Dry eye is a multifactorial disease of the ocular surface characterized by loss of tear film homeostasis and ocular symptoms. Instability of the tear film, inflammation and injury of the ocular surface, and neurosensory abnormalities all play important roles in dry eye [
Vitamin B1 (thiamine) given perineurally exerts analgesic effects through axonal flow by enhancing the synthesis of acetylcholine in dorsal horn inhibitory neurons [
The study was approved by the Human Research and Ethics Committee of Peking University Third Hospital (No. M2018149), adhered to the tenets of the Declaration of Helsinki, and was performed at Peking University Third Hospital Eye Center from October 2018 to March 2019. Written informed consent was obtained from each patient before enrollment in the study.
A randomized controlled trial was conducted at Peking University Third Hospital. DED was diagnosed according to the diagnostic criteria established by the Tear Film and Ocular Surface Society (TFOS) Dry Eye WorkShop II (DEWS II) [
DED patients with corneal nerve layer injury were divided into the Langerhans group and non-Langerhans group based on the presence of Langerhans cells in the corneal nerve layer on IVCM. Patients in the former group were administered with corticosteroid eye drops (Flumetholon, Saten, Japan) and randomly assigned to receive oral vitamin B1 (vitamin B1 tablets, Shanxi Hengruida Pharmaceutical Co., China), mecobalamin (mecobalamin tablets, Weicai (China) Pharmaceutical Co., China), and/or artificial tears (Hycosan, URSAPHARM, Germany, and Systane Ultra Lubricant Eye Drops, Alcon Laboratories, USA). Patients in the latter group were randomly assigned to receive oral vitamin B1, mecobalamin, and/or artificial tears (Hycosan, URSAPHARM, Germany, and Systane Ultra Lubricant Eye Drops, Alcon Laboratories, USA) or artificial tears alone as a control. Thus, the patients were ultimately divided into 4 groups: group 1, only artificial tears; group 2, corticosteroid eye drops and artificial tears; group 3, oral vitamin B1, mecobalamin, and artificial tears; and group 4, oral vitamin B1, mecobalamin, corticosteroid eye drops, and artificial tears. Each patient underwent continuous treatment for 2 months and was subjected to clinical assessment before treatment (baseline) and at 1 and 2 months after treatment. The treatments and follow-up protocols for all groups are shown in Figure
Treatment 1 (group 1): only artificial tears; treatment 2 (group 2): corticosteroids and artificial tears; treatment 3 (group 3): oral vitamin B1, mecobalamin, and artificial tears; treatment 4 (group 4): oral vitamin B1, mecobalamin, corticosteroids, and artificial tears.
At every follow-up, each participant completed a questionnaire regarding subjective symptoms and satisfaction with treatment [
A Placido ring-based, noncontact corneal topographer (Keratograph 5 M; OCULUS, Wetzlar, Germany) was used to evaluate the tear film [
IVCM was used to observe the microstructure of the cornea. All patients were examined with a digital corneal confocal laser-scanning microscope (HRT II RCM Heidelberg Engineering Inc., Heidelberg, Germany, Rostock Cornea Module) equipped with the built-in software Heidelberg Eye Explorer version 1.5.10.0. Two-dimensional images with a definition of 384 ∗ 384 pixels over an area of 400
All patients were asked to complete two questionnaires to evaluate their symptoms and satisfaction with treatment before and at 1 month and 2 months after treatment. The patients responded to the questions using a 10-point scale. The first questionnaire comprised 10 questions (questions 1–10) related to 10 DED symptoms, including dryness, foreign body sensation, pain, burning, watering, asthenopia, blurred vision, itching, increased secretions, and photophobia. The responses ranged from “have no feelings (score 0)” to “very serious (score 10).” The second questionnaire was related to satisfaction with treatment and included 4 questions regarding how the patients felt about their condition before and after treatment (responses ranged from “very bad (score 0)” to “very good (score 10)”), the ease of following doctors’ advice (from “very difficult (score 0)” to “very easy (score 10)”), and improvement after treatment (from “none (score 0)” to “significantly improved (score 10)”).
