ABSTRACT
Objective:To explore the damage of panretinal photocoagulation (PRP) to the subbasal nerve plexus (SNP) and its related mechanisms by comparing SNP changes in wide-field mosaic between before and after PRP treatment in diabetic patients.Methods:A randomized controlled study was conducted.Fifty-seven patients (114 eyes) with type 2 diabetes mellitus and binocular diabetic retinopathy (DR) stage IV to receive PRP treatment in Shanxi Eye Hospital from April to November 2019 were enrolled.The subjects were randomly divided into horizontal-vertical laser group and vertical-horizontal laser group according to a random number table.Twenty-nine eyes from 29 patients were assigned to the horizontal-vertical laser group with the photocoagulation sequence of temporal-nasal-inferior-superior.Twenty-eight eyes from 28 patients were assigned to the vertical-horizontal laser group with the photocoagulation sequence of inferior-superior-temporal-nasal.The severer eyes of each subject were chosen as the treatment eye and the contralateral eyes were chosen as the control eye.Corneal confocal laser scanning microscopy (CCM) was performed before PRP treatment, 1 week after each photocoagulation, and 1 month after the completion of PRP treatment to collect images of the SNP over an area of 2-3 mm around the whorl-like pattern.Captured images at each time were merged into one image by using the Photoshop CC 2017 image processing software, and then the nerve fiber length (NFL) of whorl-like pattern was measured by Neuron J image analysis software.McGill pain questionnaire was used to investigate the pain of patients after each photocoagulation.The NFL changes of SNP at different time points were compared between different eyes and different photocoagulation sequence groups.The study protocol adhered to the Declaration of Helsinki and was approved by an Ethics Committee of Shanxi Eye Hospital (No.201804b). Written informed consent was obtained from each patient prior to entering the study cohort.Results:After PRP treatment, there were different degrees of neural structure loss of SNP nerve fibers in 11 treatment eyes, but there was no significant change in SNP nerve fibers in the control eyes.There were significant differences in NFL between the treatment eyes and the control eyes at various time points ( Feyes=2.020, P=0.039; Ftime=4.062, P=0.001). In the horizontal-vertical laser group, different degrees of neural structure loss on the photocoagulation side were found in SNP nerve fibers after the first and second photocoagulation.In the vertical-horizontal laser group, different degrees of neural structure loss on the photocoagulation side were found in SNP nerve fibers after the third and fourth photocoagulation.There was no significant difference in NFL of treatment eyes between the two groups ( Fgroup=0.099, P=0.754), but there was a significant difference in NFL at various time points before and after treatment ( Ftime=5.231, P<0.001). There were 9 (9/57) patients who complained of pain after PRP, which occurred at the first time of photocoagulation in 7 of them. Conclusions:SNP damage may occur after PRP in patients with DR, and SNP is prone to be damaged on the photocoagulation side when performing horizontal photocoagulation.
ABSTRACT
Objective To construct an objective analysis system of corneal nerve tortuosity and detect the changes of corneal subbasal nerve tortuosity in patients with dry eye and diabetes. Methods GradeⅠtoⅣnerve tortuosity were evaluated and 80 photos of each grade were randomly chosen from the in vivo confocal microscopy library. Nerve fibers were extracted,segmented and then analyzed by 6 tortuosity related parameters including L C, Seg L C mean,Cur mean,Specific p,ICM and SCC mean. After verifying the validaty of parameters above,a cross-sectional study was conducted. Subjects were collected from June,2018 to February,2019 in Peking University Third Hospital,and were divided into healthy control group (28 persons 56 eyes),dry eye without diabetes group (28 patients 56 eyes),diabetes without dry eye group(24 patients 48 eyes),diabetes with dry eye group (23 patients 46 eyes) . Basic and dry eye information includes sex,age,ocular surface disease index ( OSDI) ,tear film break-up time (TBUT),Schirmer Ⅰ test (SⅠt) and corneal fluorescence staining (CFS) score. Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) were detected in diabetic patients. Cochet-Bonnet examination (C-BE) was detected to evaluate corneal sensation and 2 corneal subbasal nerve photos of each eye were selected for effective tortuosity and density related parameters analysis. Data was analyzed by SPSS and diagnostic test were perfomed by MedCalc. This study followed the Declaration of Helsinki. This study protocol was approved by Ethic Committee of Peking University Third Hospital ( No. IRB00006761-M2017354 ) . Written informed consent was obtained from each subject prior to entering study cohort. Results L C,Seg L C mean,Cur mean,Specific p,ICM and SCC mean increased as the nerve tortuosity increased from Grade Ⅰ to Grade Ⅳ,with an overall significance among 4 groups (F=39. 100, 36. 367,57. 743,4. 043,6. 818,33. 493;all at P<0. 01). Among the above 6 parameters,Cur mean and L C of any two groups were of significant difference (all at P<0. 01). Twenty three to twenty eight persons were enrolled in each group of the cross-sectional study. Sex and age were comparable among 4 groups. Diagnostic criteria were met in dry eye and diabetes. Corneal sensation parameter C-BE decreased in diabetes without dry eye group and diabetes with dry eye group compared with healthy control group ( all at Adj P<0. 05 ) , other than in dry eye without diabetes group (AdjP≥0. 05). Nerve density of diabetes without dry eye group and diabetes with dry eye group was lower compared with healthy control group(all at P<0. 001),while no significant difference between dry eye without diabetes group and healthy control group(P≥0. 05). Among the effective parameters of tortuosity,L C,Cur mean,Seg L C mean and SCC mean of dry eye without diabetes group,diabetes without dry eye group,diabetes with dry eye group were higher compared with healthy control group ( all at P<0. 05 ) . Diagnostic tests of tortuosity related parameters all showed an area under curve (AUC) from 0. 5 to 0. 7. Conclusions L C and Cur mean can be used to analyze corneal nerve curvature more reliably. Compared with normal volunteers,patients of dry eye or diabetes show higher corneal subbasal nerve tortuosity.