1128 AMERICAN JOURNAL OF OPHTHALMOLOGY DECEMBER, 1969

those who do not already hold this point of view. Furthermore, it seems unjustified to dismiss the possibility that the relationship which probably exists between poor control and increased frequency and severity of vas­cular complications may not be one of cause and effect (page 83). It is certainly conceiv­able that difficulty of diabetic control and se­verity of vascular complications may repre­sent parallel effects of some underlying cause. This consideration is, indeed, of im­portance when discussing physicians' "duty to their patients" (page 81 ).

There are a few other minor criticisms, such as the statements that ultraviolet light is used in fluorescein angiography (page 22), that a "decrease of refractile power of the lens as a whole" results in myopia (page 124) and that "the use of enzymatic zonu-lysis makes no difference to the incidence of rupture of the capsule either in diabetics or nondiabetics." Although evidence is given that this last statement is true in the authors' hands, it is hardly true as a generalization.

The potential reader should not be de­terred from careful study of this book by the shortcomings mentioned, for it represents a complete, critical and extremely valuable re­view of this increasingly important area in ophthalmology.

Matthew D. Davis

L 'HUMEUR AQUEUSE ET L A BARRIÈRE H É -MATO-CAMERULAIRE. By Jean Michiels. Bruxelles, Compagnie Belge d'Editions, 1968. Clothbound, 242 pages, bibliography, 44 tables, 50 figures (38 black and white, 12 color). This volume represents the first mono­

graph on aqueous humor dynamics since the monograph by Amsler, Huber and Verrey presented as a report to the French Ophthal-mological Society in 1955. As such, this work by Professor Michiels of the Université Catholique de Louvain presents a compilation of modem concepts and facts regarding the aqueous.

In logical fashion, the author sketches the embryology and histology of the anterior chamber and includes electron photomicro­graphs. The chemical and physiologic prop­erties of the aqueous in its normal state are discussed, followed by a detailed examina­tion of the aqueous in pathologic situations such as hyphemia, uveitis and intraocular tu­mors. Considerable emphasis is placed on the blood aqueous barrier and its alterations.

This book recommends itself for its ex­haustive discussion of a topical subject. It suffers, however, from the inclusion of some of the author's own experimental and clini­cal data which distract from the flow of in­formation without necessarily being original.

Marcel Frenkel

GEOMETRICAL OPTICS. By Glenn A. Fry. Philadelphia, Chilton Book Co., 1969. Clothbound, 290 pages, index, figures in black and white. Price : $9.50. Fry presents a classical and thorough

treatment of geometrical optics. The text is well illustrated with many line drawings and requires no advanced mathematics. All the formulas are derived using plane geometry and trigonometry; it will be important for students using this book to be well versed in these subjects.

The first 11 chapters contain fundamen­tals of paraxial optics (covering both refrac­tion and reflection) for single spherical sur­faces and simple lenses. Both the Smith-Helmholtz (or Lagrange) equations and Newtonian form are developed and Fry pre­sents two techniques for precise ray tracing. There is a good treatment of the cardinal points and planes. There is a chapter on op­tical instruments followed by a detailed con­sideration (14 chapters) of the monochro­matic and chromatic aberrations. The com­putations for the aberrations of a single sur­face are again derived from geometric con­siderations. In a later chapter Fry gives the Seidel formulas for use with multiple sur­faces; a fuller discussion and derivation of