1. MARCO TEÓRICO
1.10 ELABORACIÓN CASERA DE BIODIESEL
photodynamic therapy in chronic central
serous chorioreti nopathy
Myrte B. Breukink, Freerk G. Venhuizen, Elon H.C. van Dijk, Anneke I. den Hollander, Jan E. E. Keunen, Carel B. Hoyng, Clara I. Sánchez & Camiel J.F. Boon
Purpose:
To analyse if characteristics of the subretinal fluid pocket in chronic central serous chorioretinopathy (CSC) on spectral-domain optical coherence tomography (SD-OCT) correlate with response to half-dose photodynamic therapy (PDT) treatment.
Methods:
Forty-eight eyes of 48 treatment-naive chronic CSC patients who underwent half-dose PDT for active chronic CSC as the first treatment were included. Clinical information including visual acuity, SD-OCT, fluorescein angiography, and indocyanine green angiography was retrospectively collected. The SRF collection seen on SD-OCT imaging was analysed by a a machine-learning algorithm, specifically designed for this purpose. SRF volume and morphology, as well as SRF reflectivity characteristics were computed and correlated to response to half-dose PDT treatment (persistent or absent SRF on SD-OCT after treatment).
Results:
A complete resolution of SRF was seen in 24 eyes (51%). In a total of 47 SD-OCT scans (98%) the SRF accumulation could be segmented as a whole and SRF volume, and pixel information analyzed. The median intensity of the SRF accumulation was lower in the group with complete absence of SRF after treatment. Also, the skewness of the histogram of the pixel intensity values was significantly higher in this group. No significant difference was seen when comparing the total SRF volume before treatment between the groups.
Conclusions:
Characteristics of SRF on SD-OCT are significantly different between chronic CSC patients who do or do not respond well to half-dose PDT treatment. Using the described semi- automated segmentation program to analyse these imaging characteristics may help to
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3.2
Introduction
Central serous chorioretinopathy (CSC) is a relatively common early-onset eye disease, characterized by an accumulation of leaked serous subretinal fluid (SRF) causing a detachment of the neuroretina. This leakage of SRF results from dysfunction of the retinal pigment epithelium (RPE) outer blood-retinal barrier, caused by choroidal congestion and thickening and hyperpermeability of the choroid.1-4 Although the etiology of CSC is largely unknown, previous studies have described the male gender, the use of corticosteroids, hypercortisolism, stress, and possibly type A personality as risk factors.1, 5, 6 Genetic predisposition also appears to play a role, as single nucleotide polymorphisms in the Complement Factor H and ARMS2 have recently been found in association with sporadic chronic CSC,7, 8 and familial CSC cases have been described.9, 10
In contrast to acute CSC, chronic CSC is usually not self-limiting, with persisting SRF on OCT. Persistent serous neuroretinal detachments can cause progressive and irreversible photoreceptor damage, resulting in a lower visual prognosis of chronic CSC as compared to acute CSC.2, 11, 12 Therefore, patients with chronic CSC who are affected by fluid leakage in the macula are often treated. A broad spectrum of treatment modalities has been used in chronic CSC, such as Argon or micropulse laser treatment of the leaking “hot spot” on fluorescein angiography (FA), intravitreal injections with anti-vascular endothelial growth factor or systemic drug treatments (e.g. spironolactone and eplerenone).2, 13-17 Currently, photodynamic therapy (PDT) is among the more frequently used treatments, that is effective in reducing SRF, with studies describing improvement of retinal anatomy and visual acuity (VA) in 70-100%.18-22 It is not precisely known why some patients respond well to PDT, and others respond poorly to therapy.
Inoue et al. found a correlation between the degree of hyperpemeability on indocyanine green angiography (ICGA) and the efficacy of PDT in CSC patient. In addition, Kim et al. demonstrated that patients that respond well to intravitreal injections with anti-vascular endothelial growth factor have a significant thicker subfoveal choroidal thickness on enhanced depth optical coherence tomography (OCT). OCT, which is a non-invasive imaging technique, gives high-resolution, cross-sectional images of the retina and choroid,23 and can provide 3-dimensional information about the SRF accumulation, that can be used to monitor the disease activity over the time. Using retinal OCT-scans, correlations that have been found to be of importance in the prediction of the visual outcome are outer nuclear layer thickness in spontaneous resolved CSC,24 and foveal thickness after resolution of SRF partially after photocoagulation.25 In addition, Landa et al. also found a correlation between the thickness of the subfoveal deposits that are sometimes present in CSC and the BCVA and the time of spontaneous CSC resolution.26
Recently, differences in the optical density ratio of the SRF accumulation in serous neuroretinal detachment were demonstrated to be a valuable tool to differentiate chronic CSC from polypodial choroidal vasculopathy, two entities that may be strikingly similar and may partly have overlapping pathophysiology.27-29 In addition, Ahlers et al. found that the optical density ratio in the SRF correlates well with the functional outcome of an anti-vascular endothelial growth factor therapy in patients with age-related macular degeneration.30 Also, in longer lasting SRF detachments, subretinal hyperreflective material on SD-OCT in chronic CSC can appear and may become increasingly prominent.31 Therefore, parameters obtained from SD-OCT in chronic CSC, which cannot be visualized with funduscopy or other imaging methods, could not only provide important information on the prognosis, but may also help in predicting the treatment outcome after half-dose PDT. The purpose of this explorative study was to identify possible biomarkers from the SRF accumulation on SD-OCT that can predict the treatment response to half-dose PDT in chronic CSC patients.
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3.2