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Patients with retinitis pigmentosa (RP) experience variations in retinal layer and choroidal degeneration depending on disease severity, according to a 4-year study published in the American Journal of Ophthalmology.
Researchers enrolled 69 patients with RP and 69 age- and sex-matched controls in a retrospective, observational cohort study between 2009 and 2019. They classified RP severity into 1 of 3 stages based on the integrity of the inner segment ellipsoid zone: early (n=13), moderate (n=17), or advanced (n=39). The team segmented retinal and choroidal layers from optical coherence tomography (OCT) images and analyzed the areas of retinal pigment epithelium (RPE) atrophy and choroidal vascular index (CVI). They compared longitudinal changes of the OCT parameters among the groups.
The researchers found significant thinning (median [interquartile range]) in the ganglion cell inner plexiform layer (GCIPL; -1.04[-2.41-(-0.17)]), outer nuclear layer (ONL; -1.44[-1.86-(-0.28)]), and inner segment ellipsoid (ISE; -0.74 [-1.33 (-0.49)]) in patients with moderate stage RPE. They also noted significant thinning in the retinal nerve fiber layer (RNFL; -1.49[-2.08-(-0.66)]) and GCIPL (-0.58[-1.79-0.06]) among patients with advanced stage RP. At all stages, choroidal thickness decreased significantly from -7.62 to – 9.40 um/year. The team observed RPE atrophy and CVI reduction at the advanced stage. They reported no changes among the control group. During the follow up period, visual acuity worsened significantly in the advanced group (P =.005).
“RP treatment can be effective, at least until the moderate stage, when the inner retina, RPE, and choroidal circulation are not substantially impaired,” according to the investigators. “This study can also help select optimal excitatory targets for artificial retina or optogenetic treatments according to the patients’ stage of retinal degeneration.”
Study limitations include failure to incorporate eye tracking into the OCT follow-up and the use of structural OCT instead of OCT angiography.
Reference
Yoon CK, Bae K, Yu HG. Longitudinal microstructure changes of the retina and choroid in retinitis pigmentosa. Am J Ophthalmol. Published online May 8, 2022. doi:10.1016/j.ajo.2022.05.002
