Corneal densitometry (CD) values are lower in children with hyperopia compared with those observed in children who are myopic or emmetropic, according to research published in Photodiagnosis and Photodynamic Therapy. The report also found that increased age may be associated with increased CD values for patients with emmetropia.
Researchers enrolled 211 children, (age range, 6-18 years; 77.3% boys) in the prospective, cross-sectional analysis. Participants underwent best corrected visual acuity, pupillary reflex, intraocular pressure (IOP), biomicroscopy, and CD measurements. Patients were stratified according to refractive error (emmetropia, 28.9%; myopia, 29.4%; and hyperopia, 41.7%) and those with corneal or ocular surface disease were excluded from the analysis. A single blind technician performed all measurements without mydriasis.
Overall, children with hyperopia had lower mean anterior corneal curvature (42.7±1.7 diopters [D]; P <.001), maximal corneal curvature (44±1.8 D; P =.010), anterior chamber depth (3±0.4 mm; P <.001), anterior chamber volume (175.7±34.9 mm3; P <.001), and iridocorneal angle (36.7±5.7°; P =.043) compared with children with emmetropia or myopia. Mean posterior corneal curvature was also significantly different in patients with hyperopia (-6.2±0.3 D; P =.001) compared with participants with myopia and emmetropia.
Higher CD values were noted in the corneal apex (0-2 mm zone), and pericentral cornea (2- 6 mm zone) compared with the peripheral zones (6-10 mm) in all corneal layers for each refractive error. The annular zone (10-12 mm diameter) had the highest mean CD value for all groups except for the posterior layer.
Age correlated with CD in the anterior (0-2 and 2-4 mm zones only; P <.001 for both), central (P =.019) and posterior layers (P =.019) in patients with emmetropia.
“[I]ncreased light backscattering results in the reduction of the amount of light reaching the retina and impairs the quality of vision,” according to the researchers. “In the present study, the CD values were significantly lower in hyperopic eyes than in myopic and emmetropic eyes in children. The CD values also increased with age in emmetropic eyes.”
Study limitations include small subgroup samples and failure to include children who were not of White ethnicity in the study.
Nalcacioglu P, Sen E, Aydemir E, Kiziltoprak H, Yasar HH. Objective assessment of corneal backscattered light in myopic, hyperopic, and emmetropic children. Photodiagnosis Photodyn Ther. Published online July 23, 2022. doi:10.1016/j.pdpdt.2022.103031