Abstract:

Objective

The aim of this study is to investigate corneal sensitivity and tear film stability in patients with neurodegenerative diseases（ND）.

Methods

A total of 145 clinically diagnosed ND patients（145 eyes）and 182 age-and gender-matched non-ND controls（182 eyes）from the Department of Neurology，Affiliated Hospital of Xuzhou Medical University between January and December 2023.The cohort comprised 150 males and 177 females with an average age of（51.7±7.8）year-old（ranging from 30 to 82 year-old）.According to the disease type，patients were divided into Alzheimer′s disease（AD），multiple sclerosis（MS），Parkinson′s disease（PD），Friedreich′s ataxia（FA），Huntington′s disease（HD），and control groups were established with matched demographics.Ocular assessments included corneal sensitivity measurement using Cochet-Bonnet esthesiometer.Blink frequency analysis via LipiView ocular surface interferometer tear film evaluation through ocular surface disease index（OSDI），tearmeniscus height（TMH），non-invasive tear film breakup time（NIBUT），corneal fluorescein staining（CFS），lipid layer thickness（LLT）.OSDI，TMH，NIBUT，corneal fluorescein staining score，LLT，blink frequency and corneal sensitivity were all in line with normal distribution，and were described by（±s），and the comparison between groups was performed with t test.Gender was a dichotomous variable，expressed in cases and percentages，using chi-square test.

Results

ND subgroups included AD patients with 36 cases（36 eyes），MS patientswith 30 cases（30 eyes），PD patients with 50 cases（50 eyes），FA patients with（13 cases）13 eyes and HD patients with 16 cases（16 eyes）；AD patients control with 43 cases（43 eyes），MSpatients controlwith 33 cases（33 eyes），PD patients controlwith 50 cases（50 eyes），FA patients controlwith 28 cases（28 eyes），and HD patients control with 28 cases（28 eyes）.OSDI scores TMH，NIBUT，corneal fluorescein staining score，LLT，the blink frequency and corneal sensitivity of patients in AD，FA，PD，MSand HD groupswere（27.97±8.12）score，（27.30±6.89）score，（24.94±5.79）score，（26.31±6.78）score，（25.38±5.71）score，respectively（0.16±0.02）mm，（0.22±0.02）mm，（0.17±0.01）mm，（0.23±0.02）mm，（0.17±0.02）mm，（5.25±1.27）s，（5.33±1.21）s，（5.84±1.42）s，（6.23±1.48）s，（6.19±1.42）s，（2.03±0.14）points，（1.77±0.77）points，（1.26±0.63）points，（1.31±0.48）points，（1.31±0.48）points，（68.50±11.57）μm，（70.60±10.96）μm，（69.90±9.25）μm，（71.31±6.13）μm，（71.38±7.72）μm，（8.72±1.11）times/min，（8.77±1.01）times/min，（8.88±1.54）times/min，（8.31±0.86）times/min and（8.25±0.86）times/min，（37.36±9.89）mm，（39.00±12.25）mm，（38.40±9.87）mm，（39.（23±9.97）mm and（36.88±9.64）mm.The corresponding control groups were（14.05±5.28）score，（12.03±4.65）score，（17.58±5.20）score，（14.11±5.42）score，（14.50±4.81）score，respectively（0.22±0.03）mm，（0.25±0.03）mm，（0.23±0.02）mm，（0.25±0.02）mm，（0.24±0.02）mm，（12.35±2.84）s，（12.12±1.90）s，（13.16±2.07）s，（12.43±2.03）s，（12.32±1.83）s，（0.42±0.50）points，（0.33±0.48）points，（0.22±0.42）points，（0.25±0.44）points，（0.21±0.42）points，70.42±9.69）μm，（69.30±9.22）μm，（70.34±10.28）μm，（70.14±8.70）μm，（70.75±8.78）μm，（12.63±1.27）times/min，（12.91±1.38）times/min，（12.30±1.42）times/min，（12.82±1.44）times/min，（12.93±1.48）times/min，（55.35±5.61）mm，（55.61±5.27）mm，（56.50±4.55）mm，（54.82±4.55）mm，6.16）mm and（55.71±5.72）mm.The differences between AD，FA and PD groups and the corresponding control group were statistically significant（t＝－6.500，－6.440，－5.673，10.412，－4.614，－13.883，－14.706，－16.710，－20.597，－7.126， －6.053， －7.208， －7.450， －6.723， －8.198， －10.144， －7.615，－11.780；P＜0.05）.Compared with the control group，the TMH of patients in FA group and HD group decreased.Compared with the control group，the nibut time of patients in FA group and HD group was shortened.Compared with the control group，the corneal fluorescein staining scores of patients in FA group and HD group were increased.Compared with the control group，the blink frequency of patients in FA group and HD group was decreased.Compared with the control group，the corneal sensitivity of patients in FA group and HD group was decreased.

Conclusions

Patients with various NDs exhibit characteristic dry eye manifestations characterized by impaired tear film stability and diminished corneal sensitivity.

Key words: Neurodegenerative diseases, Corneal sensitivity, Dry eye, Tear film