The questionnaire scores, satisfaction scores, TMH, TBUTF, TBUTA, and CNFD of each group at each time point were compared within the individual groups and between groups to evaluate the therapeutic effects of the different treatments.
SPSS software version 22 (SPSS Inc., Chicago, IL, USA) was used for statistical analysis. The Kolmogorov-Smirnov test was used to check the normality of the data distribution. Descriptive data are presented as the mean and standard deviation (SD). The mixed linear model was used to compare differences before and after treatment. To analyze repeated measurements, the patient was selected as the subject, and the time point was set as the repeated factor. In the model, the covariance type was chosen based on the covariance matrix from our preliminary analysis.
A total of 152 eyes from 76 individuals (age, 55.25 ± 18.16 years; 56 females) were included and divided into 4 groups according to treatment. Significant age and sex differences were not found among the groups. The demographic characteristics of the patients are shown in Table
Basic information.
Group 1 | Group 2 | Group 3 | Group 4 | ||
---|---|---|---|---|---|
Sex (male %) | 20 | 30 | 25 | 31.25 | ns |
Age (years, mean ± SD) | 57.35 ± 16.37 | 51.90 ± 18.57 | 53.85 ± 17.93 | 58.56 ± 19.40 | ns |
Number | 40 | 40 | 40 | 32 |
ns: no statistical significance.
As shown in Table
Comparison of pre- and posttreatment in each group.
Group 1 | Group 2 | Group 3 | Group 4 | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | ||||||
Signs (mean ± SD) | TMH (mm) | 0.18 ± 0.05 | 0.20 ± 0.07 | 0.21 ± 0.07 | 0.16 ± 0.06 | 0.18 ± 0.07 | 0.17 ± 0.07 | 0.18 ± 0.05 | 0.17 ± 0.06 | 0.18 ± 0.07 | 0.17 ± 0.05 | 0.19 ± 0.06 | 0.18 ± 0.07 |
TBUTF (s) | 5.19 ± 2.65 | 5.23 ± 2.20 | 5.85 ± 2.60 | 4.70 ± 1.80 | 4.87 ± 2.37 | 6.12 ± 3.81 | 4.21 ± 1.21 | 4.89 ± 1.80 | 5.31 ± 2.07# | 3.98 ± 1.80 | 4.55 ± 1.62 | 5.10 ± 2.74 | |
TBUTA (s) | 6.60 ± 2.85 | 7.06 ± 2.15 | 7.55 ± 3.28 | 5.93 ± 1.79 | 6.15 ± 2.15 | 7.55 ± 3.28∂# | 5.70 ± 1.71 | 6.46 ± 1.48 | 6.44 ± 2.33 | 5.09 ± 1.97 | 5.95 ± 1.95 | 6.71 ± 2.78 | |
CNFD (mm/mm2) | 14.14 ± 2.84 | 16.56 ± 1.76 | 17.51 ± 1.05 | 13.47 ± 1.14 | 13.33 ± 1.93 | 14.36 ± 1.61 | 6.54 ± 1.85 | 9.71 ± 2.49 | 13.93 ± 2.59# | 7.11 ± 2.48 | 10.55 ± 2.12 | 15.98 ± 1.72# | |
