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Congenital Cataract
CONGENITAL CATARACT PAUL A. CHANDLER, M.D.
The term "congenital cataract" usually designates a significant opacity in the lens present at birth or developing shortly afterwards. It thus includes a wide variety of lens opacities with various etiologies. ETIOLOGY
From the standpoint of etiology* congenital cataract may be divided into three main categories: (l) true hereditary cataract, (2) cataract due to metabolic disorders, (3) cataract due to infectious agents during pregnancy. Hereditary cataract is by far the most frequent type. It affects both males and females and is usually transmitted as a dominant character, but may occur sporadically. It may develop several weeks after birth. Certain metabolic disorders are occasionally responsible ,for the development of cataract in infancy and childhood. Tetany in the mother during pregnancy or in the child after birth results in a high incidence of cataract. Cataract is often seen in association with rickets, but it is now felt that it is not rickets per se, but the low calcium-high phosphorus ratio which occurs in some cases at some stages that is responsible for the development of cataract. Galactosemia, although not a frequent cause of cataract, is of great interest in that it represents a disturbance in metabolism that has been found attributable to a single enzyme system. The cataract associated with galactosemia may be reversible if the underlying metabolic disorder is corrected in time. Of the infectious agents responsible for congenital cataract, rubella is the most important. This was first recognized by Gregg * * after a wide-
* Cataract due to injury or other ocular disease in infancy or childhood will not be considered in this discussion. ** N. M. Gregg: Congenital Cataract Following German Measles in Mother. Tr. Ophth. Soc. Australia, 3:35-46, 1942.
170
CONGENITAL CATARACT
spread epidemic in Australia. If the mother acquires rubella during the first trimester of pregnancy, the incidence of cataract in the offspring is high. Other types of infection have been held responsible for congenital cataract, but the evidence is not so clear cut as in rubella. Rubella cataract is often associated with other congenital defects. MORPHOLOGIC TYPES
There are many morphologic types of congenital cataract. The opacity may be confined to a small area anywhere in the lens. It may involve only the anterior capsule in the axial zone (pyramidal cataract), or it may be perinuclear (lamellar cataract). A morphologic classification has practical value only so far as vision is affected. The location, size and density of the opacity of whatever type are the most important factors. As a rule the opacity shows little or no increase in density with the passage of time. When the opacity is small or not very dense, vision may be little affected. On the other hand, in the case of complete cataract vision is reduced to the perception of light. Between these two extremes all degrees of visual impairment may exist. If the cataract is sufficiently dense at birth or shortly after, visual acuity does not develop properly, and nystagmus results. This nystagmus is permanent, whether or not operation is performed. If the cataract develops some time after birth, when central vision is well established, nystagmus does not occur. With unilateral cataract, if it is of sufficient density to impair vision seriously, amblyopia develops just as in cases of unilateral squint, and a curious vertical nystagmus in the affected eye is often noted. TREATMENT
The decision as to whether or not operation is indicated is based on the degree of visual impairment. For bilateral complete or nearly complete cataract there can be no question but that operation is indicated. If the opacity is slight, it is readily apparent that no treatment will be required. One sees many borderline cases with some visual impairment, but in which the vision is sufficient to permit a fairly normal life. What degree of visual impairment requires operation? If visual acuity is 20/50 or better, most ophthalmologists feel that operation should not be done, Some children with a vision of 20/70 are able to get along satisfactorily without operation. In doubtful cases the child may be given a trial in school. If he gets along well, no operation is indicated. If, on the other hand, he appears to have great difficulty in school, then operation is advised. In all borderline cases it is important that operation be deferred until the child is old enough for an accurate measurement of visual acuity. This may mean that in some cases operation is not done
PAUL A. CHANDLER
171
