Abstract
Purpose:
To describe retinal structure in carriers and affected individuals with choroideremia, as evaluated by spectral domain optical coherence tomography (SD-OCT) in a prospective, case series study.
Methods:
SD-OCT evaluations using the HRA-OCT Heidelberg Spectralis were performed on 10 carriers and 31 affected subjects. Prevalence, location and area of hyporeflective (HR) areas, outer retinal tubulations (ORT), retinal pigment epithelial (RPE) and retinal atrophy, schisis-like formations and other anomalies were noted. Retinal segmentation and thickness measurements were also obtained.
Results:
Among affected individuals, bilateral HR areas were found in 8 of 31 CHM patients. 4 of 31 patients had unilateral HR areas. Overall 12 of 31 patients were observed to have HR areas. The HR areas theoretically could be intraretinal fluid, swollen degenerating cells or other structural anomalies in the degenerating retina. Additionally, 15 of the affected patients had ORT, RPE mottling, atrophy or schisis-like formations. Also noted were discrete regions of intact retinal laminations that were horizontally adjacent to regions of significant retinal degeneration. In transition zones between relatively intact retina and degenerating retina, remnants of outer nuclear layer (ONL) could persist without an underlaying RPE, as well as the reverse. Total retinal and ONL thickness decreased with age in CHM patients, with the central region maintaining retinal and ONL thickness and structural laminations the longest. Carriers exhibited decreased levels of ONL thickness overall, but generally maintained retinal lamination. Three of the 10 carriers also exhibited RPE changes and ORT.
Conclusions:
The prevalence of bilateral HR areas in CHM subjects was 25.8% (8/31), unilateral in 12.9% (4/31) and 32.9% in all CHM cases (12/31). HR areas,, ORT, atrophy and schisis-like formations were relatively common characteristics seen on SD-OCT in CHM patients. The sequential degeneration of RPE vs ONL may be variable, as both scenarios were evident. CHM carriers have some degree of structural retinal degeneration as evidenced by decreased ONL thickness and the presence of ORT. SD-OCT real-time structure imaging could help determine the sequence of retinal layer degeneration, with potential implications in illustrating disease progression and prognosis.
Keywords: 696 retinal degenerations: hereditary •
550 imaging/image analysis: clinical •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)