Contractile morning glory disk anomaly: analysis of the cyclic contractions and literature review

Abstract

Purpose: To investigate the contraction mechanism of morning glory disk anomaly using computer-assisted analysis of the cyclic contractions frame by frame and to review the literature on contractile morning glory disk anomaly cases.

Methods: The fundus video of the patient under anesthesia was recorded using RetCam C300 lens. Frames at 1 second intervals were extracted to quality-preserving TIFF images and manually selected areas of cup, disk, and pigmented ring were measured with image analysis software. Measurements were repeated twice, and estimated uncertainties were calculated.

Results: Two full-contraction phases and 1 half- and 1 full-dilation phase were recorded and analyzed. At the end of the second dilation phase, cup, disk, and pigmented ring were dilated to 93.7%, 97.6%, and 98.3% of their areas after first dilation. At the end of the second contraction cup, disk and pigmented ring areas remained 1.24, 1.01, and 1.01 times larger, respectively, than the areas at the end of the first contraction.

Conclusions: Ectopic cholinergic muscle contraction alone is unlikely to explain the cyclic contraction dilation movements under constant stimulus. Potentially present smooth muscle cells can be provoked by the stretch caused by the influx of fluid into the subretinal space. Change in spatial configuration and oscillations with decreasing magnitudes can be explained by decreasing contractions due to decreasing stretch with decreasing fluid influx in each cycle after the initial triggering of outside pressure, causing the greatest pressure gradient and the greatest fluid influx.