Growth of the human lens in the Indian adult population: preliminary observations

Abstract

Context: The eye lens grows throughout life by the addition of new cells inside the surrounding capsule. How this growth affects the properties of the lens is essential for understanding disorders such as cataract and presbyopia.

Aims: To examine growth of the human lens in the Indian population and compare this with the growth in Western populations by measuring in vitro dimensions together with wet and dry weights.

Settings and design: The study was conducted at the research wing of a tertiary eye care center in South India and the study design was prospective.

Materials and methods: Lenses were removed from eye bank eyes and their dimensions measured with a digital caliper. They were then carefully blotted dry and weighed before being placed in 5% buffered formalin. After 1 week fixation, the lenses were dried at 80 °C until constant weight was achieved. The constant weight was noted as the dry weight of the lens.

Statistical analysis used: Lens parameters were analyzed as a function of age using linear and logarithmic regression methods.

Results: Data were obtained for 251 lenses, aged 16-93 years, within a median postmortem time of 22 h. Both wet and dry weights increased linearly at 1.24 and 0.44 mg/year, respectively, throughout adult life. The dimensions also increased continuously throughout this time.

Conclusions: Over the age range examined, lens growth in the Indian population is very similar to that in Western populations.

Figure 1

In vitro changes in human lens diameter (blue) and thickness (orange) with increasing age. The dimensions were measured with a digital caliper

Figure 2

Human lens in vitro aspect ratio as a function of age. The aspect ratio was calculated as the ratio of lens thickness to lens diameter (thickness/diameter)

Figure 3

Wet weights for human lenses as a function of age. The wet weight of the lens was measured using an analytical balance after extraction from the eyeball

Figure 4

Relationship between human lens dry weight and age. The dry weight of the lens was measured after a week of formalin fixation, followed by complete drying at 80°C in hot air oven for 2 weeks

Figure 5

Lens volume, calculated from the wet and dry weights of the lens, as a function of age (volume = wet weight – 0.25 × dry weight)