OHTS system has high reproducibility for classifying field defects

The Ocular Hypertension Treatment Study classification system may provide surgeons with a reliable nomenclature for characterizing visual field defects because of its high reproducibility, according to researchers involved in the study.

Visual field tests are given every 6 months to participants in the study and monitored for abnormalities. As of January 2002, 1,636 patients had 2,509 abnormal visual fields. Three independent readers were used to classify each hemifield using a classification system developed for the OHTS. Half of the abnormal visual fields were reread to evaluate test-retest reader agreement.

The average hemifield classification agreement (between any two of the three readers) for 5,018 hemifields was 97%. Agreement for 1,266 abnormal fields that were reread was 88%. Glaucomatous patterns of loss composed the majority of the defects.

The study is published in the May issue of Archives of Ophthalmology.