ABSTRACT
OBJETIVOS: Desenvolver um sistema digital, com capacidade de induzir acomodação, para medida do diâmetro e formato da pupila para dez diferentes níveis de iluminação (LUX), variando do nível mesópico ao fotópico. MÉTODOS: Um sistema óptico para conjugar imagens da pupila iluminada por LED infravermelho e branco foi projetado e montado usando um capacete típico de oftalmoscópio e uma máscara típica de mergulhador como suporte e uma câmera CCD de alta resolução e sensibilidade. Algoritmos usando princípios de processamento de imagens foram implementados para leitura do arquivo de vídeo e a detecção automática do centro geométrico e diâmetro da pupila para cada quadro. RESULTADOS: Apresentamos dados preliminares deste sistema para um paciente voluntário. Os dados sobre posição horizontal (x), vertical (y) do centro geométrico e do diâmetro da pupila foram exportados para arquivos texto que podem ser impressos usando um programa convencional de planilha (Excel). O processo de acomodação é garantido por uma mira virtual (LED branco) localizada a 6 metros do olho do paciente e o nível de iluminação é precisamente controlado por uma placa eletrônica que alimenta o LED central que tem sua potência controlada pelo "software". CONCLUSÕES: Com o instrumento desenvolvido dados precisos da posição e tamanhos da pupila podem então ser obtidos estereoscopicamente (para ambas as pupilas e ao mesmo tempo) para qualquer paciente. Acreditamos que tal instrumento possa ser útil em algumas práticas oftálmicas onde as características geométricas da pupila sejam importantes.
PURPOSE: We developed a digital system with accommodation capacities for measurement of the diameter and shape of the in vivo pupil for 10 different levels of illumination intensity, varying from mesopic to photopic. METHODS: An optical system for conjugating images from an infrared and white light illuminated pupil was designed and mounted using an ophthalmoscope helmet and a typical diving mask as support for a high-resolution and sensitivity CCD. Using an IBM compatible computer sequences of video in AVI format were digitized for several seconds at a mean rate of 30 Hz. Algorithms using principles of image processing were implemented for detection of the pupil edges. RESULTS: We present preliminary results of this system for a voluntary patient. Data for the horizontal (x) and vertical (y) central position and for the diameter of the pupil were then exported to files that could be read by typical spread sheet programs (Excel). CONCLUSIONS: In this manner, precise data can be obtained stereoscopically (for both pupils at the same time) for any patient, given that the accommodation process is guaranteed by using a white LED virtual mire located 6 meters from the patient's eye. An electronic board precisely controls the level of illumination. We believe here developed instrument may be useful in certain ophthalmic practices where precise pupil geometric data are needed.
Subject(s)
Adult , Humans , Male , Adaptation, Ocular/physiology , Image Processing, Computer-Assisted/instrumentation , Photic Stimulation/methods , Pupil/physiology , Algorithms , Equipment Design , Fixation, Ocular/physiology , Iris/anatomy & histology , Lighting/methods , Mesopic Vision/physiology , Ophthalmoscopes , Optical Devices , SoftwareABSTRACT
PURPOSE: To evaluate of the mesopic vision and glare in normal subjects and post-LASIK patients by using mesoptometer. METHODS: One hundred sixty eyes of eighty subjects with normal vision and no ocular disease were divided into four groups. Each twenty subjects were followed up for more than 3 months and the authors tested the mesopic vision and glare disability with Mesotest II. The authors also measured eighty eyes of forty patients by same means depending on pupil size and high order root mean square (RMS) values before LASIK surgery in 1st and 3rd months postoperatively and compared with data of normal subjects. RESULTS: The mesopic vision and glare disability at 1: 5 contrast level were extremly reduced in the group over 60 age old but there was no statistical significance. In post-LASIK patients, mesopic vision and glare disability were significantly reduced in 1st month after surgery. However the values returned nearly to preoperative figures in 3rd month. Patients with large pupil and high order RMS values reduced more in mesopic vision and glare disability but there was not statistical significance. CONCLUSIONS: The mesopic vision and glare disability were reduced in older age group and they were reduced in the patients with large pupils and high order RMS values in the early postoperative period after LASIK.