Symptoms (mean ± SD, scores) | Dryness | 5.13 ± 3.41 | 6.03 ± 3.03 | 5.83 ± 3.61 | 6.15 ± 3.14 | 5.58 ± 2.92 | 5.70 ± 2.79 | 6.15 ± 3.07 | 6.43 ± 3.54 | 4.69 ± 3.30∂# | 5.88 ± 3.13 | 4.47 ± 3.32 | 4.64 ± 3.03 |
Foreign body sensation | 3.70 ± 3.70 | 4.88 ± 3.47 | 4.88 ± 3.40 | 3.38 ± 3.61 | 3.30 ± 3.07 | 3.98 ± 3.36 | 5.38 ± 3.64 | 5.30 ± 3.43 | 3.42 ± 3.41∂# | 4.66 ± 3.76 | 3.47 ± 3.79 | 3.59 ± 3.57 | |
Pain | 1.95 ± 3.00 | 1.50 ± 2.61 | 2.00 ± 2.88 | 2.65 ± 3.18 | 2.75 ± 2.97 | 2.83 ± 3.03 | 3.63 ± 3.18 | 2.80 ± 3.30 | 2.04 ± 2.86 | 4.03 ± 3.61 | 2.53 ± 3.29 | 3.82 ± 3.57 | |
Burning | 1.15 ± 1.86 | 1.65 ± 2.77 | 1.45 ± 2.73 | 2.25 ± 3.18 | 2.40 ± 2.99 | 2.93 ± 2.74 | 2.10 ± 3.18 | 2.33 ± 3.34 | 0.96 ± 1.97# | 2.47 ± 3.65 | 1.44 ± 2.33 | 1.27 ± 2.90 | |
Watering | 2.10 ± 2.92 | 2.50 ± 3.10 | 2.48 ± 3.03 | 2.30 ± 3.04 | 2.28 ± 3.04 | 2.33 ± 2.78 | 4.05 ± 3.59 | 3.33 ± 3.87 | 3.73 ± 3.54 | 1.94 ± 3.15 | 2.16 ± 3.33 | 2.00 ± 3.27 | |
Asthenopia | 4.50 ± 3.80 | 5.30 ± 3.07 | 5.10 ± 3.39 | 5.75 ± 3.46 | 6.23 ± 2.95 | 5.75 ± 3.20 | 5.65 ± 3.22 | 6.00 ± 3.22 | 4.96 ± 3.37 | 4.31 ± 3.76 | 3.97 ± 3.34 | 5.23 ± 3.19∂ | |
Blurred vision | 3.55 ± 3.56 | 2.20 ± 3.12 | 3.60 ± 3.51# | 3.10 ± 3.62 | 3.45 ± 3.04 | 3.20 ± 3.43 | 3.13 ± 3.49 | 2.85 ± 3.42 | 3.81 ± 3.37 | 3.97 ± 4.04 | 2.81 ± 3.41 | 3.41 ± 3.59 | |
Itching | 2.85 ± 2.89 | 2.60 ± 2.47 | 3.15 ± 2.98 | 2.15 ± 3.45 | 2.25 ± 3.10 | 3.48 ± 3.23 | 2.98 ± 3.33 | 3.23 ± 3.18 | 2.58 ± 3.20 | 2.59 ± 3.26 | 1.88 ± 2.65 | 1.91 ± 2.86 | |
Increased secretions | 1.25 ± 2.81 | 1.05 ± 2.63 | 1.23 ± 1.82 | 1.35 ± 2.72 | 2.48 ± 3.45 | 2.20 ± 2.59 | 2.43 ± 3.61 | 2.48 ± 3.22 | 3.27 ± 2.99 | 3.66 ± 3.53 | 3.28 ± 3.74 | 2.73 ± 3.38 | |
Photophobia | 3.40 ± 3.82 | 3.95 ± 3.74 | 3.33 ± 3.59 | 4.80 ± 3.69 | 4.90 ± 3.64 | 4.03 ± 3.29 | 5.00 ± 3.82 | 4.63 ± 3.93 | 3.54 ± 3.39# | 4.84 ± 3.90 | 3.75 ± 3.67 | 3.68 ± 3.71 | |
Total | 29.58 ± 17.97 | 31.33 ± 14.67 | 32.95 ± 19.70 | 33.88 ± 12.88 | 35.60 ± 17.47 | 36.40 ± 15.38 | 40.48 ± 21.45 | 39.35 ± 20.73 | 32.73 ± 23.33 | 38.34 ± 23.67 | 29.75 ± 23.07 | 32.27 ± 25.31 | |
Satisfaction (mean ± SD, scores) | Before | 4.00 ± 2.63 | 3.60 ± 2.99 | 3.82 ± 2.60 | 4.50 ± 2.40 | 4.22 ± 2.50 | 4.20 ± 2.56 | 4.41 ± 2.97 | 3.40 ± 2.19 | 2.82 ± 1.30 | 3.29 ± 2.59 | 3.60 ± 2.17 | 3.50 ± 3.13 |
After | 5.21 ± 2.62 | 5.72 ± 2.21 | 5.67 ± 2.32 | 6.05 ± 2.14 | 5.87 ± 2.62 | 6.27 ± 2.10 | 4.67 ± 1.67 | 5.31 ± 3.03 | |||||
