Purpose:
To study the change in optic nerve head (ONH) topography after reduction of intraocular pressure (IOP) in exfoliation glaucoma (ExG) and normal tension glaucoma (NTG).
Methods:
Included were 20 eyes of 20 patients (median age 73 years; range 53-84 years) with ExG and 24 eyes of 24 patients (age 67 years; 53-86 years) with NTG before deep sclerectomy performed.Scanning laser ophthalmoscopy of the ONH was performed with the Heidelberg Retina Tomograph (HRT) before and three months after the operation.
Results:
Three months after deep sclerectomy, median (range) IOP was significantly reduced in ExG eyes from 24 (16-33) mmHg to 13 (4-18) mmHg (p<0.001) and in NTG from 15 (11-20) mmHg to 10 (3-20) mmHg (p<0.001). The eyes with IOP reduction of 30% or more were included in HRT analysis In ExG eyes (n=17) most HRT parameters showed a significant change (improvement) after the operation compared to pre-operative values (Table 1). In NTG eyes (n=20) HRT parameters were comparable before and after the operation. In NTG eyes with IOP reduction of 6 mmHg or more, RV was significantly increased, and the increase in RA and RNFLCSA, and the decrease in CA and CV were of borderline significance (Table 2).
Conclusions:
A marked IOP reduction will cause changes in the HRT parameters indicating cup reversal in eyes with high-pressure glaucoma, and also in low-tension glaucoma if the absolute IOP reduction is large enough. IOP changes should be accounted for when using HRT for follow-up of the ONH.
Keywords: optic disc • topography • imaging/image analysis: clinical