A Case of Infantile Cataract and Neonatal Hypoglycemia

Abstract

Purpose:

To describe a case of lamellar cataract in a child with a history of neonatal hypoglycemia and illustrate the importance of meticulous history-taking in children with cataracts, especially before planning surgery.

Methods:

A single case report.

Results:

A 7-year-old girl with a history of neonatal hypoglycemia and ketoacidosis with high suspicion of a primary defect in ketone body utilization who presented with bilateral progressive blurred vision. Her best-corrected visual acuity (BCVA) was 20/200 in her right eye (OD) and 20/400 in her left eye (OS). Slit-lamp examination showed the presence of bilateral dense lamellar cataract. Fundus examination was unremarkable in both eyes (OU). She underwent cataract surgery with intraocular lens implantation under general anesthesia without prolonged fasting. Final BCVA was 20/82 in OD and 20/63 in OS.

Conclusion:

Our aim through this case is to emphasize the importance to screen for episodes of hypoglycemic attacks in children with infantile cataracts.

INTRODUCTION

The main etiologies of cataracts in children are idiopathic, hereditary, and infectious. Less commonly cataract formation could be secondary to a metabolic disorder such as galactosemia or hypocalcemia1 Pediatric cataracts associated with hypoglycemia have been rarely documented, especially during the last decades. We believe that the varying time intervals between the hypoglycemic attack and the initial diagnosis of cataract can lead clinicians to overlook a possible link between the two diseases2

CASE REPORT

A 7-year-old girl presented to our department with bilateral progressive blurred vision with learning difficulties that have worsened during the last 2 years. At presentation, ophthalmic examination revealed the presence of bilateral, horizontal conjugate nystagmus with fixation instability. Both pupils were isochoric and ocular movements were full. Objective refraction was –5.25 diopters (D) in the right eye (OD) and –5.75 D in the left eye (OS). Best-corrected visual acuity (BCVA) was 20/200 OD and 20/400 OS. The cornea, anterior chamber, and iris were unremarkable. Her intraocular pressure was 11 mmHg in OD and 12 mmHg in OS. After dilation, slit-lamp examination showed the presence of bilateral dense lamellar cataracts [Figure 1 respectively in OD: a and b, and in OS: c and d]. Funduscopy was unremarkable in both eyes. She was born from a consanguineous marriage with full-term uncomplicated pregnancy. Congenital TORCH infections were ruled out and no family history of infantile cataracts or any other ocular diseases was found. Both her parents and her brother had unremarkable ophthalmic examinations. Further questioning revealed a history of respiratory distress, tachypnea, and vomiting happening within 8 days of birth. She was transferred at that time to a neonatal care unit where investigations showed a low blood glucose level (1.98 mmol/l). Urine was strongly positive for ketones and there was no evidence of enlarged liver (liver span = 4 cm). She was treated with intravenous infusions of 10% glucose solution. Further blood analysis revealed metabolic acidosis (pH = 7.365; HCO3^– = 15; pCO2 = 29). Serum calcium, lactate and ammonia levels were within the normal range (calcium = 2.5 mmol/l; lactate = 1.5 mmol/l; ammonia = 34 μmol/l). Thin layer amino acid chromatography in plasma was normal. Coupled gas chromatography/mass spectrometery organic acids profile in urine collected in acute phase showed an accumulation of lactate (16%) and 3-hydroxybutyrate. The latter analysis was normal when it was controlled at a stable metabolic state. A primary defect in ketone body utilization was highly suspected. Unfortunately, further confirmatory testing by measuring the activity of Succinyl-CoA-Transferase and Mitochondrial acetoacetyl-coenzyme A thiolase along with genetic analysis were not available. The patient was then discharged and put on a normal diet with the prohibition of overnight fasting. During her follow-up, there were no documented recurrences of ketoacidosis attacks with or without hypoglycemia. She showed normal psychomotor development with no neurological disabilities.

Figure 1.