After-before | 1.43 ± 2.39 | 1.89 ± 1.97 | 1.44 ± 1.92 | 1.85 ± 1.39 | 2.47 ± 2.65 | 3.45 ± 2.24∂ | 0.50 ± 1.77 | 2.00 ± 2.18 | |||||
Following advice | 9.07 ± 2.33 | 8.94 ± 2.18 | 8.83 ± 1.44 | 8.50 ± 1.55 | 9.53 ± 1.28 | 9.55 ± 0.80 | 9.86 ± 0.36 | 9.29 ± 1.20 | |||||
Improvement | 6.00 ± 3.11 | 5.56 ± 3.16 | 6.28 ± 3.19 | 6.80 ± 2.89 | 6.33 ± 2.77 | 7.36 ± 2.32 | 6.57 ± 2.34 | 5.86 ± 3.90 |
B: baseline; 1: 1 month; 2: 2 months; TMH: tear meniscus height; TBUTF: tear film breakup time first; TBUTA: tear film breakup time average; CNFD: corneal nerve fiber density. Satisfaction: before: pretreatment satisfaction with ocular surface; after: posttreatment satisfaction with ocular surface; following advice: compliance with the doctor's advice; improvement: satisfaction with therapeutic effects.
These two images are from the same corneal nerve layer of subepithelial corneal epithelium of the IVCM in the same patient in group 4: (a) before treatment; (b) 1 month after treatment.
As shown in Table
Comparison of pre- and posttreatment among the groups.
1 month-baseline | 2 months–-baseline | 2 months-1 month | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
G1 | G2 | G3 | G4 | G1 | G2 | G3 | G4 | G1 | G2 | G3 | G4 | |||||
Signs (mean ± SD) | TMH (mm) | 0.02 ± 0.06 | 0.02 ± 0.06 | −0.01 ± 0.06 | 0.02 ± 0.07 | 0.03 ± 0.07 | 0.01 ± 0.06 | 0.01 ± 0.05 | 0.00 ± 0.08 | 0.01 ± 0.06 | −0.01 ± 0.06 | 0.01 ± 0.08 | −0.01 ± 0.06 | |||
TBUTF (s) | 0.04 ± 3.49 | 0.17 ± 2.35 | 0.69 ± 2.04 | 0.59 ± 1.76 | 0.66 ± 3.79 | 1.42 ± 4.26 | 1.15 ± 1.57 | 0.79 ± 2.74 | 0.62 ± 3.39 | 1.25 ± 3.42 | 0.48 ± 1.86 | 0.66 ± 2.54 | ||||
TBUTA (s) | 0.46 ± 2.87 | 0.22 ± 2.50 | 0.74 ± 1.97 | 0.43 ± 1.77 | 0.62 ± 3.38 | 1.62 ± 3.82 | 0.97 ± 2.43 | 1.37 ± 2.67 | 0.16 ± 2.68 | 1.40 ± 2.96 | 0.02 ± 1.51 | 0.82 ± 2.71 | ||||
CNFD (mm/mm2) | 2.42 ± 1.75 | −0.13 ± 1.66 | 3.16 ± 1.94ε | 3.44 ± 3.55∂ | 0.021 | 3.37 ± 2.60 | 0.89 ± 1.07 | 7.39 ± 3.57ε | 9.32 ± 3.00∂ | 0.001 | 0.95 ± 1.43 | 1.03 ± 1.53 | 4.22 ± 2.83 | 4.93 ± 3.21 | 0.002 | |
Symptoms (mean ± SD, scores) | Dryness | 0.90 ± 2.11 | −0.58 ± 2.52 | 0.28 ± 3.03 | −1.41 ± 3.64# | 0.005 | 0.70 ± 2.39 | −0.45 ± 2.96 | −0.81 ± 2.37 | −1.18 ± 2.65# | 0.028 | −0.20 ± 2.54 | 0.13 ± 2.48 | −1.81 ± 2.47ε | 0.23 ± 2.99∀ | 0.015 |
