FATTY SUBSTANCES ON CONJUNCTIVA

Natural fat in external eye. Vital-stained by Sudan III powder

Examination of 113 eyes vital-stained by Sudan powder revealed that fat on the skin of outer canthus may pass onto the precorneal film (in 68%), and that the most reliable staining is obtained by application on the bulbar conjunctiva below the limbus corneae at 6 o'clock. In 41%, the precorneal film had stained drops or foam, with a tendency towards an increase among pathological cases (infectious conjunctivitis and blepharitis). An increased amount of fat was found in the mucous thread of eyes affected with infectious conjunctivitis and lagophthalmos. In a small number of pathological cases fat was also detected on cornea, bulbar conjunctiva, and inferior fornix. The fatty layer on the lower lid margin was stained more frequently and more intensely than that on the superior. The secretion of the meibomian glands was stained in no more than a scant one half of the glands (on an average 44%), independently of age, sex, site, and diagnosis.

Semiquantitative interference study of fatty layer of precorneal film

Reflecting colours from the fatty layer of the precorneal film have been studied using mat filter (grease-proof paper, parchment paper, tracing paper) in front of the slit lamp mirror, maximally open light slit in a half-lit room, and magnification x 15. The palpebral fissure was narrowed until occurrence of red interference colour (2000 A). In 206 normal eyes the fatty layer was 102 +/- 3nm (+/- SEM), or about 0.1 micron, independent of age, sex and BUT (break up time). Maximum on awakening. Coefficient of variation 12.7 per cent. An increased fatty layer was noticed in cases of blepharitis (129 +/- 8 nm), in 91 per cent wearing hard contact lenses and 73 per cent wearing soft contact lenses. The fatty layer was likewise seen to be augmented in patients with acute infectious conjunctivitis (193 +/- 3 nm), chronic infectious conjunctivitis (164 +/- 7 nm), and in all states complicated by bacterial infection. The fatty layer is normal in allergic and chronic simple conjunctivitis. Silicone oil was found to effect reduction of the fatty layer.