Abstract
Purpose :
Adaptive optics scanning light ophthalmoscopy (AOSLO) can be achieved in ~50% of patients with achromatopsia (ACHM), which is largely attributed to nystagmus.1 The selection bias therefore inherent in subsequent analysis may result in a non-representative ACHM phenotype. Here we compared foveal optical coherence tomography (OCT) metrics and AOSLO imaging success/failure in subjects with ACHM.
Methods :
One eye from 112 subjects with genetically-confirmed ACHM (43 CNGA3 and 69 CNGB3) was imaged with OCT (foveal line scan) and non-confocal split detection AOSLO. Foveal outer nuclear layer (ONL) thickness was measured using a longitudinal reflectivity profile. Ellipsoid zone (EZ) integrity was graded.2 Subjects were separated into two groups: AOSLO success or failure. AOSLO success was defined as sufficient image quality in a montage for cone counting at the fovea. OCT metrics (ONL thickness, EZ grade, presence of foveal hypoplasia) and age were then compared between the two groups.
Results :
OCT imaging was successful in all subjects. Subjects with EZ grade 5 (macular atrophy, n = 4) were excluded from further analysis. AOSLO was successful in 57/108 subjects; CNGA3- (56%) and CNGB3-associated ACHM (51%) did not differ in success rate. Subjects with successful AOSLO imaging were generally older than those with failed imaging (mean ± SD, 25.9 ± 10.9 vs 20.2 ± 12.4 years; p = 0.001, Mann-Whitney test), which is likely because nystagmus tends to decrease with age in ACHM.3 Foveal ONL thickness was significantly greater in subjects with failed AOSLO imaging compared to those with successful imaging (mean ± SD, 80.9 ± 18.7 µm vs 68.9 ± 18.7 µm; p = 0.001, unpaired t-test), and this difference was larger than what would be expected based on the age difference between the groups.4 There was an association between EZ grade and AOSLO success (p = 0.023, Chi-squared test). Presence of foveal hypoplasia was not predictive of AOSLO success in ACHM (p > 0.999, Fisher’s Exact test).
Conclusions :
Increased ONL thickness and age are associated with AOSLO imaging success. These results may be useful in guiding recruitment in AOSLO imaging studies. Moreover, the differences observed here should be considered when describing the natural history of ACHM or comparing phenotypes between ACHM cohorts.
1PMID:27479814
2PMID:24148654
3PMID:26304472
4PMID:29522565
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.