Correlation of Optical Coherence Tomography and Autofluorescence in the Outer Retina and Choroid of Patients With Choroideremia

Abstract

PurposeTo evaluate the relationships between RPE, photoreceptor, and choroidal degeneration in choroideremia.MethodsEnhanced-depth imaging optical coherence tomography (EDI-OCT), scanning laser ophthalmoscopy (SLO), and autofluorescence (AF) were performed on 39 patients (78 eyes) with choroideremia. The edges of surviving outer retina on OCT and residual AF were aligned. The distribution of outer retinal tubulations was mapped over a range of ages (16–71 years), and comparison made between pre- and postsubretinal gene therapy. Subfoveal choroidal thickness (SFCT) was compared between 23 choroideremia patients (42 eyes) and 20 age- and refraction-matched male controls (40 eyes).ResultsThe edges of RPE AF aligned with a reduction in outer nuclear layer thickness (Spearman's rho = 0.9992). Correlation was also found between the quality of AF and integrity of ellipsoid zone within islands of surviving retina. Tubulations existed in 71 of 78 (91%) eyes with choroideremia and remained stable following gene therapy. Subfoveal choroidal thickness was reduced at baseline in choroideremia (179.7 ± 17.2 μm) compared with controls (302.0 ± 4.8 μm; P < 0.0001), but did not undergo significant thinning until end-stage retinal degeneration (43.1 ± 6.5 μm).ConclusionsThe data suggest that RPE loss is the primary cause of photoreceptor degeneration in choroideremia. The choroid is thinner than controls from early stages, in keeping with a mild developmental defect. Photoreceptors appear to lose outer segments following loss of underlying RPE and form tubulations at the edges of degeneration. The preservation of tubulations over time and after subretinal injection would be consistent with these structures maintaining attachment to the inner retina and hence being potentially light responsive (ClinicalTrials.gov, NCT01461213).

Natural History of the Central Structural Abnormalities in Choroideremia

“…1, P1, vertical arrow ) of attenuation and then loss of the IZ signal in nasal retina with approximation of the EZ to the RPE and mild ONL thinning, consistent with photoreceptor outer segment shortening (POS) and cell loss. 8,10,42-44 Further nasal to this point there is increased backscattering posterior to the RPE/BM. The structural change co-localizes with a transition of the NIR-REF signal from normal to a brighter signal near the nerve (Fig.…”

The Impact of Progressive Visual Field Constriction on Reading Ability in an Inherited Retinal Degeneration

“…The patient characteristics are shown in Table 1. The eyes were classified into three groups depending on the position of the anatomical fovea relative to the remaining functional visual island based on AF imaging [14,16]: (1) eyes whose fovea fell within the functional retinal island;…”

“…A caliper tool was used to measure the horizontal and vertical dimensions of the AF area extending from the centre of the fovea; these dimensions were subsequently broken down into their constituent nasal, temporal, superior and inferior parts. The horizontal and vertical dimensions of AF were used to approximate the functional visual field of each subject, the AF area being representative of the presumed surviving retina [16]. For those patients whose fovea fell outside their surviving retina, the caliper tool was used to measure the distance from the fovea to the closest edge of the surviving retina, which was assigned a negative value.…”

Optical coherence tomography angiography and fundus autofluorescence in the eyes with choroideremia

“…This suggests that the RPE atrophy occurred before the choriocapillaris atrophy in this eye with choroideremia although the choriocapillaris might be damaged to some degree. Xue et al 11 reported that RPE loss is the primary cause of choroideremia in their study of the relationship between outer retina/choroid using OCT and RPE atrophy using FAF. Their study also supported our findings.…”