The precision of ophthalmic biometry using calipers

Area of Science:

• Ophthalmic biometry
• Ophthalmology
• Medical device precision

Background:

• Accurate ocular measurements are crucial for ophthalmic procedures.
• Calipers are commonly used instruments for biometry, but their precision requires evaluation.

Purpose of the Study:

• To determine the precision of whole globe and cornea measurements using calipers.
• To quantify the intraoperator and interoperator variance in these measurements.

Main Methods:

• Experimental study involving ten human donor eyes.
• Measurements of globe and cornea dimensions using digital Vernier and Castroviejo calipers.
• Three operators performed five repeat measurements for each dimension.

Main Results:

• No significant differences in globe measurements (anteroposterior length, diameters) were found.
• Horizontal corneal diameter consistently exceeded vertical diameter across all measurements.
• Variability was similar across operators and measurement scales, with no significant difference between caliper types.
• Mean intraoperator standard deviation was 0.127 ± 0.023 mm (digital caliper) and 0.094 ± 0.056 mm (Castroviejo caliper).

Conclusions:

• Commercially available calipers offer limited precision for ophthalmic biometry, approximately 0.1 mm.
• The precision is consistent across operators and measurement scales for both globe and cornea dimensions.