Foreign body sensation | 1.18 ± 3.21 | −0.08 ± 3.27 | −0.08 ± 3.11 | −1.19 ± 3.11# | 0.021 | 1.18 ± 3.38 | 0.60 ± 3.16 | −1.31 ± 3.65 | −1.50 ± 5.18# | 0.011 | 0.00 ± 2.65 | 0.68 ± 3.12 | −1.88 ± 3.14ε | −0.91 ± 4.25 | 0.013 | |
Pain | −0.45 ± 2.16 | 0.10 ± 3.57 | −0.83 ± 3.17 | −1.50 ± 2.51 | 0.05 ± 3.43 | 0.18 ± 3.46 | −1.38 ± 3.09 | −0.91 ± 3.71 | 0.50 ± 3.21 | 0.08 ± 3.44 | −0.46 ± 2.45 | 0.91 ± 3.50 | ||||
Burning | 0.50 ± 3.00 | 0.15 ± 3.33 | 0.23 ± 2.28 | −1.03 ± 3.03 | 0.30 ± 2.57 | 0.68 ± 3.12 | 0.12 ± 1.93 | −0.55 ± 2.44 | −0.20 ± 3.39 | 0.53 ± 2.97 | −0.46 ± 2.25 | −0.09 ± 1.23 | ||||
Watering | 0.40 ± 2.91 | −0.03 ± 2.11 | −0.73 ± 2.41 | 0.22 ± 1.56 | 0.38 ± 2.25 | 0.03 ± 2.79 | 0.00 ± 3.01 | 0.55 ± 2.22 | −0.03 ± 2.09 | 0.05 ± 3.39 | 0.23 ± 3.02 | 0.41 ± 1.22 | ||||
Asthenopia | 0.80 ± 3.67 | 0.48 ± 2.37 | 0.35 ± 2.66 | −0.34 ± 2.72 | 0.60 ± 3.88 | 0.00 ± 2.31 | −0.31 ± 2.77 | 0.77 ± 2.41 | −0.20 ± 2.15 | −0.48 ± 2.54 | −1.00 ± 3.20 | 1.41 ± 2.13 | 0.009 | |||
Blurred vision | −1.35 ± 3.08 | 0.35 ± 4.33 | −0.28 ± 3.49 | −1.16 ± 2.07 | 0.05 ± 3.59 | 0.10 ± 3.89 | 0.46 ± 1.70 | −1.32 ± 2.83 | 1.40 ± 3.24 | −0.25 ± 2.85 | 1.50 ± 3.48 | −0.23 ± 1.85 | 0.020 | |||
Itching | −0.25 ± 2.70 | 0.10 ± 3.95 | 0.25 ± 3.09 | −0.72 ± 2.56 | 0.30 ± 2.52 | 1.33 ± 4.37 | −0.46 ± 3.11 | −0.82 ± 3.06 | 0.55 ± 1.91 | 1.23 ± 3.91 | 0.23 ± 3.18 | 0.32 ± 1.46 | ||||
Increased secretions | −0.20 ± 1.14 | 1.13 ± 3.13 | 0.05 ± 2.77 | −0.38 ± 2.55 | 0.045 | −0.03 ± 2.12 | 0.85 ± 3.67 | 0.54 ± 3.85 | −0.23 ± 1.90 | 0.18 ± 1.91 | −0.28 ± 2.75 | 0.54 ± 2.92 | 0.09 ± 1.19 | |||
Photophobia | 0.55 ± 2.23 | 0.10 ± 3.68 | −0.38 ± 1.44 | −1.09 ± 2.98 | −0.08 ± 2.37 | −0.78 ± 3.35 | −1.08 ± 2.67 | −0.95 ± 2.21 | −0.63 ± 1.82 | −0.88 ± 2.84 | −0.81 ± 1.88 | 0.50 ± 2.94∂∀ | ||||
Total | 1.75 ± 13.11 | 1.73 ± 17.65 | −1.13 ± 14.26 | −8.59 ± 15.46∂# | 0.017 | 3.38 ± 11.51 | 2.53 ± 13.08 | −4.23 ± 13.60 | −6.14 ± 15.06# | 0.011 | 1.63 ± 11.89 | 0.80 ± 16.35 | −3.92 ± 13.11 | 2.64 ± 8.94 | ||
Satisfaction (mean ± SD, scores) | Before | −0.57 ± 3.03 | −0.71 ± 2.35 | −0.59 ± 4.11 | 0.00 ± 3.71 | −0.63 ± 2.68 | −0.21 ± 3.48 | −0.92 ± 3.00 | −0.13 ± 4.94 | 0.21 ± 3.13 | −0.22 ± 3.84 | −0.88 ± 2.50 | −0.13 ± 1.73 | |||
After | 0.46 ± 2.10 | 0.17 ± 3.42 | 0.63 ± 3.26 | 1.38 ± 1.51 | ||||||||||||
Following advice | −0.14 ± 0.65 | −0.28 ± 1.43 | −0.38 ± 0.72 | −0.50 ± 0.93 | ||||||||||||
Improvement | −0.07 ± 2.68 | 0.33 ± 2.44 | 0.38 ± 2.93 | 0.25 ± 1.58 |
