Abstract
Purpose: :
To determine characteristics associated with the presence and laterality of asymmetric glaucomatous visual field damage.
Methods: :
Consecutive patients undergoing evaluation from June to August 2009 were screened for this retrospective study. Included patients had open angles and at least one bilaterally reliable and repeatable 24-2 SITA-standard automatic perimetry with the Humphrey Field Analyzer II with the glaucoma hemifield test borderline or outside normal limits in at least one eye. Asymmetry was defined as a difference of greater than or equal to 2 dB of mean deviation (MD) between the two eyes. Patients with nonglaucomatous field loss were excluded. Each patient underwent ocular response analyzer (ORA) assessment. Central corneal thickness (CCT), MD, most recent intraocular pressure (IOP), and maximum documented IOP (Tmax) were obtained for both eyes by chart review. A single masked observer evaluated optic disc stereophotos for cup-to-disc ration (CDR) and presence of parapapillary atrophy (PPA). Conditional logistic regression was used to evaluate relationships between glaucoma asymmetry and independent variables.
Results: :
410 patients were screened and asymmetric field damage was identified in 170 eyes of 85 patients who met inclusion criteria; patients had an average of 6.70 dB (+/- 5.42) of asymmetry. In simple conditional logistic models, greater CDR, greater PPA and ORA variables (greater corneal compensated IOP, greater Goldmann correlated IOP and lower corneal hysteresis [CH]) were each associated with glaucoma asymmetry of greater than or equal to 2dB (p less than or equal to 0.01). The same results were seen when predictor variables were dichotomized for each patient (better/worse eye) and used to predict glaucoma asymmetry. In a multivariable model, VCDR, IOPg and CH were all significant predictors of glaucoma asymmetry (p less than or equal to 0.05; pseudo-R2 = 0.245).
Conclusions: :
Optic disc cupping, PPA, IOPg, IOPcc and CH are significantly and independently predictive of visual field damage laterality in asymmetric glaucoma. As our results suggest that CH, a marker of corneal viscoelasticity, may be a marker of glaucoma susceptibility the role of this and other corneal biomechanical properties in shaping glaucoma risk should be further elucidated.
Keywords: perimetry • intraocular pressure • optic disc