Dewlop. Med. Child Neuvol. 1971, 13, 231-245

Annotat ions

CONGENITAL GLAUCOMA ONE of the most gratifying advances in ophthalmology is in the management of congenital glaucoma or buphthalmos (ox-eye). In this condition there is present at birth a develop- mental obstruction to the outflow of aqueous from the eye. The resulting rise in intra-ocular pressure, and its clinico-pathological changes, may be present at birth or they may appear at any time within the first three years of life. It is not a common disorder, but it is a treat- able one, which any doctor who sees babies may have the opportunity and responsibility of recognising.

This account excludes glaucoma in the infant found in association with other ocular developmental defects such as microcornea, aniridia, Axenfeld's and Rieger's anomalies, spherophakia and persistent hyperplastic primary vitreous, or with other systemic develop- mental defects such as neurofibromatosis, Sturge-Weber's syndrome, homocystinuria, trisomy 13-15, and in the syndromes of Marfan, Lowe, Pierre-Robin and Turner'. The danger signals are the same as those discussed below for congenital glaucoma and the action required is urgent reference to an ophthalmologist. Primary congenital glaucoma must also be distinguished from glaucoma secondary to ocular inflammation or neoplasm arising in fetal or neonatal life.

I n congenital glaucoma, whereas the anatomical defect is by definition present at birth, the rise in intra-ocular pressure and the resultant manifestations of this may not be.

It is sobering to recall what ANDERSON? wrote in only 1939: '. . . the future of patients with hydrophthalmia is dark. Little hope of preserving sufficient sight to permit the earning of a livelihood can be held out to them.' Effective treatment can now be offered, and the earlier i t is instituted the better will be the prognosis. Hence the importance of making an early diagnosis whenever possible.

Most cases of congenital glaucoma are sporadic but it may be genetically determined as an autosomal recessive trait. Either sex may present with it, but boys form 65 per cent of patients.

Atiaronzy and Pathophysiology The angle of the anterior chamber lies between the cornea and the root of the iris and at

its apex is the trabecular meshwork through which aqueous from the anterior chamber filters into the circumferential canal of Schlemm (See Figure). Any obstruction to this outflow will cause a rise in intra-ocular pressure, and in congenital glaucoma abnormal tissue can be seen occluding the angle both in the living eye and in histological preparations. Schlemm's canal is usually patent. The origin of the developmental defect remains unsettled. Either the mesoderm in the fetal angle fails to absorb completely3 or there may be an incomplete cleavage between the cornea and the growing ciliary body and iris, or some ciliary muscle fibres are inserted abnormally, so that upon contracting, they close the spaces in the meshwork and thereby impair outflow of aqueous1.

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DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY. I97 1, 13

Anterior chamber Canal of Schlemm Filtration angle at root

of iris Ciliary body

Normal eye Buphthalmic eye ‘I1 Under a sustained, raised intra-ocular pressure the corneoscleral envelope becomes

markedly thinned and stretched. This plasticity of tissue is lost after the age of three. Grossly enlarged eyes gave rise to the classic description of the buphthalmic or ox-eye. As the corneal diameter increases, the relatively inelastic membrane of Descemet gives way and tears in places; aqueous then enters the cornea which becomes oedematous. The globe enlarges slowly but, as the lens is not displaced, the anterior chamber becomes deeper. Both choroid and retina undergo atrophy and, despite the globe yielding, the optic disc becomes cupped early in the disease4.

Early Diagnosis: the Paediatrician’s Responsibility Early diagnosis in congenital glaucoma is essential, even though it may be difficult, and

the paediatrician, the family doctor and the doctor at the child health centre are most likely to be given this opportunity. They should know the three common signs and, although buphthalmos is uncommon and they may never have seen a case before, be alert to respond to them. Approximately one-third of cases will have clinical signs at birth. Two-thirds of affected children will have signs by the age of six months and about 80 per cent can be diagnosed by twelve months.

