Saturday, 23 July 2011

Treating Cataract in Children

Published in "Panorama"

Cataract Surgery Brings Hope to Visually Impaired Children

Baby Dinesh received the best birthday gift one co9uld ever get – the gift of vision! For, born of congenitally blind parents, Dinesh was born blind with cataract in both eyes. Fortunately for him, his condition was diagnosed promptly and he underwent cataract surgery, a week before he turned one.

World wide, 0.03% to 0.1% children are believed to be affected by cataract and impaired vision. While some cataracts are present at birth, others develop during the first few months or years of life, reveals Dr.Arun Samprathi, Pediatric Ophthalmologist, Narayana Nethralaya, Bangalore.

What causes cataract? Dr.Samprathi explains, “There is certainly a heredity factor involved. The risk of congenitally blind parents giving birth to a baby with cataract, is as high as 50%. Metabolic or systemic abnormalities are other contributory factors to the condition. In cases where a pregnant woman is infected with Rubella or German Measles, especially in the first
trimester of pregnancy, she is likely to give birth to a child with cataract. Similarly, when pregnant women are exposed to radiation or laser during pregnancy, or they take certain drugs like steroids or even some analgesics or antibiotics, the risk giving birth to babies with cataract.

If the mother suffers from Galactocemia, a metabolic disorder which affects the eye, she is likely to transmit the condition to the child who is then likely to be born with cataract. Though injury during childbirth is not a common cause of childhood cataract, it can nevertheless be a contributory factor. Post-birth injury to the cornea, can cause cataract,” adds Dr.Samprathi.

In many instances, however, there is no known cause for childhood cataract, reveals Dr.Samprathi. In the older children, cataracts are often associated with injuries or ocular inflammation related to jevenile rheumatoid arthritis, he adds.

What is a cataract and how does is form in newborns? Dr.Samprathi explains, “The first three months of pregnancy are very crucial to the development of the eye lens, which is naturally and normally transparent. So any insult during this period to the lens, can lead to its becoming abnormal. If for any reason, this lens becomes cloudy or opaque, inhibiting the passage of light to pass through it to the retina, thus impairing vision, we have cataract. Again, during the development of a child, the first 2-3 years are extremely crucial for the development of the eye, particularly the retina which is not mature at birth.

As the child keeps seeing, it stimulates the retina to mature. 80% of the retinal maturation occurs by the end of 2 years. Therefore any injury or insult during this period, will affect the retinal development, leading to a condition called lazy eye or amblyopia. Also, if the cataract is present in just one eye, the child will usually use the normal eye and ignore the eye with a cataract, leading to the lazy eye and strabismus or wandering eye.”

The cataract in children may cause partial or total visual impairment, depending on the extent of opacity of the lens and whether the opacity is in the center of the lens or in the periphery.

How is cataract in children diagnosed? Simple torch light, slit lamp and ophthalmoscope are the main diagnostic tools, with ultrasound used to confirm diagnosis, reveals Dr.Samprathi.

But how can the condition be diagnosed in newborns unless you are aware of the risk factors? “Yes,” admits Dr.Samprathi, “it is difficult to assess the visual aspect in a new born, immediately after birth. One thing, where risk factors are known, as in the case of Dinesh where both parents were congenitally blind, necessary measures have to be taken diagnose the problem in the child, through the use of the diagnostic tools mentioned. If for example, the baby’s eye lens is totally opaque, it can be diagnosed using the slit lamp. In all other cases, routine eye check by a pediatrician is imperative following birth so as not to miss diagnosis.”

Dr.Samprathi elaborates on simple measures to diagnose the condition in babies: “If you simply flash a torch light, any child who is more than 6 weeks, will immediately respond and look at the light. If you move the light from side to side, the child will shift its focus in the direction of the light, indicating all is well with its vision. Additionally, if we find that the child is able to keep its gaze fixed at the source of light, all is fine with its vision. On the other hand if its gaze starts wandering from the light source, we know something is wrong.”