G1: group 1; G2: group 2; G3: group 3; G4: group 4; TMH: tear meniscus height; TBUTF: tear film breakup time first; TBUTA: tear film breakup time average; CNFD: corneal nerve fiber density. Satisfaction: before: pretreatment satisfaction with ocular surface; after: posttreatment satisfaction with ocular surface; following advice: compliance with the doctor’s advice; improvement: satisfaction with therapeutic effects.
The correlations between pre- and posttreatment signs/symptoms/treatment satisfaction scores and sex/age are shown in Table
The correlations between pre- and posttreatment signs/symptoms/treatment satisfaction scores and sex/age.
G1 | G2 | G3 | G4 | ||||||
---|---|---|---|---|---|---|---|---|---|
Estimate (sex) | Estimate (age) | Estimate (sex) | Estimate (age) | Estimate (sex) | Estimate (age) | Estimate (sex) | Estimate (age) | ||
Signs | TMH | Ns | ns | 0.056 | ns | ns | ns | ns | ns |
TBUTF | Ns | ns | ns | −0.029 | 0.719 | −0.025 | ns | ns | |
TBUTA | ns | ns | ns | ns | ns | −0.034 | ns | ns | |
Symptoms | Dryness | ns | ns | ns | −0.065 | −1.892 | ns | −2.182 | ns |
Pain | ns | −0.060 | ns | −0.891 | ns | ns | ns | −0.083 | |
Burning | ns | ns | ns | ns | ns | −0.048 | −2.072 | ns | |
Watering | ns | ns | ns | ns | ns | ns | −2.734 | ns | |
Asthenopia | ns | ns | ns | −0.085 | ns | ns | ns | −0.054 | |
Blurred vision | ns | ns | 1.820 | ns | ns | ns | ns | 0.069 | |
Itching | ns | ns | ns | ns | 2.012 | −0.091 | −2.636 | ns | |
Photophobia | ns | ns | 2.736 | ns | −2.969 | ns | −3.873 | 0.054 | |
Total | ns | ns | ns | ns | ns | −0.346 | −26.519 | ns | |
Satisfaction | Before | ns | ns | ns | ns | ns | 0.030 | −1.579 | −0.113 |
After | ns | ns | ns | ns | ns | −0.049 | 3.627 | −0.055 | |
After-before | ns | ns | ns | ns | ns | −0.082 | ns | ns | |
Following advice | −2.223 | ns | 0.951 | ns | ns | ns | −0.019 | 0.003 | |
Improvement | ns | ns | ns | ns | ns | ns | ns | −0.136 |
G1: group 1; G2: group 2; G3: group 3; G4: group 4; TMH: tear meniscus height; TBUTF: tear film breakup time first; TBUTA: tear film breakup time average; Satisfaction: before: pretreatment satisfaction with ocular surface; after: posttreatment satisfaction with ocular surface; following advice: compliance with the doctor's advice; improvement: satisfaction with therapeutic effects. ns: no statistical significance.
