PEDIATRIC APHAKIA

Complications in Pediatric Aphakic Extended Wear

By Donna Wicker, OD, FAAO, and Mark Ventocilla, OD, FAAO
December 2000

This study examines the risk of com-plications for pediatric aphakic extended wear to determine if it is a safe mode of correction.

What constitutes an acceptable risk for patients? Contact lens use can contribute to keratoconjunctivitis, ulcerative keratitis, corneal neovascularization and giant papillary conjunctivitis. The risk for such complications increases substantially when hydrogel soft contact lenses are worn for a week of extended wear. We suggest a daily wear schedule for most of our patients, with an allowance for flexible wear or occasional overnight use in extenuating circumstances.

Our young pediatric patients are an exception. We frequently prescribe a weekly extended wear schedule for aphakic infants and young children using the pediatric Silsoft contact lens from Bausch & Lomb. We reviewed the incidence of keratitis and conjunctivitis in our pediatric population, as compared to pediatric contact lens complications reported in previous studies. The results of our study can help determine the appropriateness of a one-week extended wear schedule when fitting the pediatric Silsoft lens.

Aphakic Treatment

Aphakic spectacles, contact lenses, intraocular lens implants and epikeratophakia are all options for optically correcting pediatric aphakia. Aphakic spectacles can cause image distortion in peripheral vision and prismatic effects. Up to 25 percent magnification occurs with the high plus powers required in aphakic spectacles, and patients with unilateral aphakia can suffer diplopia or suppress the image from the aphakic eye.

Choyce surgically implanted the first intraocular lens into a child in 1955. Postoperative complication rates for children under 1 year of age have been documented as high as 42 percent by Hiles in his review of 225 children with monocular cataracts from 1977 to 1983.

Epikeratophakia is a reversible surgical technique which involves suturing a lathed lamellar corneal disc to the anterior surface of the cornea after the epithelium is removed. Unfortunately, frequent epithelial defects and infections, as well as suture removal, all delay amblyopia therapy estimated at four to six weeks.

Contact lenses, on the other hand, provide clear optics and prompt optical correction without compromising peripheral vision or causing retinal image size disparity. Moreover, the correct refractive power can be readily adjusted as needed by replacing the contact lenses. Today, most ophthalmologists and optometrists view contact lenses as the most practical form of optical correction for pediatric aphakia.

TABLE1: Review of Patients with Complications

The Silsoft extended wear lens is a 100 percent silicone polymer with a Dk value of 360, substantially greater than other soft or even rigid gas permeable (RGP) lenses. Most soft lenses absorb medications and preservatives, potentially contributing to eye irritations and interfering with distribution of the prescribed medication. The Silsoft lens has low water content and hydrophobic properties such that ocular medications can be given during lens wear.

We have noted minimal fitting problems and good patient tolerance when prescribing the Silsoft contact lens. We typically perform the initial lens fit within a few days following cataract surgery and recommend a one-week extended wear schedule. If on follow-up we note deposits on the lens within the one-week wearing time, we recommend a more frequent cleaning schedule. As the child reaches the preschool or early elementary years, he or she is typically refit with a daily wear soft lens or RGP lens. In general, once the initial hurdle of insertion and removal of the contact lenses is mastered, the main barrier to achieving maximum vision is in maintaining a consistent patching schedule for amblyopia therapy.

Study Inclusion/Exclusion Criteria

We performed a retrospective review of medical records for all patients who ordered pediatric aphakic Silsoft lenses from calendar year 1994 to 1998. The study included patients with congenital and developmental cataracts who had been fit with extended wear Silsoft lenses. Patients who had suffered trauma or had any other significant ocular pathology (such as congenital glaucoma) were excluded.

We reviewed medical charts for a history of keratitis, conjunctivitis or other corneal pathology. Office visits as well as phone calls and verbal history of red or irritated eyes were recorded, regardless of whether the patients saw a pediatrician or returned to our office for care.

We also recorded a profile of our patient population. Prescriptions at ages up to 3 months, 6 months, 12 months, 18 months, 2 years and 3 years were identified. (Patients with microphthalmia were excluded from prescription averages.) The total number of contact lenses ordered and the number of prescription changes per year for the first, second and third year of life were noted.

Results

Some 88 eyes from 69 patients who ordered lenses in the past four years were included in this study. Eighteen patients had bilateral cataracts and 51 had unilateral cataracts.

