This study describes topographical thickness changes in the choroidal layer using OCT for an eye with CSC undergoing PDT with verteporfin. Thickness changes are described with regard to FA findings and treatment location. The authors are not aware that this has been previously described. Prior reports on choroidal thickness in CSC have only described subfoveal thickness findings with no reference to location of FA leakage or PDT laser spot. Understanding the topographic changes of the choroid following PDT for CSC may be important, both for advancing our understanding of CSC and also improving our ability to restore vision.
Our findings of decreased choroidal thickness following PDT concur with prior reports [4
]. In 2010, Maruko et al. found subfoveal choroidal thickness decreased from 389 ± 106 micron at baseline to 330 ± 103 microns at one month [4
]. Our patient's mean (SD) subfoveal choroidal thickness decreased from 576 microns (52) to 370 microns (81) (P
< 0.01 Mann-Whitney test). Interestingly, our report suggests that the reduction in choroidal thickness is diffuse and extends further than just under the fovea as previously reported. We measured a statistically significant reduction in choroidal thickness from up to 3
mm temporal of the fovea to 3
mm nasal of the fovea following a 1.5
mm juxtafoveal PDT laser spot applied to an area of juxtafoveal leakage as seen on FA (). It remains unclear whether a similar diffuse effect or as significant of an effect would occur if the PDT laser spot was not applied over the leakage as seen on FA. Distinguishing these effects may be important for some cases, especially when FA leakage is subfoveal and the treating physician wishes to avoid exposing the fovea to PDT laser.
It is interesting to observe that the single thickest measurement of the choroid (648 microns) before treatment was in the area of leakage as seen on FA. Following treatment, this single location decreased to 504 microns but was still the point of greatest choroidal thickness (). Unfortunately, the authors cannot comment on how abnormal either of these measurements is since complete normative data on choroidal thickness correcting for age, race, refractive area, and fundus location is not available [6
Limitations of our study include the single sample size, the retrospective nature, short duration of follow-up, and limited sampling of choroid. Additionally, indocyanine green angiography which can provide information on choroidal hyperpermeability was not obtained on this patient. Nonetheless, the authors feel publishing this case is valuable since its unique combination of small focal juxtafoveal leakage on FA and small PDT laser spot allows us to make some interesting observations. Certainly, further studies are needed to corroborate our findings.