This study was conducted in accordance with the Declaration of Helsinki, with the approval of the Kırıkkale University Ethics Committee (Date: 19.12.2019 Decision No: 29/01 No: 2019/29). Patients admitted to Kırıkkale University Faculty of Medicine, Department of Ophthalmology between June 2020 and March 2021 who diagnosed with cataract and recommended surgical treatment were included in the study. Forty-five patients who were non-DM at the time of admission were stated as group 1, and 55 patients with DM were noted as group 2. Detailed anamnesis were taken from the patients. Their systemic and ocular diseases and the drugs they used were recorded. Best-corrected visual acuity with Snellen chart, intraocular pressure measurement with air-puff tonometry, biomicroscopic anterior segment, and fundus inspections were performed for patients' eye examinations. Cataract classification and grading were performed according to the Age-Related Eye Disease Study (AREDS) clinical lens grading system, with dilated ophthalmological examination and images taken in the operating room . According to the cataract type, the patients were divided into nuclear, posterior subcapsular, mixed, and graded as grades 2, 3, and 4. There was no pure cortical cataract or grade 1 cataract patient. The patients were grouped as mature and immature cataract according to their cataract maturity.
Patients with any thyroid, kidney, and liver dysfunction, a history of smoking and alcohol use within the last year, patients with a history of acute infection, acute myocardial infarction, ocular surgery, and patients with traumatic and toxic cataracts were not included in the study.
The procedures to be performed were explained to the patients participating in the study, and informed consent forms were obtained from all patients.
Collection and Storage of Samples
At the beginning of standard cataract surgery, approximately 0.1 cc aqueous humor was aspirated from the anterior chamber with a 27-gauge cannula connected to an insulin syringe through the corneal side entrance, which is routinely applied with an MVR (microvitreoretinal) blade, and was poured into the Eppendorf microtube. Samples were stored at -80 °C until analysis. Aqueous humor TOS, TAS levels and ARE enzyme activities (Rel Assay Diagnostics kit, Baran Medikal, Ankara, Turkey) were measured using an automated measurement method with Mindray BS400 autoanalyzer.
Total Oxidant Status Measurement
In the new method, oxidants present in the sample oxidized the ferrous ion-o-dianisidine complex to ferric ion. The oxidation reaction was enhanced by glycerol molecules abundantly present in the reaction medium. The ferric ion produced a colored complex with xylenol orange in an acidic medium. The color intensity, which could be measured spectrophotometrically, was related to the total amount of oxidant molecules present in the sample. The assay was calibrated with hydrogen peroxide and the results were expressed in terms of micromolar hydrogen peroxide equivalent per liter (μmol H2O2 equivalent/L).
Total Antioxidant Status Measurement
The novel automated method is based on the bleaching of characteristic color of a more stable ABTS (2,2 ′- Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical cation by antioxidants. The assay has excellent precision values, which are lower than 3%. The results were expressed as mmol Trolox equivalent/L.
Oxidative Stress Index
The ratio of TOS to TAS was accepted as OSI. For calculation, the resulting TAS unit was converted to μmol/L, and the OSI value was calculated according to the formula:
OSI (arbitrary unit) =TOS (μmol H2O2 equivalent/L) /TAS (μmol Trolox equivalent/L)
Arylesterase Enzyme Activity Measurement
Phenylacetate was used as the substrate to measure ARE activity. The enzymatic activity was calculated as 1310 M − 1 cm − 1 from the molar absorption coefficient of the produced phenol. One unit of ARE activity was defined as 1 µmol of phenol produced per minute under the above conditions.
Statistical analyzes were performed with IBM SPSS Statistics, Version 23.0 (SPSS Inc., Chicago, USA). Difference analysis in terms of continuous variables between the two groups was performed using the Student's t-test, in which the means were compared for those with normal distribution, and the Mann-Whitney U test, where the median values were compared for those who did not. In the analysis of dependent variables with more than two groups, the One-way Anova test was used for those with normal distribution and the Kruskal-Wallis test for those who did not. To examine the relationship between the groups, Pearson and Spearman correlation analyzes were performed, and the correlation coefficients were reported. The limit of significance was accepted as p <0.05.