Using Scheimpflug photography, Hu et al.1 observed in vivo that anterior chamber depth decreased until 20 years of age and increased thereafter. This is consistent with in vitro biometric measurements of fresh, intact, post-mortem human lenses that demonstrate central thickness decreases from birth until 20 years of age and then increases throughout the rest of life.2
The authors' findings are important. They demonstrate that while the lens changes shape because its central thickness is decreasing and increasing between birth and 40 years of age, the amplitude of accommodation declines in a linear fashion.3,4 Therefore, it is unlikely that the age-related change in lens shape or central thickness is the etiology of the age-related linear decline in accommodation that results in presbyopia.
Ronald A. Schachar MD, PhD
Dallas, Texas, USA
REFERENCES
1. Hu C-Y, Jian J-H, Cheng Y-P, Hsu H-K. Analysis of crystalline lens position. J Cataract Refract Surg 2006; 32:599-603
2. Schachar RA. Growth patterns of fresh human crystalline lenses measured by in vitro photographic biometry. J Anat 2005; 206:575-580
3. Donders FC. On the Anomalies of Accommodation and Refraction of the Eye; translated from the author's manuscript by WD Moore. London, New Sydenham Society, 1864; 204–214
4. Fuchs E. Textbook of Ophthalmology, 5th ed, authorized translation by A Duane. Philadelphia PA, JB Lippincott, 1917; 859–863
