October 1, 2016
Screenings for the Young and the Old
I turned the big 50 this year!! I explicitly asked my wife not to do anything special and my birthday was passed unceremoniously with a nice dinner and chocolate cake at home with the kids. I “celebrated” this milestone by running the Vancouver marathon in May which I did when I was forty. Nobody in the right mind would think of 26.2 miles of pain and sweat as a form of celebration. I guess it is a male ego thing; still trying to prove that I am in my prime. In the end, I ran it faster by one hour and ten minutes compared to a decade ago. It was a sweet personal victory after six months of daily training in preparation for this race. I gorged myself with the amazing Chinese food and dessert crepes in Vancouver as my reward. It was all worth it.
While I feel great at my age, my family doctor reminded me that I am no spring chicken when I went for my regular check-up two weeks ago. He checked my PSA (prostatic surface antigen), cholesterol, thyroid function which I all passed in flying colors. I dreaded, however, the obligatory colonoscopy screening at 50 for colon polyps and cancer. They say that doctors make the worst patients. It is true. I rationalized the many reasons why I do not need a colonoscopy. Lack of family history, good health etcetera, etcetera. My family physician offered me a new screening test called Cologuard which detect for DNA fragments in stool sample for colon cancer. The idea was so very appealing to me. No need to take two days off from work, no drinking that awful colonics as a prep, no pain, no risk! Why not? On further research though, it does not appear that I can take this short cut.
First off, my insurance carrier won’t cover for it. They considered it experimental and it will cost me over $600 every three years, the recommended testing interval. Secondly, while the test has a very high sensitivity (92%) and specificity (90%) for colon cancer, the detection rate for polyps, the precursors to colorectal cancer, is much lower (69%).
What do these numbers mean? For every test that we doctors administer, we have to consider the sensitivity and the specificity of the test. Sensitivity means the likelihood of the test in correctly identifying those with the disease and specificity means the likelihood of the test in correctly identifying those without the disease. Obviously, a test that is 100% sensitive and 100% specific would be ideal but that is often not achievable. A test that has a high sensitivity and low specificity meant that it is very good at picking up the disease but many of those that are tested positive may actually be free of the disease (false positives). This might cause unnecessary emotional burden or further unnecessary investigations (and potential harm) for the patient. On the other hand, a test that has a low sensitivity might simply miss the boat. So, the Cologuard, as a one-time screening test for colon polyps may miss it 31% of the time. In three to five-year time, can a polyp potentially turn into a deadly cancer? Unlikely but possible. Not taking any chance, I will bite the bullet and go the colonoscopy route.
We screen for colon cancer because the early stages of the disease, which is curable, is usually without any symptoms. In the same token, children with eye conditions or risk factors that can lead to permanent visual loss (amblyopia) are not easily identifiable. They cannot express their visual difficulty and they simply don’t know what the norm is. That is why we need to do vision screening in young children to identify those eye conditions that are potentially treatable when they are young but irreversible by age nine. The screening method is dependent on the age of the child. The first screening is often done at the nursery when the pediatricians check the overall structure of the eyes, the pupils and the red reflex (the light reflex that is reflected from the back on the eye). By six months of age, when the eyes are expected to be straight, the corneal light reflexes can be checked. In this test, we are looking at the light reflection on the surface of the cornea when the baby focuses on a light source. Normally, the corneal light reflexes should be smacked in the center of the pupils.
By three years of age, many children are cooperative enough for visual acuity testing with a picture chart set at 10 feet. It is recommended that if a child fails or is unable to cooperate for visual acuity testing at age three, a second attempt should be made within six months at the primary care doctor’s office. For a four year-old, a second attempt should be made within one month. If retesting is impossible or inconclusive, then the child should be referred for a comprehensive eye examination by an eye care professional like me who is experienced in taking care of children.
My twins just turned three this summer and they had their first visual acuity testing at their well-child check-up. The nurses lined them up 10 feet from the eye chart and they could not correctly identify the pictures on the 20/40 line. OMG!! I panicked and took them to my office the next weekend and thoroughly checked their eyes in and out. They turned out just fine with normal eye sight for their age. Well, I definitely did not follow the official guidelines for my children. I made an emotional decision, not a scientific one. I am often asked by parents if their children who have no eye issue need to be seen by me for a regular check-up. Generally, the answer is no. They should be screened first by the family doctors and the pediatricians. West of the Puget Sound, I am the only ophthalmologist who has additional fellowship training for pediatric eye care. My office simply does not have the capacity to see all the children in this county. While they happen to be “free” for my twins, comprehensive eye exams are not inexpensive either. Our health care dollars can be spent more rationally and effectively with a sensitive vision screening program. Nevertheless, if a child has known risk factors for eye disease, if there is a family history of pediatric eye disease, or if a child has signs or symptoms suspicious for a vision problem, it is reasonable and appropriate for a child to have a comprehensive eye examination by me.
The ideal screening program for any medical condition should be safe, non-invasive, inexpensive, easy to preform and operator independent. Compared to colonoscopy, the traditional vision screening program is far safer and cheaper. However, it may not be highly specific. Like the twins, many of the kids that I see who failed vision screening turn out just fine. How can we do better? Can we eliminate the subjectivity of an uncooperative child?
In the past decade, great strides have been made in the development of photoscreeners. These are special cameras that use the red reflex to help identify risk factors for poor vision and to detect for other abnormalities in the eyes (cataracts, for example). It is fast and easy to learn and is now widely used in primary care offices and in community group screenings. A print out or a picture can be provided to the parents as to the reasons for the referral to an eye doctor. Our local Bremerton Lions club has been very active in this cause and it was a great pleasure working with them to find the right photoscreener that fits their needs.
To keep us healthy throughout life, we do screenings for the young and the old for a whole range of conditions. It is important to remember that screening is a single measurement of one aspect of your health at a single point in time. Check with your doctor if there is any doubt so to the result of a screening test. Your overall sense of well-being and confidence in a healthy future should always be our ultimate objective