Eye plaques containing gamma-emitting radioactive sources are widely used in brachytherapy for the treatment of ocular melanoma. In this therapeutic approach, accurate dose distribution plays a crucial role in improving treatment effectiveness while minimizing the radiation dose delivered to the surrounding healthy tissues. In the present study, the three-dimensional dose distribution of the COMS eye plaque for the radionuclides Iodine-125 and Palladium-103 was investigated using Monte Carlo simulation, and the obtained results were compared with previously published data. All calculations were performed based on the TG-43 formalism recommended by the American Association of Physicists in Medicine. Simulations were carried out using the MCNPX and Geant4 codes while considering a heterogeneous human eye phantom. The results showed that the maximum absorbed dose within the tumor volume was approximately 91.2 Gy for Palladium-103 and 91.8 Gy for Iodine-125. Comparison of the results with previous TG-43-based studies demonstrated good agreement, with relative differences below 5% and statistical uncertainties less than 2%. Therefore, both radionuclides are capable of providing an appropriate dose distribution within the tumor volume, and the observed differences remain within the range of computational uncertainty. Consequently, the selection of an appropriate radionuclide should be based on clinical considerations, including tumor size, tumor location, and treatment planning objectives.