Pattern of intraocular pressure in epidemic dropsy in India

Experimental glaucoma model with controllable intraocular pressure history

Glaucoma-like neuropathies can be experimentally induced by disturbing aqueous outflow from the eye, resulting in intraocular pressure (IOP) changes that are variable in magnitude and time course and permanent in duration. This study introduces a novel method of glaucoma induction that offers researchers round-the-clock measurement and reversible control of IOP for the first time. One eye of Brown-Norway rats was implanted with a cannula tethered to a pressure sensor and aqueous reservoir. IOP was raised 10 mmHg for weeks-to-months in treated animals and unaltered in control animals. Counts of Brn3a-expressing retinal ganglion cells (RGCs) in implanted eyes were indistinguishable from non-implanted eyes in control animals and 15 ± 2%, 23 ± 4%, and 38 ± 4% lower in animals exposed to 2, 4, and 9 weeks of IOP elevation. RGC loss was greater in peripheral retina at 2 weeks and widespread at longer durations. Optic nerves also showed progressive degeneration with exposure duration, yet conventional outflow facility of implanted eyes was normal (24.1 ± 2.9 nl/min/mmHg) even after 9-weeks elevation. Hence, this infusion-based glaucoma model exhibits graded neural damage with unimpaired outflow pathways. The model further revealed a potentially-significant finding that outflow properties of rat eyes do not remodel in response to chronic ocular hypertension.

Case Study

Epidemic dropsy is a multi-system disease involving the cardiovascular, hepatic, renal, ocular and other systems. Onset is usually subacute or insidious with watery diarrhea and vomiting. This lasts from a few days to more than a week. Bilaterally symmetrical pitting edema of the lower limbs extending from the ankles up to the scrotum and abdominal wall is a constant feature. It is a toxic disease caused by the unintentional ingestion of Argemone mexicana (prickly yellow poppy) seeds as an adulterant of wheat flour, or more commonly, of cooking oil such as mustard oil. Sanguinarine and dehydrosanguinarine are two major toxic alkaloids of Argemone oil. It is a rare phenomenon for practicing ophthalmologists to observe cases of epidemic dropsy, and the possibility of glaucoma should be kept in mind in cases of epidemic dropsy, when members of same family or village report with raised IOP, pedal edema and history of use of mustard oil for cooking or massage. Glaucoma is hypersecretory in nature; prostaglandin and histamine release may have significant roles in its pathogenesis. The disease has self limiting course but needs good control of intraocular pressure (IOP) medically till it returns to normal and visual field changes have stabilized. Its early diagnosis is very important to prevent grievous complications; hence, all cases should be followed up regularly for IOP measurement and visual field analysis up to 8-12 weeks, because, if ignored, optic atrophy may develop.