IOP Measurements by Different Devices in Children
In a study in South Korea, Feng et al. compared intraocular pressure (IOP) measurements in children by means of rebound, noncontact, and Goldmann applanation tonometry (GAT) and assessed the relationship of each to central corneal thickness (CCT). They found that all methods can be considered appropriate for routine clinical use in children and that IOP readings of each tonometry positively correlated with CCT.
Measurements were taken in the right eyes of 419 children, who had a mean age of 8.89 ± 3.41 years (range, 3-15 years). Using the 3 types of tonometry, the researchers assessed mean IOP, rates of successful measurement with each type, and the intermethod agreement by Bland-Altman plot. The influences of CCT and of average IOP of the 3 tonometries on IOP differences between methods were also evaluated.
The researchers found significant differences in mean IOP with each tonometry method, with GAT showing the lowest readings. In children younger than 10 years old, IOP was successfully measured by noncontact tonometry in 89%, by rebound tonometry in 75%, and by GAT in 64%. In children older than 10, the rates were 100%, 98%, and 94%, respectively, for those methods. The IOP of each tonometer positively correlated with CCT. Rebound and noncontact tonometry overestimated IOP relative to GAT for thicker CCT. Rebound tonometry overestimated IOP relative to both GAT and noncontact tonometry at higher average IOPs.
The researchers concluded that IOP readings obtained with the 3 types of tonometry showed a reasonable concordance with each other, and all of them can be considered appropriate for routine clinical use. The noncontact method has the highest rate of success in obtaining an IOP measurement in children. The researchers added that, given the risk of false-positive diagnosis of pediatric glaucoma, attention should be devoted to children whose IOP is in a suspicious high range or who have thicker corneas.
The Association of Race With Childhood Uveitis
Using a retrospective cohort study design, Angeles-Han et al. identified risk factors for a severe disease course among children with noninfectious uveitis. This study reported that non-Hispanic African-American race is a potential predictor of a severe uveitis course; children in this group had an accelerated rate of ocular complications and an increased likelihood of vision loss.
The records of 94 children with uveitis were reviewed at enrollment and every 3 to 6 months thereafter (2011-2015). Severe uveitis was defined as a history of ocular complications or a visual acuity (VA) of 20/200 or worse. Children were compared by disease, VA, complications, and race. When examining race, the researchers focused on non-Hispanic African-American and non-Hispanic white children only.
Of 85 children with uveitis and complete ocular examinations, 27 (32%) had a history of VA of 20/200 or worse. A subanalysis of non-Hispanic African-American and white children showed an increased prevalence of VA of 20/200 or worse in the former group. In addition, non-Hispanic African-Americans were more likely to be diagnosed at an older age and to have intermediate uveitis, bilateral disease, and a higher rate of complications. On multivariable analysis, non-Hispanic African-American race was a significant predictor of blindness, after controlling for uveitis duration. Non-Hispanic African-Americans developed 2.2 times more unique complications per year of disease than non-Hispanic whites when controlling for uveitis type and duration.
The researchers noted that these findings could be secondary to biological differences or to socioeconomic factors such as health care access. They recommended further study to reduce vision-threatening outcomes among minority patients.
Tear Dysfunction, Corneal Sensitivity, and Correlation With Blink Rate
In a comparative observational case series, Rahman et al. assessed corneal sensitivity in patients with tear dysfunction due to a variety of causes and evaluated correlations between corneal sensitivity, blink rate, and clinical parameters. Outcome measures included corneal and conjunctival staining, corneal sensitivity, blink rate, tear meniscus height, and irritation symptoms.
Ten controls and 33 patients with tear dysfunction were evaluated; in the latter group, 11 had meibomian gland disease, 10 had aqueous tear deficiency, and 12 had conjunctivochalasis. Corneal sensitivity was measured by Cochet-Bonnet and air jet esthesiometers, and blink rate by electromyography. Eye irritation symptoms, tear meniscus height, tear break-up time (TBUT), and corneal and conjunctival dye staining were evaluated.
Compared with the controls, mean sensory thresholds, as measured by either of the esthesiometers, were significantly higher in the aqueous tear deficiency group but were not significantly different in the other groups. Reduced corneal sensitivity correlated significantly with more rapid TBUT and blink rate and with greater irritation and ocular surface dye staining. Mean blink rates were significantly higher in both aqueous tear deficiency and conjunctivochalasis compared with the controls. Among all subjects, blink rate positively correlated with ocular surface staining and irritation and inversely correlated with TBUT.
The authors concluded that among conditions causing aqueous tear dysfunction, reduced corneal sensitivity was associated with greater irritation, tear instability, ocular surface disease, and blink rate. Rapid blinking is associated with worse ocular surface disease and tear stability.
Impact of Free Glasses and Teacher Incentive on Children’s Use of Eyeglasses
Yi et al. studied the effect of free eyeglasses combined with a teacher incentive on in-school wear of glasses among Chinese urban migrant children. Using a cluster-randomized controlled trial design, the researchers found that free spectacle distribution in combination with education on their use and a teacher incentive maintained high rates of classroom wear over a school year.
Children with visual acuity (VA) of 6/12 or worse in either eye due to refractive error were identified in 94 randomly chosen schools. In 47 schools, the children received free glasses and education on their use, and teachers received an incentive (intervention group); in the 47 control schools, children received glasses prescriptions only. Intervention group teachers received a tablet computer if 80% or more of the children given glasses were wearing them during unannounced visits 6 weeks and 6 months (main outcome) after intervention. Among 4,376 children, 728 met enrollment criteria: 358 were allocated to intervention and 370 to control; 693 completed the study and underwent analysis.
Spectacle wear was significantly higher among intervention children. By direct classroom observation at 6 months, 68.3% of the intervention group and 23.9% of the control group were wearing their eyeglasses. Other predictors of observed wear at 6 months included baseline spectacle wear, uncorrected VA worse than 6/18, and parental spectacle wear.
In a previous trial by these researchers, the 6-month observed wear rate was only 41% among similar-aged children who were provided free glasses without teacher incentives. Both that earlier study and the current trial demonstrate the need for interventions—and not just free spectacles—in encouraging children to wear their glasses.
American Journal of Ophthalmology summaries are edited by Thomas J. Liesegang, MD.
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