Anterior Ocular Wall Thickness Mapping: Anatomical Adequacy of Fixed-Depth Suprachoroidal Injection

To map anterior ocular wall thickness across quadrants and eccentricities in a heterogeneous adult population and to evaluate the anatomical adequacy of fixed-depth suprachoroidal injection strategies currently used in clinical practice.

A cross-sectional observational study.

A total of 110 eyes from 110 participants (18-75 years; +3.00 to -11.00D) were included. Swept-source anterior segment optical coherence tomography was used to measure central corneal thickness, anterior scleral thickness (AST), conjunctival-tenon capsule thickness, anterior choroidal thickness, anterior conjunctival-scleral thickness, and anterior conjunctival-scleral-choroidal thickness. Measurements were obtained in four quadrants at 0 to 5 mm posterior to the scleral spur at 1-mm intervals. Associations between thickness parameters and demographic, refractive, and anatomical factors were analyzed using mixed-effects models. The frequency of measurements below commonly used suprachoroidal injection depths (900 and 1100 µm) was determined.

Anterior ocular wall thickness exhibited marked spatial variability across quadrants (P < .001), decreasing sharply 1 to 2 mm posterior to the scleral spur before stabilizing. At 4 mm posterior to the scleral spur, all eyes exhibited AST values below 900 µm, and anterior conjunctival-scleral-choroidal thickness was below 900 µm in 63.64% of eyes. AST was independently associated with age and central corneal thickness but showed no association with spherical equivalent or axial length.

Anterior ocular wall thickness varies substantially by quadrant and eccentricity. While fixed-depth needles are clinically safe, understanding this anatomical variation may clarify injection mechanics and support anatomically guided approaches to optimize suprachoroidal drug delivery.