Pediatric cataract surgery

Published on 08/03/2015 by admin

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Last modified 08/03/2015

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CHAPTER 17 Pediatric cataract surgery

Ken K. Nischal

Chapter outline

INTRODUCTION 79
EPIDEMIOLOGIC CONSIDERATION AND TERMINOLOGY 79
CLINICAL FEATURES, DIAGNOSIS, AND DIFFERENTIAL DIAGNOSIS 79
ANATOMICAL CONSIDERATIONS 80
FUNDAMENTAL PRINCIPLES AND GOALS OF SURGERY 80
INDICATIONS FOR SURGERY 80
PREOPERATIVE ASSESSMENT 80
ANESTHESIA 80
OPERATION TECHNIQUES 80
INTRAOPERATIVE COMPLICATIONS 82
POSTOPERATIVE CARE 82
POSTOPERATIVE COMPLICATIONS 82
ASSESSMENT OF SURGERY: SELF-EVALUATION; RESULT OF SURGERY 83
REFERENCES 83

Introduction

The child’s eye is unique. Not only does the surgeon dealing with a pediatric cataract need to understand its neurophysiology and anatomy in the here and now, but he or she needs to be able to predict the effect of his/her surgical actions on the phenomenon that is emmetropization and the consequences thereof decades into the future. The surgery itself while extremely important is merely the first step in a long journey; the younger the child the harder that journey is likely to be.

Epidemiologic consideration and terminology

The incidence of pediatric cataract varies from 1 to 6/10 000 live births in Europe. Infant refers to children less than 1 year of age, and pediatric refers to children under the age of 16 years.

Clinical features, diagnosis, and differential diagnosis

Five components are needed to define a cataract: when they appear, the degree to which the opacity occupies the capsular bag, anatomically where in the lens the opacity lies, its etiology, and morphology. Cataracts may present at birth (congenital) or develop through the first few years of life (developmental); they may be total or partial; they may be nuclear (fetal or embryonal), sutural, lamellar, capsular (usually anterior) or subcapsular (usually posterior), or polar (posterior or anterior); they may be inherited or sporadic with the latter including the acquired variety such as infectious (in utero TORCH infections), metabolic (e.g. galactosemia, Lowe syndrome, galactokinase deficiency) or secondary to other ocular conditions (e.g. persistent fetal vasculature, PFV). Morphology of cataracts includes descriptions such as anterior pyramidal, membranous, pulverulent, blue dot, and other specific entities such as anterior or posterior lenticonus. Such specifications sometimes help with systemic diagnoses (e.g. anterior lenticonus should alert the surgeon to the possibility of Alport syndrome) while pyramidal cataracts are often associated with corneal astigmatism1.

It is very important that the parents of all children with cataracts are also examined with dilation of the eyes to exclude an inherited opacity. It is worth noting that an autosomal dominant cataract may express itself phenotypically differently in the same family pedigree.

The differential diagnosis of a pediatric cataract is that of leukocoria. In infants and toddlers this differential includes retinoblastoma, total retinal detachment (stage V retinopathy of prematurity, Norrie disease, and incontinentia pigmentii), large retinochoroidal colobomas, Coats disease and rarely Toxocara granulomas.

Anatomical considerations

The average axial length of an infant is 16.5 mm at birth. There is a rapid growth of the eye in the first 18 months of life with an average growth of 3.75 mm. By 13 years of age the average axial length is 23 mm2. Parents often ask if an intraocular implant would have to be removed as the child’s eye grows; this is not so if the implant is placed in the bag. This is because once the lens fibres are removed the bag stops growing. It is therefore important to know that the capsular bag diameter also changes with age. (The capsular bag diameter for the purposes of understanding the dimension available for an implant to be placed is the diameter of the crystalline lens + 1 mm). On average, the capsular bag diameter is 7 mm at birth, 9 mm at 2 years, 9–10 mm at 5 years, 10–10.5 mm at 16 years, and 10.5 mm > 21 years of age2.

Fundamental principles and goals of surgery

There are three important fundamental principles for successful pediatric cataract surgery:

1 The parents/guardians of the child are the most important carers. As such they must understand everything that is proposed. They and the surgeon are a team.
2 The surgery must do no long-term harm. While in adult cataract surgery failing to place an implant may be deemed a failure, for children the parents must be counseled that the goal of surgery is to remove the obstruction from the visual axis to allow normal visual development especially in children under the age of 8 years and even more importantly in children under the age of 3 months. Irrefutable evidence exists that there is a sensitive period in infants after which removal of a vision depriving pathology has little or no effect on the visual development in the child. For bilateral total cataracts this is thought to be 12 weeks but in unilateral cataracts it is likely to be less than this. In circumstances where an implant can clearly not be placed safely in the bag it is better to leave the child aphakic and then return in a few months (when the eye is bigger) to place a secondary implant in the sulcus3. If the child copes well with contact lenses or aphakic spectacle correction then there is no impetus to place a secondary implant until the child is much older.
3 Postoperative visual rehabilitation with frequent and appropriate refractive correction, surveillance for onset of glaucoma or other complications, and amblyopia therapy, if appropriate, must be offered.

Indications for surgery

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