Journal of Pediatric Ophthalmology and Strabismus

Original Article 

Amblyopia Risk Factors in Newborns With Congenital Nasolacrimal Duct Obstruction

Aldo Vagge, MD, PhD; Claudia Tulumello, MD; Marco Pellegrini, MD; Marco Di Maita, MD; Michele Iester, MD, PhD; Carlo Enrico Traverso, MD

Abstract

Purpose:

To investigate the presence of amblyopia risk factors in newborns with congenital nasolacrimal duct obstruction (CNLDO) and age-matched healthy control subjects.

Methods:

This retrospective case-control study involved newborns aged 30 to 60 days with CNLDO and age-matched healthy control subjects. Amblyopia risk factors were identified in accordance with the American Association for Pediatric Ophthalmology and Strabismus Vision Screening Committee recommendations. The prevalence of amblyopia risk factors was compared in newborns with CNLDO and age-matched healthy control subjects, newborns with unilateral and bilateral CNLDO, and the affected eye and fellow eye of newborns with unilateral CNLDO.

Results:

Amblyopia risk factors were found in 18 patients (11.9%) with CNLDO and 19 control subjects (8.7%) (P = .314). Eyes with CNLDO showed a significantly lower spherical equivalent compared to control eyes (2.01 ± 1.21 vs 2.79 ± 1.14 diopters, P < .001). No difference in amblyopia risk factors was found in eyes with unilateral and bilateral CNLDO (11.5% vs 12.1%; P = .908) or in eyes with unilateral CNLDO and fellow eyes (9.8% vs 12.3%; P = .540).

Conclusions:

CNLDO does not seem to be associated with amblyopia risk factors in newborns. Because anisometropia might develop later on, all patients with CNLDO should be monitored for amblyopia.

[J Pediatr Ophthalmol Strabismus. 2020;57(1):39–43.]

Abstract

Purpose:

To investigate the presence of amblyopia risk factors in newborns with congenital nasolacrimal duct obstruction (CNLDO) and age-matched healthy control subjects.

Methods:

This retrospective case-control study involved newborns aged 30 to 60 days with CNLDO and age-matched healthy control subjects. Amblyopia risk factors were identified in accordance with the American Association for Pediatric Ophthalmology and Strabismus Vision Screening Committee recommendations. The prevalence of amblyopia risk factors was compared in newborns with CNLDO and age-matched healthy control subjects, newborns with unilateral and bilateral CNLDO, and the affected eye and fellow eye of newborns with unilateral CNLDO.

Results:

Amblyopia risk factors were found in 18 patients (11.9%) with CNLDO and 19 control subjects (8.7%) (P = .314). Eyes with CNLDO showed a significantly lower spherical equivalent compared to control eyes (2.01 ± 1.21 vs 2.79 ± 1.14 diopters, P < .001). No difference in amblyopia risk factors was found in eyes with unilateral and bilateral CNLDO (11.5% vs 12.1%; P = .908) or in eyes with unilateral CNLDO and fellow eyes (9.8% vs 12.3%; P = .540).

Conclusions:

CNLDO does not seem to be associated with amblyopia risk factors in newborns. Because anisometropia might develop later on, all patients with CNLDO should be monitored for amblyopia.

[J Pediatr Ophthalmol Strabismus. 2020;57(1):39–43.]

Introduction

Congenital nasolacrimal duct obstruction (CNLDO) is one of the ophthalmic conditions most commonly encountered by pediatric ophthalmologists,1,2 occurring in 5% to 15% of full-term newborns.3,4 CNLDO is characterized by unilateral or bilateral epiphora and/or intermittent mucopurulent discharge that in approximately 90% of patients resolves spontaneously in the first 12 to 18 months of life.5 Although CNLDO is considered a benign condition, several authors have reported a possible association between CNLDO and amblyopia risk factors.6–15 In particular, hyperopia and anisometropia have been observed to be associated with same-sided unilateral CNLDO. This condition may predispose affected children to develop clinical amblyopia.8 However, as far as we know, no previous study has extensively investigated these aspects in newborns.

The aim of this study was to compare amblyopia risk factors in (1) newborns with CNLDO and age-matched healthy control subjects, (2) newborns with unilateral and bilateral CNLDO, and (3) the affected eye and fellow eye of newborns with unilateral CNLDO.

