Calcium-containing opacities in the human lens.

Area of Science:

• Ophthalmology
• Materials Science
• Biochemistry

Background:

• Cooperative Cataract Research Group (CCRG) photographic methods allow detailed analysis of lens opacities.
• Previous research identified lens opacities with high phosphorus/sulfur ratios and accumulated unit membranes.

Purpose of the Study:

• To describe a novel variety of human lens opacity characterized by high calcium content.
• To determine the chemical composition and morphology of these calcium-rich opacities.

Main Methods:

• Energy Dispersive X-ray Analysis (EDXA) in scanning electron microscopy (SEM) for elemental composition.
• Microchemical analysis to identify the form of calcium.
• Analysis of Cooperative Cataract Research Group (CCRG) stereo photographs for morphological characteristics.

Main Results:

• A new type of human lens opacity was identified with high calcium, low sulfur, and undetectable phosphorus.
• These opacities are spheroidal, up to 300 microns in size, and birefringent.
• Microchemical analysis confirmed calcium is present as calcium oxalate.
• Detected in 14 out of 406 cataractous lenses, exhibiting characteristic morphology.

Conclusions:

• A distinct type of calcium oxalate-containing opacity exists in human cataracts.
• The characteristic morphology allows for accurate detection using CCRG photographs.
• This finding contributes to the understanding of cataract ultrastructure and composition.