Predictors of Confirmed Visual Field Conversion in Eyes Suspected of Having Glaucoma

Abstract

 

Purpose:

 

To evaluate which clinical characteristics affect the probability of subsequent confirmation of the development of visual field (VF) loss in glaucoma suspects.

 

Methods:

 

The study included a cohort of 171 eyes of 157 glaucoma suspects selected from the DIGS (Diagnostic Innovations in Glaucoma Study) and ADAGES (African Descent and Glaucoma Study). All eyes had normal standard automated perimetry (SAP) tests at baseline and developed at least two consecutive abnormal SAPs after a mean follow-up of 2.6 (±2.2) years. An abnormal SAP was defined as a pattern standard deviation with P less than 5% or a Glaucoma Hemifield Test result outside normal limits. After development of 2 consecutive abnormal SAPs, these eyes were followed for an additional mean period of 4.6 (±2.6) years with an average of 6.2 (±3.1) SAPs. We evaluated which clinical characteristics observed at the time of apparent conversion were predictive of future confirmation of SAP abnormalities.

 

Results:

 

The probability of subsequent confirmation of VF abnormality was only 58% in eyes who had conversion defined by the presence of only 2 consecutive abnormal SAPs. In eyes with conversion defined based on 3 consecutive abnormal tests, the probability increased to 75%. Table 1 shows the variables associated with the probability of confirming an abnormal result after a conversion by 2 or 3 SAPs. Eyes who had conversion based on 3 repeatable abnormal SAPs by both GHT and PSD and who also had presence of glaucomatous optic neuropathy at the time of conversion had a 95% probability of confirming the abnormality on subsequent VF tests.

 

Conclusions:

 

The presence of VF conversion based on 3 repeatable abnormal SAPs increases the chance of subsequent abnormal results. Certain clinical and SAP characteristics are useful in determining which eyes with apparent VF conversion have higher chance of subsequent confirmation of abnormalities.  

 

Keywords: visual fields • clinical (human) or epidemiologic studies: risk factor assessment