Patients and Methods

A chart review of consecutive patients aged 30 to 60 days examined at the University Eye Clinic of Genova, Policlinico San Martino, Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Genova, Italy, for CNLDO was conducted. The study itself was performed in accordance with the tenets of the Declaration of Helsinki. Institutional review board approval was obtained. As is standard practice in our clinic, all records reviewed for this study documented a detailed anterior segment evaluation, a complete cycloplegic refraction, red reflex test, and fundus examination performed 30 minutes following the instillation of one to two drops of a pediatric “combo drop” of tropicamide 1% and phenylephrine 2.5%. The diagnosis of CNLDO was made clinically, based on the presence of epiphora, discharge, and presence of reflux with digital pressure over the nasolacrimal sac. At the examiner's discretion, CNLDO was confirmed with the dye disappearance test. Only first-encounter records were used. Exclusion criteria for this study were eyes with any findings that could cause excess tearing, such as trichiasis.

Data were collected regarding patient demographics, including age, gender, birth weight, gestational age, laterality of CNLDO, and other ophthalmologic diagnoses. CNLDO was classified into unilateral and bilateral. Amblyopia risk factors were identified in accordance with the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) Vision Screening Committee recommendations.15 In particular, guidelines for detection of amblyopia risk factors in toddlers were followed. The recommended target refractive magnitude for detection was astigmatism of greater than 2.00 diopters (D), hyperopia of greater than 4.50 D, myopia of greater than 3.50 D, and anisometropia of greater than 2.50 D. Any media opacity greater than 1 mm in size was considered a nonrefractive amblyopia risk factor.

Statistical Analysis

The SPSS statistical software (SPSS, Inc., Chicago, IL) was used for data analysis. The chi-square or Fisher's exact test was used to compare categorical variables between patients with CNLDO and control subjects, eyes with unilateral and bilateral CNLDO, and affected and fellow eyes of patients with bilateral CNLDO. Continuous variables were expressed as means ± standard deviation. An independent samples t test was used to compare continuous variables between patients with CNLDO and control subjects and eyes with unilateral and bilateral CNLDO. A paired-samples t test was used to compare continuous variables between affected and fellow eyes of patients with bilateral CNLDO. A P value of less than .05 was considered significant.

Results

Medical records of 151 consecutive patients with a diagnosis of CNLDO (mean age: 44.4 ± 9.0 days) were compared with those of 218 healthy control subjects (mean age: 45.8 ± 9.6 days). Demographic and clinical characteristics of the study population are reported in Table 1. No significant differences were found in age, gender, birth weight, and gestational age between the two groups (all P > .05). CNLDO was unilateral in 122 patients (80.8%) and bilateral in the remaining 29 patients (19.2%).

Characteristics of Patients With CNLDO and Control Subjects

Table 1:

Characteristics of Patients With CNLDO and Control Subjects

The amblyopia risk factors observed in patients with CNLDO and control subjects are reported in Table 2. Overall, 18 patients with CNLDO (11.9%) and 19 control subjects (8.7%) had amblyopia risk factors, and the difference was not statistically significant (P = .314). In particular, no significant differences were found between the two groups in astigmatism of greater than 2.00 D (P = .403), hyperopia of greater than 4.50 D (P = .923), myopia of greater than 3.50 D (P = 1.000), anisometropia of greater than 2.50 D (P = .309), and media opacity of greater than 1 mm (P = .570). Eyes with CNLDO showed a significantly lower spherical equivalent compared to control eyes (2.01 ± 1.21 vs 2.79 ± 1.14 D, P < .001). Conversely, no significant difference in astigmatism between the two groups was found (0.23 ± 0.50 vs 0.23 ± 0.47 D, P = .919).

Amblyopia Risk Factors in Patients With CNLDO and Control Subjects

Table 2:

Amblyopia Risk Factors in Patients With CNLDO and Control Subjects

The amblyopia risk factors observed in eyes with unilateral and bilateral CNLDO are reported in Table 3. Overall, 14 eyes (11.5%) of patients with unilateral CNLDO and 7 eyes (12.1%) of patients with bilateral CNLDO had amblyopia risk factors (P = .908). In particular, no significant differences were found between the two groups in astigmatism of greater than 2.00 D (P = .552), hyperopia of greater than 4.50 D (P = .932), myopia of greater than 3.50 D (P = 1.000), anisometropia of greater than 2.50 D (P = .595), and media opacity of greater than 1 mm (P = .542). No significant difference between the two groups was found for spherical equivalent (2.04 ± 1.24 vs 1.96 ± 1.06, P = .674) and astigmatism (0.25 ± 0.53 vs 0.18 ± 0.37, P = .403).

