The Relationship Between FD-OCT Structure And Visual Field Function In Glaucoma

PurposeTo evaluate the relationship between visual field function and structure detected by frequence domain optical coherence tomography (FD-OCT) in glaucoma.MethodsNineteen eyes from 14 primary open angle glaucoma (POAG), forty eyes from 23 suspected open angle glaucoma (SOAG) and twenty-nine eyes from 15 normal age-matched controls. The participants were examined by FD-OCT and standard automated perimetry (SAP).The parameters of FD-OCT included disc area,cup area,rim area,cup volume,rim volume,cup/disc ratio,linear cup/disc ratio, disc height, disc width;the six regions average RNFL thickness of temple (R1),temple-superior(R2), nasal-superior(R3),nasal(R4),nasal-inferior(R5) and temple-inferior (R6).The parameters of the SAP included the six regions average visual field loss of papillomacular bundle (T1/D1), inferior bjerrum(T2/D2), inferior(T3/D3), temple(T4/D4), superior(T5/D5), superior bjerrum (T6/D6). The average RNFL thickness of the six regions was plotted against the six districts average total deviations (linear units).RNFL thickness and visual field loss were analyzed in a line model. According to the model, the RNFL thickness R=soT+b, where T is the relative SAP sensitivity loss (on a linear scale), so is the RNFL thickness attributable to axons in the healthy or normal state (T≥1), and b is the residual RNFL measured when all sensitivity and axons are lost.ResultsMost of the parameters of FD-OCT were different from groups (P<0.01),except rim volume and disc height.Cup area,rim area,cup volume, cup/disc ratio, linear cup/disc ratio have significant difference between POAG,SOAG and control group (P<0.05). All of the six districts average RNFL thickness were have significant difference between POAG,SOAG and control group (P<0.05),but R2-R6 have no difference between SOAG and control group.Three of the parameters of SAP were different from groups (P< 0.01).T1-T6 have significant difference between POAG,SOAG and control group (P< 0.05).but T2-T4,T6 have no different between SOAG and control group.There were correlation between optic nerve head parameters (CA,RA,CDR,LCDR),RNFL thickness (R1-R6) and visual field loss (T1-T6, D1-D6), especially of R1-T1 (r=0.812), R2-T2 (r=0.858), R6-T6 (r=0.751), R1-D1 (r=0.742), R2-D2 (r=0.746),R6-D6 (r=0.725), (P< 0.001). The linear model about R6-T6 was R6=100.59T6+50.30 (T6<1);R6= 150.89 (T6≥1);The linear model about R2-T2 was R2=92.60T2+46.30 (T2<1);R2=138.90 (T2≥1);The linear model about R1-T1 was R1=54.80 T1+33.03 (T1<1); R1=87.83 (T1≥1).ConclusionsCup area,rim area, cup/disc ratio,linear cup/disc ratio detected by FD-OCT can well reflect the structure change with glauma.The six regions average RNFL thickness detected by FD-OCT can reflect local structure change with glaucoma.Three of the six regions average visual field loss detected by SAP,like papillomacular bundle(Tl/Dl), inferior Bjerrum(T2/D2),and superior Bjerrum (T6/D6),can well reflect local function change with glaucoma.There were the high correlationship between R1-T1/D1, R2-T2/D2,and R6-T6/D6.Therefore, it was possible to evaluate of regions relationship between structure and function in glaucoma.The linear model that relates RNFL thickness to visual field loss in SAP sensitivity,can well fitted our data. It provided a framework for assessing the relative efficacy of structural and functional tests throughout the course of the disease.