Ennio Coscarelli Eye Clinic Belo Horizonte 30140-001 Brazil;
Escola Paulista de Medicina Sao Paulo 04023-062 Brazil;
Hospital de Olhos de Brasilia Brasilia 70200-670 Brazil;
Center of Excellence in Ophthalmology Para de Minas 35660-051 Brazil;
high myopia; intrastromal corneal ring segments; photorefractive keratectomy;