Ganglion Cell Complex Map for Detecting Early Damage in High Tension and Normal Tension Glaucoma

Abstract

Glaucoma is one of the leading causes of irreversible blindness worldwide. We aimed to compare the findings of a ganglion cell complex (GCC) test with a test of the retinal nerve fibre layer (RNFL) in high and normal tension glaucoma patients. Sixty-two patients were enrolled in the study: 12 glaucoma suspects, 30 with diagnosed glaucoma and 20 with normal tension glaucoma. All subjects had visual acuity testing, tonometry, computer perimetry (Humphrey) and optical coherence tomography (OCT) with an OCT RTvue (RNFL 3.45, NHM4 and GCC). In 58 % of the glaucoma suspects, there were no changes in the perimetry results, as well as with OCT. In 42 % of the subjects, pathological changes in the GCC map preceded those of the RNFL. In patients with HTG, an almost linear correlation was found between the RNFL changes and GCC alterations. Statistical analysis showed that, in glaucoma suspects, the diagnostic value of the average GCC thickness was more significant than the average NFL thickness (0.90 [0.02] to 0.78 [0.02] µm). In 56 % of normal tension glaucoma patients, changes in the RNFL prevailed over those in the GCC. OCT diagnosis is an important tool for detecting early glaucoma changes. In glaucoma suspects, however, GCC changes can be more sensitive. In NTG, the results are still considered controversial. Nevertheless, in the majority of subjects, the RNFL changes prevailed over the GCC changes. The findings in NTG are similar to those in neurological diseases such as multiple sclerosis and Alzheimer's disease.