The glacier geometry of the Antisana volcano is influenced by air temperature fluctuations, an increase in global anthropogenic emissions, tropical climate, the El Niño-Southern Oscillation (ENSO), and inconclusive sources such as volcanism and Amazon tropical forest fires. To analyze glacier cover changes over longer periods, Landsat collection data and the Normalized Difference Snow Index (NDSI) are used. As a result, an area of 2.621 km2 that represented 22.67% of the glacier area in 1987 has been lost until 2022 without regard to seasonal patterns. Besides, the greatest and lowest areas were 24.278 km2 and 8.940 km2 in 1996 and 2022, respectively. Changes in glacier surface area are produced at elevations below 5300 m and above 4500 m. Finally, the NDSI value of 0.4 works as a threshold for snow cover identification.