Optical Coherence Tomography in Knobloch Syndrome.

BACKGROUND AND OBJECTIVE: Knobloch syndrome is a genetic disorder defined by occipital defect, high myopia, and vitreoretinal degeneration. The authors studied retinal changes in patients with Knobloch syndrome using optical coherence tomography (OCT). PATIENTS AND METHODS: The authors report patients with Knobloch syndrome who received OCT testing during their care from 2011 to 2016. Diagnosis was based on high myopia, characteristic fundus, and occipital scalp or skull abnormalities with/without featureless irides and/or ectopia lentis. When available, diagnosis was confirmed by the detection of COL18A1 mutations. RESULTS: The authors studied eight eyes from five patients. Two eyes were excluded due to chronic retinal detachment. OCT findings included epiretinal membrane, peripapillary vitreoretinal traction with retinoschisis, absent or rudimentary foveal pits, mean macular thickness of 113.4 µm, poor lamination, retinal pigment epithelium (RPE) atrophy, photoreceptor depletion, and mean choroidal thickness of 168.5 µm with enlarged choroidal vessels. CONCLUSION: OCT findings in Knobloch syndrome include abnormal vitreoretinal traction, poor foveal differentiation, poor retinal lamination, retinal thinning, RPE attenuation, myopic choroidal thinning, and pachychoroid. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:e203-e210.].

Spectral-domain optical coherence tomography findings in Alström syndrome.

BACKGROUND: Alström syndrome is a multi-system recessive disorder caused by mutations in ALMS1 gene. The aim of this study was to characterize morphological retinal changes in Alström patients using spectral-domain optical coherence tomography. METHODS: We studied volunteer patients attending the conference of Alström Syndrome International, a support group for affected families, using hand-held spectral-domain optical coherence tomography (SD-OCT) in an office setting. Patients had a clinical dilated retinal examination. Past medical records were reviewed. RESULTS: Twenty-two Alström patients (mean age 17 years, range 2-38 years, 12 males) were studied. OCT imaging demonstrated that central macular OCT changes are often mild during the first decade of life and gradually progress, demonstrating disruption of normal retinal architecture, and progressive loss of photoreceptors and retinal pigment epithelium. Other changes found included hyperreflectivities in all retinal layers, severe retinal wrinkling, optic nerve drusen, and vitreoretinal separation. Vision correlated with severity of OCT macular changes (r = 0.89, p = 0.002). CONCLUSIONS: This study reports on OCT findings in a large group of patients with Alström syndrome. We document a panretinal gradual progression of retinal changes, which are often mild during the first years of life. Previously unreported observations include intraretinal opacities, optic nerve drusen, and foveal contour abnormalities. Morphological retinal changes demonstrated by SD-OCT may help in understanding the pathophysiology of the disease and defining strategies for treatment such as gene therapy.

Segmental Analysis of Macular Layers in Patients With Unilateral Primary Open-Angle Glaucoma.

PURPOSE: To measure the thicknesses of the inner layers of the macula in both eyes of patients with unilateral primary open-angle glaucoma (POAG) and compare them with normal control eyes. METHODS: This prospective, cross-sectional pilot study enrolled patients with unilateral POAG, who had visual field defect in only 1 eye, and controls with a normal eye examination. Horizontal and vertical B-scan images centered on the fovea were obtained using spectral domain optical coherence. Semiautomatic delineation and segmentation of the inner layers of the retina were performed to evaluate macular retinal nerve fiber layer (mRNFL), ganglion cell complex (GCC) and ganglion cell-inner plexiform layer (GC-IPL) thicknesses. Mean, superior, inferior, nasal, and temporal inner macular layer thicknesses were compared between affected eyes, fellow eyes without visual field defect, and control eyes. RESULTS: Nineteen patients with unilateral POAG and 14 normal control eyes were enrolled. In the affected POAG eyes, thinning of the mRNFL, GCC, and GC-IPL layers on horizontal and vertical scans were significant when compared with controls (P<0.05), particularly on vertical scans (P<0.001). The mean regional macular GCC and GC-IPL were most severely thinned in the inferior and temporal perifoveal regions. The unaffected eye of patients with unilateral POAG showed significant thinning of the mRNFL only in the vertical scan when compared with normal controls (P<0.05). CONCLUSIONS: Spectral domain optical coherence tomography detected significant thinning of the mRNFL, GCC, and GC-IPL in the affected eyes of patients with unilateral POAG. Fellow eyes showed early structural changes only in the vertical mRNFL scans when compared with normal controls.

