Abstract
Purpose: :
To visualize and quantify changes in the outer retinal cell layers after surgery for idiopathic macular hole.
Methods: :
A methodological study investigating the intraretinal thickness from the outer border of the RPE to the photoreceptor inner– and outer segment junction (IS/OS–RPE) after surgery for full–thickness macular hole stage 3. Patients underwent vitrectomi and gas tamponade followed by facedown (10 hours for 5 days). Information about the use of ICG–assisted ILM–peeling, or not, are not available, since the patients are included in a randomized clinical trial evaluating the effect of ILM–peeling and ICG–staining in macular hole surgery.
Using enhanced OCT3 imaging which is based on computerised horizontal and vertical alignment of sets of B–scans to increase the signal to noise ratio, we are able to visualize the retinal cell layers. We have developed an automated measuring software capable of differentiating the intraretinal layers and calculating the thickness of the IS/OS–RPE layer.
Results: :
Two cases are presented, both of which were operated for full–thickness macular hole stage 3. Patients presented with loss of central vision and pincushion distortion. The duration of symptoms were less than 12 months in both patients and the preoperative visual acuity was 49 ETDRS letters (case 1) and 47 ETDRS letters (case 2). 6 months after surgery the macular hole was closed in both cases, but the reflectivity and thickness of the IS/OS–RPE layer were different. In case 1 the visual outcome was 85 ETDRS letters and the IS/OS–RPE thickness at the foveolar centre was 70 µm. In case 2 the visual outcome was 59 ETDRS letters and the foveolar IS/OS–RPE thickness was 20 µm.
Conclusions: :
Standard OCT3 imaging only can evaluate the morphological features of the macula and does not provide information of the functional status of the RPE and photoreceptors. Using enhanced OCT imaging and an automated measuring software it is possible to differentiate and quantify small changes in the intraretinal layers. We presented two cases with different quantitative and qualitative appearances of the IS/OS–RPE layer after macular hole surgery. Using enhanced OCT imaging we found thinning of the IS/OS–RPE layer and loss of photoreceptor outer segments in the patient with worse visual outcome, possibly due to photoreceptor atrophy. Using this method in a large randomized setup could help clarify the topic of a possible toxic effect of ICG–assisted ILM peeling in macular hole surgery.
Keywords: macular holes • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials