Retinal vessel tortuosity in response to hypobaric hypoxia

Area of Science:

• Ophthalmology
• Altitude Physiology
• Vascular Biology

Background:

• Retinal vascular tortuosity is linked to various retinopathies.
• Pathophysiology of altitude-induced retinal changes requires further investigation.
• Clinical trials NCT00664001 and NCT00627965 registered this study.

Purpose of the Study:

• To map retinal vascular tortuosity changes at high altitude.
• To assess the impact of sildenafil and antioxidants on altitude-induced tortuosity.
• To explore the pathophysiology of retinal vascular changes under hypoxic conditions.

Main Methods:

• Semi-automated measurement of retinal vessel tortuosity in 35 healthy subjects.
• Comparison of tortuosity at sea level versus 7 days at 5200 m.
• Analysis within a randomized double-blind placebo-controlled trial of sildenafil and antioxidants.

Main Results:

• High altitude exposure significantly increased retinal vessel tortuosity.
• A trend indicated that sildenafil or antioxidant prophylaxis may limit this increase.
• No definitive conclusions on prophylactic efficacy due to non-significant trend.

Conclusions:

• Retinal vessel tortuosity increases rapidly under high altitude conditions.
• Increased sheer stress may cause vessel elongation, leading to tortuosity.
• Agents preserving nitric oxide-dependent vasodilation might limit altitude-induced tortuosity.