Amblyopia Risk Factors in Eyes With Unilateral and Bilateral CNLDO

Table 3:

Amblyopia Risk Factors in Eyes With Unilateral and Bilateral CNLDO

The amblyopia risk factors observed in eyes with unilateral CNLDO and fellow eyes are reported in Table 4. In the 122 patients with bilateral CNLDO, 12 of the affected eyes (9.8%) had amblyopia risk factors compared to 15 of the unaffected eyes (12.3%) (P = .540). No significant differences were found between the two eyes in astigmatism of greater than 2.00 D (P = .136), hyperopia of greater than 4.50 (P = 1.00), myopia of greater than 3.50 D (P = 1.00), and media opacity of greater than 1 mm (P = 1.00). No significant difference was found between the two groups for spherical equivalent (2.03 ± 1.24 vs 2.00 ± 1.23, P = .213) and astigmatism (0.25 ± 0.53 vs 0.25 ± 0.53, P = .319).

Amblyopia Risk Factors in Eyes With Unilateral CNLDO and Fellow Eyes

Table 4:

Amblyopia Risk Factors in Eyes With Unilateral CNLDO and Fellow Eyes

Discussion

The possible relationship between CNLDO and amblyopia has been increasingly studied. Several studies evaluated the presence of amblyopia risk factors in patients with CNLDO, reporting a prevalence ranging from 9.5% to 35%.6,9–14 In addition, a significantly higher incidence of anisometropia with higher hyperopia was observed in eyes with unilateral CNLDO compared to fellow eyes.7,11,14 Similarly, a higher rate of anisometropia was reported in eyes with unilateral compared to bilateral CNLDO.8,13 However, other studies did not identify any significant difference in the incidence of amblyopia between eyes with CNLDO and control eyes,16 and between eyes with unilateral CNLDO and fellow eyes.17 This heterogeneity may depend on differences in inclusion criteria, sample sizes, and definitions of anisometropia or amblyopia.

In the current study, we evaluated the presence of amblyopia risk factors in newborns with CNLDO. Patients with CNLDO and healthy control subjects showed no significant difference in amblyopia risk factors. In addition, no significant differences in amblyopia risk factors were observed in eyes with unilateral and bilateral CNLDO or in eyes with unilateral CNLDO and fellow eyes. These results are in agreement with those of Ellis et al.,16 who found no relationship between CNLDO and amblyopia in a large cohort of 4,792 children. However, in contrast to Ellis et al., our study included only newborns aged 30 to 60 days. To the best of our knowledge, this is the first study evaluating the association between CNLDO and amblyopia in this age group. This may explain the discrepancies with other studies, which documented an increased risk of amblyopia in older children with CNLDO.6–15

The mechanism by which patients with CNLDO might develop anisometropia and amblyopia is still unknown. One hypothesis is that a congenital abnormality of the orbit may lead to both an impaired canalization of the nasolacrimal duct and a reduced axial length of the globe.12 The results of this study are in contrast with this hypothesis, because no relationship between CNLDO and anisometropia or hyperopia was found in newborns. Furthermore, eyes with CNLDO were slightly less hyperopic compared to control eyes. Interpreting such an observation is not certain and requires further investigation to be confirmed.

Another possibility is that watering and mucopurulent discharge in eyes with CNLDO might cause the development of anisometropia and amblyopia.8,12 The rapid phase of emmetropization takes place between 3 and 9 months of age, mainly because of an increase in axial length.18 This age is also associated with peak symptoms of CNLDO. Therefore, blurring of vision caused by CNLDO may interfere with the visual feedback guiding emmetropization, resulting in increased incidence of anisometropia. This may explain why newborns with CNLDO showed a similar incidence of amblyopia risk factors as healthy control subjects in this study, whereas other studies including older children reported a higher risk of amblyopia risk factors associated with CNLDO. The hypothesis is further supported by the results of Bagheri et al.,7 who documented that increasing age in patients with CNLDO is associated with a higher prevalence and severity of anisometropia.