Optical coherence tomography in optic nerve head avulsion.

Early diagnosis of optic nerve head (ONH) avulsion may be difficult due to an obscured fundus view. Although B-scan ultrasonography is more useful than MRI and CT imaging, it has limited sensitivity and specificity. Optical coherence tomography (OCT) can be used to identify optic nerve pathology. Utilization of OCT has not been widely reported in the diagnosis of ONH avulsion. Two cases OCT use in ONH avulsion are reported. The utility of OCT in the diagnosis of ONH avulsion is of limited value.

Imaging modalities for localization of an iStent(®).

The iStent (Glaukos Corporation, Laguna Hills, CA) is a 1-mm, titanium trabecular bypass stent implanted across the inner wall of Schlemm's canal under direct gonioscopy. This study was designed to determine the best modality to identify iStent placement when gonioscopic visualization is not possible. In this in vitro study on a human cadaver eye, ultrasound biomicroscopy (UBM), anterior segment optical coherence tomography (AS-OCT), and B-scan ultrasonography were done to visualize and precisely locate two intentionally misplaced iStents. UBM could localize both intentionally misplaced stents, whereas AS-OCT could not visualize the iStent that was lodged in the sulcus. B-scan ultrasonography was unable to detect either of the stents. UBM may be a useful imaging modality to identify iStent in the anterior or posterior chamber, whereas AS-OCT is limited to detection of stents in the anterior chamber alone. B-scan ultrasonography is unable to identify iStent in either the anterior or posterior chamber.

High prevalence of plateau iris configuration in family members of patients with plateau iris syndrome.

PURPOSE: The purpose of the study was to ascertain the prevalence of plateau iris syndrome in the first-degree relatives of those patients affected with plateau iris syndrome. METHODS: All patients seen with plateau iris syndrome over a 5-year period were identified. These patients were approached for participation and first-degree family members above 18 years of age were screened. All people identified with plateau iris configuration underwent ultrasound biomicroscopy to document and confirm the angle configuration and subsequent gonioscopy after laser iridotomies. RESULTS: Sixteen patients were identified; 3 refused to participate, 2 were unable to be contacted, and 1 withdrew after initially consenting to participate. In this case, the patient agreed to participate, but all her living first-degree family members refused to be screened. Among the 10 patients whose living first-degree relatives were screened, we found 5 families with at least 1 additional first-degree family member having plateau iris syndrome. CONCLUSIONS: Some families have more than 1 member with plateau iris syndrome. The pattern of inheritance resembles an autosomal dominant pattern with incomplete penetrance.

Voluntary suppression of the multifocal electroretinogram.

OBJECTIVE: To describe multifocal electroretinogram (mfERG) responses in 2 patients with nonorganic visual loss and in 11 eyes of 6 healthy persons who suppressed their mfERG responses. DESIGN: Observational case series. METHODS: The mfERG results were recorded in all individuals using the Veris Science 4.2 instrument. All subjects were instructed to adjust the hexagonal test pattern so that it was in best focus. A second mfERG was recorded subsequently in volunteers who attempted suppression with inattention and poor fixation and by adjusting the focus to greatest blur. MAIN OUTCOME MEASURES: Amplitude and latency of mfERG responses. RESULTS: Suppressed mfERGs in patients with nonorganic visual loss and healthy volunteers demonstrated reduced amplitude, especially centrally. Amplitude reduction was statistically significant in the postsuppression as compared with the presuppression recordings in wave forms N1 and N2. Statistically significant shortening of postsuppression implicit times of P1 and N2 waveforms also was demonstrated. CONCLUSIONS: The mfERG responses may be suppressed voluntarily. Amplitude may be reduced. In contrast to most reported pathologic conditions, the implicit time is shortened.