Limbal and axial chamber depth variations. A population study in Eskimos

Area of Science:

• Ophthalmology
• Anatomy
• Public Health

Background:

• Anterior chamber dimensions are critical for ocular health, particularly in glaucoma risk assessment.
• Ethnic and demographic variations in ocular anatomy are well-documented but require population-specific data.
• The van Herick method is a common clinical bedside technique for estimating limbal chamber depth (LCD).

Purpose of the Study:

• To investigate limbal chamber depth (LCD) and axial chamber depth (ACD) in an unselected Greenlandic Eskimo population.
• To compare ocular chamber dimensions between Greenlandic Eskimos and Danes.
• To evaluate the diagnostic accuracy of the van Herick slit-lamp test for detecting shallow anterior chambers in the Eskimo population.

Main Methods:

• Limbal chamber depth (LCD) estimated via van Herick method (1969) in 505 adult Greenland Eskimos.
• Axial chamber depth (ACD) measured optically using Haag Streit pachymetry.
• LCD also assessed in 308 Danes over 40 years for comparison.

Main Results:

• A significant naso-temporal asymmetry in LCD was observed, with shallower temporal limbal chambers.
• Elderly individuals, women, and Eskimos exhibited lower LCD and ACD values.
• The van Herick test at the temporal limbus showed 91% sensitivity and 96% specificity for detecting shallow chambers (ACD ≤ 2.0 mm) in Eskimos.
• 25% of eyes with LCD ≤ 1/4 corneal thickness had ACD > 2.0 mm, indicating potential narrow angles missed by ACD alone.

Conclusions:

• Greenlandic Eskimos have distinct ocular chamber dimensions, generally shallower than other populations studied.
• The van Herick test is a valuable screening tool for shallow anterior chambers in this population.
• Gonioscopy may be necessary even with normal ACD if LCD suggests a narrow angle, highlighting ethnic-specific anatomical considerations.