Frequency of hypotonic maculopathy observed by spectral domain optical coherence tomography in post glaucoma filtration surgery eyes

PURPOSE: To report the frequency of post glaucoma filtration surgery hypotonic maculopathy determined by spectral domain optical coherence tomography (SD-OCT). METHODS: A cross-sectional retrospective observational study. Post glaucoma filtration surgery patients whose intraocular pressures (IOP) achieved 30% reduction from baseline or was controlled to IOP <14 mm Hg and had SD-OCT images and fundus photographs were enrolled. Hypotonic maculopathy was diagnosed independently on SD-OCT images and on fundus photographs. RESULTS: 112 eyes of 88 patients were included in this study. 17 eyes of 14 patients were diagnosed with hypotonic maculopathy on SD-OCT images (17/112, 15.2%). Among these eyes, only 3 eyes were also diagnosed with hypotony maculopathy on fundus photography. Hypotonic maculopathy on SD-OCT was found only in eyes with IOP ≤10 mm Hg. (17.4% in eyes with IOPs between 7 and 10 mm Hg, and 22.7% in eyes with IOP ≤ 6 mm Hg). Associations with age, sex, central corneal thickness, refractive error, IOP reduction rate and interval between surgery and OCT acquisition were not significant (P > 0.05). CONCLUSION: In most cases, hypotonic maculopathy detected by SD-OCT were not recognizable on fundus photographs. Hypotonic maculopathy was detected not only in eyes with conventional ocular hypotony (IOP < 6 mm Hg) but also in eyes with IOP between 7 and 10 mm Hg.