Retinal cavitations in macular telangiectasia type 2 (MacTel): longitudinal structure-function correlations

To quantify retinal cavitation size over time in macular telangiectasia type 2 (MacTel) and to correlate changes with visual acuity and area of ellipsoid zone loss.

Optical coherence tomography (OCT) macula volume scans from sham eyes included in a prospective, phase II clinical trial of human ciliary neutrophic factor for MacTel at baseline, 1 year and 2 years of follow-up were analysed. Cavitations were segmented by two independent readers. Total cavitation volume was compared with area of ellipsoid zone loss and best-corrected visual acuity (BCVA).

Fifty-one eyes from 51 unique patients (mean age 62 years, range 45-79 years) were included. Intraclass correlation between readers for cavitation volume was excellent (>0.99). Average cavitation volume was 0.0109 mm³, 0.0113 mm³ and 0.0124 mm³ at baseline, 1 year and 2 years, respectively. The average rate of cavitation volume change was +0.0039 mm³/year. 10 eyes (20%) had a significant change in cavitation volume during the study (3 decreased, 7 increased). Eyes with increased cavitation volume had worse BCVA compared with eyes with no change/decreased cavitation volume (71.5 vs 76.1 ETDRS letters, respectively). Cavitation volume was negatively correlated to BCVA (r=-0.37) but not to area of ellipsoid zone loss. Cavitation volume was negatively predictive of BCVA in both univariate and multivariate mixed-effects modelling with ellipsoid zone loss.

Retinal cavitations and their rate of change in MacTel can be reliably quantified using OCT. Cavitations are negatively correlated with visual acuity and may be a useful OCT-based biomarker for disease progression and visual function in MacTel.