Measurement of the posterior precortical vitreous pocket in fellow eyes with posterior vitreous detachment and macular holes.

Abstract

To evaluate the premacular vitreous zone of liquefaction (the posterior precortical vitreous pocket [PPVP]) using contact B-scan ultrasonography and to compare the size of the observed PPVP in fellow eyes with posterior vitreous detachment (PVD) as compared with fellow eyes with macular holes. Patients with a fellow eye having a PVD or macular hole but not having a PVD in the examined eye were evaluated with contact B-scan ultrasonography to measure the PPVP. The mean age +/- SD of the 19 patients was 63.9 +/- 7.8 years. There were 13 patients in the PVD group and 6 in the macular hole group. All patients in the macular hole group had a vitreous detachment in the macular region of the eye with the macular hole. There was no difference in the mean age (P = 0.44, independent samples t test) or mean refractive error (P = 0.56) of the two groups. The PPVP was seen to be round to ovoid in shape with a mean anteroposterior dimension of 8.4 mm and a mean horizontal dimension of 9.2 mm for all patients. The mean anteroposterior measurement was 7.6 mm in the PVD group versus 10.3 mm in the macular hole group, a difference that was significant (P = 0.004, independent samples t test). In a similar manner, the mean horizontal dimension was 8.2 mm in the PVD group and 11.1 mm in the macular hole group, a difference that was significant (P = 0.031). The PPVP was larger in fellow eyes in the macular hole group. The larger PPVP would be expected to cause a greater degree of force concentration and a more pronounced shifting of the direction of the force vector for anteroposterior tensile stress to one being more tangential to the surface of the retina in these patients.