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Artur William Caldeira Abreu Veloso, Daniel Vítor de Vasconcelos Santos, Sebastiao Cronemberger; Multimodal imaging analysis in patients with transient ocular hypotony after antiglaucomatous surgery. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2080.
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© ARVO (1962-2015); The Authors (2016-present)
In ocular hypotony, permanent structural and functional damage may occur because of a delayed normalization of intraocular pressure (IOP). Early recognition and appropriate treatment of ocular hypotony is crucial to prevent that damage, however the hypotony duration is not very well established. This study tested the hypothesis that even a transient hypotony (≤ 6 weeks) can pose a risk to the eye.
We analyzed 14 eyes of 11 patients with transient ocular hypotony (IOP≤6 mmHg) for a maximum period of 6 weeks after either trabeculotomy or trabeculectomy or needling with mitomycin C. They were imaged by spectral domain optical coherence tomography (SD-OCT) including B-scans, improved by enhanced deep imaging mode, topographic macular thickness map, en face images segmented at various levels, retinal nerve fiber layer analysis, blue-light fundus autofluorescence and infrared fundus photo. Images were analyzed by a specialist masked to clinical findings and duration of hypotony.
The mean age of patients was 54±16 [standard deviation (SD)] years (range 14–73 years). Most patients were male (63%). Mean IOP before surgery was 25.7±10.5 mmHg (95% CI 19.6-31.7) and mean central corneal thickness was 492±53.5 µm [95% confidence interval (CI) 451-532]. During the period of hypotony (mean ± SD: 3±2 weeks), the mean IOP was 3.5±1.7 mmHg (95% CI 2.5-4.4). Abnormal SD-OCT findings [retinal folds and/or intraretinal fluid and/or cystoid macular edema (Fig. 1)] were present in 4 (28%) eyes, 2 of them (50%) had hypotony for less than 4 weeks. Patients with hypotony duration < 4 weeks had a reduced mean foveal thickness (245±22 versus 296±30 µm; P<0.007, Student’s t- test) compared to those with ≥4 and ≤6 weeks of hypotony.
The longer period of hypotony was statistically associated with central macular thickening, when comparing the hypotony duration of <4 weeks with that of ≥4 and ≤6 weeks. However, even hypotony duration <4weeks was associated with changes in the SD-OCT, suggesting that even a transient hypotony may be harmful to patients. If these findings can impose relevant visual disturbances on the long term, is something still to be confirmed by further prospective studies.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1a. SD-OCT showing cystoid macular edema of the right eye of a patient who had 6 weeks postoperative hypotony.
b. Normal SD-OCT of the left eye of the same patient without postoperative hypotony.
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