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

BACKGROUND/AIMS: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.