Incidence and distribution of ocular disorders in the first year of life

Abstract

Purpose

To describe the incidence and distribution of eye diseases affecting children in the first year of life in Olmsted County, Minnesota.

Methods

We conducted a population-based, retrospective medical record review of infants (≤1 year of age) residing in Olmsted County diagnosed with an ocular disorder from January 1, 2005, through December 31, 2014.

Results

A total of 4,223 infants were diagnosed with an ocular disorder, yielding an incidence of 20,242/100,000 births per year, or 1 in 4.9 live births (95% CI, 19,632–20,853). The median age at diagnosis was 3 months, and 2,179 (51.5%) were female. The most common diagnoses included conjunctivitis, in 2,175 (51.5%), nasolacrimal duct obstruction, in 1,432 (33.6%), and pseudostrabismus, in 173 (4.1%). Visual acuity was decreased in one or both eyes in 23 (0.5%) infants because of strabismus in 10 (43.5%) and cerebral visual impairment in 3 (13.0%). A majority of the infants (3,674 [86.9%]) were diagnosed and managed by a primary care provider, and 549 (13.0%) were evaluated and/or managed by an eye care provider

Conclusions

Although ocular disorders occurred in 1 in 5 infants in this cohort, most conditions were evaluated and managed by primary care providers. Understanding the incidence and distribution of ocular diseases among infants is useful for planning clinical resources.

Ocular disorders affecting infants can, if not promptly detected and managed, lead to lifelong visual impairment and associated psychosocial concerns. Examining the eyes of infants is challenging, and many regions within the United States and around the world report a shortage of pediatric ophthalmologists.¹ Primary care providers, including pediatricians, nurse practitioners, and family medicine physicians perform the bulk of eye screening examinations in this age group, beginning soon after birth, making decisions regarding the management or referral of infants with eye diseases. The American Academy of Pediatrics recommends screening for visual disorders in the newborn to 6-month period by performing an ocular history, external inspection, red reflex, pupil examination, and fix-and-follow response.² Additionally, ocular motility examination and instrument-based screening is recommended in the 6- to 12-month period.² There is limited population-based data on the burden of ocular disease in the first year of life.³ The purpose of this study was to report the incidence and distribution of ocular disease observed in a population-based cohort of infants diagnosed over a 10-year period.

Methods

The medical records of all patients ≤1 year of age who were diagnosed with any ocular disease from January 1, 2005, through December 31, 2014, while residing in Olmsted County, Minnesota, were retrospectively and individually reviewed. Patients were identified using the Rochester Epidemiology Project, a medical record linkage system designed to capture data on any medical encounter in the county.⁴ The county is relatively isolated from urban areas and nearly all health care is provided to its residents by Mayo Clinic, Olmsted Medical Group, and their affiliated hospitals. Institutional Review Board approval was obtained from Mayo Clinic and Olmsted Medical Group.

A database search of 1,007 International Classification of Diseases, Ninth Revision (ICD-9) diagnostic codes to include all eye conditions was performed (eSupplement 1, available at jaapos.org). Of the 5,611 patients identified through the search, 675 were excluded for a diagnosis code not supported by clinical notes, 502 were duplicate records, 190 denied research authorization, 11 lived outside Olmsted County, and 10 had incomplete records. The remaining 4,223 patients were included in the study and their entire medical records were reviewed for pertinent demographic and clinical information. Infants whose diagnosis codes indicated only refractive error and whose refractive error was <5 D were excluded unless there was concurrent anisometropia and/or amblyopia.

Population figures for 2000 and 2010 were used to determine the incidence of ocular diagnoses among the infants, based on the US census data. Figures for inter-census years were estimated through linear interpolation. Ocular disease incidence was calculated based on the number of cases divided by the population for those individuals’ years over the course of the study. The 95% confidence interval for the overall incidence was calculated to provide range of the true incidence. Poisson regression was used to test for trends over time and between sexes. Statistical analyses were completed using SAS version 9.4 (SAS Institute Inc, Cary, NC).

Results

A total of 4,223 children were diagnosed with an ocular condition or disease involving the visual pathway during the 10-year period, yielding an incidence of 20,242/100,000 births per year (95% CI, 19,632–20,853), or 1 in 4.9 live births. The incidence ranged from 14,817 to 26,318 per 100,000 over the years (Table 1) with the more recent years (2012–2014) showing a significantly decreased (P < 0.001) incidence compared with the earliest years (2005–2008). The median age at diagnosis was 3 months (range, birth to 12 months), 1951 (46.2%) were female, and 3,185 (75.8%) were white. Nearly half (1,838 [43.5%]) of the infants were considered to have a congenital onset to their disorder, with 211 (5.0%) diagnosed as newborns.

