Effect of Tropicamide on Laser Flare Meter Measurements in Patients with Pseudoexfoliation

ABSTRACT

Purpose

To investigate the effect of 1% tropicamide on anterior chamber aqueous flare (ACAF) measurements acquired with laser flare meter in patients with pseudoexfoliation.     

Effects of sex and age on strength-duration properties.

OBJECTIVE: To evaluate the possible effects of sex and age on strength-duration time constant (SDTC). METHODS: The SDTC of 126 healthy volunteers was measured following stimulation of right median nerve at the wrist. Variations in values were evaluated according to sex and age. RESULTS: The SDTC was 438.6+/-114.5 micros in women and 396.2+/-90.3 in men (P=.023). In men, as age increased, so did SDTC. However, this was not true in women. Comparing the values of women and men, aged below 40, demonstrated a difference in excitability, confined to younger patients. CONCLUSIONS: As SDTC depends on the biophysical properties of the axonal membrane and can provide some information about Na(+) channel function, these data raise the possibility of a difference in Na(+) channel function between men and women and a difference in the conductance with age. SIGNIFICANCE: The age- and sex-related differences shown in this study suggest a possible biochemical or hormonal influence on axonal excitability.     

The effect of hyperventilation on strength-duration properties in diabetic polyneuropathy.

OBJECTIVE: Hyperventilation and ischaemia increase axonal excitability by changing Na+ conductance in healthy subjects. However, the changes in excitability during and after ischaemia in diabetic patients are less than in healthy controls. This is known as ischaemic resistance. In this study, we investigated the effects of hyperventilation for 20 min on strength-duration time constant (SDTC) of motor axons of the median nerve of diabetic patients with polyneuropathy to determine whether diabetics are less affected by hyperventilation, a form of resistance similar to the ischaemic resistance of diabetics. METHODS: The SDTC of 14 diabetic patients with polyneuropathy and 10 healthy volunteers were measured following stimulation of right median nerve at the wrist prior to and after hyperventilation for 20 min. RESULTS: There was a significant increase in the SDTC in control subjects, but no significant change in the SDTC for patients with diabetic polyneuropathy. The score of the clinical response (paraesthesiae and carpopedal spasm) to hyperventilation of controls was also significantly greater in the controls than the patients. CONCLUSION: Hyperventilation for 20 min has little influence on SDTC in patients with diabetic polyneuropathy. SIGNIFICANCE: The 'resistance' of diabetic nerve is not confined to ischaemia but involves other manoeuvres that can alter axonal excitability.