Vitreous Substitutes: The Present and the Future

Vitreoretinal surgery has advanced in numerous directions during recent years. The removal of the vitreous body is one of the main characteristics of this surgical procedure. Several molecules have been tested in the past to fill the vitreous cavity and to mimic its functions. We here review the currently available vitreous substitutes, focusing on their molecular properties and functions, together with their adverse effects. Afterwards we describe the characteristics of the ideal vitreous substitute. The challenges facing every ophthalmology researcher are to reach a long-term intraocular permanence of vitreous substitute with total inertness of the molecule injected and the control of inflammatory reactions. We report new polymers with gelification characteristics and smart hydrogels representing the future of vitreoretinal surgery. Finally, we describe the current studies on vitreous regeneration and cell cultures to create new intraocular gels with optimal biocompatibility and rheological properties

Evaluation of the Effectiveness of Treatment with Dexamethasone Intravitreal Implant in Cystoid Macular Edema Secondary to Retinal Vein Occlusion

Purpose. To evaluate retinal functional improvement by means of visual acuity and retinal sensibility examination after intravitreal dexamethasone implant in patients affected by cystoid macular edema secondary to retinal vein occlusion. Methods. Twenty-six consecutive patients affected by retinal vein occlusion complicated by cystoid macular edema were enrolled in this prospective interventional study. All patients underwent a baseline complete ophthalmological evaluation as well as retinal angiography, OCT examination, and microperimetry evaluation. Each patient was treated with intravitreal injection of a long-term steroid implant (Ozurdex, Allergan). Follow-up evaluations were performed at months 1, 3, and 6 and completed by OCT and MP1 examination. Clinical data underwent statistical analysis. Results. Baseline functional evaluation showed mean visual acuity of 0,63\ub10,42 LogMAR and retinal sensitivity of 7,93\ub14,73 dB (mean\ub1standard deviation); after treatment, at day 30 we found, respectively, 0,43\ub10,38 LogMAR (p<0.05, compared to baseline) and 10,15\ub14,410 dB (p<0.05); at day 90, we found 0,44\ub10,32 (p<0.05) and 9.61\ub14,29 dB (p<0.05); at day 180, we found 0,41\ub10,31 (p<0.05) and 9,95\ub13,79 dB (p<0.05). Fixation pattern improved significantly (p<0.05), showing a stable fixation in 30% of patients at baseline, increasing to 77% of patients at day 180. Baseline morphological evaluation showed a central retinal thickness (CRT) of 398,21\ub1181,65 \u3bcm after treatment; we found a CRT of 222,64\ub195,21 \u3bcm at day 30 (p<0.05, compared to baseline), 307,50\ub1120,25 \u3bcm (p<0.05) at day 90, and 294,93\ub1135,86 \u3bcm (p<0.05) at day 180. About 15,3% patients showed already at month 3 a recurrence of macular edema. They underwent a retreatment before month 6 as for treatment guidelines. Conclusion. Our detailed analysis showed the significative increase in retinal function in the early phases of the follow-up. Retinal sensibility showed a stronger correlation than VA in macular edema reabsorption, better underlying the progressive functional recovery and increase in quality of vision and life for the patients. This trial is registered with ClinicalTrials.gov NCT03559491

Morphological and Functional Retinal Assessment in Epiretinal Membrane Surgery

Purpose: To analyze functional and morphological findings after surgery for idiopathic epiretinal macular membrane (IEMM). Materials and Methods: Twenty eyes of 20 patients affected by IEMM underwent 23-Gauge surgery. Morphological and functional examinations were assessed at baseline and at 30, 90, and 180 days after surgery. SD-OCT evaluated foveal morphology and thickness, photoreceptor inner/outer segment junction, and external limiting membrane. Functional assessment evaluated visual acuity, retinal sensitivity, and fixation patterns. Statistical analysis was performed with the Student’s t test and Pearson correlation test. Results: Mean central retinal thickness (CRT), visual acuity (VA), and retinal sensitivity (RS) at baseline were respectively 494.90 ± 38.73 µm, 0.55 ± 0.08 LogMAR, and 11.13±1.02; after surgery, at day 180, we observed a significant decrease in mean CRT to 326.90±32.68 µm, an increase in mean VA to 0.33 ± 0.05 LogMAR (p < 0.05), and in mean RS to 13.25 ± 0.73 dB (p < 0.05). A stable fixation increased from 40% of patients at baseline to 75% of patients at day 180 (p < 0.05). Discussion: IEMM surgery results in continuous improvement in visual function, not only at month one but also beyond month six, due to the progressive reduction of residual intraretinal edema and recomposition of retinal layers