Table 1.

Year-wise incidence of ocular disease in the first year of life over a 10-year period in Olmsted County, Minnesota

Year	No. live births in Olmsted Co.	Incidence of ocular disorders per 100,000 births per year	Incidence of ocular disorders per live birth (95% CI)
2005	1938	21827 (19747–23907)	1 in 4.6 live births
2006	1975	24304 (22130–26478)	1 in 4.1 live births
2007	2011	24366 (22209–26523)	1 in 4.1 live births
2008	2048	26318 (24096–28540)	1 in 3.8 live births
2009	2084	22313 (20285–24341)	1 in 4.5 live births
2010	2121	18765 (16921–20608)	1 in 5.3 live births
2011	2140	20840 (18906–22774)	1 in 4.8 live births
2012	2157	15252 (13604–16900)	1 in 6.6 live births
2013	2187	14817 (13203–16430)	1 in 6.7 live births
2014	2202	14944 (13329–16558)	1 in 6.7 live births

CI, confidence interval.

The ocular diagnosis was most commonly made by a primary care provider in 3,674 cases (87.0%), and by an eye care provider in only 549 (13.0%). Vision-threatening conditions, defined in Table 2, were present in 314 infants (7.4%), but visual acuity was adversely affected in only 23 infants (0.5%). The conditions associated with decreased vision were strabismus in 10 (43.5%), cerebral visual impairment in 3 (13.0%), and optic atrophy, optic nerve hypoplasia, retinopathy of prematurity, cataract, nystagmus in 2 each (8.7%). The demographics and clinical characteristics of the cohort are summarized in Table 3.

Table 2.

Twenty most prevalent ocular diagnoses among infants born in Olmsted County, Minnesota, 2005–2014

Ocular diagnosis	No. (%)	Incidence per 100,000 live births (95% CI)
Conjunctivitis	2175 (51.5)	10425 (9984–10860)
Nasolacrimal duct obstruction	1432 (33.9)	6864 (6506–7217)
Pseudostrabismus	173 (4.1)	829 (706–953)
Strabismusa	103 (2.4)	494 (398–589)
Retinopathy of prematuritya	76 (1.8)	364 (283–446)
Ptosisa	39 (0.9)	187 (128–246)
Preseptal cellulitisa	35 (0.8)	168 (112–223)
Subconjunctival hemorrhage	29 (0.7)	139 (88–189)
Physiological anisocoria	23 (0.5)	110 (65–155)
Periorbital edema	18 (0.4)	86 (46–126)
Refractive errora,b	17 (0.4)	81 (43–121)
Nystagmusa	15 (0.4)	72 (36–108)
Capillary hemangiomaa	14 (0.3)	67 (32–103)
Cataracta	12 (0.3)	58 (25–90)
Eczema eyelids	9 (0.2)	43 (15–71)
Congenital anomaly eyelida	9 (0.2)	43 (15–71)
Delayed visual maturation	9 (0.2)	43 (15–71)
External hordeolum	8 (0.2)	38 (12–65)
Optic nerve hypoplasiaa	8 (0.2)	38 (12–65)
Cerebral visual impairmenta	7 (0.2)	34 (9–58)
Vision-threatening conditions	326 (7.7%)	1558 (1389–1728)

CI, confidence interval.

^aIncluded as vision-threatening conditions (defined as those with potential to result in vision loss without intervention), along with globe malformations (anophthalmos-microphthalmos spectrum), colobomas, anterior segment dysgenesis, ocular trauma, congenital glaucoma, corneal opacities, keratitis, retinal dystrophy, and optic nerve disorders.

^b2 with myopia, 8 with hyperopia, and 7 with astigmatism.

Table 3.

