history of such myopia is that it continues to progress even after growth has ceased. Thus we have attempted to show that such cases are not cases of myopia but they are essentially cases of congenital increase of I.O.P. where a slowly increasing intraocular pressure succeeds in distending the scleral envelop, without causing chorioretinal changes, resulting in a distended eyeball ending in myopia.
The analogy to genital glaucoma is further emphasized by the sex incidence. As worked out by Sorsby [7] and also by Francois, [3] the ratio for buphthalmos between males and females is 2: 1. Incidentally Barken [1] who has described the results of surgery in buphthalmos in 10 cases, although he does not make a point of it, it is significant that 9 of the cases described were boys and only 1 girl. In our small series of myopia with glaucoma, the sex ratio is as high as 4 males: I female. It can be seen that the genetic (sex) characteristic in cases of myopia with glaucoma is the same as in buphthalmos or congenital glaucoma.
The presence of goniscopic changes, sex incidence and the after history of the operated cases vindicate our hypothesis.
| Summary | | |
High degrees of myopia, particularly in the young with high intraocular tension and gonioobstruction, have to be recognised in a class quite distinct from the degenerative type and purely physiological myopia. They may be classed as variants of buphthalmos or congenital glaucoma.
All myopias which do not come to a stop at the age of 20 and have good vision and few chorio-retinal changes must be investigated for glaucoma.
The importance of trapping such cases and treating them surgically offers a means of preventing increase of myopia and of countering glaucoma, if untreated.
| References | | |
| 1. | Barkan, O.: Operation for Congenital Glaucoma. Amer. J. Ophth. 25, 552-563. (1942).  |
| 2. | Busacca, A.: Elements of Gonioscopy (in French). p. 27, Sao Paulo, Brazil. (1945). |
| 3. | Francois, J.: Heredity in Ophthalmology, p. 218. The C. V. Mosby Co., St. Louis. (1961). |
| 4. | Fuchs, E.: As quoted by Sorsby in Modern Ophthalmology, Vol. IV, p. 582, Butterworth and Co. Ltd., (1964). |
| 5. | Mann, Ida.: Development of Anterior Chamber-Chapter IV in A Treatise on. Glaucoma pp. 68, 69 by Troncose U.B., F.A. Davis Co. Philadelphia. (1947). |
| 6. | Maumenee, A. E.: The Pathogenesis of Glaucoma: A New Theory. Trans. Amer. Ophth. Soc., 56, 507, (1958). |
| 7. | Sorsby, A.: Modern Ophthalmology, Vol. IV, p. Butterworth and Co. Ltd. London (1964). |
| 8. | Troncoso, U. B.: A Treatise on Gonioscopy, p. 27, F.A. Davis Co., Philadelphia (1947). |
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8]
[Table - 1], [Table - 2], [Table - 3]
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