Elements and Organic Substances Analyzed with a Time–of-flight Secondary Ion Mass Spectrometer in the Internal Limiting Membrane of Macular Hole

Abstract

Abstract: : Purpose: To examine the quantities of each element and each organic substance in the internal limiting membrane (ILM) of macular hole with a Time-Of-Flight Secondary Ion Mass spectrometer (TOF-SIMS). Methods: The ILMs were excised at viteous surgery from 10 patients with macular hole and 10 patients with macular edema during vitreous surgery. The specimens were washed in distilled water because intraocular irrigating solution contains elements such as Na, K, Ca and Mg, placed on silicon wafer plates, and stocked in vials stored in liquid nitrogen. For TOF-SIMS (TRIFT, Physical Electronics, USA) examination the specimens were dried, and elements, vitamins A and E, and fatty acids were measured with a TOF-SIMS. The number of specimens examined was 10 in both diseases, and during the analysis, the large specimens were measured 2 or 3 times at different sites. A total of 15 sites in all 10 macular hole specimens and that of 14 sites in all 10 macular edema specimens were measured. Then the average ratio of each substance count / total substance count was calculated. Results: The average ratio of vitamin A ion count to the total count of spattered ions was significantly larger in the ILMs of macular hole than in those of macular edema. The average ratio of maleic acid ion count to the total count of spattered ions was also significantly larger in the ILMs of macular hole than in those of macular edema. Conclusions: TOF-SIMS data suggest that proliferative tissues including the ILM in macular hole come from the photoreceptor cells and pigment epithelium containing vitamin A and maleic acids.

Keywords: retina • macular holes • macula/fovea