Historical and clinical characteristics of 4,223 infants (≤1 year of age) diagnosed with an ocular disorder in Olmsted County, Minnesota, 2005–2014

Characteristic	Result
Sex, no. (%)
Female	1951 (46.2)
Male	2272 (53.8)
Ethnicity, no. (%)
White	3185 (75.4)
Asian	175 (4.1)
African American	214 (5.7)
Unknown or refused	285 (6.7)
Other	364 (8.6)
Age at diagnosis, months
Median (Q1, Q3)	3 (0,7)
Range	0–12
Age at diagnosis, no. (%)
0–3 months	2202 (52.1)
3–6 months	838 (19.8)
6–9 months	766 (18.1)
9–12 months	417 (9.9)
Diagnosis made by, no. (%)
Non-eyecare provider	3674 (86.9)
Pediatrician	2185 (51.7)
Family Medicine provider	726 (17.2)
Primary Care provider, not specified	513 (12.1)
Emergency physician	189 (4.5)
Nurse practitioner	61 (1.4)
Eyecare provider	549 (13.1)
Ophthalmologist	545 (12.9)
Optometrist	4 (0.2)
Visual acuity,a no. (%)
Normal	4183 (99.0)
Affected (right or left or both eyes)	23 (0.6)
Missing	17 (0.4)

^aVisual acuity was assessed by the examining provider using age-appropriate testing methods such as response to light, fixation (central, steady, maintained),and, follow response to a small target and assessing pupil response to light.

The 20 most common ocular diagnoses are shown in Table 2, with conjunctivitis (n = 2,175) and congenital nasolacrimal duct obstruction (CNLDO) (n = 1,432) comprising 85.4% of the cohort. The clinical characteristics of infantile conjunctivitis from this population have been reported.⁵ Pseudostrabismus (n = 173) occurred more frequently than strabismus (n = 103). The incidence of ocular anomalies by anatomic location are reported in Table 4. Deforming ocular anomalies of the globe, eyelids, or anterior segment occurred in 29, 336, and 14 per 100,000 births, respectively. Strabismus was observed in 494/100,000 births.

Table 4.

Incidence of ocular anomalies among 1838 infants diagnosed with ocular disorders with onset at birth over a 10-year period, Olmsted County, Minnesota, 2005–2014

Ocular structure from external to internal anatomically (anomaly)	Incidence of congenital ocular anomalies (95% CI)
Globe (anophthalmos, microphthalmos, coloboma)	29/100,000 births per year (6–52)
Lid (capillary hemangioma, coloboma, ptosis, dermoid)	336/100,000 births per year (257–414)
Lacrimal (NLDO, punctal anomaly, dacryocystocele)	6888/100,000 births per year (6531–7244)
Orbit (hypertelorism, orbital tumors)	14/100,000 births per year (0–31)
Cornea (corneal opacity, limbal dermoid)	14/100,000 births per year (0–31)
Anterior segment dysgenesis	14/100,000 births per year (0–31)
Lens (cataract)	58/100,000 births per year (25–90)
Optic disk (atrophy, coloboma, hypoplasia)	72/100,000 births per year (36–108)
Glaucoma	10/100,000 births per year (0–23)
Cortical visual impairment	72/100,000 births per year (35–108)

NLDO, nasolacrimal duct obstruction.

Ninety-five children (2.2%) required surgery for their ocular condition, yielding an incidence of 455/100,000 births per year. The median age of surgery was 11 months (range, 3 days to 108 months). The most common surgeries performed were probing for CNLDO in 35 (36.8%), followed by strabismus in 30 (31.58%), laser photocogulation for retinopathy of prematurity in 11 (11.5%), cataract in 6 (6.3%), ptosis repair in 3 (3.2%), other lid surgery in 3 (3.2%), dermoid excision in 2 (2.1%), and nystagmus, glaucoma and vitrectomy procedures in 1 each (1.1%).

Discussion

In this population-based study of infants conducted over a 10-year period, approximately 1 in 5 infants was diagnosed with an ocular condition, with nearly half occurring at birth. Conjunctivitis and congenital nasolacrimal duct obstruction (CNLDO) were the most prevalent diagnoses; vision-threatening disorders, such as strabismus and cerebral visual impairment, made up only 7.4% of the cohort. A majority of the infants were diagnosed and managed by a primary care provider, and 1 in 8 was evaluated and treated by an eye care specialist. Decreased vision and the need for surgical intervention were relatively rare in this cohort of infants.

