Abstract
Purpose:
to evaluate the role of the choroid in the different degrees of retinal nerve fiber layer(RNFL) damage in patients affected by ocular hypertension(OH) and primary open angle glaucoma(POAG).
Methods:
117 eyes of 117 patients with POAG or OH (66.8±12.8 years) and 50 healthy subjects (HS) (63.09±21.42 years)were enrolled. Patients were classified into 2 groups according to RNFL classification: 54 eyes within normal limits (WNL) and 48 eyes outside normal limits(ONL). Borderline eyes (n=15) were excluded. Peripapillary RNFL thickness was obtained by spectral domain optical coherence tomography (SD-OCT,Heidelberg Engineering). Peripapillary choroidal thickness (CT) was measured from the outer border of the retinal pigment epithelium and the chorio-scleral interface, using enhanced depth imaging mode. CT and RNFL thickness maps were compared between the groups for global(G)and infero-temporal (IT),infero-nasal (IN), supero-temporal (ST), supero-nasal (SN), nasal(N), temporal(T) quadrants. Statistical analysis was performed with Mann-Whitney U test (non-normal distribution, Shapiro-Wilk test p<0.05) or independent Student’s t-test (normal distribution). Spearman’s rank correlation coefficient was calculated for comparisons.
Results:
Mean global CT was 129.23±49.93 µm in POAG/OH eyes and 143.71±40.0 µm in HS (p=0.04). There was a negative correlation between CT and age in POAG/OH eyes (r=-0.48,p<0.0001) and HS (r=-0.63,p<0.0001). In POAG/OH eyes the mean peripapillary CT in the inferior quadrants was significantly thinner than all other quadrants (p<0.001). Peripapillary CT in WNL group was significantly thinner than HS in NS, NI and TI quadrants (p=0.03,p=0.01 and p=0.05 respectively). In ONL group NS, NI, TI, T quadrants and G were significantly less than HS (p=0.05,p=0.02,p=0.02,p=0.05 and p=0.04 respectively).
Conclusions:
In POAG/OH eyes CT in NS,NI and TI quadrants was compromised when compared with HS even if the RNFL thickness was WNL, that suggests that the thinning of the choroid may precede the morphological glaucomatous damage. Moreover in ONL eyes also the T quadrant and global CT were significantly thinner than HS. It could be related with the progression of morphological damage otherwise related to a tendency of eyes with thinner CT to develop a more advanced glaucomatous damage.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
610 nerve fiber layer •
452 choroid