Título

COMPARISON OF CUP DEPTH, MINIMUM RIM WIDTH AND RETINAL NERVE FIBER LAYER IN COMPRESSIVE OPTIC NEUROPATHY AND GLAUCOMA

Objetivo

Optic disc cupping(ODC) is often related to glaucomatous optic neuropathy(GON), but can be caused by compressive optic neuropathies(CON). The differentiation between them may be challenging. We previously found that a ratio between Minimal Rim Width(MRW) and peripapillary retinal nerve fiber layer(RNFL) provided significant discrimination ability between CON and GON, but information regarding ODC was lacking. In this study we investigated the role of cup depth(CD) along with MRW and RNFL in differentiating CON, GON and controls.

Método

Forty-seven eyes of 34 patients with CON from pituitary tumors, 27 eyes of 21 patients with GON and 41 eyes of controls underwent ophthalmologic examination, including SD-OCT testing, with acquisition of MRW and pRNFL measurements. CD was manually calculated(Fig.1). Data were compared using Generalized Estimated Equations. Area under the ROC curves, positive(PLR) and negative likelihood ratios(NLR) were calculated.

Resultado

CD mean values were significantly higher in GON when compared to CON and controls, but no significant difference was found between CON and healthy eyes. When comparing the ability of each OCT parameter to discriminate CON from GON, AUCs showed no statistic difference. However, CD alone showed greater PLR and NLR values than the other parameters. When combining CD to other parameters, both ratios CD/MRW and CD/RNFL showed greater mean values in GON. Considering the discrimination ability between the diseases, AUCs showed no difference between the ratios and CD/MRW had better likelihood ratios(Table).

Conclusão

Our results showed that despite significant overlapping in ODC between groups, cups were shallower in CON than in GON, with no difference to normal eyes. This corroborates that retrograde axonal damage from optic pathway compression isn’t associated to significant laminar displacement. Moreover, our study highlights CD as a useful tool in differentiating glaucoma from cupping due to CON, as its diagnostic performance was comparable to MRW and RNFL measurements.