Anophthalmia and Microphthalmia
Alaska, 2007-2021
Background
Anophthalmia and microphthalmia are rare birth defects of one or both of a newborn’s eye(s). Anophthalmia is the complete lack of a developed eye. Microphthalmia occurs when the eye(s) do not develop fully and are undersized or underdeveloped.1 Researchers estimate that about 1 in every 5,200 babies is born with anophthalmia/microphthalmia in the United States.2 Anophthalmia and microphthalmia can create issues with vision or blindness. Both conditions can include changes in the bones around the eye, resulting in changes in the shape of a skull.3 The causes of anophthalmia and microphthalmia are not always known. Anophthalmia and microphthalmia can arise independently or with other eye defects, such as coloboma and orbital cyst, or as part of more generalized syndromes, such as CHARGE syndrome.4 An ophthalmologist typically guides the treatment of newborns with either anophthalmia or microphthalmia. No medical therapy can provide typical eye function to people born with anophthalmia or microphthalmia. However, early treatment can help babies and children with these conditions grow and develop optimally. A newborn’s care team can include a pediatrician and other medical disciplines such as oculoplastic specialists, family support services, and genetic counseling.3
Epidemiology
Alaska Birth Defects Registry (ABDR) registers birth defects as reported from health care providers using International Classification of Disease (ICD) billing codes. The use of these ICD codes can lead to misclassification of diagnosed conditions. Prior to this report, all prevalence estimates were based on the number of unique children reported to ABDR with an ICD code representing a specified condition regardless of case confirmation status.
The estimates in this report were derived by conducting medical record review and case confirmation of a random sample of cases of the condition reported to ABDR. The confirmation probability from the sample was used to develop informed estimates of the actual diagnosed defect prevalence. See Defect prevalence calculation.
For explanations of table columns see Column descriptions.
Prevalence
Anophthalmia or microphthalmia occurs in about 1 in every 5,200 babies in the United States.[2]
In Alaska, during 2007-2021, the prevalence of Anophthalmia and microphthalmia was 0.3 per 10,000 live births.| Reports | Defects | Births | Prevalence (95% CI) |
|---|---|---|---|
| 27 | 4.9 | 162989 | 0.3 (0.1, 0.6) |
| Notes: 95% CI = 95% Confidence Interval | |||
Trend
Prevalence per 10,000 births of Anophthalmia and microphthalmia during 2007-2021 by five-year moving averages, with 95% confidence interval band and Poisson estimated fitted line.| Estimate | Std. Error | t value | Pr(>|t|) |
|---|---|---|---|
| 0.08904 | 0.04240 | 2.10000 | 0.06512 |
| Notes: 95% CI = 95% Confidence Interval | |||
Regional Distribution
Distribution of Anophthalmia and microphthalmia in Alaska by Public Health Region of maternal residence at the time of birth. A description of regional breakdowns can be found here. Data suppressed for # of reports < 6.
Demographics
Some subgroups may be more at risk for having a baby with Anophthalmia and microphthalmia. This section provides the descriptive epidemiology of specified maternal, birth, and child characteristics identified from the birth certificate.
Accompanying Diagnoses
The ten diagnoses most commonalty associated with Anophthalmia and microphthalmia.
Technical notes
Column descriptions
# Reports: Unless otherwise noted, the number of unique reports of the defect received by ABDR during the specified birth year(s). Each report represents a unique child with the specified defect.
# Defects: The estimated true number of reports that are diagnosed defects based on medical record review and case confirmation.
# Births: The number of live births among Alaskan residents that occurred in Alaska during the specified birth year(s).
Prevalence (95% CI): The estimated diagnosed prevalence of the condition and corresponding 95% Confidence Interval. (For information on how the defect prevalence was estimated see below).
Defect prevalence calculation
The estimated defect prevalence was calculated using a Bayesian approach based on the reported prevalence, PPV and 1-NPV (see formula below).
Through medical records review and case confirmation of a random sample of reported cases, the defect prevalence is calculated as:
\[PPV (Positive Predictive Value) = p(defect|report)\] \[NPV (Negative Predictive Value) = p(\overline{defect}|\overline{report})\]
\[p(defect) \approx [p(report)\cdot PPV]+[p(\overline{report})\cdot (1-NPV)]\]
Defect prevalence estimates are a more accurate estimation of the actual diagnosed prevalance of birth defects compared to the reported prevalance estimates in Alaska. ABDR obtains reports from medical providers using International Classification of Disease (ICD) codes that are extracted from individual systems which when aggregated may not reflect true diagnostics. Caution should be used when interpreting and comparing the reported prevalence estimates with national estimates.
See Data analysis methods for more information.
P-value estimate
To evaluate the trend over time and account for under/over-dispersion we constructed a quasi-Poisson regression model. This model assumes the variance is a linear function of the mean and models the estimated number of annual defects by year with a natural log (ln) offset of the annual births. P-values < 0.05 are considered significant, which indicates that the predicted slope is significantly different from a slope of zero.
Data suppression
For region and demographic data tables, values are suppressed based on the number of reports received during the observation period. Counts less than 6 are suppressed (as indicated by ‘-’ in the table). For regions or demographics with only one cell count suppressed a second is suppressed to eliminate the ability to back-calculate the estimate.
References
[1] Facts about Anophthalmia / Microphthalmia (CDC), from https://www.cdc.gov/ncbddd/birthdefects/anophthalmia-microphthalmia.html (2024) [accessed April, 04 20234]
[2] Mai CT, Isenburg JL, Canfield MA, Meyer RE, Correa A, Alverson CJ, Lupo PJ, Riehle‐Colarusso T, Cho SJ, Aggarwal D, Kirby RS. National population‐based estimates for major birth defects, 2010–2014. Birth Defects Research. 2019; 111(18): 1420-1435
[[3]]https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/anophthalmia-and-microphthalmia#:~:text=Anophthalmia%20is%20when%20a%20baby,born%20with%20anophthalmia%20or%20microphthalmia.) National Eye Institute - At a glance: Anophthalmia and Microphthalmia (NIH), from https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/anophthalmia-and-microphthalmia#:~:text=Anophthalmia%20is%20when%20a%20baby,born%20with%20anophthalmia%20or%20microphthalmia. (2024). [accessed April, 04 2024]
[4] Ragge, N. K., I. D. Subak-Sharpe, and J. R. O. Collin. “A practical guide to the management of anophthalmia and microphthalmia.” Eye 21.10 (2007): 1290-1300.
Suggested Citation
State of Alaska Department of Health and Social Services, Division of Public Health, Section of Women’s, Children’s, and Family Health. Alaska Birth Defects Registry Condition Report: Anophthalmia and microphthalmia, Alaska, 2007-2021. Updated May 01, 2024. Available at: http://rpubs.com/AK_ABDR/Anophthalmia and microphthalmia.
Contact
Alaska Birth Defects Registry (ABDR)
3601 C Street, Suite 358
Anchorage, AK 99503
(907) 269-3400 phone
(907) 754-3529 fax
hssbirthdefreg@alaska.gov
Updated: May 01, 2024
Code source:
R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\Targets_publications\anoph_tar.Rmd