DED is a multifactorial disease with various symptoms and signs [
In this study, the scores of four dry eye symptoms (dryness, foreign body sensation, burning, and photophobia) and TBUTF improved significantly at 2 months after treatment with oral vitamin B1, mecobalamin, and artificial tears (group 3). When corticosteroid eye drops were added to this treatment (group 4), pain, blurred vision, and total symptom scores were significantly improved at 1 month after treatment. We also observed an obvious decrease in Langerhans cells in the corneal nerve layer at 1 month after treatment. In addition, the CNFD proved obviously improved in both groups 3 and 4 at 1 and 2 months after treatment. These observations suggest that oral vitamin B1 and mecobalamin can help nourish and repair the corneal nerve layer to some extent, thereby alleviating burning and photophobia.
The cornea possesses approximately a hundred times more nociceptors than the dermis. These nociceptors are located slightly below the lacrimal layer, between the epithelial cells, and are unmyelinated, leading to extreme sensitivity in nociceptive sensation [
Previous studies have shown that the analgesic effect of vitamin B1 occurs via indirect enhancement of axonal flow [
The significant differences in satisfaction scores between baseline and 1 and 2 months after treatment in group 3 are consistent with previous reports and are not unexpected because photophobia, burning, and pain are subjective symptoms and have a greater impact on satisfaction scores [
Unexpectedly, demographic differences in the effectiveness of the treatments for DED were observed: oral vitamin B1 and mecobalamin were more effective for men than women, particularly for dryness and photophobia. We speculate that this may be related to the decline in hormone levels in older women, but additional experiments are needed to confirm this possibility. These findings could be used to guide treatment in the future.
In summary, our study showed that oral vitamin B1 and mecobalamin can relieve some DED symptoms such as dryness, foreign body sensation, and photophobia; stabilize the tear film; and improve patient satisfaction with regard to treatment. We speculate that neurotrophism may be one of the mechanisms underlying these effects. However, at least 2 months of treatment were required for these benefits to be evident, which demands patient compliance. Corticosteroid eye drops can help relieve the overall symptoms of dry eyes, but any withdrawal may cause rebound.
Our study provides new therapeutic options for the treatment of DED as well as guidance regarding the duration and combined use of different DED treatments. A limitation of this study is the relatively small sample size. In addition, this was a trial treatment, and we did not check serum vitamin B1 and vitamin B12 levels in the DED patients. We do not know whether there is synergy or interaction between vitamin B1 and mecobalamin, or do we know which is more effective in the treatment of DED. Answering these questions will be the focus of our subsequent research. As noted previously [
Breakup time
Dry eye disease
Tear film breakup time average
Tear film breakup time first
Tear meniscus height
In vivo confocal microscopy
Corneal nerve fiber density.
The data used to support the findings of this study are available from the first author upon request.
An earlier version of the manuscript has been presented as a conference abstract in The 24th Congress of Chinese Ophthalmological Society. The sponsor or funding organization had no role in the design or conduct of this research.
All authors declare that they have no conflicts of interest.
Xiaotong Ren, Yilin Chou, Xiaodan Jiang, and Ran Hao contributed equally to this work.
The publication of this paper was supported by a grant from Capital’s Funds for Health Improvement and Research (Grant no. CFH2018-2-4093).