Rapid pneumatic and Mackey-Marg applanation tonometry to evaluate the postural effect on intraocular pressure.

A postural study was conducted in three separate groups of subjects. The first group comprised 20 women volunteers with an average age of 20-75 years. In this group, the study was conducted by the pneumatonograph only. Mean pressure recorded was 15-65 +/- 0-25 mmHg and there was an average rise of 1-4 mmHg in supine posture. Groups 2 and 3 comprised 151 non-glaucomatous and 108 glaucomatous eyes respectively in the age range of 30 to 85 years. In these two groups, the study was conducted using the PTG and the Mackay-Marg tonometer. Clinical evaluation of the Mackay-Marg with the PTG gave significant correlation, with mean Mackay-Marg readings being 1-13 mmHg higher. The intraocular pressure when changing from seated to the supine position increased on average by 2-71 and 4-04 mmHg, respectively in Groups 2 and 3 and by 2-51 and 3-72 mmHg by Vackay-Marg, suggesting a higher change in glaucomatous subjects. Pressure on resumption of sitting was found to be lower than the initial pressure. Postural change also showed some direct relationship with age in non-glaucomatous subjects.