Retinal and choroidal thickness changes after photodynamic therapy: a comparison study between reduced-duration and standard-duration photodynamic therapy

Session Details

Session Title: Free Paper Session 9: AMD III

Session Date/Time: Friday 08/09/2017 | 08:00-09:30

Paper Time: 08:00

Venue: Room 117

First Author: : W.Ngo SINGAPORE

Co Author(s): :    C. Tan   T. Lim                          

Abstract Details

Purpose:

The EVEREST study reported superior outcomes in polyp closure rates using verteporfin photodynamic therapy (PDT) (in combination with intravitreal ranibizumab or monotherapy) over intravitreal ranibizumab alone. However, the optimal PDT protocol remains controversial. Some authors suggest that reduced-fluence or variable-duration PDT may reduce complications including subretinal, vitreous and suprachoroidal haemhorrage, as well as tears and rips of the retinal pigment epithelium. PDT is also believed to cause choroidal ischaemia which may lead to chorio-retinal atrophy. We aimed to evaluate the efficacy of reduced-duration PDT and compare it with standard-duration PDT in the treatment of polypoidal choroidal vasculopathy (PCV).

Setting:

Tertiary ophthalmology referral centre in central Singapore

Methods:

Retrospective review of all consecutive PDT-naïve patients diagnosed with PCV and treated with PDT from January 2011 to December 2013. Patients treated with reduced (light dose, 50 J/cm2; dose rate, 600 mW/cm2; wavelength, 689 nm; time, 42 seconds) and standard-duration (light dose, 50 J/cm2; dose rate, 600 mW/cm2; wavelength, 689 nm; time, 83 seconds) PDT were recruited for this study. Central foveal thickness (CFT) in the central 1-mm ETDRS subfield and central choroidal thickness (CCT: manual sub-foveal point choroidal thickness using caliper measurement) were generated using spectral domain optical coherence tomography (SD-OCT) for analysis. The changes in CFT and CCT after PDT were used to evaluate the efficacy of treatment. These were compared between standard and reduced-duration PDT.

Results:

Thirty-six eyes of 36 patients (23 males and 13 females) with a mean age of 70.2 years (range 50 – 89 years old, S.D. ± 8.7) were included the analysis. They were followed-up for a mean duration of 22.4 months (range 6 – 48 months). Of these, 28 (77.8%) were treated with standard-duration PDT while 8 (22.2%) had reduced-duration PDT. There were no statistically significant differences when comparing mean decrease in CFT between eyes which underwent standard-duration PDT compared to eyes which underwent reduced-duration PDT respectively (3 months: -146.4µm vs. -120.3µm, p=0.62; 6 months: -124.2µm vs. -119.5µm, p=0.94; 12 months: -129.3µm vs. -101.5µm, p=0.62). Similarly, there were no statistically significant differences when comparing mean decrease in CCT between the two groups (3 months: -22.3µm vs. -10.8µm, p=0.46; 6 months: -29.9µm vs. -15.9µm, p=0.43; 12 months: -18.5 vs. -5.6, p=0.56). Recurrence rates (standard-duration vs. reduced-duration: 64.3% vs. 50%, p=0.47) and number of anti-vascular endothelial growth factor (VEGF) injections administered (standard-duration vs. reduced duration: 6.0 vs. 4.8, p=0.45) during the course of the follow-up were similar between the two groups. There were no significant adverse events reported in both groups.

Conclusions:

From these results, reduced-duration PDT has similar efficacy when compared to standard-duration PDT in reducing retinal oedema, while having negligible effect on the thickness of the choroid at the end of 1 year. Further studies are needed to further ascertain if reduced-duration PDT results in less chorio-retinal atrophy compared to standard-duration PDT in the longer term.

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