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Quan V. Hoang, Ronald H. Silverman, Raksha Urs, Stanley Chang; Utility of B-Scan Ultrasonography to Assess Posterior Staphyloma in Pathologic Myopia Patients. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2669.
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Myopic progression occurs in up to 50% of myopic patients. In such eyes, the development of a posterior outpouching, or staphyloma, may be associated with vision-threatening myopic maculopathy such as foveoschisis, atrophy or choroidal neovascularization. We evaluate the utility of B-scan ultrasonography in assessing the posterior eye wall in patients with myopic posterior staphyloma and determine if staphyloma are deformed by adjacent extraocular structures during eye movements, as a potential mechanical etiology for myopic maculopathy.
Four eyes of three patients with clinically-diagnosed myopic staphyloma underwent contact B-scan ultrasonography (Quantel CineScan, 10 MHz) oriented in the anterior-posterior direction to assess the dimensions of their eye wall at rest in primary position (in horizontal and vertical planes), as well as in 4 cardinal directions of gaze. Two or more scans were recorded and analyzed at each orientation. Images were exported and the eye wall and the staphyloma were separately best fit with a circle in MatLab. The radius of curvature and the root mean error (rms) deviation of the vitreoretinal interface from the best-fit circle (felt to predominately represent the area contributed by the staphyloma) was calculated. The effect of eye orientation on radius and rms values was assessed by ANOVA.
Radius of curvature was significantly affected by orientation (F = 4.646, p < 0.001), while the rms values was not significantly affected by orientation (F = 1.34, p = 0.247). For example, radius of curvature of the horizontal dimension of one staphyloma in primary gaze was 6.93 ± 0.29 mm (mean ± standard deviation, n = 3), which was smaller than that found with gaze oriented nasally (7.49 ± 6.24) and temporally (11.02 ±3.74).
B-scan ultrasonography is a valid tool for assessing and potentially tracking myopic staphyloma. Staphyloma do appear qualitatively to be deformed with eye movement on initial studies. Mechanical deformation of staphyloma by surrounding extraocular structures may contribute to progression of staphyloma and /or myopic maculopathy.
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