In-vivo confocal microscopy, ocular surface, tear neuromediator parameters at the time neuropathic corneal pain was diagnosed
| Smile | Lasik | |||||
| Parameters | Non-NCP | NCP | P value* | Non-NCP | NCP | P value† |
| In-vivo confocal microscopy | ||||||
| Corneal nerve parameters | ||||||
| CNFD | 11.9±4.9 | 11.4±2.2 | 0.83 | 5.0±3.0 | 0.6±0.9 | 0.06 |
| CNBD | 9.1±6.7 | 10.9±6.4 | 0.63 | 3.1±2.4 | 0.6±0.9 | 0.16 |
| CNFL | 8.7±2.5 | 9.5±2.2 | 0.56 | 5.4±1.3 | 3.0±1.4 | 0.02 |
| CTBD | 18.8±11.8 | 26.3±17.1 | 0.29 | 10.1±5.8 | 13.7±1.8 | 0.40 |
| CNFA | 0.004±0.001 | 0.005±0.002 | 0.11 | 0.003±0.001 | 0.003±0.002 | 0.37 |
| CNFW | 0.02±0.001 | 0.02±0.001 | 0.76 | 0.02±0.002 | 0.03±0.001 | 0.04 |
| CFracDim | 1.41±0.04 | 1.41±0.05 | 0.97 | 1.35±0.04 | 1.26±0.04 | 0.003 |
| Dendritic cells | ||||||
| Count | 10.8±5.6 | 9.8±3.6 | 0.75 | 8.2±6.0 | 6.2±1.2 | 0.64 |
| Density (μm-2) | 0.02±0.002 | 0.02±0.003 | 0.73 | 0.02±0.002 | 0.02±0.001 | 0.24 |
| Area (μm2) | 45.4±3.7 | 44.8±4.8 | 0.78 | 45.9±3.1 | 43.7±2.2 | 0.34 |
| Average length (μm) | 18.9±0.9 | 10.8±1.1 | 0.83 | 11.2±0.6 | 10.5±0.3 | 0.16 |
| Elongation (μm) | 0.6±0.04 | 0.6±0.04 | 0.99 | 0.6±0.04 | 0.6±0.07 | 0.22 |
| Neuroma | ||||||
| Total area (μm2) | 405.1±255.8 | 720.0±325.7 | 0.09 | 401.6±73.2 | 1232.8±799.2 | 0.04 |
| Average size (μm) | 49.6±26.2 | 17.6±13.8 | 0.81 | 70.2±38.9 | 43.1±13.8 | 0.40 |
| Perimeter (μm) | 25.9±8.6 | 20.8±13.8 | 0.29 | 32.2±14.1 | 17.8±4.0 | 0.24 |
| Ocular surface assessments | ||||||
| TBUT (seconds) | 8.7±4.8 | 6.3±4.9 | 0.29 | 7.5±3.5 | 4.0±0.0 | 0.17 |
| Schirmer’s I (mm) | 11.9±6.5 | 7.0±3.8 | 0.09 | 9.0±7.8 | 12.5±3.5 | 0.55 |
| Corneal sensitivity | 28.9±1.1 | 29.0±1.5 | 0.83 | 28.0±1.7 | 30.0±0.0 | 0.12 |
| Oxford score | 0.1±0.3 | 0.5±0.8 | 0.04 | 0.7±0.9 | 0.00±0.00 | 0.26 |
| NEI score | 0.1±0.3 | 0.7±1.2 | 0.03 | 1.0±1.4 | 0.00±0.00 | 0.31 |
| Tear neuromediator concentration | ||||||
| Substance P (pg/mL) | 2331.6 ± 2013.7 | 4282.3 ± 2833.5 | 0.07 | 1255.2 ± 1185.3 | 5083.7 ± 2410.2 | <0.0001 |
| NPY (ng/mL) | 1.1±0.5 | 1.0±0.4 | 0.9 | 0.9±0.3 | 1.5±0.4 | 0.004 |
| NGF (pg/mL) | 18.0±10.7 | 109.4±175.9 | 0.05 | 18.1±8.2 | 44.5±53.4 | 0.03 |
| CGRP (ng/mL) | 1.8±1.0 | 3.6±2.3 | 0.01 | 1.6±0.9 | 2.6±0.5 | 0.04 |
*Indicates the comparison between the patients without NCP and patients with NCP after SMILE.
†Indicates the comparison between the patients without NCP and patients with NCP after LASIK.
CFracDim, corneal nerve fibre fractal dimension; CGRP, calcitonin gene-related peptide; CNBD, corneal nerve branch density; CNFA, corneal nerve fibre area; CNFD, corneal nerve fibre density; CNFL, corneal nerve fibre length; CNFW, corneal nerve fibre width; CTBD, corneal nerve fibre total branch density; LASIK, laser-assisted in-situ keratomileuses; NCP, neuropathic corneal pain; NEI, National Eye Institute; NGF, nerve growth factor; NPY, neuropeptide Y; SMILE, small incision lenticule extraction; SP, substance P; TBUT, tear break-up time.