Purpose:
The purpose of this study was to determine the distribution of inter–eye asymmetry of rim area and disc area (IEARADA) values in a normal and glaucoma population
Methods:
This was an observational, cross–sectional, tertiary clinic–based study. Subjects underwent confocal scanning laser ophthalmoscopy (HRT II) frequency doubling perimetry (FDP) and complete ophthalmic examination including visual acuity, gonioscopy, intraocular pressure–IOP, central corneal pachymetry–CCT, optic disc grading and fundoscopy. Normal, suspect and glaucoma diagnosis were given based on ophthalmic examination and FDP result. IEARADA values were calculated based on stereometric HRT values by dividing the value of the smaller rim / disc area to the value of the greater rim / disc area. Statistical analyses including student T–tests and Pearson correlation were performed
Results:
Of 477 subjects, 136 were normals, 106 glaucoma suspects and 235 glaucoma. IEARADA mean values was 0.78 (±0.17) for glaucoma; 0.85(±0.15) for suspect and 0.91 (±0.09) for normals. There was a significant statistical difference between glaucoma and normals (p<0.0001), glaucoma suspects and normals (p=0.0003), as well as glaucoma and glaucoma suspects (p=0.002). 90% of normals have an IEARADA superior to 0.83, as compared to 50 % for glaucoma. Additionally, there was no normals with an IEARADA less than 0.64. IEARADA correlated with age (r = –0.24, p=0.000), DDLS (OD r = –0.37, p=0.000; OS r = –0.42, p=0.000), MNRFL (OD r = 0.46, p=0.000; OS r = 0.40, p=0.000), CSM (OD r = –0.31, p=0.000; OS r = –0.38, p=0.000), CDAR (OD r = –0.35, p=0.000; OS r = –0.33, p=0.000), RA (OD r = 0.33, p=0.000; OS r = 0.41, p=0.000), DA (OD r = –0.16, p=0.000; OS r = –0.15, p=0.001). No correlation was found between IEARADA and gender, IOP, and HVC. , however in the glaucoma group, IEARADA correlated with IOP (OD r =0.17, p=0.009; OS r =0.141, p=0.03).
Conclusions:
Inter–eye asymmetry of rim area and disc area (IEARADA) is a novel parameter for HRT–based diagnosis of glaucoma. Knowledge of its distribution in various populations may aid in clinical diagnosis of asymmetric glaucomatous damage