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Background The aim was to investigate the effect on the measured amplitude of accommodation and repeatability of using the minus lens technique with the target at distance or near. Methods Forty-three students (average age: 21.17 ± 1.50 years, 35 female) had their amplitude of accommodation measured with minus lenses on top of their distance correction in a trial frame with the target at far (6.0 m) or near (0.4 m). The minus lens power was gradually added with steps of 0.25 D. Measurements were taken on two occasions at each distance, which were separated by a time interval of at least 24 hours. Results The measured amplitude at six metres was significantly lower than that with the target at 40 cm, by 1.56 ± 1.17 D (p < 0.001) and this varied between individuals (r = 0.716, intraclass correlation coefficient = 0.439). With either target distance, repeated measurement was highly correlated (r > 0.9) but the agreement was better at 6.0 m (±0.74 D) than at 40 cm (± 0.92 D). Conclusion The measurements of the amplitude of accommodation with the minus lens technique using targets at far or near are not comparable and the difference between the target distances may provide clinically relevant information. [ABSTRACT FROM AUTHOR]

Background: Today, contact lenses have extensive usages. Contact lens places on cornea, so it may induce variation on cornea and these variations can influence the measurement of intraocular pressure (IOP) by Goldman tonometer. The aim of this research was to study the effect of various contact lenses on measurement of intraocular pressure by Goldman tonometer. Materials and Methods: In this study, 80 subjects aged 18-25 were selected randomly among patients of Al-Zahra ophthalmology center. None of them has any eye pathological problems. Before wearing the lens, intraocular pressure was measured, and then patients were divided into two groups of soft and hard contact lenses. Soft and hard contact lenses were placed on the eye for two hours, and the intraocular pressure was measured again. Results: The mean of IOP before wearing contact lenses and two hours later was 15.96 mmHg and 13.93, s respectively. Paired test showed a significant difference between IOP before and after wearing contact lenses (p=0.001).There was no significant differences in mean of intraocular pressure decline before and after placing the contact lens in both soft and hard lenses. Conclusion: According to this study, the intraocular pressure decreases after wearing contact lenses (CL). This decline may be due to variation in properties of cornea after wearing CL that can also affect IOP measurement. [ABSTRACT FROM AUTHOR]