Length of Follow-up

Our review found 42 patients with less than one year of follow-up. The average length of follow-up was 5.25 years in the patients seen for longer than one year. Of the 17 who had less than one year of follow-up, five were recent new fits on young babies. Some 12 patients who purchased one or two contact lenses were lost to follow-up and likely returned to care from the referring doctor.

The range of follow-up care was 0 to 11.5 years. The range in patient age at initial fitting was 13 days old to 5 years, 2 months old. Some 51 of the 69 patients were fit when under 1 year old.

Complications

Twelve patients had a history of superficial keratitis, corneal abrasion, corneal ulcer or conjunctivitis during the four-year study period. One of the 12 patients now wears aphakic spectacles and the other 11 have returned to contact lens wear with no subsequent complications. One case of conjunctivitis was accompanied by an upper respiratory infection and another by chicken pox. One patient has a permanent corneal scar resulting from three episodes of corneal ulcers. The vision in that eye is 6/24 (20/80) now. The corneal scar may play a role in the reduced acuity; however, the interruption in amblyopia treatment and contact lens wear may be of more significance (Table 1).

Contact Lens Power and Lens Loss over Time

The Silsoft contact lens prescriptions gradually decreased over time (Table 2). The number of Silsoft contact lenses ordered varied widely from one per year up to 14 per year (Table 3), but decreased gradually with age. The number of contact lens prescription changes, on the other hand, was only 0.84 +/- 0.8 in the first year of life, 0.77 +/- 0.5 from age 1 to 2 years and 0.76 +/- 0.6 from age 2 to 3 years old.

TABLE 2: Contact Lens Prescription (in diopters) versus Age

Prior Studies

Previous studies have recommended both daily wear and extended wear schedules for aphakic patients. Neumann advocates using daily wear soft contact lenses for pediatric aphakia since his study found no serious complications with daily wear lenses. Cutler looked at both Silsoft and other extended wear soft lenses. Her study found eight of 52 patients with red eyes during the course of the study but no permanent corneal pathology. Baker's study disclosed one of 29 eyes with a corneal ulcer and a small scar. In this case the eye was red for several days before the parents removed the contact lens. Amaya followed 83 patients (141 eyes) for three years. Some 85 percent of the patients tolerated the contact lenses for the entire study period. Some 46 eyes had various complications, yet only two stopped wearing contact lenses. The wearing schedule varied from daily wear to one-week extended wear. Since these studies included both hydrogel and silicone polymer lenses worn both daily wear and extended wear, it is difficult to assess the effects of wearing schedule on the incidence of complications.

On one hand, disinfecting the lens daily may prevent bacterial growth. The Silsoft lens has only 0.02 percent water, minimizing bacterial or viral contamination. On the other hand, removing and reinserting the contact lenses may actually increase the risk of a corneal abrasion. The parents handling the lenses may try several times before they are able to insert the lens, and the lens may fall on an unsanitary surface during this process.

The previous evidence has been consistent when evaluating hydrogel extended-wear contact lenses. Glynn found an annualized incidence of ulcerative keratitis in 52 cases per 10,000 adult aphakic contact lens wearers. The risk of extended wear was seven-fold more than daily-wear aphakic lenses. Several doctors have included statements suggesting that it may be safer to avoid risks of extended wear lenses for all pediatric aphakia patients, but the evidence has substantiated this for hydrogel lenses only.

TABLE 3: Number of Prescription Changes by Age Group

Conclusion

Based on our study results, we plan to continue to prescribe a one-week extended wear schedule when initially fitting the pediatric Silsoft contact lens. Our findings do not indicate a high risk associated with this wearing schedule. Data from previous studies are confounded by the use of both daily wear and extended wear schedules. Based on our study we feel that the benefit to wearing the lens on an extended wear basis outweighs the risk of contact lens related complications.

To receive references via fax, call (800) 239-4684 and request document #66. (Have a fax number ready.)

Dr. Wicker practices at the W.K. Kellogg Eye Center, University of Michigan Department of Ophthalmology, a specialty practice that fits contact lenses for pediatric aphakia, keratoconus, corneal transplants and trauma.

Dr.Ventocilla taught specialty contact lens fitting for five years while on faculty with the University of Michigan, Department of Ophthalmology. He is currently in private practice in Tallahassee, Florida where he specializes in difficult-to-fit contact lens cases.