Antonio Queiros

The purpose of this study was to compare refractions measured with an autorefractor and by retinoscopy with and without cycloplegia. The objective refractions were performed in 199 right eyes from 199 healthy young adults with a mean age of 21.6 ± 2.66 years. The measurements were performed first without cycloplegia and repeated 30 min later with cycloplegia. Data were analysed using Fourier decomposition of the power profile. More negative values of component M and J0 were given by non-cycloplegic autorefraction compared with cycloplegic autorefraction (p < 0.0001). However more positive values for the J45 vector were given by non-cycloplegic autorefraction, although this difference was not statistically significant (p = 0.233). By retinoscopy, more negative values of component M were obtained with non-cycloplegic retinoscopy (p < 0.0001); for the cylindrical vectors J0 and J45 the retinoscopy without cycloplegia yields more negative values (p = 0.234; p = 0.112, respectively). Accepting that differences between cycloplegic and non-cycloplegic retinoscopy are only due to the accommodative response, the present results confirm that when performed by an experienced clinician, retinoscopy is a more reliable method to obtain the objective starting point for refraction under non-cycloplegic conditions.

The aim of this study was to evaluate the accuracy of measurement of intraocular pressure (IOP) using a new induction/impact rebound tonometer (ICare®) in comparison with the Goldmann applanation tonometer (AT).The left eyes of 46 university students were assessed with the two tonometers, with induction tonometry being performed first. The ICare® was handled by an optometrist and the Goldmann tonometer by an ophthalmologist.In this study, statistically significant differences were found when comparing the ICare® rebound tonometer with applanation tonometry (AT) (p < 0.05). The mean difference between the two tonometers was 1.34 ± 2.03 mmHg (mean ± S.D.) and the 95% limits of agreement were ±3.98 mmHg. A frequency distribution of the differences demonstrated that in more than 80% of cases the IOP readings differed by <3 mmHg between the ICare® and the AT.In the present population the ICare® overestimates the IOP value by 1.34 mmHg on average when compared with Goldmann tonometer. Nevertheless, the ICare® tonometer may be helpful as a screening tool when Goldmann applanation tonometry is not applicable or not recommended, as it is able to estimate IOP within a range of ±3.00 mmHg in more than 80% of the population.

Purpose:  The main objectives of this study were to determine the differences between non-synchronized intraocular pressure (IOP_N) and intraocular pressure readings synchronized with cardiac pulse and try to determine if these parameters are related to blood pressure values.Methods:  One hundred and sixty-five right eyes from 165 volunteers (107 females, 58 males) aged from 19 to 73 years (mean ± S.D., 29.93 ± 11.17) were examined with the Nidek NT-4000, a new non-contact tonometer that allows the measurement of IOP synchronized with the cardiac rhythm. IOP measurements in the four different modes of synchronization were taken in a randomized order. Three measures of each parameter were taken and then averaged. The blood pressure was determined three times with a portable manometer and mean values of systolic and diastolic pressure and the pulse rate were computed. Mean arterial pressure (MAP) was determined as being 1/3 of systolic plus 2/3 of diastolic blood pressure.Results:  The mean ± S.D. values for the standard intraocular pressure (IOP_N: 14.76 ± 2.86), intraocular pressure in the systolic instant or peak (IOP_P: 14.99 ± 2.85), intraocular pressure in the middle instant between heartbeats or middle (IOP_M: 14.68 ± 2.76), and intraocular pressure in the diastolic instant or bottom (IOP_B: 13.86 ± 2.61) were obtained. The IOP_P was higher than the remaining values. A significant difference in mean IOP existed between IOP_B and the remaining modes of measuring (p < 0.05). Differences were statistically significant for all pair comparisons involving IOP_B. Arterial blood pressure values were systolic 125.5 ± 14.22, diastolic 77.7 ± 8.38 and MAP 93.64 ± 9.44 mmHg. The pulse rate was 77.3 ± 12.6 beats per minute. Except for the MAP (p = 0.025) there was no significant correlation between different IOP values and systolic or diastolic blood pressure, or pulse rate.Conclusions:  NT-4000 is able to differentiate IOP values when synchronized with the cardiac rhythm and those differences are expected to be within a range of ±2.5 to ± 3.0 mmHg. IOP_B seems to be the parameter whose value differs from the non-synchronized and the remaining synchronized parameters in a significant way. Other than a weak association with MAP, no significant correlation between IOP and BP was found. The measurements of IOP readings for the three modes are consistent with timings during the cardiac cycle and IOP pulse cycle.

