Sunday, 12 January 2014

Classification of stages of xerophthalmia

The ocular signs of vitamin A deficiencies include nightblindness, conjunctival xerosis, Bitot's spots, corneal xerosis, and keratomalacia. The classification proposed for general use is as follows:

Classification X1A
Signs -primary
Conjunctival xerosis-dryness or lack ofluster, loss of ability to re­tain moisture no matter whether tears are present or absent, loss of transparency, thickening, wrin­kling, pigmentation, accumula­tion of debris.

Classification X1B
Signs -primary
Bitot's spot with conjunctival xe­rosis-a small plaque with a sil­very gray hue and a foamy surface; it is quite superficial and is raised above the general level of the conjunctiva

Classification X2
Signs -primary
Corneal xerosis-follows con­junctival xerosis. The corneal sur­face has a rough, fine pebbly appearance and lacks luster. Later, cellular infiltration of the corneal stroma contributes to the intense haziness of the cornea, which frequently has a bluish, milky appearance.

Classification X3A
Signs -primary
Corneal ulceration wi th xerosis­involving loss of substance of a part or of the whole of the corneal thickness.

Classification X3B
Signs -primary
Keratomalacia - consists of a characteristic softening of the en­tire thickness of a part or, more often, the whole of the cornea, leading to deformation or destruc­tion of the eyeball. The process is a rapid one, the corneal structure melting into a cloudy gelatinous mass which may be dead white or dirty yellow in color.

Classification XN
Signs -secondary
Night blindness-impairment of the ability to adapt to the dark.

Classification XF
Signs -secondary
Xerophthalmia fundus-multiple lesions, sometimes glaring white, scattered profusely along the course of the vessels.

Classification XS
Signs -secondary
Corneal scars-resulting from the healing of irreversible corneal changes.

Classification XB
Signs -secondary
Bitot's spot with conjunctival xe­rosis-a small plaque with a sil­very gray hue and a foamy surface; it is quite superficial and is raised above the general level of the conjunctiva
Stage XN, or night blindness, indicates a functional impairment ofthe retina and is difficult to diagnose in the young child (1-4 yr) unless the mother is aware that the child cannot see well at night. As a method of screening, the child may be asked to walk into a darkened room.
The first sign of xerophthalmia is xerosis of the con­junctiva (stage X1A). This dryness and dullness associated with the stability of the precorneal film is considered complete alteration of the reflection of light from the conjunctiva. Night blindness (XN) and Bitot's spots (ac­cumulation of debris and fatty material near the edge of the eye) are frequently present at stage X1B. At stage X2, when there is xerosis of the cornea itself, the pre corneal film fails to cover the cornea, which now appears dry and opaque. Small erosions or perforations begin to occur if treatment with massive doses of vitamin A (100,000 IU/day, orally or intramuscularly) is not provided within 1 to 3 days of inception, and irreversible damage will soon result. However, if treated, the corneal xerosis will clear up within a short period of time.
Irreversible damage occurs once deeper layers of the cornea are involved, as in stage X3A. The cornea may liquety and melt away, resulting in large perforations and extrusion of the iris, the lens, and the vitreous (X3B). The permanent scarring effects (stage X5) may differ depend­ing on whether or not intraocular pressure was restored at stage X3B. It is essential that medical and paramedical personnel be alert to the signs of xerophthalmia and that treatment be instituted immediately when symptoms are recognized in order to prevent blindness.

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