Author: Mariacristina Parravano (Italy)
Co-authors: Serena Fragiotta, Eliana Costanzo, Monica Varano, Enrico Borrelli, Riccardo Sacconi, Giuseppe Querques
Purpose
To analyze anatomical response in diabetic macular edema (DME) characterized by suspended scattering particles in motion (SSPiM) after intravitreal dexamethasone implant. Further, to characterize the clinical response of other cystic subtypes to treatment
Setting/Venue
Tertiary referral center at Department of Ophthalmology, IRCCS-Fondazione Bietti, Rome.
Methods
A retrospective review of type 2 diabetic patients suffering from DME treated with a single intravitreal injection of dexamethasone (DEX) implant 0.7 mg (Ozurdex; Allergan, Inc, Irvine, CA) was performed for those with complete medical records and multimodal imaging at 2- and 4- months after injection. Swept-source optical coherence tomography angiography (OCTA, PLEX Elite 9000, Carl Zeiss Meditec, Inc, Dublin, CA) with a 3 mm x 3 mm volume cube were performed in all the cases. After checking the segmentation, OCTA slabs from superficial vascular complex (SVC) and deep capillary plexus (DCP) were analyzed using OCTA b scans as reference. Cystic phenotypes were classified in: cysts with SSPiM with variably hyperreflective decorrelation signal on OCTA, hyperreflective corpuscular cysts without a detectable decorrelation signal on OCTA, and optical empty or pure hyporeflective cysts. The area occupied by the different cystic subtypes and SSPiM was quantified in the entire 3 mm OCTA slabs for SVC and DCP using Fiji software (version 2.1.0/1.53.c, available at http://fiji.sc). The definition for ‘improvement’ was set for a central macular thickness (CMT) reduction of at least 10% and ‘no improvement’ for a CMT +/-<10% since baseline visit.
Results
A total of 18 eyes of 18 patients (69.1 ± 8.5 years) were consecutively enrolled, of whom 6/18 eyes (33.3%) were treatment naïve. In the SVC, the area of hyporeflective cyst occupied 40.7% (0.13 mm2 ± 0.18) of the total cystic area, followed by corpuscular cysts (36.9%, 0.15 mm2 ± 0.18) and SSPiM (22.4%, 0.07 mm2 ± 0.14). In the DVC, the area occupied by the corpuscular component was 38.5% (0.20 mm2 ± 0.4) of the total, followed by hyporeflective (34.1%, 0.26 mm2 ± 0.3) and SSPiM (27.3%, 0.18 mm2 ± 0.27). Eyes with SSPiM presented an older age (p=0.03) and a history of previous intravitreal treatment (75% of cases, r=0.53, p=0.02). Qualitative and quantitative evaluation of the different cystic area demonstrated substantial reabsorption of the hyporeflective component in the SVC (-95.4% at 2- and -84.4% at 4-months, P=0.001) and DVC (-84.4% at 2 months), with a less critical decrease of the corpuscular component in the SVC (-41.9% 2 months, p=0.001 and -1.8% at 4 months, P=0.73), and not significant in the DVC. SSPiM did not significantly change in both the SVC and DVC neither at 2- and 4-months (P>0.05, for all).
Conlusions
The present work analyzed longitudinal anatomical changes in various cystic phenotypes in DME after dexamethasone implant. On morphometric analysis, SSPiM tended to accumulate with a pyramidal stratification from the outer to the inner retinal layers. The association of SSPiM with older age may indicate an easier blood-retinal barrier (BRB) rupture for a physiologic aging process. After a single dexamethasone implant, the clearance of different cystic phenotypes proceeds with resorption of hyporeflective fluid component, followed by a corpuscular component without decorrelation signal on OCTA, starting from the innermost retinal layers. SSPiM persisted despite treatment, representing a factor of a severe BRB breakdown that may require repeated treatment to reach a satisfactory anatomical response.
Financial Disclosure
Advisory board partecipation: Allergan, Bayer, Novartis, Sifi
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