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Larger optic disc crescent sizes may be associated with higher spherical error (SER) in eyes with myopia, according to a study published in Ophthalmic and Physiological Optics. Crescent positioning may also affect SER.
Investigators retrospectively evaluated retinal photographs from 400 healthy participants with myopia (mean age 41±16.24 years, 73% women, mean SER -3.74±2.32 D). A masked researcher evaluated the photographs and recorded maximum crescent width (CW), vertical disc diameter (VDD), and crescent location. Patients with known ocular pathologies and surgeries were excluded from the analysis. The primary objective was to investigate associations between optic disc crescent parameters and their association with myopia levels.
The investigators determined that CW was 0.24±0.24 mm and that it was associated with both age and SER (r=0.26 and -0.45, respectively, P <.001 for both). Researchers note that most crescents were located temporally (74%) or inferior temporally (17%). VDD was 1.75 mm, and the ratio of maximum CW to VDD was 0.17.
The team noted that SER varied on the basis of crescent position. It was lowest for the nasal position (−6.20±1.75 D), followed by inferior (−5.32±2.68 D), inferior temporal (−5.01±2.37 D), halo (−4.64±3.40 D), nasal and temporal (−4.50±3.71 D), and temporal (mean, −3.50±2.14 D) positions. Patients with no crescents were the least myopic (mean, −3.03±1.97 D). Similarly, the CW varied according to crescent position, ranging from 0.49±0.97 mm for nasal and temporal position to 0.23±0.17 mm for the temporal position.
“Higher myopia (SER) was associated with the presence of an optic disc crescent as well as larger and inferior-temporally located crescents,” according to the researchers. “Monitoring the appearance of optic disc crescents from childhood using clinical imaging would allow study of whether crescent formation and change precedes and/or is capable of predicting the development of myopic ocular pathology.”
Study limitations include a lack of axial length measurements, a retroscopic nature, and single center design.
Reference
Hill D, Heitmar R, Logan NS. Size and position of the optic disc crescent in a white European population with myopia. Ophthalmic Physiol Opt. Published online June 20, 2022. doi:10.1111/opo.13018
