gms | German Medical Science

Recently, scanning laser tomography (SLT) for the evaluation of the optic disc and scanning laser polarimetry (SLP) for the analysis of the retinal nerve fiber layer have become increasingly important in glaucoma diagnostics. But until today long-term results of the different diagnostic techniques are missing which enable the follow-up of glaucoma for many years with high precision and to validate the diagnostic importance of the different techniques.

Therefore, we want to compare evidence based long-term results of ophthalmologic standard examination techniques, SLT and SLP of NTG and POAG patients. Forty-eight POAG patients (average age 62.8 years, follow-up 59.1 +/- 1.7 months) and forty-nine NTG patients (average age 65.5 years, follow-up 59.9 +/- 1.8 months) were enrolled. Besides ophthalmologic standard examinations including automated perimetry (Oculus, Twinfield 30°), SLT (TopSS, LDT, USA) and SLP (NFA II and GDx, LDT, USA) were performed. Progression of glaucoma was defined as a decrease in perimetry of at least one stadium according to the glaucoma classification of Aulhorn and follow-up results of NTG and POAG patients were compared.

In automated perimetry, 17 of 49 NTG patients and 12 of 48 POAG patients showed progression. In NTG, the intraocular pressure (IOP) was not statistically different in the two groups, whereas in the stabile but not in the progressive POAG group a significant lowering of IOP from 18.2 mmHg to 14.6 mmHg could be achieved.

In SLT, there was no significant progression in both POAG groups and in the NTG group without progression. But in the NTG group with progression the SLT parameters 'average excavation depth', 'neuroretinal rim area', and especially 'cupping shape' became worse. Polarimetrical results, however, revealed a significant decrease especially of the superior average nerve fiber layer thickness which could also be observed tendentially but not significantly in the other areas. The decrease in polarimetry was larger in eyes with initially thicker nerve fiber layers as in those with initially thinner nerve fiber layers.

In the long-term follow-up we found only little progression in SLT and perimetry. The most pronounced finding was a significant loss of nerve fiber layer thickness especially in the upper hemisphere in NTG and POAG patients. These results with new scanning laser technologies are in accordance to clinical and histological findings demonstrating the importance of nerve fiber diagnostics in glaucoma.

In the opposite to POAG patients the IOP was not different in NTG patients with and without disease progression pointing to a larger importance of additional risk factors.

Supported by Alfried Krupp von Bohlen und Halbach-Stiftung