Anales de la RANM

254 A N A L E S R A N M R E V I S T A F U N D A D A E N 1 8 7 9 Laura Morales An RANM. 2021;138(03): 246 - 255 ASSOCIATION BETWEEN VASCULAR AND STRUCTURAL PARAMETERS Multiple studies have confirmed the reductions in microvasculature in peripapillary, macular and whole image scans using OCTA in adult glaucoma and the association between severity of glaucoma and vascular damage has been reported (10,11). Changes in peripapillary and macular vascular parameters were reported to have a strongly positive correla- tion with structural parameters (GCC thickness and RNFL thickness) and a negative correlation with the severity of glaucoma, which mean the more severe the glaucoma was, the lower vascular parameters were (12). In this study, all peripapillary and macular vascular parameters in the superficial plexus were measured in patients with PCG using Angioplex TM . Recently, Garcia-Perez et al (6) described normal values for all vascular parameters using Angioplex TM , and in comparison, our results show a reduction of all vascular parameters (peripapillary and macular measurements) affecting to all quadrants, in PCG patients. And remarkably, a higher reduction of peripapillary vascular measurements (FI and pPD) was observed in vertical quadrants. These results support the idea of previous studies in children with PCG, suggesting that glaucoma damage in PCG children could differ from that produced in adults, typically with a global loss of ganglion cell complex thickness and circumpapillary RNFL thickness that was particularly marked in the superior and inferior quadrants (7,13). As in POAG, our results showed a strongly positive correlation between structural and vascular parame- ters, FI and pPD with cpRNFL thickness in PCG. Indeed, stronger correlation between peripapillary vascular measurements (FI and pPD) and cpRNFL thicknesses was found in superior and inferior quadrants. This finding is consistent with previous studies, showing that these sectors are the most vulnerable sectors to glaucomatous damage (14). And in concordance, also other criteria of severity of PCG such as average C/D ratio, vertical C/D ratio or cup volume, showed negative correlation with vascular measurements (15). The relationship between vascular and structural parameters has been reported in other studies in adult glaucoma patients. Yarmohamadi et al. (16) reported that the quadratic model provides a better fit for the relationship between vessel density, RNFL thickness and MD than the linear model. And a different behaviour was described in the relation- ship between structure and vascularization through the stages of severity of glaucoma. Song et al. (17) showed that the relationship is more linear in the early stage of glaucoma. Indeed, in advanced glaucoma (>20db) the decrease in pfVD is almost linear (18 ). This suggest that OCTA measurements may offer some advantages for detecting damage of glaucoma, first, in early glaucoma. OCTA measurements may have a potential role in monitoring visual function in eyes with onset glaucoma especially for those who cannot perform a good quality visual field. Supporting this conclusion, Akil et al. (19) reported that the pVD could differentiate early glaucoma from pre-perimetric glaucoma and normal eyes. And, peripapillary VD showed higher diagnostic capacity for detecting functional damage in early glaucoma, even more than cpRNFL thickness (20,21). cpRNFL thickness reaches its baseline level or floor effect before peripapillary vascular parameters (5,21). So, in advanced glaucoma vascularization function allow a better monitoring of the visual function than cpRNFL or GCC thickness (21). Despite this, the relationship between functional and vascular parameters remain unclear in PCG. In adults, Hollo G et al. (11) found that pVD signifi- cantly correlated with the corresponding Visual field in glaucomatous eyes, and Kwon JM et al. (20) (reported a significantly correlation between pVD and visual field loss in central field, suggesting that glaucomatous eyes with central field affectation tended to have vulnerable vasculature. New lines of investigation are needed to determine the associa- tion between visual field loss and vascular changes in PCG. The main limitation of our study was, first, the number of cases. PCG is a rare disease and in several cases, it is associated with an opacity of the ocular media, poor fixation or poor vision so those cases are excluded. Indeed, those young patients presents lack of cooperation so very early paediatric ages cannot be considered to be included. As a consequence, a selection bias towards eyes with less severe glaucoma exists. Second, due to the cross-sectional design of the study, to evaluate the impact of other interfering factors such as ocular hypotensive eye drops on vascular measurements is not possible. In this line, longitudinal studies investigating the temporal sequence of OCTA changes would be interesting to address whether those changes are cause or consequence of ONH damage in glaucoma. Third, the possible effect of AL on OCTA measurements was not considered. AL could artefact our results because the magnification effect has been demonstrated for OCT thickness measurements, however some authors reported no correlation between vascular parameters and AL (22). To conclude, these results highlight the associ- ation between the severity of glaucoma and vascular damage in congenital glaucoma. In the clinical practice, OCTA could offer the opportu- nity to measure vascular parameters and could be a useful tool to determine quantifiable changes on vascular loss specially in early and severe cases of glaucoma. 1. J Jia Y, Morrison JC, Tokayer J, et al. Quantitative OCT angiography of optic nerve head blood flow. Biomed Opt Express. 2012 3(12):3127–3137. DISCUSION BIBLIOGRAPHY