Slit-lamp anterior segment photographs. (a and b) of the right eye, showing the presence of a dense lamellar cataract seen at the optical section of the lens as a lamella of concentric opacification surrounding a clear nucleus, (c and d) of the left eye, showing a dense lamellar cataract on both reduced slit-lamp brightness and retro illumination, respectively

She underwent two-timed bilateral cataract surgery with intraocular lens implantation under general anesthesia without prolonged fasting. At follow-up, her BCVA was 20/82 in OD and 20/63 in OS. Corrective lenses were prescribed for near vision and part-time occlusion therapy was initiated. We completed with a retinal autofluorescence, macular optical coherence tomography and an electroretinogram in order to rule out associated retinal dystrophies especially since there was a parent consanguinity. The overall examination was unremarkable. Consent for the publication of the report was obtained from the patient's parents.

DISCUSSION

Lamellar cataracts are a subtype of zonular cataracts characterized by a lamella of concentric opacification between the nucleus and the cortex believed to be secondary to an insult to the lens occurring during its development1 Cases of autosomal dominant lamellar cataracts have been reported and associated with mutations in the HSF4 gene3 In our case, genetic analysis was not performed. However, both parents had unremarkable ophthalmic examination and no family history of congenital cataract was found. Children with a history of neonatal hypoglycemia have been found to develop a distinctive lamellar/zonular cataract. 2,4,5 In a study of 40 patients with a history of ketotic hypoglycemia, the prevalence of cataracts was 37.5%, and zonular cataracts were the most common morphological type2 The interval between the first documented episode of hypoglycemia and the diagnosis of cataracts ranged from 1 month to 8 1/3 years. The discovery of an infantile cataract preceded the diagnosis of ketotic hypoglycemia in three patients. The authors of this study suggested that the lens opacification could happen during hypoglycemic attacks. In another case series of 13 children with cataracts and a history of neonatal hypoglycemia, 10 of them had lamellar cataracts5 On the other hand, a follow-up study of 151 children with a history of neonatal hypoglycemia found that only one patient developed a zonular cataract at the age of 3 years6 However, the short follow-up period ranging from 1 to 4 years and the inclusion of asymptomatic patients with mild hypoglycemia are important limitations of this study.

The mechanism of lens opacification during hypoglycemic cataracts is still unclear. Experiments on animal lenses suggest a possible correlation between hypoglycemia and the deactivation of hexokinase, an essential glycolytic enzyme in the lens4,7 Hypoglycemia leads to a drop in aqueous humor glucose and because of its lack of glycogen and gluconeogenic potential, the lens is unable to restore the levels of intracellular glucose back to normal4 In 1975, Chylack found that depriving rat lenses of glucose led to the formation of a lamellar opacity similar to what has been described in children with a history of hypoglycemia8 After 8 h of glucose deprivation, lens hexokinase undergoes an irreversible deactivation leading to the loss of adenosine triphosphate7 This metabolic stress causes weight gain and disorganization of lens fibers proportional to the degree of hypoglycemia4 The lenses of younger animals seem to be more susceptible to glucose deprivation7 A previous study of the activity of hexokinase in the human lens found that it was the highest in fetal lenses, much lower in clear adult lenses, and nonmeasurable in senile cataracts9 This same study proved the existence of similarities between the human and rat lenses.

Also, our patient had nystagmus and poor visual acuity which are uncommon in lamellar cataracts. Another explanation might be the effect of neonatal hypoglycemia on visual development. Nystagmus along with other ocular developmental anomalies such as optic nerve hypoplasia, refractive errors, strabismus, and abnormal cortical processing has been associated with neonatal hypoglycemia. Conversely, because of the frequent coexistence of neonatal hypoglycemia with other severe comorbidities, its effect on visual development remains unclear10

To conclude, detailed ophthalmic examination and regular follow-up should be performed on children with a history of neonatal or recurrent hypoglycemia. Looking for episodes of hypoglycemic attacks in children with cataracts may decrease the number of cataracts classified as idiopathic. It is also important to consider in the preanesthetic assessment of these patients.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.