Visual acuity loss in patients with age-related macular degeneration measured using a novel high-pass letter chart

Abstract

VA measurements with the MAC chart appear to be more sensitive to functional loss in AMD compared with conventional letter charts, with similar TRV. Simulations indicate this may be because the high-pass filtered letters are more vulnerable to undersampling as a result of retinal cell loss in the disease process.

The Auckland Optotypes: An open-access pictogram set for measuring recognition acuity

“…The role of vanishing optotypes is potentially of further interest; vanishing optotypes have lower testretest variability (Shah et al, 2014) and may be particularly sensitive for detecting macular pathology (Shah et al, 2016). Starting with enclosed shapes and intentionally limiting acute angles and internal lines reduced the presence of high contrast regions that can arise in vanishing Sloan letters (e.g., at line endings or junctions), further reducing interoptotype variability.…”

“…This feature of the proposed optotype set is an additional advantage over other well designed pictogram sets (for example Lea symbols [Hyvarinen et al, 1980] and the newly designed Kay pictures [Milling et al, 2016]), adding a level of flexibility to the type of testing which can be done. For example, since vanishing optotypes may be helpful for monitoring visual loss arising from macular degeneration (Shah et al, 2016), having a set of 10 vanishing optotypes that do not rely on the familiarity with Roman letters could be useful in a culturally diverse clinical setting. Whether there is an appropriate clinical application of vanishing optotypes for children is less well understood.…”

“…Vanishing symbols appear practical for children; early work suggests vanishing optotypes may lead to more accurate acuity measures in children (Fariza et al, 1990), and within the Cardiff Acuity Test, vanishing symbols are effective for testing infants and those with cognitive impairment (Adoh et al, 1992). However, whether some childhood conditions differentially impact vanishing or regular acuity thresholds has not been explored as it has in adults (Shah et al, 2013;Shah et al, 2016). Since TAO allows direct comparison between regular and vanishing formats, it could be a useful tool to further explore clinical applications for vanishing optotypes in children.…”

“…However, results do not align well with recognition acuity tests using regular optotypes (Paudel et al, 2017), perhaps due to perception of vanishing compared to regular optotypes, or perhaps because of the testing protocol. It would therefore be useful to compare measures of acuity made with vanishing and regular versions of identical optotypes with the same test protocol, as has been done with Sloan letters (Shah et al, 2011;Shah et al, 2012;Shah, Anderson, Tufail, Egan, & Dakin, 2013;Shah et al, 2014). Finally, we note that optotype features such as internal junctions and acute angles can prevent uniform vanishing of pseudo-high pass symbols.…”

MACUSTAR: Development and Clinical Validation of Functional, Structural, and Patient-Reported Endpoints in Intermediate Age-Related Macular Degeneration

“…Shah et al[28] have developed a new set of optotypes for measuring visual acuity that consist of pseudo high-pass letters. The authors have demonstrated that the new optotypes have better test-retest variability than traditional optotypes, and recent evidence suggests that they are more sensitive to vision loss in early AMD to iAMD [29]. …”