Posterior Lens Capsulectomy during Primary Cataract Surgery in Children MARSHALL M. PARKS, MD

Abstract: Concern continues about the best and safest method to surgically manage cataracts in children. Posterior capsulectomy and anterior vitrectomy with a vitreous suction cutter eliminates the need for secondary surgery. It is the best method to avoid development of amblyopia resulting from gradual posterior lens capsule opacification. However, cystoid macular edema is reo ported to occur more frequently with this approach as opposed to leaving the posterior lens capsule intact. Amblyopia, however, at this time may be a greater risk to final visual acuity than cystoid macular edema. [Key words: amblyopia, anterior vitrectomy, capsulectomy, cataract, cystoid macular edema.] Ophthalmology 90:344-345, 1983

The procedure of choice for extracting the lens in infants and children is the aspiration popularized by Scheie. 1 The procedure leaves the posterior lens capsule intact, yet in almost every patiene lens epithelium per­sistently grows in from the periphery and covers the anterior surface, changing the immediate postoperative transparent capsule to a translucent membrane. As the posterior lens capsule becomes cloudy, retinoscopy be­comes more difficult, the proper corrective lens power cannot be determined, and this diminishes the quality of the retinal image. Secondary surgery to open the clouded posterior lens capsule eventually becomes nec­essary within several weeks to several months following the primary surgery. Before the secondary surgery is performed, the risk of amblyopia is increased.

In spite of the technical advantages the aspiration procedure offered in removing the cataract, an essential element was still lacking for producing a successful vi­sual outcome. The missing link necessary for obtaining a good visual result was knowledge about amblyopia. It is now apparent that successful treatment of cataracts in infants and young children must focus on amblyopia treatment. Many researchers3

-11 have contributed to our

better understanding of amblyopia as it pertains to clin­ical management of cataracts in infants. Clinical re­search l2

-16 has recently determined the critical period

Reprint requests to Marshall M. Parks, MD, 3400 Massachusetts Avenue, N.W, Washington, DC 20008.

for the development of the fixation reflex to be between 2 and 3 months of age. To permit unequal inputs into the two retinal cortical systems during this period leads to intractible deprivation amblyopia. Unequal inputs remain a diminishing amblyopiagenic force until the child reaches visual adulthood at age 8 or 9 years.

Removal of all but 2 mm of the peripheral posterior lens capsule with a vitreous suction cutter leaves a clear pupil. Anterior vitrectomy places the vitreous face pos­terior to the plane of the iris. As a result, posterior syn­echia formation and development of iris bombe are un­likely making iridectomy unnecessary. The pupil re­mains active, centered, and dilates well with a mydriatic, affording accurate retinoscopy and a complete view of the fundus by indirect ophthalmoscopy.

The skiascopy and ophthalmoscopy performed dur­ing the postoperative period was strikingly improved because of the permanently large clear pupil, resulting from the above described new surgical technique begun in 1976. The surgical technique used prior to 1976 re­sulted in a postoperative intact translucent posterior cap­sule that interfered with the patient's fixation reflex de­velopment and determination of the optimal aphakic optical correction. This frequently causes unequal visual inputs into the infant's paired retinocortical system and produces intractible amblyopia.

Posterior capsulectomy therefore, reduces the risk of amblyopia. Fringe benefits associated with removing the posterior lens capsule during the primary cataract sur-

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PARKS • POSTERIOR LENS CAPSULECTOMY

gery are many. Parental worry and ophthalmologist's concern about the need for secondary surgery is reduced. The expense to the health care provider, whether family or third part payer, is significantly reduced by there being one rather than two surgeries.

Some alteration in our surgical and optical techniques was required because of new knowledge regarding the causes of and age of susceptibility of amblyopia. It was necessary to evolve a technique that: (1) produced a clear adequate pupillary space in one intervention, (2) re­duced the need of a secondary procedure, and (3) per­form bilateral cataract surgery separately on each eye a few days apart.

A technical adjustment in the optical correction in­volved applying properly powered contact lenses a few days after surgery and making frequent power changes to ensure that maximally focused images continue to be projected onto the retina throughout the critical period. Recently, a continuous wear soft contact lens has been applied at the completion of surgery. The power varies according to the chronological age of the patient: ap­proximately 35+ diopters for those less than 1 month old, 30+ diopters at 1 month of age, 25+ diopters for 2 months of age and 20+ diopters at 3 months of age. Refraction is started within the first few days after sur­gery and adjustments made in the lens power to over­correct the refractive error by + 1 to + 3 diopters. The permanently clear pupil permits accurate refraction. Frequent lens changes are made to supply the optimal correction during the first several postoperative weeks. If the extended wear soft contact lens is not centering properly, unavailable, or frequently lost, the soft contact lenses made of hydroxyethyl-methacrylate, with a 43% water content or polymethyl-methacrylate hard contact lenses are substituted.

The initial report l4 about vitreous removal being as­sociated with increased frequency of cystoid macular edema (CME) is worrisome, however, final documen­tation that clinically significant CME in infants and chil­dren being caused by this technique is not available. I wonder how a secondary invasion of the vitreous for opening or removal of the opacified posterior lens cap­sule is less likely to cause CME than opening the capsule during the primary surgery? Unlike in adults, the vit­reous face in young children is invariably opened when the posterior lens capsule is cut since the two are inti­mately joined. Consequently, at present, the advantages

in the trade-off of undesireables, as I analyze the pros and cons for removal of the lens capsule and anterior vitrectomy at the time of the initial surgery, favors this technique. The best visual acuity in patients with in­tractible amblyopia can be far worse than the best acuity in recovered clinically significant CME.

REFERENCES

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2. Parks MM, Hiles DA. Management of infantile cataracts. Am J Ophthalmol 1967; 63:10-9.

3. Wiesel TN, Hubel DH. Effects of visual deprivation on morphology and physiology of cells in the cat's lateral geniculate body. J Neu­rophysiol 1963; 26:978-93.

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6. Wiesel TN, Hubel DH. Comparison of the effects of unilateral and bilateral eye closure on cortical unit responses in kittens. J Neuro­physiol 1965; 28:1029-40.

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11. von Noorden GK, Crawford MLJ. The sensitive period. Trans Ophthal­mol Soc UK 1979; 99:442-6.

12. Vaegan, Taylor D. Critical period deprivation for amblyopia in children. Trans Ophthalmol Soc UK 1979; 99:432-9.

13. Rogers GL, Tishler CL, Tsou BH, et al. Visual acuities in infants with congenital cataracts operated on prior to 6 months of age. Arch Ophthalmol1981; 99:999-1003.

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