Both eyes are involved in 75 per cent of children, but when it is unilateral the pressure may, in later life, rise in the other seemingly normal eye, which emphasises the importance of lifelong follow-up.

The classic triad of signs is photophobia, lacrimation and blepharospasm. A hazy cornea may be glimpsed, caused by oedema, initially of the epithelium and later of the stroma. However, the intolerance of light may be so distressing that the baby lies with eyes shut tight and face buried in the pillow; the photophobia is a result of the corneal oedema or of a mild kerato-uveitis. Attempts to assess the ocular pressure by palpation, even with a co-operative chdd, are both unreliable and unrewarding, although in advanced cases the affected eye will feel harder and appear larger than usual.

Acute ruptures in Descemet’s membrane cause a temporary worsening in the corneal oedema, but when healed such tears can be recognised as fine glassy lines in the cornea. The anterior chamber is abnormally deep and, if ophthalmoscopy is possible, the optic disc may show cupping.

It is uncertain whether infants less than six weeks old have established normal, unstimu- lated tear production, but it does seem that most neonates have reflex lacrimation. Since the buphthalmic infant may present with irritable, red or watery eyes, the paediatrician must avoid failing to recognise congenital glaucoma by attributing these to conjunctivitis, whether primary or secondary to an obstruction of the naso-lacrimal passages. These are two common pitfalls in differential diagnosis.

High myopia, which gives prominence of the eye, particularly if unilateral, and the

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ANNOTATIONS

corneal dystrophies enter the differential diagnosis as do the kerectasias, notably megalo- cornea. (The normal upper limit of width is 11.5mm). Corneal oedema may be congenital, idiopathic, or may arise from birth trauma, and corneal clouding is found in the mucopoly- saccharidoses, lipidoses and cystinosis. The possibility must be remembered too, of congenital glaucoma being associated with, or secondary to, other infantile diseases as were listed earlier.

The diagnosis of one congenital defect in a child will alert the physician to search for abnormalities in other systems. Very young infants with buphthalmos may occasionally exhibit signs of cardiac anomalies or pyloric stenosis; since others have deafness and mental deficiency, these will be looked for at the time of onset or later when, at the age of six months, i t becomes possible to test for them.

What the Ophthalmologist Does To establish the diagnosis, the child must be examined under general anaesthesia5. The

horizontal corneal diameter is recorded and, if more than 11.5mm, is considered patho- logical. Subsequent increases in diameter indicate uncontrolled intra-ocular pressure. The pressure is measured with a tonometer, paying attention to the child’s hydration, prernedication, depth of anaesthesia and especially to the choice of anaesthetic agent used. Tonography, which records the facility or otherwise of aqueous outflow, helps both in diagnosis and evaluating response to treatment. Using a contact lens, the surgeon can examine the angle and an excellent view of the detailed anatomy is obtained through the operating microscope. If considered necessary, the ophthalmologist can proceed there and then with surgery.

Treatment The treatment of congenital glaucoma is surgical and the operation of choice is goniotomy.

This aims at restoring the physiological pathway from the anterior chamber into Schlemm’s canal by incising the obstructing tissue. A goniotomy knife is introduced into the anterior chamber and passed across into the opposite angle, where the tip engages the trabecular tissue which is swept by a circumferential incision6. The operation is repeatable if necessary. Post-operatively. miotics are used for several months until filtration is satisfactorily established.

It is interesting that, following the first description of goniotomy by CARLO DE VINCENTIIS in 1893’, it fell into disregard for 40 years. BARK AN^ reinstated it in 1936 and today, with few modifications, it is practised universally.

In t rabecul~tomy~, an external radial incision over Schlemm’s canal allows a probe to be inserted into it. This is rotated towards the pupil and enters the anterior chamber, having broken through the trabecular meshwork. Operations aimed at producing a fistula between the anterior chamber and the subconjunctival or the suprachoroidal space have had disappointing results, except perhaps goniopuncturelO.

