VIII. VITAMIN' A DEFICIENCY IN HUMAN BEINGS 147 



than mild xerosis, and that the lacrimal and tarsal {2;lands may manifest 

 some degree of hypofunction but no morphologic change other than that 

 which may be secondary to keratinizing metaplasia of their duct epithelium. 



4. Response to Therapy 



With adequate vitamin A therapy, there is disappearance of Bitot's spots 

 within 2 weeks or less,'--- -^ and of other signs of xerophthalmia within 1 or 

 2 weeks thereafter; complete histologic restitution of all tissues involved 

 may require as long as 2 months, though disappearance of excess pigment 

 may require many months. 



In keratomalaeia there is a striking improvement in gross appearance of 

 the eye during the first week of therapy, with rapid healing of ulcerated 

 areas, but maximal repair usually requires many months. Pillat'®--' has 

 given the most complete description of progressive stages of repair. Scars 

 may be left in local areas of irreparable damage. 



When corneal perforation, panophthalmitis, and prolapse of the iris have 

 occurred, partial or complete impairment of vision results. It is stated that 

 about one-fourth of cases of well-established keratomalaeia which survive 

 become totally blind, and about the same proportion lose vision in one eye; 

 the latter is related to the fact that one eye is usually more involved than 

 the other. In Occidental and Oriental countries keratomalaeia has repre- 

 sented the most common cause of blindness. A recent report from Calcutta''* 

 refers to 150 cases seen in an out-patient clinic over a 6-month period, 

 with a high incidence of night blindness and xerophthalmia, and states that 

 "Vitamin A deficiency is a common disease amongst the children in this 

 country. It heads the list of avitaminoses . . . ." 



D. METAPLASIA OF EPITHELIA (INTERNAL) 



Early clinicians frequently commented upon dryness of oral, nasal, and 

 phar\'ngeal membranes, hoarseness, husky voice, and dry cough in patients 

 with keratomalaeia; also the frequency with which respiratory infections, 

 chiefl}' pneumonia, were associated with acute phases of the disorders and 

 constituted the primary cause of death in untreated or inadequateh' treated 

 cases. Mention has been made of the areas of keratinization in the mucosa of 

 the renal pelvis noted by Leber^ in 1883. No other post-mortem studies on 

 avitaminosis A were reported until 1922, when Wilson and DuBois^" de- 

 scribed widespread keratinizing metaplasia in epithelia of the respiratory 

 tract and of ducts of various glands in a 5-month infant with keratomalaeia. 

 Some years later there followed reports on 1 case by Thatcher and Sure,^^ 



=8 J. C. Spence, Arch. Disease Childhood 6, 17 (1931). 



29 D. Pal, Indian J. Pedial. 16, 1 (1949). 



" J. R. Wilson, and R. O. DuBois, Am. J. Diseases Children 26, 431 (1923). 



" H. S. Thatcher and B. Sure, Arch. Pathol. 13, 756 (1932). 



