Visual Function at the Atrophic Border in Choroideremia Assessed with Adaptive Optics Microperimetry

Area of Science:

• Ophthalmology
• Retinal Imaging
• Vision Science

Background:

• Recent retinal imaging advances enable cellular-level visualization of retinal disease abnormalities.
• Choroideremia is characterized by specific phenotypic features, including atrophic lesion borders and outer retinal tubulations (ORTs).

Purpose of the Study:

• To assess visual sensitivity with high spatial precision using adaptive optics (AO) microperimetry.
• To examine functional variations across atrophic lesion borders and ORTs in choroideremia patients.

Main Methods:

• A custom AO scanning light ophthalmoscope (AOSLO) was used for high-resolution imaging of photoreceptor mosaics.
• AO microperimetry presented small stimuli to precisely measure visual sensitivity at targeted retinal locations.
• Psychophysical detection thresholds were measured at atrophic borders and along ORTs in choroideremia patients.

Main Results:

• Sharp functional transitions were observed at the borders between intact photoreceptor mosaic and outer retinal atrophy.
• Visual sensitivity decreased abruptly across these borders, often over distances smaller than a standard stimulus.
• No visual sensitivity was detected over ORTs, despite the presence of remnant cone inner segments.

Conclusions:

• Choroideremia patients show distinct functional and structural transitions in affected retinal areas.
• High-resolution AO microperimetry provides insights into choroideremia disease mechanisms.
• This technique may enable precise evaluation of the functional efficacy of experimental therapies like gene therapy.