High myopia, also known as high myopia, manifests itself when a patient with this refractive error presents between 6 and 8 diopters. In myopic patients, objects are focused in front of the retina and not on it, causing distance vision to be blurred, while near vision remains in good condition. (Advanced Ophthalmology Area, 2022). When a patient presents this type of visual problem, it is necessary that they constantly go to an optometric consultation to prevent permanent vision loss. This clinical case deals with a 12-year-old male patient who tells us that he has lost visual acuity constantly in recent months, in addition to symptoms such as headache, burning, tearing, dizziness and problems focusing on nearby objects. In order to provide an adequate diagnosis, tests such as retinoscopy, Donders test, auto refractometer and complementary tests such as biomicroscopy, Worth light test, among others, were performed. After careful analysis of the various tests carried out, it is determined that the patient suffers from high myopia due to not having received preventive treatment from an early age.High myopia, also known as high myopia, manifests itself when a patient with this refractive error presents between 6 and 8 diopters. In myopic patients, objects are focused in front of the retina and not on it, causing distance vision to be blurred, while near vision remains in good condition. (Advanced Ophthalmology Area, 2022). When a patient presents this type of visual problem, it is necessary that they constantly go to an optometric consultation to prevent permanent vision loss. This clinical case deals with a 12-year-old male patient who tells us that he has lost visual acuity constantly in recent months, in addition to symptoms such as headache, burning, tearing, dizziness and problems focusing on nearby objects. In order to provide an adequate diagnosis, tests such as retinoscopy, Donders test, auto refractometer and complementary tests such as biomicroscopy, Worth light test, among others, were performed. After careful analysis of the various tests carried out, it is determined that the patient suffers from high myopia due to not having received preventive treatment from an early age.La miopía magna, también conocida como alta miopía, se manifiesta cuando un paciente con este error refractivo presenta entre 6 y 8 dioptrías. En los pacientes miopes los objetos se enfocan delante de la retina y no sobre ella, ocasionando que la visión de lejos sea borrosa, mientras que la cercana se mantiene en buen estado. (Área Oftalmológica Avanzada, 2022). Cuando un paciente presenta este tipo de problema visual es necesario que acuda constantemente a consulta optométrica para prevenir la pérdida de visión de manera permanente. El presente caso clínico trata sobre un paciente masculino de 12 años que nos indica que ha perdido agudeza visual de manera constante durante los últimos meses además de síntomas como dolor de cabeza, Ardor, lagrimeo, mareos y problemas para enfocar objetos cercanos. Con el fin de aportar con un adecuado diagnóstico se realizaron exámenes como retinoscopia, prueba de Donders, auto refractómetro y pruebas complementarias como bio microscopía, test luces de Worth entre otras. Después del análisis minucioso de los diversos exámenes realizados se determina que el paciente padece de una miopía magna por no haber recibido tratamiento preventivo desde temprana edad.