Cataract in developing countries.
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Blindness↗
Biomedical subjects
D Yorston
Publications and source records attributed to D Yorston.
Herpetic keratitis in Tanzania: association with malaria.
Of 103 patients who presented to a rural clinic in Africa with corneal ulceration, 62 (60.2%) had corneal ulcers which on clinical diagnosis were attributable to herpes simplex virus. There was a strong association between herpetic ulceration and a history of recent malaria; 37 of 62 (59.7%) herpetic ulcers occurred in the 3 month period from April to June which corresponds to the end of the peak season for malaria compared with 14 of 41 (34%) of the non-herpetic ulcers. Fifty per cent of herpetic ulcers had a geographic morphology, 27.4% were dendritic, and 22.6% presumed herpetic ulcers were stromal: 38.7% of herpetic ulcers occurred in children under 5 years of age. Bilateral herpetic ulcers occurred in 16.1% of patients but were more common in children under 2 years of age. Geographic and stromal ulcers tended to heal more slowly than dendritic ulcers (mean time to healing 12.6, 12.2, and 6.6 days respectively), and were more likely to result in severe corneal scarring (45%, 29%, and 0% respectively). Herpes simplex keratitis is a major cause of corneal scarring in Africa. It is often seen in children, may be bilateral, commonly is geographic in morphology, and has a strong association with malaria infection. Because it is not easily preventable, more effort must be made to ensure early diagnosis and prompt, effective treatment in order to prevent severe scarring and visual loss.
Adolescent↗
Corneal ulceration in Tanzanian children: relationship between measles and vitamin A deficiency.
Two 3-year prospective studies from 1982-1984 and 1986-1988 in Tanzania identified 189 children with corneal ulceration, of whom 31 (16.4%) were due to vitamin A deficiency. In 1982-1984, vitamin A deficiency was responsible for 23.4% of corneal ulcers (25 of 107) compared with 7.3% (6 of 82) from 1986-1988 (P = 0.006). It is postulated that the decrease in corneal ulceration due to vitamin A deficiency can be attributed to improved measles immunization coverage.
Child, Preschool↗
Corneal ulceration in Tanzanian children: relationship between malaria and herpes simplex keratitis.
Two 3-year prospective studies from 1982-1984 and 1986-1988 in Tanzania identified 189 children with corneal ulceration, of whom 92 (48.7%) were due to herpes simplex keratitis. In 1982-1984 herpes simplex keratitis was responsible for 35.5% of corneal ulcers (38 of 107), compared with 65.8% (54 of 82) in 1986-1988 (P = 0.00006). It is postulated that the increase in corneal ulceration due to herpes simplex keratitis can be attributed to an increase in the incidence and severity of malaria infection.
Age Factors↗