Detecting the Progression of Normal Tension Glaucoma: A Comparison of Perimetry,Optic Coherence Tomography,and Heidelberg Retinal Tomography

Purpose

We compared the abilities of Stratus optical coherence tomography (OCT), Heidelberg retinal tomography (HRT) and standard automated perimetry (SAP) to detect the progression of normal tension glaucoma (NTG) in patients whose eyes displayed localized retinal nerve fiber layer (RNFL) defect enlargements.

Methods

One hundred four NTG patients were selected who met the selection criteria: a localized RNFL defect visible on red-free fundus photography, a minimum of five years of follow-up, and a minimum of five reliable SAP, Stratus OCT and HRT tests. Tests which detected progression at any visit during the 5-year follow-up were identified, and patients were further classified according to the state of the glaucoma using the mean deviation (MD) of SAP. For each test, the overall rates of change were calculated for parameters that differed significantly between patients with and without NTG progression.

Results

Forty-seven (45%) out of 104 eyes displayed progression that could be detected by red-free fundus photography. Progression was detected in 27 (57%) eyes using SAP, 19 (40%) eyes using OCT, and 17 (36%) eyes using HRT. In early NTG, SAP detected progression in 44% of eyes, and this increased to 70% in advanced NTG. In contrast, OCT and HRT detected progression in 50 and 7% of eyes during early NTG, but only 30 and 0% of eyes in advanced NTG, respectively. Among several parameters, the rates of change that differed significantly between patients with and without progression were the MD of SAP (p = 0.013), and the inferior RNFL thickness (p = 0.041) and average RNFL thickness (p = 0.032) determined by OCT.

Conclusions

SAP had a higher detection rate of NTG progression than other tests, especially in patients with advanced glaucoma, when we defined progression as the enlargement of a localized RNFL defect. The rates of change of the MD of SAP, inferior RNFL thickness, and average RNFL thickness differed between NTG patients with and without progression.