- Email: [email protected]
Dr. Miles' Reply
CORRESPONDENCE
tion and convergence impulses change with maturity. There is no hesitancy about doing multiple operations on the extraocular muscles, including the vertical muscles, and inferior oblique surgery is often included with surgery on the lateral muscles. Finally, I would say that Europe, particularly the Common Market countries, is booming scientifically as well as economically and it behooves us in this country to be more competitive and less complacent and self-satisfied. For example, to how many foreign eye journals do American ophthalmologists subscribe? Yet every Dutch ophthalmologist reads all of our journals as well as the European journals and I am happy to report that T H E AMERICAN JOURNAL OF
OPHTHALMOLOGY was conspicuous in every library and clinic and private office I visited. S. Rodman Irvine.
CORRESPONDENCE
877
out bifocals was 0.75 diopter per year, and that with bifocals it was 0.40 diopter per year, is without meaning. It is quite likely that in a heterogeneous group such as this, this small difference is insignificant. The fact that Dr. Miles found the majority of his myopic children to be esophoric is interesting. Again, this statement would only be valid if the data were subjected to proper statistical analysis. It is important to know under what conditions the heterophoria was measured. Many children show a considerable esophoria with the Maddox rod if the measurement is made immediately after a refraction and with the new correction in place in the trial frame. This esophoria is much reduced after the new correction is worn for a few days. I hope Dr. Miles will allay the skepticism which he invites. (Signed) Daniel Snydacker, Chicago, Illinois.
* * *
BIFOCALS I N MYOPIA
Editor,
DR. M I L E S ' REPLY
American Journal of Ophthalmology:
Editor,
Dr. Paul Miles in his article on bifocals for myopic children ("Heterophoria and myopia in children," Am. J. Ophth., 54:111114 [July] 1962) states that "one is justified in some skepticism." Lest this skepticism remain unvoiced, may I point out what I consider to be some of the flaws in Dr. Miles' statistical analysis of his data?
American Journal of Ophthalmology: Dr. Snydacker correctly guessed my custom of testing heterophoria in children with the newly increased correction. This is a good index of the "breaking in" discomfort to be expected. H e is right that this increases the incidence of esophoria. In this instance, the tests were repeated yearly which improved the reliability.
Proper application of biostatistical methods might allow one to decide what changes in refractive error were within normal range and hence to be expected, and what changes were so great as to be outside the normal range. Dr. Miles has arranged his curves in such a way that they defy interpretation. H i s statistics would be more meaningful if they were averaged for each year of life and the standard deviations determined. If there were statistical changes in the average following the use of bifocals, his claims might then be justified. H i s simple statement that the average yearly increase in myopia with-
H e is also correct in pointing out the unrealized statistical possibilities. Five of my figures were raw data of myopic decline, while one did average for each year of life the change in myopia per year. Anyone who finds it necessary for his own opinion may apply statistics. I consider inspection of the raw data in this instance sufficient. Those who hold that statistics can mislead may be the majority. Unfortunately, this subject is emotional. For 20 years I have been taking bifocals away from myopic children and thinking
tion and convergence impulses change with maturity. There is no hesitancy about doing multiple operations on the extraocular muscles, including the vertical muscles, and inferior oblique surgery is often included with surgery on the lateral muscles. Finally, I would say that Europe, particularly the Common Market countries, is booming scientifically as well as economically and it behooves us in this country to be more competitive and less complacent and self-satisfied. For example, to how many foreign eye journals do American ophthalmologists subscribe? Yet every Dutch ophthalmologist reads all of our journals as well as the European journals and I am happy to report that T H E AMERICAN JOURNAL OF
OPHTHALMOLOGY was conspicuous in every library and clinic and private office I visited. S. Rodman Irvine.
CORRESPONDENCE
877
out bifocals was 0.75 diopter per year, and that with bifocals it was 0.40 diopter per year, is without meaning. It is quite likely that in a heterogeneous group such as this, this small difference is insignificant. The fact that Dr. Miles found the majority of his myopic children to be esophoric is interesting. Again, this statement would only be valid if the data were subjected to proper statistical analysis. It is important to know under what conditions the heterophoria was measured. Many children show a considerable esophoria with the Maddox rod if the measurement is made immediately after a refraction and with the new correction in place in the trial frame. This esophoria is much reduced after the new correction is worn for a few days. I hope Dr. Miles will allay the skepticism which he invites. (Signed) Daniel Snydacker, Chicago, Illinois.
* * *
BIFOCALS I N MYOPIA
Editor,
DR. M I L E S ' REPLY
American Journal of Ophthalmology:
Editor,
Dr. Paul Miles in his article on bifocals for myopic children ("Heterophoria and myopia in children," Am. J. Ophth., 54:111114 [July] 1962) states that "one is justified in some skepticism." Lest this skepticism remain unvoiced, may I point out what I consider to be some of the flaws in Dr. Miles' statistical analysis of his data?
American Journal of Ophthalmology: Dr. Snydacker correctly guessed my custom of testing heterophoria in children with the newly increased correction. This is a good index of the "breaking in" discomfort to be expected. H e is right that this increases the incidence of esophoria. In this instance, the tests were repeated yearly which improved the reliability.
Proper application of biostatistical methods might allow one to decide what changes in refractive error were within normal range and hence to be expected, and what changes were so great as to be outside the normal range. Dr. Miles has arranged his curves in such a way that they defy interpretation. H i s statistics would be more meaningful if they were averaged for each year of life and the standard deviations determined. If there were statistical changes in the average following the use of bifocals, his claims might then be justified. H i s simple statement that the average yearly increase in myopia with-
H e is also correct in pointing out the unrealized statistical possibilities. Five of my figures were raw data of myopic decline, while one did average for each year of life the change in myopia per year. Anyone who finds it necessary for his own opinion may apply statistics. I consider inspection of the raw data in this instance sufficient. Those who hold that statistics can mislead may be the majority. Unfortunately, this subject is emotional. For 20 years I have been taking bifocals away from myopic children and thinking