until the child is five or six or even seven years of age. This delay in borderline cases, even at the expense of losing a year in school, is well worth while if, thereby, operation can be avoided. When should operation be done? There is a considerable difference of opinion among ophthalmologists concerning this point. All are agreed that in borderline cases operation should be deferred until the vision can be accurately measured. It is in the cases of complete or nearly complete cataract that a difference of opinion exists as to the optimum time for operation. From a theoretical standpoint it would appear that the earlier operation is done, the better the ultimate visual acuity. However, there are no statistics available which prove that this is true. There is no doubt that the child develops faster in other ways if operation is done early. Advocates of deferring operation until the child is two or three or even four years of age point to the fact that the incidence of complications in the reported cases in which operation is done under the age of two years is definitely greater than in cases in which operation is done after the age of two years. Some of us feel that most of these complications can be avoided, even if operation is done in infancy, if the proper choice of operation is made and it is properly carried out, and hence that there is no really valid reason for deferring operation in a child totally blind from congenital cataract. A number of different operative procedures have been used for congenital cataract. The technical aspects of these various procedures need not be discussed here. Suffice it to say that the judgment of the surgeon in selecting the proper operation for a given case is of paramount importance. The technical aspects of the operation are often much more difficult than in the adult, and demand the utmost in judgment and skill on the part of the surgeon. The results of congenital cataract surgery are far inferior to those of cataract surgery in the adult. Eyes may be lost from postoperative inflammation, from glaucoma, from detached retina and other complications. With a perfect operative result 20/20 vision is rarely obtained. In incomplete cataract when no nystagmus is present, vision is usually good enough, provided there are no operative or postoperative complications, for the patient to lead a normal life. In complete cataract, nystagmus is always present and, as stated above, persists throughout life. In these cases with a perfect surgical result visual acuity is usually on the order of 20/200 or 20/70, sometimes less than 20/200. These children are therefore on the borderline between education as a seeing child and education in a school for the blind. They should be given a trial in sight-saving classes. The more intelligent may get along, though with some difficulty. Others will not do well and had best go to a school for the blind.
172
CONGENITAL CATARACT
SUMMARY
The subject of congenital cataract is discussed from the standpoints of etiology, classification of the various types, operative treatment, and the results of surgery. From the standpoint of etiology it can be seen that there is opportunity for preventive measures. Patients with the hereditary type of cataract should be advised against having children. Prompt attention in cases of tetany and galactosemia may prevent cataract. In the case of known infection with rubella during the first trimester of pregnancy, therapeutic abortion should be seriously considered. The type of cataract is of importance only in accordance with its effect on vision. Operation for congenital cataract is accompanied by many more hazards than is cataract surgery in the adult, and the operative results are far inferior. Nevertheless, if the operation is properly selected and properly performed, most patients have sufficient vision to lead a useful life. 5 Bay State Road Boston 15, Massachusetts
The term "congenital cataract" usually designates a significant opacity in the lens present at birth or developing shortly afterwards. It thus includes a wide variety of lens opacities with various etiologies. ETIOLOGY
From the standpoint of etiology* congenital cataract may be divided into three main categories: (l) true hereditary cataract, (2) cataract due to metabolic disorders, (3) cataract due to infectious agents during pregnancy. Hereditary cataract is by far the most frequent type. It affects both males and females and is usually transmitted as a dominant character, but may occur sporadically. It may develop several weeks after birth. Certain metabolic disorders are occasionally responsible ,for the development of cataract in infancy and childhood. Tetany in the mother during pregnancy or in the child after birth results in a high incidence of cataract. Cataract is often seen in association with rickets, but it is now felt that it is not rickets per se, but the low calcium-high phosphorus ratio which occurs in some cases at some stages that is responsible for the development of cataract. Galactosemia, although not a frequent cause of cataract, is of great interest in that it represents a disturbance in metabolism that has been found attributable to a single enzyme system. The cataract associated with galactosemia may be reversible if the underlying metabolic disorder is corrected in time. Of the infectious agents responsible for congenital cataract, rubella is the most important. This was first recognized by Gregg * * after a wide-
* Cataract due to injury or other ocular disease in infancy or childhood will not be considered in this discussion. ** N. M. Gregg: Congenital Cataract Following German Measles in Mother. Tr. Ophth. Soc. Australia, 3:35-46, 1942.
