A physical and morphometric analysis of intraocular foreign bodies and their clinical correlation

PURPOSE: Penetrating injuries with intraocular foreign bodies (IOFB) remain a major cause of ocular morbidity worldwide. This study aimed to determine the physical and morphometric characteristics of IOFBs and investigate the correlation to the injury pattern. METHODS: Intraocular foreign bodies retrieved between January 2018 and December 2023 were examined for dimension, weight, shape, and magneticity. In order to classify the shape of the IOFB, various indices were calculated. Clinical records, imaging data, and operative reports were retrospectively analyzed to determine the course of the incident, point of entry, and final intraocular position. RESULTS: Fifty-four IOFBs were removed during the study period. Of these, 39 met the inclusion criteria. The majority of IOFBs were metal and magnetic (n = 32; 82%). Three IOFBs consisted of glass, two were made of wood and 2 eyelashes were extracted. The mean length, width and thickness were 4.95 mm, 1.70 mm and 0.86 mm, respectively. The average weight was 20.49 mg (0.2-112 mg; SD: 31 mg). The final intraocular location of foreign bodies was highly variable. With the exception of one case, all wire-shaped foreign bodies entered through the limbal cornea and penetrated into the suprachoroidal space. The variables of roundness, moment of inertia, length, circumference, and secondary moment of the major axis were identified as significant predictors of penetration depth. CONCLUSION: In order to break through the corneal or scleral rigidity, foreign bodies must have certain physical properties and sufficient kinetic energy upon impact. Specific foreign body shapes can also lead to specific injury patterns. These precise measurement data may be important for future studies in trauma prevention, materials research, or the development of ophthalmic instruments.