Selective Retina Therapy (SRT) in Patients With Idiopathic Central Serous Retinopathy

Selective Retina Therapy (SRT) in Patients With Idiopathic Central Serous Chorioretinopathy: A Prospective Randomized Controlled Trial

Medical Laser Center Lübeck, Lübeck, Germany, Institute for Medical Informaties and Statistics Kiel, Germany

The purpose of this study is to evaluate the efficacy of Selective Retina Therapy (SRT) for treating acute idiopathic central serous chorioretinopathy (ICSC). Patients with acute symptomatic ICSC of at least 3 months duration were recruited. The patients were randomized by equal terms to SRT- (Treatment) and control group. After 3 months follow up patients of control group with persistence of disease activity were allocated to crossover group and received either SRT. Crossover group was followed up for further 3 months. The primary outcome measure of the study are the serial changes in Early Treatment of Diabetic Retinopathy Study (ETDRS) letterscore and edema in optical coherence tomography (OCT) at 3 months. Secondary outcome measures included the proportion of eyes with complete absorption of subretinal fluid, leakage in fluorescein angiography and the systemic and ocular complications during the study at 3 months.

Idiopathic central serous chorioretinopathy (ICSC) is characterized by a serous detachment of the neurosensory retina in the macular region secondary to a focal or retinal pigment epithelial defect. Patients with ICSC, oftentimes young male adults, experience visual disturbances including micropsia, metamorphopsia, central scotoma, reduced visual acuity and loss of contrast sensitivity. Most cases of ICSC are presumed to be self-limiting and usually resolve spontaneously within 3 to 4 months.Nevertheless the duration of the disease is strongly related to the vision prognosis and reattachment within 4 months of onset is considered as a relevant therapeutic target because prolonged detachment is associated with photoreceptor atrophy. The therapeutic effect of focal cw laser photocoagulation has not been fully established. One obvious theory postulates that the beneficial effect of photocoagulation is associated with the establishment of a new barrier of RPE cells which subsequently reintegrate the RPE pump function and the integrity of the RPE as a barrier. Based on this theory, the destruction of tissues surrounding the RPE, in particular Bruch's membrane, the choroid and the photoreceptors, would be an unwanted side effect. On the basis of this consideration Selective Retina Therapy (SRT), which is a innovative laser technology that selectively damages the RPE and spares the neurosensory retina, suggests itself as an ideal treatment for ICSC with focal leakage, especially if the RPE leak is located close to the fovea. It has been proved as safe, and microperimetry has shown that SRT does not cause microscotoma. SRT has already been adopted in the treatment of diverse macular diseases inter alia in patients with ICSC with promising performance.

Treatment was performed with the SRT-Laser system (Medical Laser Center Lübeck, Germany), which consists of a Q-switched frequency doubled Nd:YLF laser (527nm), operating with a pulse repetition rate of 100 Hz. The pulse duration (full width at half maximum) was 1.7 µs. The laser energy was transmitted via fiber to a Lumenis slitlamp allowing the application of a fixed spot size diameter of 200 µm in air. A Mainster central field contact lens with a magnification of 1.05 was used for all irradiations. Per foot switch, 30 pulses are emitted, the pulse energy was chosen by the physician up to a maximum of 370 µJ. According to the treatment protocol, prior to each treatment 5 test shots with increasing energy were applied adjacent to the vessel arcades, in each patient in order to determine the appropriate pulse energy for treatment by recording the OA-value.

After 3 months follow up patients of control group with persistence of disease activity were allocated to crossover group and received either SRT. Crossover group was followed up for further 3 months.

The maximum distance between the RPE and the outer neurosensory retina in the area of Subretinal fluid accumulation

Inclusion Criteria: Anamnestic reduction of visual acuity Atients with best-corrected visual acuity (BCVA) of 20/200 or better Presence of subretinal fluid (SRF) on optical coherence tomography (OCT) Presence of active angiographic (multi)focal leakage in fluorescein angiography (FA) caused by ICSC but not choroidal neovascularisation (CNV) or other diseases Absence of other retinal or ocular diseases (e. g. glaucoma, vessel diseases, vein occlusion or proliferative retinopathy) Absence of cataract or media opacities of a degree which precludes taking retinal photographs and FA's Absence of angle closure glaucoma which precludes pharmacological dilatation of the pupil. Exclusion Criteria: Patients who received any previous treatment, including PDT or focal cw laser photocoagulation for ICSC, or who had evidence of CNV, PCV, or other maculopathy on clinical examination or FA were excluded. Patients receiving exogenous corticosteroid treatment, with systemic diseases such as Cushing's disease or renal diseases, and pregnant patients also were excluded. Informed consent was obtained from all subjects, and the study protocol was approved by the ethics committee of the University of Kiel.

Elsner H, Porksen E, Klatt C, Bunse A, Theisen-Kunde D, Brinkmann R, Birngruber R, Laqua H, Roider J. Selective retina therapy in patients with central serous chorioretinopathy. Graefes Arch Clin Exp Ophthalmol. 2006 Dec;244(12):1638-45. doi: 10.1007/s00417-006-0368-5.

Klatt C, Elsner H, Porksen E, Brinkmann R, Bunse A, Birngruber R, Roider J. [Selective retina therapy in central serous chorioretinopathy with detachment of the pigmentary epithelium]. Ophthalmologe. 2006 Oct;103(10):850-5. doi: 10.1007/s00347-006-1415-7. German.

Klatt C, Saeger M, Oppermann T, Porksen E, Treumer F, Hillenkamp J, Fritzer E, Brinkmann R, Birngruber R, Roider J. Selective retina therapy for acute central serous chorioretinopathy. Br J Ophthalmol. 2011 Jan;95(1):83-8. doi: 10.1136/bjo.2009.178327. Epub 2010 Jun 15.