Dr. Cheung’s blog 5/1/2013

Dr. Cheung’s blog 5/1/2013

May 1, 2013


I have some very amazing and exciting news to share.  My wife and I are pregnant, with twins!!!  We just had our 20-week prenatal ultrasound appointment last week, and here are some  photos for me to brag about.   One of them, the boy, is destined to be a yoga master.  He is practicing the plow pose in utero, far more flexible than his old man.

The other twin, the girl, is a bit more subdue.  She appears to be reclining in a chaise lounge, posing as a model in a classic Italian painting. 
I am predicting trouble and she will make my hair much grayer than it is now.

The ultrasonographer who took these photos was very kind and highly skilled.  Knowing that we are both physicians, she asked us if there was anything specific that we wanted to see.   As the ophthalmologist, I, of course, said eyes.  And there they are: the developing eyes of my boy within his orbits in axial cross section.  The two tiny bright spots within the circles of darkness are the developing lens!

The fetal development of the human eyes is a highly complex and fascinating process.  The first sign of the developing eyes occurs at 22 days of gestation as a thickening of the embryo’s surface at the widest part of the head.  This thickening then enlarges and balloons outwards into a C-shaped cup but remains connected to the rest of the head through a tubular stalk.   At 28 days, another thickening on the surface develops and this will become the baby’s lens when it eventually pinches off from the surface and moves into the center of the C-shaped developing eye.

Do you know that the eye is the first part of the body to development pigment?  By the second month of gestation, pigment granules (melanin) begin to appear in the retina.  The pigment helps guide the traffic pattern of the nerve fibers from the eye to the brain.  That is why patients with albinism have abnormal optic nerve conduction and their vision is usually abnormal.  In the second month, eyelid folds and the eye muscles that move the eyeballs also start to develop.  The eyelids meet and fuse by the third month and they begin to separate by the fifth.  This is the stage where the twins are now.

Sometimes, knowing too much may not be a blessing.  Over the years, I have seen enough as to what can go wrong in this miraculous process that keeps me up at night about the twins.  While the majority of cataracts that I see in my office occur in the senior population, babies and children can develop cataract too.  In fact, I just removed one from a delightful five year old girl yesterday.  There are many causes of pediatric cataracts, any misstep along the development process as outlined above can cause a cataract.  In addition, infections, inflammation, trauma, metabolic diseases can all cause cataracts among the youngs.  Genetics is an important factor too. Inherited cataracts are most commonly transmitted to the offsprings in an autosomal fashion, that is, the baby has a 50/50 chance of inheriting and developing the cataract from the parents.  Often time, when I see a cataract in a child, I can also find one in the parents.  The parents are just lucky that they have a mild form of the disease.

Removing a cataract in a young child or infant is technically more challenging than in an adult.  The wall of the eye in an infant is very soft and the eye has a tendency to collapse when we enter the eye to remove the cataract.  The capsule that surrounds the cataract lens is also far more elastic than in adults.  It is much more likely to rip when we open the capsule to gain access to the cataract.  The size of the eye, of course, is much smaller.  Manipulating instruments or placing an intraocular implant is awkward within this tight space and experience really counts in these cases.

In adult cataract surgery, an intraocular implant is almost always placed to replace the eye’s natural lens.  In a young child, since the eye is still growing, an implant that produces a sharp image at the time of the surgery will not be the right one for the child in several years.  An alternative is contact lens, which power can be changed to match the growing eye.  Putting a contact lens in an infant, however, is not an easy matter and may create a fair amount of parental stress.  To compare these two options, a multicenter randomized clinical trial was conducted for infants less than 6 months of age with cataract in one eye.  The Infant Aphakia Treatment Study Group found that the visual outcome at one- year of age is the same for the contact lens and the implant groups, although the babies that received the implant had more complications and require more additional surgeries than the contact lens group.

Perhaps the most difficult aspect of taking care of a child with congenital cataract for both the doctor and the parents is amblyopia.  Amblyopia is reduced vision in one or both eyes due to form deprivation or abnormal interaction between the two eyes.  Children with cataract in one eye and a normal fellow eye are at highest risk of developing amblyopia in the affected eye.  In these children, the neural pathway from the eye with the cataract to the brain is underdeveloped compared to the fellow eye.  Even when the cataract is removed and a good image is obtained with contact lens or implant, this disadvantage in the neuro-circuitry still persists.  The only way that this can be reversed is by penalizing the good eye by putting a patch over it or by putting a drop in to blur that eye.  Patching the good eye is not fun for the child or the parents.  To make matter worse, this treatment is only effective in the first few years of life when the brain is still amenable to be changed.  Once that window of opportunity is over, no amount of patching, drops, glasses or implants can make a substantial difference in the visual outcome for the child.

Delivering this kind of bad news to parents is never easy and we doctors strive to do this in a way that is compassionate and informative at the same time.  Being a father helps me put my doctor self in the parents’ shoes – to really know how it feels to receive the diagnosis and the prognosis.   Three months after my first daughter, Claire, was born, I saw a baby girl in my office with a cataract in one eye.  She was the same age as my daughter and just as angelic.  As I was explaining to the mother the risks and potential complications of the surgery, she started to cry.  While I had gone through that with parents many, many times before and I am generally not an emotional person, I too was struck with an overwhelming sense of grief and loss and tears began to roll down my cheeks.  I thought of Claire as the patient in the room and the realization that her life would be very different than what I imagined for her.  It was the best lesson in empathy and I firmly believe that I am a better doctor because I am a father.  I am so looking forward to fatherhood again with the twins.  They will make my life immensely richer, both personally and professionally.