Macular changes detected by Fourier-domain optical coherence tomography in patients with hypotony without clinical maculopathy.

PURPOSE: To investigate macular changes in eyes with postoperative hypotony without clinical maculopathy using high-resolution Fourier-domain optical coherence tomography (FD-OCT). METHODS: Fourteen eyes of 12 patients with postoperative intraocular pressure (IOP) ï¿¡ 6 mmHg for at least 4 weeks but with no detectable clinical features associated with hypotony maculopathy were imaged by FD-OCT prospectively. Images were analysed by two retina specialists masked to clinical findings. RESULTS: Most patients were female (83%) and myopic (75%) with a mean age of 65 ± 17 [standard deviation (SD)] years (range 2­86 years). Mean central corneal thickness was 519 ± 34 lm [95% confidence interval (CI) 502­537] and mean IOP before surgery was 20 ± 8 mmHg (95% CI 15­24). During the period of hypotony (mean 15 ± 6 weeks), the average mean IOP was 4 ± 1 mmHg (95% CI 3­5). Abnormal FD-OCT findings (retinal folds and / or intraretinal fluid) were present in eight eyes. These patients had a higher rate of visual symptoms (75% versus 17%), visual acuity loss (‡ 2 lines; 63% versus 17%) and increased mean foveal thickness (250 ± 26 versus 210 ± 12 lm; p < 0.01, Mann­Whitney U-test) compared with those with normal FD-OCT. CONCLUSION: FD-OCT identified subclinical macular abnormalities in over half of the eyes with postoperative hypotony. These findings were accompanied by visual disturbances and central macular thickening. FD-OCT can be an important diagnostic tool for this disorder when clinical features are absent.

Spectral-domain optical coherence tomography for early glaucoma assessment: analysis of macular ganglion cell complex versus peripapillary retinal nerve fiber layer.

OBJECTIVE: We sought to compare the glaucoma discrimination ability of macular inner retinal layer (MIRL) thickness with that of conventional peripapillary retinal nerve fiber layer (pRNFL) thickness as measured by spectral-domain optical coherence tomography (SD-OCT) in patients with early glaucoma. DESIGN: Cross-sectional study. PARTICIPANTS: We studied 67 patients with early glaucoma (visual field mean deviation index ≥-6 dB), and 56 healthy subjects were prospectively enrolled. METHODS: All patients underwent MIRL thickness measurement (ganglion cell complex [GCC] scan) and pRNFL thickness measurement (3.45 mm scan) by SD-OCT. Whenever both eyes were eligible, one was randomly selected. Receiver operating characteristic curves and sensitivities at fixed specificities were generated for different parameters. The areas under the receiver operating characteristic curves (AUCs) of each parameter were compared. RESULTS: The average mean deviation for the glaucomatous eyes was -2.5 ± 1.6 dB. The AUCs for average (0.815); superior (0.807); and inferior (0.788) MIRL thicknesses were not significantly different (p ≥ 0.18). The AUCs for average (0.735); superior (0.728); and inferior (0.697) pRNFL thicknesses were also similar (p ≥ 0.15). Average MIRL thickness had a significantly larger AUC compared to average pRNFL thickness analysis (0.815 vs 0.735; p = 0.03). Sensitivities at 80% specificity for average MIRL and pRNFL thicknesses were 66.7% (cutoff, 89.9 µm) and 62.9% (cutoff, 111.8 µm), respectively. CONCLUSIONS: The GCC scan showed a similar or even a slightly better ability to discriminate between healthy and early glaucomatous eyes compared to the pRNFL scan. Different from previous analyses considering total macular thickness, the GCC macular scan seems to be a useful tool for identification of early structural damage in patients with glaucoma.

Clinical assessment of mirror artifacts in spectral-domain optical coherence tomography.

PURPOSE. To investigate the characteristics of a spectral-domain optical coherence tomography (SD-OCT) image phenomenon known as the mirror artifact, calculate its prevalence, analyze potential risk factors, measure severity, and correlate it to spherical equivalent and central visual acuity (VA). METHODS. OCT macular cube 512 x 128 scans taken between January 2008 and February 2009 at the New England Eye Center were analyzed for the presence of mirror artifacts. Artifact severity was determined by the degree of segmentation breakdown that it caused on the macular map. A retrospective review was conducted of the medical records of patients with artifacts and of a random control group without artifacts. RESULTS. Of 1592 patients, 9.3% (148 patients, 200 eyes) had scans that contained mirror artifacts. A significantly more myopic spherical equivalent (P < 0.001), worse VA (P < 0.001), longer axial lengths (P = 0.004), and higher proportions of moderate to high myopia (P < 0.001) were found in patients with mirror artifacts than in patients without artifacts. Worse VA was associated with increased artifact severity (P = 0.04). CONCLUSIONS. In all scans analyzed, a high prevalence of mirror artifacts was found. This image artifact was often associated with patients with moderate to high myopia. Improvements in instrumentation may be necessary to resolve this problem in moderately and highly myopic eyes. Operators should be advised to properly position the retina when scanning eyes. In cases in which peripheral abnormalities in topographic measurements of retinal thickness are found, corresponding OCT scans should be examined for the presence of mirror artifacts.