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Abstract

PURPOSE: The volume of the vitreous chamber varies with the size of the eye. The space created in the vitreous cavity by a vitrectomy is called the vitrectomized space. The volume of the vitrectomized space is strongly correlated with the axial length of the eye. This study aims to present guidelines for estimating the using participants stratified by axial length, sex, and history of cataract surgery.
METHODS: This retrospective, observational, cross-sectional study included 144 randomly selected participants who underwent vitrectomies between 2013 and 2023. Before surgery, the axial lengths of participants' eyes were measured using optical biometrics. The axial lengths of the eyes in our sample were between 20-32 mm. In all cases, a complete vitrectomy was performed, followed by complete fluid-air exchange and injection of a balanced saline solution. The volume infused was recorded.
RESULTS: The median (interquartile range; range) volume of the vitrectomized space was 6.1 (3.8; 3.1-11.3) mL in men and 6.1 (3.3; 3.2-11.2) mL in women (p=0.811). The median volume of the vitrectomized space was 5.9 (3.6; 3.1-11.2) mL in patients with phakic lenses and 6.25 (3.6; 3.3-11.3) mL in those with pseudophakic lenses (p=0.533). A positive correlation was found between the axial length and the volume of the vitrectomized space in this sample (r=0.968; p<0.001). In a cubic polynomial regression, the coefficient of determination was 0.948. Similar results were observed in both sexes and in both phakic and pseudophakic patients. The estimated cubic polynomial regression equation for this sample was VVS = 0.000589052857847605 × AL³ - 0.025114926401582700 × AL² + 0.685961117595624000 × AL - 5.088226672620790000.
CONCLUSION: We developed this axial length estimation of the volume of vitrectomized space as a guideline for the determination of vitrectomized space volume using axial length.

Keywords: Cataract extraction; Retinal perforations/surgery; Epiretinal membrane/surgery; Vitreous body; Axial length, eye; Vitrectomy; Biometry/methods; Diagnostic techniques, ophthalmological; Guidelines as topic.

Abstract

PURPOSE: To compare the short-term (3-month) outcomes of intravitreal aflibercept injections versus intravitreal aflibercept combined with dexamethasone sodium phosphate in treating diabetic macular edema.
METHODS: In this Phase-2 clinical trial, 16 eyes of 16 participants with diabetic macular edema were randomly assigned to one of 2 groups. Participants in the aflibercept monotherapy group received 2 mg of intravitreal aflibercept (0.05 mL), while those in the combination therapy group received 2 mg of intravitreal aflibercept (0.05 mL) plus 0.04 mg dexamethasone sodium phosphate (0.01 mL). Identical injections were repeated after 30 and 60 days. The primary outcome was the change in central macular thickness, as measured by optical coherence tomography, from baseline to 1 month after the last injection. Secondary outcomes included changes in best-corrected visual acuity and intraocular pressure over the same period.
RESULTS: The mean baseline central macular thickness was 444 ± 86 μm in the combination therapy group and 394 ± 96 μm in the aflibercept monotherapy group (p=0.293). By day 90, the mean reduction in central macular thickness was significantly greater in the combination therapy group (176 ± 129 μm) compared to the aflibercept monotherapy group (54 ± 49 μm; p=0.034). Best-corrected visual acuity also improved significantly more in the combination therapy group, with a median gain of 0.31 ± 0.16 LogMAR, whereas the aflibercept monotherapy group experienced a minimal change (−0.06 ± 0.13 LogMAR; p=0.020). Intraocular pressure remained stable in both groups, with no significant difference (p=0.855). None of the participants developed elevated intraocular pressure (>21 mmHg) or required ocular hypotensive medications. No significant ocular or systemic adverse events were reported.
CONCLUSION: The addition of dexamethasone sodium phosphate to the standard intravitreal aflibercept regimen for diabetic macular edema can improve short-term structural and functional outcomes.

Trial registration: Brazilian Clinical Trials Registry (RBR-7468j4q)

Keywords: Diabetic macular edema; Aflibercept; Dexamethasone sodium phosphate; Intravitreal injection; Visual acuity; Central macular thickness; Intraocular pressure