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En face optical coherence tomography (OCT) can be used to quantify areas of hyperreflective lesions in macular telangiectasia type 2 (MacTel), according to research results published in Investigative Ophthalmology & Visual Science. These lesions are associated with an almost complete loss of retinal sensitivity, the research says.
In a retrospective, cross-sectional, cohort study, researchers aimed to both quantify hyperreflective lesions in OCT and study their functional relevance in MacTel. Baseline imaging and demographic data were collected from a previous multicenter clinical trial (NCT01949324).
Investigators used spectral domain OCT volume scans to generate en face images, which allowed for the measurement of size and ellipsoid zone (EZ) loss, as well as the total lesion size of hyper-reflective changes. Microperimetry images and OCT en face images were then superimposed to allow for the measurement and comparison of retinal sensitivity thresholds at different locations across the retina.
The cohort included 52 eyes from 52 patients (mean age, 59.1 years; range, 47 to 75 years; 32 women). Thirty-two eyes demonstrated hyper-reflexivity (mean lesion size, 0.11 mm2; range, 0.01 to 0.26). Ellipsoid zone loss was noted in 96% of eyes (mean size, 0.51 mm2; range, 0.02 to 1.34).
Only eyes with a noted break of the EZ demonstrated hyper-reflective changes; hyper-reflectivity was limited to areas with loss of EZ. The en face lesion size and EZ loss were “strongly correlated” (r=0.79; P <.001). Four eyes demonstrated intraretinal hyper-reflectivity, while 28 of 32 eyes indicate outer retinal hyper-reflective lesions that extended between the retinal layers and the RPE and BM.
Relative reduction of sensitivity or total scotomas was detected in 49 eyes; absolute scotomas were observed in 21 eyes; mean scotoma size was 6.6 and 2.3 test points for total and absolute scotomas, respectively (range, 1 to 20 and 1 to 7, respectively).
Investigators found that absolute scotomas were highly associated with the presence of hyper-reflectivity, and hyper-reflectivity size strongly correlated with the size of total and absolute scotomas (r=0.79 and 0.86; P <.001 for both). This correlation was, per the results, independent from EZ loss. EZ loss size correlated most closely with total scotomas size (r=0.79).
Both hyper-reflectivity and EZ loss were directly associated with a significant decrease in retinal sensitivity, although sensitivity thresholds differed between lesions. Areas that demonstrated EZ loss had a subsequent relative reduction in sensitivity; hyper-reflectivity, however, was associated with a nearly complete loss of sensitivity (mean sensitivity thresholds, 16.3 dB vs 0.9 dB; P <.001).
No correlations were noted between the size of hyper-reflectivity and best-corrected visual acuity (BCVA) or reading speed (r=0.09 and -0.17, respectively). Both BCVA and reading speed did not differ significantly between eyes with and without hyper-reflectivity.
The study’s limitations include the retrospective, cross-sectional nature of the study and the limited sample size. Early- and late-stage disease were underrepresented due to the use of previous clinical trial data.
“En face OCT can be used to quantify the area of hyperreflective lesions in MacTel [which are] associated with severe functional impairment, leading to an almost complete loss of retinal sensitivity as observed on microperimetry,” the research concludes.
Reference
Tzaridis S, Friedlander M; for the Macular Telangiectasia Type 2-Phase 2 CNTF Research Group. Functional relevance of hyper-reflectivity in macular telangiectasia type 2. Invest Ophthalmol Vis Sci. 2021;62(3):6. doi:10.1167/iovs.62.3.6
