Subjective Assessment
In December 2001, a 22-month old white male with Down syndrome was referred for contact lenses due to anisometropia. The child’s mother reported that he did not show any preferential looking. He was high functioning with a hearing deficit, and was learning to use sign language. Glasses were prescribed for him 6 months previously but he frequently removed them or they fell off. His right eye was patched for several hours a day, but it is was difficult to maintain patching.
Objective Assessment
With the glasses he was prescribed, he could follow and fixate a target with each eye independently and there was no obvious amblyopia. His extra-ocular motilities were intact with no apparent eye turn or nystagmus. His slit lamp examination was normal. A previous internal examination was normal with a myopic crescent in the left eye only. Keratometric measurements were not performed. Retinoscopy revealed the following: OD +1.25 +0.75 x 080 and OS –8.00 + 1.25 x 080. Spherical equivalent power for the left eye was –7.25D and was vertex corrected to –6.50D.
Given the refractive error and potential obstacles, I decided to fit the left eye only. Attempts to insert conventional disposable lenses that were available at the time were unsuccessful due to size of the lenses. A series of custom trial soft lenses were placed on the eye, and a lens with a 7.60 mm base curve and 11.5 mm in diameter offered the best centration and movement. As the custom lens was only approved for daily wear, it had to be removed every night. The mother, who was an ER (emergency room) nurse, was taught how to insert and remove the lens and was instructed to return in 2 weeks. At the follow-up visit, the mother reported that insertion and removal was extremely difficult and the lens was lost after about 10 days.
Although this patient may have benefited from a high Dk rigid lens, the parents were opposed to this lens type. Fortunately at this time, one of the first silicone hydrogel lenses was being launched and our office had just received a trial set. I was able to insert a lens easily and the fit and power were acceptable. We spent an extensive amount of time training the child’s mother and sister to insert and remove the lens. The patient was able to wear the lens continuously for 3 weeks at which time it was usually lost or soiled.
This patient has been wearing the same silicone hydrogel lens type for the past 4 years. During this time, his lens powers have changed so that he now requires silicone hydrogel lenses for both eyes with the following powers OD +4.00D OS –6.00D; base curve 8.4 mm.
In February 2006 his visual acuities measured 20/40 OD and 20/50 OS yet the question of amblyopia in the left still persists. His over lens retinoscopy now measures OD -0.50 +2.25 x 080 OS +0.50 +2.00 x 100 and we are concerned about correcting the astigmatism. The options we are currently considering include a silicone hydrogel toric lens or a high Dk rigid gas permeable lens, particularly if there is an increased concern for keratoconus.
Discussion
There are many ocular manifestations of Down Syndrome and our profession can provide much care to them. There is a high incidence of keratoconus, cataracts, aphakia as a result of lens extraction, high myopia, strabismus, blepharitis, and ectropia. These children must be evaluated at an early age to prevent amblyopia. Due to their characteristic depressed nasal bridge, their refractive needs are best treated with contact lenses. It has been well documented that young children, demonstrate steeper corneas and smaller iris diameters. We need to utilize this information and practice trial fitting rather than basing our perimeters on standard contact lens measurements that may not always be available to us. An examination under anesthesia would allow us to get more precise corneal and refractive measurements, however many children with Down syndrome suffer from heart defects and general anesthesia is more risky.
The contact lenses recommended for children with Down syndrome include steep hydrogel lenses in small diameters as well as rigid lenses. In this patient, we were fortunate that silicone hydrogel lenses had hit the market. Since the initial lens fitting, several other silicone hydrogel lens types have become available.
As these children mature, often we switch them from extended wear to daily wear to prevent any potential problems that may arise from noncompliance. I recall a patient who I began treating at age 5 for myopic anisometropia with a conventional hydrogel lens. When she was about 7 years, she was switched to daily wear and taught to remove her own lenses. Although this patient was mentally and physically competent, she refused to learn how to insert and remove her lenses until she was 12 - so the responsibility was on the parent. By then, the patient had developed circumferential neovascularization in both eyes and it wasn’t until I threatened to stop prescribing any more lenses, that the patient agreed to daily wear and to learn the proper technique. The patient now wears silicone hydrogel lenses on a 6 night extended wear schedule followed by sterilization, and reuse of the same lens for 1 month. As expected, compliance was a problem with this patient, and initially she wanted to discard the lenses rather than taking that extra step to disinfect. However after I explained to her parents that she was wasting the lenses and suggested that she start paying for them herself, the patient became more compliant with her lens care and replacement regimen. After 2 years with silicone hydrogel lenses, her neovascularization has regressed with only ghost vessels remaining.
The pleasant demeanor and curious nature of children aid in their adaptation to lenses. I think that the greatest fear of fitting an infant with contact lenses, is putting it on the eye. Not just for the parent, but also for the practitioner who is not accustomed to doing this. When training, it is really important that you have family support. If both parents are not available, a mature sibling will work out just fine. It makes insertion and removal much easier if there is someone available to offer a soft restraint.
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| Figure 1,
Using the family to help insert and remove contact lenses |
Insertion and removal can be a challenge both physically and emotionally. As these children get more active, there is potential for trauma if there is much aggression and the parents never like to see their young ones in turmoil. The more comfortable we make children and the more we engage them, the easier it becomes. If you can make them part of the process and give them some control, contact lens insertion and removal becomes routine. You can aid in this by having them practice putting bandages on the eyes of their favorite stuffed toy.
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| Figure 2,
Making lens insertion fun |
Help parents get over the fear of touching their child’s eyes and teach them how to inspect and re-adjust the lens on-eye. Lenses should be easy to handle and visible while in place and should be reproducible and available, because of the inevitable need for replacement due to loss, deposits, and expected perimeter changes. Since training may require more space and can get loud, you may want to do training after hours in your office so as not to scare other potential contact lens wearers. On the other hand, if these tiny patients are visible in your practice, it makes other families aware of the importance of eye care at an early age.
As this article illustrates, I am most comfortable with silicone hydrogel lenses when they fit the patient’s physical perimeters. If the absolute power is not available, I am somewhat forgiving in order to promote compliance and health. These lenses are an excellent choice, particularly for young children whose oxygen demands are greater than others because they spend many hours sleeping, and because the lenses provide a margin of confidence particularly as we know that compliance to recommended wear schedules will always be an issue for children of all ages.
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