170
CONGENITAL CATARACT
spread epidemic in Australia. If the mother acquires rubella during the first trimester of pregnancy, the incidence of cataract in the offspring is high. Other types of infection have been held responsible for congenital cataract, but the evidence is not so clear cut as in rubella. Rubella cataract is often associated with other congenital defects. MORPHOLOGIC TYPES
There are many morphologic types of congenital cataract. The opacity may be confined to a small area anywhere in the lens. It may involve only the anterior capsule in the axial zone (pyramidal cataract), or it may be perinuclear (lamellar cataract). A morphologic classification has practical value only so far as vision is affected. The location, size and density of the opacity of whatever type are the most important factors. As a rule the opacity shows little or no increase in density with the passage of time. When the opacity is small or not very dense, vision may be little affected. On the other hand, in the case of complete cataract vision is reduced to the perception of light. Between these two extremes all degrees of visual impairment may exist. If the cataract is sufficiently dense at birth or shortly after, visual acuity does not develop properly, and nystagmus results. This nystagmus is permanent, whether or not operation is performed. If the cataract develops some time after birth, when central vision is well established, nystagmus does not occur. With unilateral cataract, if it is of sufficient density to impair vision seriously, amblyopia develops just as in cases of unilateral squint, and a curious vertical nystagmus in the affected eye is often noted. TREATMENT
The decision as to whether or not operation is indicated is based on the degree of visual impairment. For bilateral complete or nearly complete cataract there can be no question but that operation is indicated. If the opacity is slight, it is readily apparent that no treatment will be required. One sees many borderline cases with some visual impairment, but in which the vision is sufficient to permit a fairly normal life. What degree of visual impairment requires operation? If visual acuity is 20/50 or better, most ophthalmologists feel that operation should not be done, Some children with a vision of 20/70 are able to get along satisfactorily without operation. In doubtful cases the child may be given a trial in school. If he gets along well, no operation is indicated. If, on the other hand, he appears to have great difficulty in school, then operation is advised. In all borderline cases it is important that operation be deferred until the child is old enough for an accurate measurement of visual acuity. This may mean that in some cases operation is not done
PAUL A. CHANDLER
171
until the child is five or six or even seven years of age. This delay in borderline cases, even at the expense of losing a year in school, is well worth while if, thereby, operation can be avoided. When should operation be done? There is a considerable difference of opinion among ophthalmologists concerning this point. All are agreed that in borderline cases operation should be deferred until the vision can be accurately measured. It is in the cases of complete or nearly complete cataract that a difference of opinion exists as to the optimum time for operation. From a theoretical standpoint it would appear that the earlier operation is done, the better the ultimate visual acuity. However, there are no statistics available which prove that this is true. There is no doubt that the child develops faster in other ways if operation is done early. Advocates of deferring operation until the child is two or three or even four years of age point to the fact that the incidence of complications in the reported cases in which operation is done under the age of two years is definitely greater than in cases in which operation is done after the age of two years. Some of us feel that most of these complications can be avoided, even if operation is done in infancy, if the proper choice of operation is made and it is properly carried out, and hence that there is no really valid reason for deferring operation in a child totally blind from congenital cataract. A number of different operative procedures have been used for congenital cataract. The technical aspects of these various procedures need not be discussed here. Suffice it to say that the judgment of the surgeon in selecting the proper operation for a given case is of paramount importance. The technical aspects of the operation are often much more difficult than in the adult, and demand the utmost in judgment and skill on the part of the surgeon. The results of congenital cataract surgery are far inferior to those of cataract surgery in the adult. Eyes may be lost from postoperative inflammation, from glaucoma, from detached retina and other complications. With a perfect operative result 20/20 vision is rarely obtained. In incomplete cataract when no nystagmus is present, vision is usually good enough, provided there are no operative or postoperative complications, for the patient to lead a normal life. In complete cataract, nystagmus is always present and, as stated above, persists throughout life. In these cases with a perfect surgical result visual acuity is usually on the order of 20/200 or 20/70, sometimes less than 20/200. These children are therefore on the borderline between education as a seeing child and education in a school for the blind. They should be given a trial in sight-saving classes. The more intelligent may get along, though with some difficulty. Others will not do well and had best go to a school for the blind.
172
CONGENITAL CATARACT
SUMMARY
The subject of congenital cataract is discussed from the standpoints of etiology, classification of the various types, operative treatment, and the results of surgery. From the standpoint of etiology it can be seen that there is opportunity for preventive measures. Patients with the hereditary type of cataract should be advised against having children. Prompt attention in cases of tetany and galactosemia may prevent cataract. In the case of known infection with rubella during the first trimester of pregnancy, therapeutic abortion should be seriously considered. The type of cataract is of importance only in accordance with its effect on vision. Operation for congenital cataract is accompanied by many more hazards than is cataract surgery in the adult, and the operative results are far inferior. Nevertheless, if the operation is properly selected and properly performed, most patients have sufficient vision to lead a useful life. 5 Bay State Road Boston 15, Massachusetts