ABSTRACT
Albinism is a genetic disorder that affects melanin synthesis of the human being. Although not very common, it has serious effects on the visual system, particularly reduced visual acuity. The pattern visual evoked potential is a reliable objective technique for diagnosing the latent and misrouting of this condition. The aim of this study was to use and evaluate the importance and accuracy of a single channel PVEP instead of common multichannel PVEP for detecting asymmetric responses between the latent and misrouting albinism and control group. In this cross sectional study, the pattern visual evoked potentials were measured using 60 min/arc check sizes with temporal frequency of 3 Hz in twenty four suspected albino people ages of 5 to 43 years [mean age of 19 years]. Amplitude and latencies time were measured for both the right and left, and then the results were compared with an age- and gender matched, normal group. The latency waves of N75, P100, N135 and P1N1 [N75-P100] amplitude between two eyes of the albino people showed a statistically significant difference. The asymmetric responses of PVEP between two of the albino people were significantly larger than than control group. There is a strong relation between asymmetric responses of single channel PVEP and other clinical signs of albinism, which make this method as a useful objective technique for diagnosing the latent albinism
ABSTRACT
Color blindness is a common disorder. The congenital type of tcolor blindness is sex-linked and the genes are located on the X chromosome. The prevalence of color blindness among males and females are 5-8% and 0.5%, respectively. Color blindness may affect daily activities and could be considered as a disability. Therefore, the aim of this study was to investigate the prevalence of color blindness and its effect on contrast sensitivity and depth perception among school children in Mashhad. Four thousand four hundred school children [2408 males and 1992 females] were selected randomly and tested by Ishihara for color blindness detection. At the second step, students with color blindness were examined at optometry clinic by the Ishihara test again. Two hundred students were also selected randomly to allocate into a control group. Cambridge and Titmouse tests were taken on the case and control groups. Among 4400 schoolchildren, 3% suffered from color blindness [5.1% in boys and 0.4% in girls]. Ishihara test showed 2.2% deuteranopia, 0.8% protanopia and 0.6% suspect. The results indicate that the congenital color blindness has no significant effect on contrast sensitivity and depth perception. The present report provides valuable information regarding color vision defectiveness among schoolchildren. Effective detection of this anomaly is expected to prevent from substantial effects on their education and future job. It is strongly recommended to perform color vision test at the beginning of a child's education
ABSTRACT
To determine the prevalence rates of refractive errors in Mashhad, Iran. In this population-based study, random cluster sampling was performed on the urban population of Mashhad and of 4453 selected individuals, 70.4% participated in the study. Refractive errors were assessed using cycloplegic refraction in participants who were 15 years of age. The prevalence of myopia and hyperopia in individuals 15 years of age was 22.36% [95% CI: 24.66 to 20.06] and 34.21% [95 CI: 36.85 to 31.57], respectively. The prevalence of astigmatism and anisometropia were 25.64% and 5.84, respectively. Astigmatism and anisometropia were significantly more [p=0.005] and less [p=0.048] prevalent in females, respectively. Anisometropia, astigmatism and hyperopia were found to be increased with age. This study highlighted the valuable information on refractive errors in Mashhad. Hyperopia was the most common refractive error. In addition to subjects who were between 5 to 15 years of age, refractive errors were also prevalent among older people; therefore, more attention should be paid to the correction of refractive errors in these groups