This study has some limitations that should be taken into account. First, amblyopia risk factors were identified using AAPOS recommendations, which are designed for children older than 12 months. However, no recognized criteria for infants exist. In addition, due to the cross-sectional design of the study, we could not determine the development of anisometropia and/or amblyopia at an older age and the possible effect of CNLDO treatment on visual development. Finally, newborns are known to display a wide range of refractive errors, and this may have reduced the power of the study to detect significant differences. Further larger studies are required to confirm our results.

CNLDO does not seem to be associated with amblyopia risk factors in newborns. However, anisometropia might develop later. Careful follow-up and monitoring for amblyopia are recommended for all patients with CNLDO.

References

  1. Guerry D III, Kendig EL Jr, . Congenital impatency of the nasolacrimal duct. Arch Ophthalmol. 1948;39(2):193–204. doi:10.1001/archopht.1948.00900020198006 [CrossRef]
  2. Kamal S, Ali MJ, Gauba V. Congenital nasolacrimal duct obstruction. In: Ali MJ, ed. Principles and Practice of Lacrimal Surgery, 2nd ed. Singapore: Springer; 2018:117–132. doi:10.1007/978-981-10-5442-6_14 [CrossRef]
  3. Sevel D. Development and congenital abnormalities of the nasolacrimal apparatus. J Pediatr Ophthalmol Strabismus. 1981;18(5):13–19.
  4. MacEwen CJ, Young JD. Epiphora during the first year of life. Eye (Lond). 1991;5(Pt 5):596–600. doi:10.1038/eye.1991.103 [CrossRef]
  5. Vagge A, Ferro Desideri L, Nucci P, et al. Congenital nasolacrimal duct obstruction (CNLDO): a review. Diseases. 2018;6(4):E96. doi:10.3390/diseases6040096 [CrossRef]
  6. Matta NS, Silbert DI. High prevalence of amblyopia risk factors in preverbal children with nasolacrimal duct obstruction. J AAPOS. 2011;15(4):350–352. doi:10.1016/j.jaapos.2011.05.007 [CrossRef]
  7. Bagheri A, Safapoor S, Yazdani S, Yaseri M. Refractive state in children with unilateral congenital nasolacrimal duct obstruction. J Ophthalmic Vis Res. 2012;7(4):310–315.
  8. Kipp MA, Kipp MA Jr, Struthers W. Anisometropia and amblyopia in nasolacrimal duct obstruction. J AAPOS. 2013;17(3):235–238. doi:10.1016/j.jaapos.2012.11.022 [CrossRef]
  9. Ozgur OR, Sayman IB, Oral Y, Akmaz B. Prevalence of amblyopia in children undergoing nasolacrimal duct irrigation and probing. Indian J Ophthalmol. 2013;61(12):698–700. doi:10.4103/0301-4738.124737 [CrossRef]
  10. Kim JW, Lee H, Chang M, Park M, Lee TS, Baek S. Amblyopia risk factors in infants with congenital nasolacrimal duct obstruction. J Craniofac Surg. 2013;24(4):1123–1125. doi:10.1097/SCS.0b013e3182902b3d [CrossRef]
  11. Eshraghi B, Akbari MR, Fard MA, Shahsanaei A, Assari R, Mirmohammadsadeghi A. The prevalence of amblyogenic factors in children with persistent congenital nasolacrimal duct obstruction. Graefes Arch Clin Exp Ophthalmol. 2014;252(11):1847–1852. doi:10.1007/s00417-014-2643-1 [CrossRef]
  12. Ramkumar VA, Agarkar S, Mukherjee B. Nasolacrimal duct obstruction: does it really increase the risk of amblyopia in children?Indian J Ophthalmol. 2016;64(7):496–499. doi:10.4103/0301-4738.190101 [CrossRef]
  13. Siddiqui SN, Mansoor H, Asif M, Wakeel U, Saleem AA. Comparison of anisometropia and refractive status in children with unilateral and bilateral congenital nasolacrimal duct obstruction. J Pediatr Ophthalmol Strabismus. 2016;53(3):168–172. doi:10.3928/01913913-20160405-06 [CrossRef]
  14. Badakere A, Veeravalli TN, Iram S, Naik MN, Ali MJ. Unilateral congenital nasolacrimal duct obstruction and amblyopia risk factors. Clin Ophthalmol. 2018;12:1255–1257. doi:10.2147/OPTH.S171029 [CrossRef]
  15. Donahue SP, Arnold RW, Ruben JBAAPOS Vision Screening Committee. Preschool vision screening: what should we be detecting and how should we report it? Uniform guidelines for reporting results of preschool vision screening studies. J AAPOS. 2003;7(5):314–316. doi:10.1016/S1091-8531(03)00182-4 [CrossRef]
  16. Ellis JD, MacEwen CJ, Young JD. Can congenital nasolacrimal duct obstruction interfere with visual development? A cohort case control study. J Pediatr Ophthalmol Strabismus. 1998;35(2):81–85.
  17. AlHammad F, Al Tamimi E, Yassin S, et al. Unilateral congenital nasolacrimal duct obstruction, is it an amblyogenic factor?Middle East Afr J Ophthalmol. 2018;25(3–4):156–160.
  18. Flitcroft DI. Emmetropisation and the aetiology of refractive errors. Eye (Lond). 2014;28(2):169–179. doi:10.1038/eye.2013.276 [CrossRef]