The purpose of this study was to compare refractions measured with an autorefractor and by retinoscopy with and without cycloplegia. The objective refractions were performed in 199 right eyes from 199 healthy young adults with a mean age of 21.6 ± 2.66 years. The measurements were performed first without cycloplegia and repeated 30 min later with cycloplegia. Data were analysed using Fourier decomposition of the power profile. More negative values of component M and J0 were given by non-cycloplegic autorefraction compared with cycloplegic autorefraction (p < 0.0001). However more positive values for the J45 vector were given by non-cycloplegic autorefraction, although this difference was not statistically significant (p = 0.233). By retinoscopy, more negative values of component M were obtained with non-cycloplegic retinoscopy (p < 0.0001); for the cylindrical vectors J0 and J45 the retinoscopy without cycloplegia yields more negative values (p = 0.234; p = 0.112, respectively). Accepting that differences between cycloplegic and non-cycloplegic retinoscopy are only due to the accommodative response, the present results confirm that when performed by an experienced clinician, retinoscopy is a more reliable method to obtain the objective starting point for refraction under non-cycloplegic conditions.

The aim of this study was to evaluate the accuracy of measurement of intraocular pressure (IOP) using a new induction/impact rebound tonometer (ICare®) in comparison with the Goldmann applanation tonometer (AT).The left eyes of 46 university students were assessed with the two tonometers, with induction tonometry being performed first. The ICare® was handled by an optometrist and the Goldmann tonometer by an ophthalmologist.In this study, statistically significant differences were found when comparing the ICare® rebound tonometer with applanation tonometry (AT) (p < 0.05). The mean difference between the two tonometers was 1.34 ± 2.03 mmHg (mean ± S.D.) and the 95% limits of agreement were ±3.98 mmHg. A frequency distribution of the differences demonstrated that in more than 80% of cases the IOP readings differed by <3 mmHg between the ICare® and the AT.In the present population the ICare® overestimates the IOP value by 1.34 mmHg on average when compared with Goldmann tonometer. Nevertheless, the ICare® tonometer may be helpful as a screening tool when Goldmann applanation tonometry is not applicable or not recommended, as it is able to estimate IOP within a range of ±3.00 mmHg in more than 80% of the population.

Purpose:  The main objectives of this study were to determine the differences between non-synchronized intraocular pressure (IOP_N) and intraocular pressure readings synchronized with cardiac pulse and try to determine if these parameters are related to blood pressure values.Methods:  One hundred and sixty-five right eyes from 165 volunteers (107 females, 58 males) aged from 19 to 73 years (mean ± S.D., 29.93 ± 11.17) were examined with the Nidek NT-4000, a new non-contact tonometer that allows the measurement of IOP synchronized with the cardiac rhythm. IOP measurements in the four different modes of synchronization were taken in a randomized order. Three measures of each parameter were taken and then averaged. The blood pressure was determined three times with a portable manometer and mean values of systolic and diastolic pressure and the pulse rate were computed. Mean arterial pressure (MAP) was determined as being 1/3 of systolic plus 2/3 of diastolic blood pressure.Results:  The mean ± S.D. values for the standard intraocular pressure (IOP_N: 14.76 ± 2.86), intraocular pressure in the systolic instant or peak (IOP_P: 14.99 ± 2.85), intraocular pressure in the middle instant between heartbeats or middle (IOP_M: 14.68 ± 2.76), and intraocular pressure in the diastolic instant or bottom (IOP_B: 13.86 ± 2.61) were obtained. The IOP_P was higher than the remaining values. A significant difference in mean IOP existed between IOP_B and the remaining modes of measuring (p < 0.05). Differences were statistically significant for all pair comparisons involving IOP_B. Arterial blood pressure values were systolic 125.5 ± 14.22, diastolic 77.7 ± 8.38 and MAP 93.64 ± 9.44 mmHg. The pulse rate was 77.3 ± 12.6 beats per minute. Except for the MAP (p = 0.025) there was no significant correlation between different IOP values and systolic or diastolic blood pressure, or pulse rate.Conclusions:  NT-4000 is able to differentiate IOP values when synchronized with the cardiac rhythm and those differences are expected to be within a range of ±2.5 to ± 3.0 mmHg. IOP_B seems to be the parameter whose value differs from the non-synchronized and the remaining synchronized parameters in a significant way. Other than a weak association with MAP, no significant correlation between IOP and BP was found. The measurements of IOP readings for the three modes are consistent with timings during the cardiac cycle and IOP pulse cycle.