BACKGROUND: Corneal confocal microscopy (CCM) is a noninvasive, reproducible ophthalmic technique to quantify corneal small nerve fiber degeneration. CCM demonstrates small nerve fiber damage in Parkinson's disease (PD), but its role as a longitudinal biomarker of PD progression has not been explored. OBJECTIVE: The aim of this study was to assess corneal nerve morphology using CCM in relation to disease progression in PD. METHODS: Sixty-four participants with PD were assessed at baseline and at 12-month follow-up. Participants underwent CCM with automated corneal nerve quantification and assessment of Movement Disorder Society Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, and Montreal Cognitive Assessment. RESULTS: Corneal nerve fiber density (CNFD), corneal nerve branch density, corneal nerve fiber length, corneal total branch density, and corneal nerve fiber area were significantly lower in participants with PD compared with healthy control subjects. Worsening of Movement Disorder Society Unified Parkinson's Disease Rating Scale part III score over 12 months was significantly greater in participants with a CNFD in the lowest compared with the highest quartile at baseline (mean difference: 6.0; 95% CI: 1.0-10.9; P = 0.019). There were no significant changes in CNFD, corneal nerve branch density, corneal nerve fiber length, corneal total branch density, corneal nerve fiber area, or corneal nerve fiber width between baseline and 12-month follow-up. CONCLUSIONS: CCM identifies neurodegeneration in patients with PD, especially those who show the greatest progression in neurological disability. CCM may be a useful tool to help enrich clinical trials with those likely to exhibit more rapid progression and reduce required sample size and cost of studies.
BACKGROUND:Corneal confocal microscopy (CCM) is a noninvasive, reproducible ophthalmic technique to quantify corneal small nerve fiber degeneration. CCM demonstrates small nerve fiber damage in Parkinson's disease (PD), but its role as a longitudinal biomarker of PD progression has not been explored. OBJECTIVE: The aim of this study was to assess corneal nerve morphology using CCM in relation to disease progression in PD. METHODS: Sixty-four participants with PD were assessed at baseline and at 12-month follow-up. Participants underwent CCM with automated corneal nerve quantification and assessment of Movement Disorder Society Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, and Montreal Cognitive Assessment. RESULTS:Corneal nerve fiber density (CNFD), corneal nerve branch density, corneal nerve fiber length, corneal total branch density, and corneal nerve fiber area were significantly lower in participants with PD compared with healthy control subjects. Worsening of Movement Disorder Society Unified Parkinson's Disease Rating Scale part III score over 12 months was significantly greater in participants with a CNFD in the lowest compared with the highest quartile at baseline (mean difference: 6.0; 95% CI: 1.0-10.9; P = 0.019). There were no significant changes in CNFD, corneal nerve branch density, corneal nerve fiber length, corneal total branch density, corneal nerve fiber area, or corneal nerve fiber width between baseline and 12-month follow-up. CONCLUSIONS: CCM identifies neurodegeneration in patients with PD, especially those who show the greatest progression in neurological disability. CCM may be a useful tool to help enrich clinical trials with those likely to exhibit more rapid progression and reduce required sample size and cost of studies.
Authors: Ioannis N Petropoulos; Gulfidan Bitirgen; Maryam Ferdousi; Alise Kalteniece; Shazli Azmi; Luca D'Onofrio; Sze Hway Lim; Georgios Ponirakis; Adnan Khan; Hoda Gad; Ibrahim Mohammed; Yacob E Mohammadi; Ayesha Malik; David Gosal; Christopher Kobylecki; Monty Silverdale; Handrean Soran; Uazman Alam; Rayaz A Malik Journal: Front Pain Res (Lausanne) Date: 2021-08-19