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RNFL, macula thinner in patients with POAG family history
Researchers found significantly thinner retinal nerve fiber layer and macular ganglion cell complex in subjects with a family history of primary open-angle glaucoma using Fourier domain optical coherence tomography, according to a new study from the British Journal of Ophthalmology.
The analysis by Rolle and colleagues included 271 eyes divided into groups: 163 eyes of first- and second-degree relatives (85 healthy, 40 with ocular hypertension and 38 with preperimetric glaucoma); and 108 eyes of subjects without a positive family history (60 healthy and 48 with preperimetric glaucoma).
All participants underwent a complete eye examination that included: best corrected visual acuity, ultrasound pachymetry, slit lamp biomicroscopy of the anterior and posterior segments, and a variety of other tests.
The comparison of retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) thickness between normal and healthy eyes with a positive history of glaucoma showed significant differences for superior RNFL parameter (p=.04), GCC average (p=.001), GCC superior (p=.005), GCC inferior (p=.004), and global loss volume percentage (p=.009).
All measurements were significantly thinner (p<.05) in the eyes with ocular hypertension and preperimetric glaucoma, while the percentage loss of ganglion cells in the macula was higher compared to healthy eyes, according to the study.
Researchers concluded that all RNFL and GCC parameters in glaucomatous eyes showed significant damage compared with healthy eyes. They added that it is “during the early stage of the disease where it is possible to make effective treatment interventions to slow the loss of nerve fibers in patients before they manifest as onset of visual field alterations.”
Disclosure: The researchers have no financial disclosures.
Perspective
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The role of genetics in primary open-angle glaucoma continues to evolve, concordant with emerging optical coherence tomography techniques that can assess microstructural changes of the inner retinal layers evident in glaucoma.
In their study, Rolle and colleagues begin to bridge the gap between genetic determinants in glaucoma and implementation of Fourier domain OCT glaucoma analysis to identify patients in the preglaucoma stage. One poignant finding in the subgroup analysis of healthy eyes with a positive family history was that despite showing no evidence of glaucoma, the ganglion cell complex (GCC) and retinal nerve fiber layers (RNFLs) were thinner compared to the control group. It is unclear if some of these patients have entered the preglaucoma stage or genetically maintain a thinner GCC and RNFL.
Likewise, the authors highlight the fact that the ocular hypertensive eyes with a positive family history also demonstrated attenuated GCC and RNFL relative to the control group. Clinically, and as seen in a previous FD-OCT study that looked at the GCC and RNFL in ocular hypertensive patients, we typically do not expect to see such changes.
At present, it is unclear how this fits into the risk assessment scheme for ocular hypertensive patients, who, by definition, have no evidence of glaucoma. In general, this study reinforces the importance of integrating information about a patient’s family history with OCT metrics to potentially identify glaucoma suspects prior to development of optic nerve or visual field changes.
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Rolle T. Br J Ophthalmol. 2014; doi:10.1136/bjopthalmol-2013-304519