A recent study from the Chinese University of Hong Kong suggests that parental astigmatism is an independent factor with a dose-dependent association to pediatric astigmatism.
Tell me about the study.
The population-based, cross-sectional study recruited participants as familial trios from the Hong Kong Children Eye Study. These familial trios consisted of one child 6 to 8 years old and two parents (astigmatic, non-astigmatic, or both). The study assessed a total of 5,708 children and 11,416 parents.
The children were categorized into 6 groups based on the severity of astigmatism of both parents, and the associations of various factors for pediatric astigmatism were evaluated with logistic regression analyses. (via)
I want to know more.
All children and their parents underwent comprehensive eye examinations, wherein cycloplegic autorefraction and autokeratometry were conducted on the children, and non-cycloplegic autorefraction and autokeratometry were conducted on the parents.
Additionally, participants filled out standardized questionnaires (Chinese translations of the Sydney Myopia Study), where they shared information about their socioeconomic status, demographic and health-related data, and environmental factors associated with risk for astigmatism.
How did the study define astigmatism?
It used absolute values with a threshold of 1.00 diopter (D). Refractive astigmatism (RA) was expressed using negative notation and defined as astigmatism of -1.00 D or less, while corneal astigmatism (CA) was expressed using positive notation and defined as astigmatism of 1.00 D or greater.
Mild RA was defined as RA between -1.00 and -2.00 D, and high RA as -2.00 D or greater. On the other hand, mild CA was defined as >1.00 D to less than 2.00 D, and high CA was defined as 2.00 D or greater.
How did it measure astigmatism?
The children were measured for refractive astigmatism following two cycles of Cyclogyl (1% cyclopentolate) and 1% tropicamide eye drops, administered 10 minutes apart. If a pupillary light reflex remained, or the pupil size remained less than 6 mm, a third cycle of eye drops was administered.
At least three readings of spherocylindrical autorefraction were obtained 30 minutes after the last dose of cycloplegic agents and then averaged. The amount of corneal astigmatism for both parents and child was calculated as the difference between the steepest and flattest meridians, and the axis of CA was defined as the meridian of the flattest curvature.
Who qualified for the study?
No restriction criteria were set for the child’s refractive status or visual acuity. Using the questionnaire, parents who reported having had keratorefractive or intraocular surgery or corneal pathology were identified and excluded.
What were the findings?
Astigmatism of 1.00 D or greater in both parents was associated with greater odds of pediatric RA (odds ratio [OR] 1.62, 95% confidence interval [CI], 1.15-2.26) and CA (OR 1.94, 95% CI, 1.50-2.50). Additionally, a dose-dependent association exists for both RA and CA, as the prevalence and odds of pediatric astigmatism increased when both parents had astigmatism of 2.00 D or greater. These odds ratios for RA and CA increased to 3.10 (95% CI, 1.34-7.21) and 4.31 (95% CI, 1.76-10.55), respectively.
Parental astigmatism demonstrated the greatest association with pediatric astigmatism among all the factors included in the multiple logistic regression.
It was also noted that the magnitudes of associations were greater in maternal and paternal CA (adjusted OR [aOR] 1.66, 95% CI, 1.47-1.88; P< 0.001 for maternal CA, and aOR 1.38, 95% CI, 1.24-1.54; P< 0.001 for paternal CA) than those observed in RA.
What does this mean?
These findings highlight the importance of counseling astigmatic parents and providing early screening for high-risk children to quickly detect and establish an intervention before it progresses to amblyopia.