Characteristics of Patients With CNLDO and Control Subjects

CharacteristicCNLDO Group (n = 151)Control Group (n = 218)P
Female gender, n (%)88 (58)131 (60).727
Age (days)44.4 ± 9.045.8 ± 9.6.310
Birth weight (g)3,185.1 ± 515.63,145.1 ± 484.9.448
Gestational age (wks)38.5 ± 2.138.7 ± 1.8.196

Amblyopia Risk Factors in Patients With CNLDO and Control Subjects

Amblyopia Risk FactorCNLDO Group (n = 151)Control Group (n = 218)P
Astigmatism > 2.00 D, n (%)3 (2.0)2 (0.9).403
Hyperopia > 4.50 D, n (%)10 (6.6)15 (6.8).923
Myopia > 3.50 D, n (%)1 (0.7)1 (0.5)1.000
Anisometropia > 2.50 D, n (%)3 (2.0)1 (0.5).309
Media opacity > 1 mm, n (%)2 (1.3)1 (0.5).570

Amblyopia Risk Factors in Eyes With Unilateral and Bilateral CNLDO

Amblyopia Risk FactorUnilateral CNLDO (n = 122)Bilateral CNLDO (n = 58)P
Astigmatism > 2.00 D, n (%)3 (2.5)0 (7.4).552
Hyperopia > 4.50 D, n (%)8 (6.6)4 (6.6).932
Myopia > 3.50 D, n (%)1 (0.8)0 (0.8)1.000
Anisometropia > 2.50 D, n (%)2 (2.0)2 (0.5).595
Media opacity > 1 mm, n (%)1 (0.8)1 (0.8).542

Amblyopia Risk Factors in Eyes With Unilateral CNLDO and Fellow Eyes

Amblyopia Risk FactorUnilateral CNLDO (n = 122)Fellow Eyes (n = 122)P
Astigmatism > 2.00 D, n (%)3 (2.5)9 (7.4).136
Hyperopia > 4.50 D, n (%)8 (6.6)8 (6.6)1.000
Myopia > 3.50 D, n (%)1 (0.8)1 (0.8)1.000
Media opacity > 1 mm, n (%)1 (0.8)1 (0.8)1.000
Authors

From University Eye Clinic of Genoa, Policlinico San Martino (AV, MD, MI, CET) and the School of Medicine and Pharmacy (CT), Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy; IRCCS Ospedale Policlinico San Martino, Genova, Italy (AV, MI, CET); and the Ophthalmology Unit, S. Orsola-Malpighi University Hospital, University of Bologna, Bologna, Italy (MP).

The authors have no financial or proprietary interest in the materials presented herein.

Correspondence: Aldo Vagge, MD, PhD, University Eye Clinic of Genoa, Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, IRCCS Ospedale Policlinico San Martino, Viale Benedetto XV, 5, 16132 Genova, Italy. E-mail: aldo.vagge@unige.it

Received: July 11, 2019
Accepted: November 05, 2019

10.3928/01913913-20191111-01

Sign up to receive

Journal E-contents