Medical Features

Living with Lowe Syndrome

III. Medical Features, cont'd.

B. Eyes
The ocular features of Lowe syndrome include congenital cataracts (in all affected males), glaucoma (in about half of all affected males), corneal degeneration, strabismus (crossed eyes), and nystagmus. The effectiveness of treatments for these conditions varies and any of these conditions may cause significant visual disability. In some rare cases in which the eye has become blind and painful, removal of the eye, or enucleation, may be the best option.

1. Cataracts. In all affected males, cataracts are present at birth although they may not be noted or diagnosed until the child is several weeks old. A cataract is an opacity or a clouding of the lens of the eyes. Normally, the lens in the eye, like the lens in a camera, is clear or transparent. The lens focuses light onto the retina, which lines the back two-thirds of the eye. The retina functions like the film in a camera to "take the picture" and transmit it through the optic nerve to the brain, where one "sees." A cloudy or milky lens prevents the passage of light into the eye and thus limits the focusing of clear pictures onto the retina. It is important to remove the cataracts as early as possible, preferably within the first few days or weeks of life, to provide the clear images to the retina (and thus to the brain) and to promote the proper visual stimulation necessary for the infant brain and the visual system to develop as much useful vision as possible.

The opaque, grey-white lens is removed surgically with microscopic instruments after the infant is placed under general anesthesia. A small opening is made into the eye, typically at the edge of the zone where the clear cornea joins the white of the eye. Microscopic instruments are inserted into this opening to cut up and fragment the cataract and to remove the small pieces.

This operation usually provides a clear pathway for images from the outside world to enter the eye. However, since the lens has been removed, the eye has lost much of its focusing ability. Eyeglasses or contact lens must be used to compensate for this loss. For most children, removal of the cataracts and the use of glasses or contact lenses yield substantial improvement in vision. Surgical implantation of artificial lenses is not usually recommended, for several reasons. These include: the small size of the eyes of infants and the inability to predict reliably the "adult size" of the eyes later in life; the possible complications from glaucoma, which has a high rate of frequency in Lowe syndrome; the risk of other complications of surgery; the uncertainty of long term stability of artificial lenses in infants in general; and the possibility of problems with the cornea in Lowe syndrome. Although some ophthalmologists are now investigating the implantation of some newer styles of artificial lenses in infants, the significant possible complications in Lowe syndrome make such implantation highly investigational at this time.

2. Glaucoma. Glaucoma develops in about half of boys affected with Lowe syndrome. Glaucoma is a disease in which the pressure within the eye becomes so high that, if sustained, the optic nerve is damaged and sight is permanently lost. Sustained, elevated pressure can cause the eye to enlarge abnormally. This condition is called buphthalmos.

Treatment of infantile glaucoma is difficult. Medicinal eye drops may be tried first to try to lower the pressure, but they are rarely effective by themselves. If eye drops do not work, various surgical procedures may be tried to create a new channel to allow the fluid inside the eye to leave more easily and thereby to lower the pressure. Sometimes an artificial valve is sutured into the front of the eye to control release of fluid and thus decrease the pressure. Unfortunately, in some cases glaucoma is so severe it cannot be controlled, ultimately causing the eye to become completely blind.

The risk of glaucoma is the major reason for frequent examinations under anesthesia during infancy and childhood. If the child is able to cooperate when he is older, examinations in the ophthalmologist's office may be possible. Although the risk of glaucoma lessens considerably after the first year, it may develop even after 10 years of age. As a result, individuals with Lowe syndrome should have routine glaucoma (pressure) checks at all ages.

3. Corneal degeneration. The cornea is the clear "watch crystal" of the front surface of the eye. By their teenage years, about half of boys with Lowe syndrome develop what appears to be scar tissue, often called a keloid [Image 1] [Image 2] [Image 3] [Image 4], over the cornea. (Some physicians believe that this growth is not a true keloid, but probably represents a fibroma or benign growth of fibrous tissue which resembles a growing scar.) The reason for this growth is unknown. Keloids, which may affect one or both eyes, can cause visual impairment when they cover the center of the cornea and prevent light from entering the eye.

Keloids may be surgically removed, but tend to recur. In addition, surgical removal may leave a scar that cannot be removed without creating more scarring. Medical treatment has been unsuccessful and corneal transplantation is not recommended because of the difficulty with postoperative management, including drops, examinations, and management of problems. Post-operative evaluation and care is difficult in children in general and even more so in boys with Lowe syndrome. In many cases, keloid formation results in progressive blindness despite all treatments.

4. Strabismus. Many children with Lowe syndrome develop strabismus (crossed eyes), a condition in which the eyes are not straight and parallel and may not move together well. In infants, this usually means that one eye turns in. Crossed eyes in infancy may adversely affect the development of the pathways for vision to the brain and as a result, eyesight can be significantly impaired. Treatment begins with a complete evaluation of the movements of the eyes and of their muscles, followed by a careful refraction evaluation to check the prescription for glasses (or contact lenses). A good prescription can help the eyes focus and stay straight.

After the best possible refraction has been obtained, treatment continues by patching one eye (usually the preferred or straight eye, in order to force improvement in the "lazy" eye with the poorer sight). As soon as the child can watch a target equally well with each eye, surgery is performed on the muscles of the eyes to align the eyes so they are straight. If the vision is equal, there is a reasonable chance that the eyes will remain straight after surgery. Even after surgery for strabismus, however, the child should be followed carefully for reoccurrence of eye crossing and for changes in refraction to maintain the best possible vision in each eye.

5. Nystagmus. The term nystagmus refers to an uncontrollable rhythmical movement of the eyes. While nystagmus by itself does not cause loss of vision, it is often caused by conditions related to poor vision. Occasionally, it may be caused by changes in brain function. The genetic defect that causes Lowe syndrome may also affect the development of the retina in the eye (which is, in reality, part of the brain). Nystagmus may be associated with abnormal function of the retina and the resultant poor vision. Unfortunately, there is no effective permanent treatment for nystagmus except to attempt to develop and retain good vision as early in life as possible.

6. Enucleation. Under rare circumstances, especially when an eye is blind and painful, it may be necessary to remove the eye surgically in a procedure called enucleation. After the eye is removed the ophthalmologist will implant a ball in order to maintain the volume inside the orbit and to stimulate normal growth of the facial bones.

After several weeks of healing, a "glass eye" shell is fitted over the healed surface. Recently developed surgical techniques use newer materials that provide better movement of the artificial shell. Because the shell is primarily cosmetic, its use is optional. Some parents may decide against the use of an artificial shell for their child, particularly if the child's level of cooperation is less than optimal.