[Clinical characteristics of eyes with unilateral disc hemorrhage in normal tension glaucoma patients].

OBJECTIVE

To investigate the clinical characteristics of the eyes with unilateral disc hemorrhage (DH) in normal tension glaucoma (NTG) patients.

METHODS

37 normal-tension glaucoma patients with unilateral DH were studied. Extensive parameters were analyzed to evaluate which parameters differ significantly between the DH eyes and the companion eyes. These parameters are: (1) intraocular pressure (IOP), (2) dioptres of refractive errors, (3) central corneal thickness (CCT), (4) disc area, (5) disc shape including horizontal diameter, vertical diameter and horizontal diameter/vertical diameter, (6) global parameters of optic disc, including rim area (G-RA), rim volume (G-RV), mean retinal never fiber layer thickness (G-MRNFLT), cup shape measure (G-CSM) and height variation contour (G-HVC), (7) sectorial parameters of DH located area, including S-RA, S-RV, S-MRNFLT, S-CSM and S-HVC, (8) parameters of the peripapillary atrophy (PPA) beta zone including the incidence rate, area, extent and maximum width. The global and sectorial parameters of the optic disc were obtained directly from HRT-II. The other parameters, such as optic disc horizontal diameter, vertical diameter and PPA, were obtained by processing the raw optic disc images acquired from HRT-II using computer software Image-pro plus version 6. Univariate and multivariate regression analyses were performed on the acquired parameters.

RESULTS

The disc vertical diameter (P < 0.01) and incidence rate (P = 0.031) of zone beta appeared to be significantly larger in the DH eyes than the ones in the contra-lateral eyes, while horizontal diameter/vertical diameter was significantly smaller in the DH eyes. As for the optic disc global parameters, the G-MRNFLT (P = 0.028), G-HVC (P = 0.047) were significantly lower in the DH eyes than in the contra-lateral eyes while the G-CSM was significantly higher in DH eyes (P = 0.047). The differences of G-RA, G-RV between two eyes were not significant. As for the regional parameters, S-RA, S-RV, S-MRNFLT were significantly smaller in the DH eyes than in the contra-lateral eyes with P-values 0.033, 0.01 and 0.008 respectively. S-CSM was significantly larger in DH eyes (P = 0.021). S-HVC did not display significant difference between two groups. There were also no significant differences in CCT, dioptres of refractive errors, IOP, PPA parameters (including area, extent and maximum width) between DH eyes and companion eyes. Multivariate regression analysis demonstrated that contained disc area, dioptres of refractive errors, G-RA, G-MRNFLT, G-CSM, horizontal diameter/vertical diameter and zone beta extent, the horizontal diameter/vertical diameter were the significant factors independently associated with disc hemorrhage (P = 0.032, OR < 0.001: < 0.001 - 0.35). Logistic regression analysis also showed that contained disc area, dioptres of refractive errors, S-RA, S-MRNFLT, S-CSM, horizontal diameter/vertical diameter and zone beta extent, the horizontal diameter/vertical diameter and S-MRNFLT were the significant factors independently associated with disc hemorrhage (S-MRNFLT: P = 0.019, OR < 0.001: < 0.001 - 0.154; horizontal diameter/vertical diameter: P = 0.02, OR < 0.001: < 0.001 - 0.124).

CONCLUSION

Our study indicates that horizontal diameter/vertical diameter is significantly smaller in NTG patients with unilateral optic disc hemorrhages. The DH located area also appears to have thinner RNFL thickness. Unilateral optic disc hemorrhages tend to have severe RNFL damage in DH located area and their optic disc shape tend to be longer, therefore we hypothesis that the elongation of the optic disc may be associated with the occurrence of DH.