There are no similar population-based studies of newborns or infants with which to compare the findings of this study. Among institution-based reports, the prevalence of ocular disease in newborns ranges from 8.2% to 14.9%.^6–8 These findings are consistent with the 10% diagnosed in the first 3 months of life in the current study but lower than the 20% observed by 1 year of age. Other institution-based studies have reported that conjunctivitis and CNLDO were the two most common ocular conditions in infants, similar to the current study.^3,9

Prior population-based reports on eye disease in children exist; however, those that include infants typically report on the preschool age range (>6 months to 6 years).^10–12 In these reports, transient or spontaneously resolving conditions such as conjunctivitis and CNLDO may be less frequent than in our study, while acquired strabismus and amblyopia may be more prevalent. Studies of school age children emphasize visually significant refractive errors, including acquired myopia, and thus report higher prevalences of vision disorders.^13–15 As evidenced by the above studies, the ocular problems affecting preschool, school-going and older children are different than those affecting infants.^10–16

The near equal distribution of acquired versus congenital disorders in this cohort is likely due to the high prevalence of conjunctivitis. Excluding those with conjunctivitis, nearly all infants had a congenital ocular anomaly, CNLDO being the most common. Other structural anomalies of the anterior segment and posterior segment were rare (0.5%), similar to the Baltimore Pediatric Eye Disease Survey (of children aged 6 months to 71 months), which reported abnormalities of the eyelid, anterior segment, and posterior segment in 0.35%, 0.56%, and 0.63%, respectively, compared with 0.3%, 0.08%, and 0.07% in the current study.¹⁰

Strabismus was seen in 0.5% of infants in our cohort. By contrast, the Multi-Ethnic Pediatric Eye Disease Study reported a strabismus prevalence of 1.1–2.4% for infants aged 6 months to 11 months; it is possible that some infants in our cohort had infantile strabismus that was not diagnosed during infancy.^17,18 Strabismus surgery was the second most common indication for surgery in the current study, after nasolacrimal duct probing.

The diagnosis of disorders in this cohort was made by a primary care provider for most infants with only 12.1% requiring an evaluation and management with an eye care provider. The American Academy of Ophthalmology (AAO) and American Academy of Pediatrics (AAP) recommend external inspection of the eyes and red reflex testing for all newborns. A repeat examination is recommended at 6- to 12-month visits, with the addition of fix-and-follow response testing and ocular motility assessment.^2,19,20 Those patients with a family history of congenital cataracts, retinoblastoma, strabismus, or amblyopia, and infants in whom systemic, genetic or metabolic disease is suspected should be promptly referred to a pediatric ophthalmologist. It is not surprising that the majority of the patients in this cohort did not require a referral to an eye specialist given that conjunctivitis and the often spontaneously-resolving nasolacrimal duct obstruction are generally straightforward to assess and manage for primary care providers.

Although it is well known that NLDO and conjunctivitis are relatively common in the first year of life, the current study provides an overview of all ocular conditions affecting infants from a well-defined population and highlights the most common vision-threatening conditions. This study supports the current visual assessment and screening guidelines recommended by the AAP and the AAO for the first year of life.² Pediatric, family medicine, and primary care nurse practitioner training programs should include training in the evaluation and management of NDLO and conjunctivitis. Pseudostrabismus, in this cohort of infants, occurred nearly twice as frequently as strabismus. Strabismus leading to amblyopia was, however, the most common cause for decreased vision. Trainees should feel comfortable distinguishing between these two conditions, especially because nearly half of the vision loss in our cohort was due to strabismus, an often treatable cause of decreased vision. Additional training should be directed toward recognizing the presentation of the other common reversible or improvable causes of decreased vision in this age group, including cerebral visual impairment and cataract. Detection of cataract with a red reflex test performed at birth and with each screening can result in better visual outcomes. The red reflex test is a cost-effective and accurate tool in identifying anterior segment disorders (sensitivity of 99.6%) when correctly performed, although it has low sensitivity for posterior segment disorders that are small or occur in the peripheral retina.^21–23

There are several limitations to the findings of this study. Its retrospective design is limited by incomplete data and irregular follow-up. The population size of Olmsted County residents contributed to the very small numbers for rare disorders such as retinal dystrophies and congenital glaucoma and thus, the incidence rates of uncommon disorders may be less accurate and not generalizable to other populations. Some patients may have avoided detection or received an inaccurate diagnosis despite having an ocular disorder, thereby underestimating the true incidence of infantile eye disorders in this population. Due to the difficulty of assessing visual acuity in infants, especially in the primary care setting, abnormal visual acuity may have been underdiagnosed. However, the medical records of all 4,223 infants who received any eye code in this study were individually reviewed for diagnosis accuracy, overcoming some of the weaknesses of other diagnostic code-dependent surveys.²⁴ Finally, the population of Olmsted County is predominantly white; therefore, the findings from this study may not apply to other regions of the country and the world. Despite these limitations, this large, population-based cohort of infants diagnosed over a 10-year period provides useful information regarding ocular disorders in the first year of life.