Indicating and predicting role of the horizontal C/D ratio in preclinical diabetic retinopathy associated with chronic angle-closure glaucoma

摘要

AIM:To observe morphological optic disc characteristics in patients with preclinical diabetic retinopathy(DR) associated with chronic angle-closure glaucoma(CACG). METHODS:Twenty-two cases(43 eyes) of preclinical DR associated with CACG were enrolled in group A;24 preclinical DR cases(46 eyes) were enrolled in group B;26 CACG cases(51 eyes) were enrolled in group C;and 49 normal controls(49 eyes) were enrolled in group D. All underwent optical coherence tomography to measure the horizontal C/D ratio(HCDR), C/D area ratio(CDaR), vertical C/D ratio(VCDR), rim area(RA), cup volume(CV), disc area(DA) and average retinal nerve fiber layer(RNFL) thickness. RESULTS:The ages of groups A, B, C, and D were 67.60±3.36, 66.78±3.33, 65.98±3.83, and 67.54±3.17 y, respectively. The HCDR values in groups A, B, and C were distinct relative to those in group D(P<0.0001, P<0.01, and P<0.05, respectively). The HCDR values in group A were higher compared with those in groups B(P<0.0001) and D(P<0.0001);while these values were virtually identical statistically between groups A and C(P>0.05). The CDaR values in group A were higher in comparison to those in groups B and D(P<0.0001 in both groups);while these values were virtually identical statistically between groups A and C(P>0.05). The RA values in group A were smaller relative to those in groups B and D(P<0.0001 in both groups);while groups A and C were not distinct statistically(P>0.05). The CV values in group A were greater in comparison to those in groups B and D(P<0.0001 in both groups);while groups A and C were not distinct statistically(P>0.05). DA was not distinct for comparisons of two groups among the four groups(P>0.05). HCDR value correlated with mean nasal RNFL thickness(r=-0.909,P<0.0001), mean superior RNFL thickness(r=-0.866, P<0.0001), mean inferior RNFL thickness(r=-0.650, P<0.001) and mean temporal RNFL thickness(r=-0.562, P<0.01) in group A. CONCLUSION:The HCDR was a sensitive morphological parameter in detecting structural visual disc changes in preclinical DR associated with CACG, which can reflect optic nerve damage caused jointly by CACG and diabetes. A higher HCDR may predict optic nerve atrophy.