Once a visually significant cataract is diagnosed, prompt surgery and rehabilitation are imperative to maximize visual development. However, the decision to perform surgery itself, will be determined by the general health of the child, emphasizes Dr.Samprathi. “Cataract surgery can be performed within 24 hours of a child’s birth if the child is fit for anesthesia. But usually, most of the times, these children will have other systemic problems which preclude anesthesia. If Rubella is the cause of the cataract, the child may also suffer from some heart problem. Many times, cataract is not alone, but is associated with other syndromes like Down’s or Lowe’s and cataract in fact, may be the first clue indicating these underlying conditions. So, though ideally, surgery should be performed at the earliest, to get the best visual result, a complete systemic evaluation of the child is a must and necessary treatment given, before plunging into cataract surgery.”

Dr.Samprathi adds, “Apart from these conditions, an eye with a cataract, may have other eye abnormalities like glaucoma or in the retina. So a complete eye evaluation is necessary

What does the actual surgery involve? The surgery, performed under general anesthesia, involves a process of irrigation and aspiration. Dr.Samprathi explains, “The lens is in a bag, in the front surgact of which we make a small opening. We then irrigate it with some fluid and suck out the cataract-affected lens, leaving the bag intact so that we may fit it with an
artificial lens, the IntraOcular Lens (IOL).”

Is the IOL implanted immediately after the cataract is removed? The eye’s natural lens has to be replaced by a “new” lens to help focus the visual image, following removal of the cataractous lens. This may be accomplished with glasses, contact lenses, or an IOL placed inside the eye at the time of the cataract surgery. But we don’t do an IOL implant in children below two years, explains Dr.Samprathi. “This is because 80% of the eye growth occurs in two years, by which time we will know its eye lens power. So below this age, it makes no sense implanting an IOL. So a child is encouraged to see using contact lens or glasses till two years. Yes, having said this, there is 100% possibility of the eye bag becoming opacified again, following the cataract removal. So what we do now is, remove a part of the eye bag which opacified, by a technique called Primary Posterior Capsulotomy, leaving the pupilary area to remain permanently clear. By doing this, we bring down the chance of recurrence of opacification to less than 2%.”

Will the cataract surgery distort the anatomical structure of the eye, thereby causing astigmatism? Dr.Samprathi responds, “Astigmatism can occur because we are making an incision on the sclera; so we are changing the curvature of the cornea. There are other complications which can occur in a child, which is why we say that surgery is only 25% of the success of the whole process. The other 75% depends on the treatment for amblyopia which has already occurred and the long follow up which is required, every six months, throughout the life of the child, to look for any complications.”

What are these other complications that could occur? One of the commonest is retinal detachment following glaucoma, because intra ocular pressure can go up after a cataract operation. This high pressure can compress the optic nerve and cause optic atrophy or damage to the optic nerves, explains Dr.Samprathi. “This has to be diagnosed and treated promptly to prevent loss of vision. So we have to keep a very close watch on children who have undergone cataract surgery.”

What are the risks of the surgery and what is the recovery period? With modern operating techniques, risk is extremely low, emphasizes Dr.Samprathi. “The child may have some redness of the eye and inflammation which should settle down within a couple of weeks. How much of vision it gets will depend on the extent of the cataract, the age at which surgery is performed, the health of the retina and its maturity. Because till such time that the child has been operated upon, it is used to the lazy eye; so some amount of lazy eye will be there. But it may improve over a period of time, though it will be difficult to say in which child it will improve and in which it will not. Having said that, playway methods to stimulate the eye, must be undertaken. For an older child, for instance, drawing, painting, writing, and reading are the best stimulants for vision development. The still smaller children should be encouraged with building blocks, toys, et al, things which will hold a child’s visual concentration. This will certainly stimulate the retina more and more and aid in better vision.”

Why is it that even when an IOL is implanted, glasses or contact lenses may still be required? Dr.Samprathi explains, “Because, the eye’s natural lens functions like a zoom camera and can focus at any range. But the IOL that we implant, it cannot change its shape to accommodate all ranges of vision; it can get focused for only one particular distance. So, usually while reading and writing, the child will have to supplement its vision with glasses or contact lenses.”


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