Research conducted at the University Hospital in Bern Switzerland suggests that scleral changes may occur in patients following repeated intravitreal injections of anti-VEGF agents in the same quadrant. The research, carried out among 35 patients under-going anti-VEGF treatment, indicated a potential association between the total number of intravitreal injections and changes in the scleral thickness in the inferotemporal quadrant (r. 0.3, P. 0.052). The authors of the study recommend that alternating the injection site should be considered in patients requiring multiple intravitreal injections.
Anti-VEGF medications such as ranibizumab (Lucentis), bevacizumab (Avastin) and aflibercept (Eylea) have been highly successful in tackling a number of retinal pathologies however, the requirement for regular injections over a number of years can present new challenges which have the potential to cause co-morbidities over time. While the standard needle for intravitreal injection is small (30-gauge) and the injection is usually performed in the same infero- or superotemporal quadrant, approximately 3 mm from the limbus, the continuing number of injections has the potential to alter the mechanical structure of the retina at the injection site. To determine the impact of such injections a retrospective controlled study was designed to record changes in the scleral architecture of patients that had received 30 or more intravitreal ranibizumab injections in the inferior temporal quadrant. The study used enhanced depth imaging anterior segment spectral domain optical coherence tomography (AS SD-OCT) to detect changes in the sclera in the study population.
The mean age of the 35 patients studied was 76 years of age and ranged from 61–87 years, with an approximate male-to-female ratio of 3:4. Twenty-seven (27) of the patients had received intravitreal anti-VEGF treatment in one eye for exudative AMD, seven were treated for cystoid macular edema (CME) due to central retinal vein occlusion (CRVO), and one patient was treated for diabetic macular edema (DME). Of the patients studied, each had at least 30 injections in one eye in the inferotemporal quadrant and 10 or less injections in the fellow eye. The research findings – the only report known to evaluate the effects of repeat injections on the sclera – showed that in the study eyes with more than 30 injections, the average scleral thickness in the inferotemporal quadrant was 568.4 μm (SD6 66 μm) and 590.6 μm (SD6 75 μm) in the fellow eyes with 10 or less injections (P. 0.003). The mean average scleral thickness in the other three quadrants (inferonasal, superotemporal, and superonasal) was 536.6 μm in the study eyes (SD 6 100 μm) and 545.2 μm (SD 6 109 μm) in the fellow eyes (P. 0.22). As such, the authors concluded that there was a borderline association which may be relevant to clinicians caring for patients requiring anti-VEFG treatment.