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Aqueous humor dynamics in low-tension glaucoma
L I Larsson1, E S Rettig, P T Sheridan
1Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905.
American Journal of Ophthalmology
|November 15, 1993
Summary
This study found no significant difference in diurnal aqueous humor flow between low-tension glaucoma patients and healthy individuals. The findings do not support the theory that reduced outflow facility and flow cause normal tension in glaucoma.
Area of Science:
- Ophthalmology
- Glaucoma Research
- Fluid Dynamics
Background:
- Low-tension glaucoma is characterized by optic nerve damage and visual field loss despite normal intraocular pressure.
- The underlying mechanisms of low-tension glaucoma remain incompletely understood.
- A potential hypothesis suggests a combination of reduced aqueous humor outflow facility and decreased aqueous humor flow may contribute to the disease.
Purpose of the Study:
- To investigate diurnal aqueous humor flow rates in patients with low-tension glaucoma.
- To compare aqueous humor flow and outflow facility between low-tension glaucoma patients and healthy controls.
- To evaluate the hypothesis that low facility and low flow contribute to normal intraocular pressure in low-tension glaucoma.
Main Methods:
- Diurnal aqueous humor flow was measured using the clearance of topically applied fluorescein in ten low-tension glaucoma patients and ten age-matched healthy volunteers.
- Tonographic facility of outflow and intraocular pressure were also assessed.
- Statistical analysis was performed to compare measurements between the two groups.
Main Results:
- Mean diurnal aqueous humor flow was 2.48 ± 0.61 µL/min in the low-tension glaucoma group and 2.58 ± 0.78 µL/min in the control group (p > 0.05).
- Nocturnal aqueous humor flow was 1.24 ± 0.45 µL/min in the glaucoma group and 0.98 ± 0.22 µL/min in controls (p > 0.05).
- There were no statistically significant differences in tonographic facility of outflow or intraocular pressure between the groups.
Conclusions:
- This study found no significant differences in diurnal or nocturnal aqueous humor flow between patients with low-tension glaucoma and healthy individuals.
- The results do not support the hypothesis that a combination of low outflow facility and low aqueous humor flow is responsible for the normal intraocular pressure observed in low-tension glaucoma.
- Further research is needed to elucidate the pathogenesis of low-tension glaucoma.