In cyclodiathermy the ciliary body is deliberately damaged, and in cycloanaemisation its blood supply is reduced, by surface diathermy. Cryotherapy may also be used, as it lessens the risk of scleral ectasia. The result of these attempts to reduce the production of aqueous is short-lived, and does no more than lessen ocular discomfort in patients who have failed to respond to treatment.

Prognosis Without any treatment, almost all infants with congenital glaucoma will go blind. The

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enlarged and weakened eye is very prone to trauma. A few cases may arrest spontaneously, either because of delayed development of the angle or because the trabecular meshwork is forced open by the rising intra-ocular pressure.

The later in infancy that clinical signs appear, the greater is the likelihood that surgery will be successful, for the presence of symptoms in the neonatal period implies a severe ob. struction in the drainage pathway. Unfortunately, bilateral cases respond less well to treat- ment than do unilateral ones and familial cases less well than those occurring sporadically. Although the results of goniotomy vary a little among surgeons, in general more than 80 per cent of buphthalmic patients may be expected to have the intra-ocular pressure controlled; some having been followed-up now for 20 years. The prognosis must also be expressed in terms of the child’s vision, but the age of these patients makes it difficult to estimate visual acuity or fields. Recently, among children with normal pressure following goniotomy (who were capable of visual assessment) surprisingly poor vision was found in approximately 50 per cent of them, despite many having full fields and normal optic discsll. In some this could be attributed to corneal scarring from oedema, but attention was drawn to the refractive state of the eye in congenital glaucoma. Although the globe becomes elongated and therefore myopic, this is partly neutralised by the corneal curvature becoming flatter, and by any retrodisplacement of the lens that may occur. Astigmatism is often found and it was considered that anisometropia-in which a refractive difference exists between the two eyes-was causing amblyopia. Besides spectacle correction of any refractive error, it is now stressed that these children may need periods of occlusion of the better seeing eye to overcome this amblyopia.

Helping the Parents The ophthalmologist, paediatrician and, later, th.e school health service doctor together

will be able to help parents meet the immediate problems of having a child with glaucoma and the later educational and social problems of buphthalmic children, especially when, in unsuccessful cases, blind or partially-sighted registration is needed. They are also in a position to offer genetic counselling. Nevertheless the greatest emphasis must still be laid upon the need to know the danger signals and be ready to suspect the presence of congenital glaucoma, for with early, effective treatment, infantile blindness can be prevented.

Moorfields Eye Hospital, City Road, London EClV 2PD.

HUGH WILLIAMS

REFERENCES I . Duke-Elder, S. (1964) System of Ophthalmology. VoI. 111. Normal and Abnormal Development. Part 2.

2. Anderson, J. R. (1939) Hydrophthalmia or Congenital Glaucoma. London: Cambridge University

3. Worst, J. G. F. (1966) The Pathogenesis of Congenital Glaucoma. Assen: Royal VanGorcnm. 4. Richardson, K. T. (1968) ‘Optic cup symmetry in normal newborn infants., Invest. OphfhaL, 7, 137. 5. Becker, B., Shaffer, R. N. (1965) Diagnosis and Therapy of the Glaucomas. 2nd edn. St Louis: C. V

6. Lister, A. (1965) ‘Technique of goniotomy.’ Brit. J. Ophthal., 49, 594. 7 . de Vincmtiis, C. (1893) ‘Incisione dell’angolo irideo nel glaucoma.’ Ann. Offa l . , 22, 540. 8. Barkan, 0. (1936) ‘A new operation for chronic glaucoma.’ Amer. J. Ophfhal., 19, 951. 9. Harms, H., Dannheim, R. (1969) ‘Epicritical consideration of 300 cases of trabeculotomy.’ Trms.

10. Scheie, H. G. (1968) ‘Congenital glaucoma.’ I n Beard, C. (Ed.) Symposium on Surgical and Medical

1 1 . Haas, J. (1968) ‘Principles and problems of therapy in congenital glaucoma.’ Invest. Ophthal., 7, 140.

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Management of Congenital Anomaliej of the Eye. St Louis. C. V. Moshv, p. 342.