Abstract
Purpose :
Macular telangiectasia type 2 (MacTel) is an inherited retinal disease following an autosomal dominant pattern with reduced penetrance. As genetic causes of MacTel remain unknown, ophthalmic imaging helps determine the diagnosis. FLIO shows distinct and early changes in MacTel. This study investigates FLIO-changes in unaffected family members with the aim to diagnose the disease at earlier stages.
Methods :
68 patients with MacTel (61±13 yrs), 41 clinically healthy children of these MacTel patients (MacTel-C, 34±8 yrs) and 30 other family members (siblings, parents, cousins) were investigated at the Moran Eye Center with a prototype Heidelberg FLIO. A healthy control group for the MacTel-C, all of whom exhibited only normal FLIO patterns, was also included. Fundus autofluorescence (FAF) was excited with a 473 nm laser, and fluorescence lifetimes were recorded in short (498-560 nm) and long (560-720 nm) spectral channels. All subjects also underwent OCT, macular pigment, autofluorescence intensity and infrared reflectance images.
Results :
All patients with MacTel show the specific MacTel-related FLIO pattern. Of the 41 investigated MacTel-C with clinically normal eye exams and conventional imaging, 16 subjects (39%) show a FLIO pattern consistent with early stages of MacTel. FAF lifetimes were significantly (p<0.001) prolonged across all regions of the fundus in FLIO-positive compared to FLIO-negative MacTel-C. This was most significant superior to the fovea (FLIO-positive 246 ps vs. FLIO- negative 207 ps).
Conclusions :
FLIO detects characteristic changes in the FLIO patterns in MacTel with high contrast. 39% of clinically unaffected children of MacTel show FLIO-patterns indicative of early stage MacTel. 19% of siblings typically manifest disease – in contrast, we have found such changes at twice that rate. FLIO is able to show abnormal patterns in some individuals who may carry a MacTel gene but show no signs of disease (e.g. some parents of MacTel patients). This indicates the very high sensitivity of the FLIO modality to detect MacTel. FLIO could help to diagnose MacTel even before conventional imaging modalities show changes and before patients experience visual disturbances.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.