Parapapillary Intrachoroidal Cavitation in Glaucoma: Association with Choroidal Microvasculature Dropout.

PURPOSE: To characterize the choroidal microvasculature in glaucomatous eyes with parapapillary intrachoroidal cavitation (PICC) using optical coherence tomography angiography (OCTA) and its association with parapapillary choroidal microvasculature dropout (MvD). METHODS: This study included 47 glaucomatous eyes with PICC, as identified by color fundus photography and optical coherence tomography scanning of the optic nerve head area. Peripapillary choroidal microvasculature was evaluated on en-face OCTA images. Choroidal MvD was defined as a focal sectoral capillary dropout with no visible microvascular network. RESULTS: PICC was visible as a well-demarcated area with homogeneously reduced vessel density in en-face OCTA images of the choroidal layer. MvD was detected in 42 eyes (89.4%). Although located in the juxtapapillary area adjacent to the PICC, MvD was confined to the area of parapapillary atrophy. MvD observed in OCTA en-face images was distinguished from the area of PICC by the absence of vascular signal. Of the 50 PICCs, 49 (98.0%) had hemifield visual field defects at the location corresponding to the hemispheric location of PICC. CONCLUSIONS: PICC was found to have a characteristic microvascular feature in choroidal en-face OCTA images, and to be topographically associated with glaucomatous visual field defect. PICC was frequently accompanied by MvD and was located adjacent to the area of MvD, suggesting that PICC and MvD have similar pathogenesis.

Association of lateral rectus muscle volume and ocular motility with the abducens nerve in Duane's retraction syndrome.

PURPOSE: To investigate the relationship between ocular motility and lateral rectus (LR) muscle volume according to the presence or absence of the abducens nerve in patients with Duane's retraction syndrome (DRS) using high-resolution magnetic resonance imaging (MRI). METHODS: A total of 54 unilateral DRS patients were divided into two groups according to high-resolution MRI findings: DRS without an abducens nerve on the affected side (absent CN6 group, n = 45) and DRS with symmetric abducens nerves on both sides (present CN6 group, n = 9). Ocular motility was measured by image analysis based on nine gaze photographs. LR volume was measured on T2-weighted coronal MRI of the orbit, and the ratio of paretic/normal side (P/N) LR volume was investigated. Association of the abducens nerve with various parameters including ocular motility, LR volume, and ratios of P/N LR volume were determined. RESULTS: LR volume was smaller in the affected eye than the non-affected eye in both groups. In the present CN6 group, abducens nerve diameter and the ratio of P/N LR volume showed a positive correlation. A smaller LR volume and more limitation of abduction in the affected eye were predictive of an absent abducens nerve in DRS. CONCLUSIONS: LR muscle hypoplasia was apparent in the affected eye of DRS patients. Abducens nerve diameter positively correlated with the ratio of P/N LR volume in the present CN6 group. Graphical abstract.

Morphometry of the Oculomotor Nerve in Duane's Retraction Syndrome.

OBJECTIVE: To investigate the morphometric characteristics of the oculomotor nerve and its association with horizontal rectus muscle volume in patients with Duane's retraction syndrome (DRS) according to the presence of the abducens nerve. METHODS: Fifty patients diagnosed with unilateral DRS were divided into two groups according to high-resolution magnetic resonance imaging (MRI) findings; DRS without an abducens nerve on the affected side (absent group, n = 41), and DRS with symmetric abducens nerves on both sides (present group, n = 9). Oculomotor nerve diameter was measured on high-resolution MRI in the middle of the cisternal space. The medial rectus muscle (MR) and lateral rectus muscle (LR) volumes were measured on T2-weighted coronal MRI of the orbit. Associations of oculomotor nerve diameter and horizontal rectus muscle volumes were performed according to the presence and absence of the abducens nerve. RESULTS: Oculomotor nerve diameter on the affected side was thicker than that of the non-affected side in the absent group (p < 0.001), but not in the present group (p = 0.623). In the absent group, there was a positive correlation between oculomotor nerve diameter and MR volume (r = 0.779, p < 0.001), as well as the LR volume (r = 668, p = 0.023) of the affected eye. CONCLUSIONS: In DRS patients with an absent abducens nerve, the oculomotor nerve diameter was thicker in the affected eye compared to the non-affected eye. Oculomotor nerve diameter was associated with MR and LR volumes in the absent group. This study provides structural correlates of aberrant innervation of the oculomotor nerve in DRS patients.