Objective:To detect the factors that influence quality of fundus photographs for grading diabetic retinopathy in diabetic patients by taking a comprehensive ophthalmic examination and fundus photos before and after pupil dilation (PD) with a dilation-free fundus camera.Methods:From January to March, 2017, the outpatients and registered patients at a hospital in Shaoguan were screened. Electronic photographs of the posterior polar fundus of both eyes with a single field of vision of 45° were taken by dilation-free fundus camera before and after PD. And all the photographs were graded and reported in a single blind condition.Results:The fundus photographs of the 289 diabetic patients (578 eyes) were taken through small and dilated pupils. The grading ratio of fundus photos after PD was significantly higher compared with that before PD [95.5% (552/578) vs. 55.4% (320/578); P＜0.001). Multivariate logistic regression analysis showed that the major influence factors of gradability of fundus photos were pupil diameter and lens opacity. When the pupil diameter was less than 3.0 mm, the proportion of fundus photos that could not be graded was 12.68 times that when the pupil diameter was greater than 3.5 mm ( OR=12.68, 95% CI 2.95-60.70, P＜0.001). The higher the degree of lens cortex and nucleus opacity, the higher the proportion of photographs that could not be graded was (for cortex opacity: OR=1.802, 95% CI 1.053-3.084, P=0.032; for nucleus opacity: OR=2.549, 95% CI 1.540-4.218, P＜0.001). Age, gender, duration of diabetes, and visual acuity showed no significant effect on the clarity of fundus photos. Conclusion:Small pupils (＜3.0 mm) and lens opacity are major influence factors of the quality of fundus photographs by a dilation-free fundus camera for DR screening. With the exclusion of relevant factors, pupil dilation can significantly improve the gradability ratio of fundus photographs.

Objective To assess central corneal thickness(CCT)and anterior chamber depth (ACD) measurements with anterior segment optical coherence tomography (AS-OCT)comparing with A-scan ultrasonography (A-scan US).Methods 54 eyes of 33 normal subjects were enrolled in the study.CCT and ACD were measured using AS-OCT and A-scan US.The measurements of two instruments were analyzed using paired t test,Pearson correlation and Bland-Altman plot,respectively.Results The CCT of AS-OCT and A-scan US were 524.41± 23.24 microm and 513.37± 22.7 microm,respectively.The CCT values measured by A-scan US were significantly greater than AS-OCT, paired difference was 11.04± 5.10 microm (t =15.906, P =0.000).There were a significantly correlation between CCTs value of two instruments (r =0.976, P =0.000). The 95% LoA (95% Limts of Agreement)was -21.03 microm to -1.04 microm.The width of 95% LoA was 28 microm,3.81% of the average pachymetry reading.The ACD of AS-OCT and A-scan US were 2.89± 0.29 mm and 3.18 ± 0.26 mm,respectively.The ACD values measured by AS-OCT were significantly greater than A-scan US, paired difference was -0.29± 0.17 mm(t =-12.052, P = 0.000).There were a significantly correla-tion between CCTs value of two instruments(r=0.803 ,P=0.000).The 95% LoA was -0.63 mm to -0.06 mm.The width of 95% LoA was 0.57 mm, 19.72% of the average A-scan reading.Conclusion CCT and ACD measured by AS-OCT were highly correlated with that from ultrasound pachymetry.ln comparison with measurements of A-scan,CCT value of AS-OCT was lower,and the ACD was deeper.However,ACD readings by AS-OCT and A-scan were consistently less than that of CCT.