The Assessment of Morphological and Functional Changes in the Detection of the Initial Stage of Primary Glaucoma

Abstract

Purpose — to study morphological and functional changes in the detection of primary glaucoma progression.Patients and methods. 128 patients (128 eyes, among them — 64 eyes with primary open angle glaucoma (POAG) and 64 with primary angle closure glaucoma (PACG)) with the initial MD of –6.0 dB were examined at the Ophthalmology Center of the FMBA of Russia from May 2016 to November 2019. The values of corneal-compensated IOP were also considered: minimal (IOPmin), peak (IOPmax) and its fluctuations (IOPfluct). The progression was measured using standard automated perimetry (SAP) and spectral-domain OCT (SD-OCT). During the observation period, each patient received the average of 8.42 ± 2.08 SAP and SD-OCT. Progressive thinning of the retinal nerve fiber layer (RNFL) and its ganglion cell complex (GCC) were evaluated using SD-OCT. If RNFL and/or GCC had a trend of significant (p < 0.05) thinning, the eye was classified as having the SD-OCT progression. The correlation between the rate of progression detected by SAP (ROP1) using thinning of RNFL (ROP2) and GCC (ROP3) with other clinical parameters was analyzed.Results and discussion. Glaucoma progression was detected in 73 eyes. While the isolated use of SAP did not allow detecting progression, it was possible to detect it in 39 % cases by SD-OCT. The combination of both methods allowed detecting progression in 57 %. In both forms, ROP1 correlated with IOPmin: in PACG r = 0.41, p = 0.023 and in POAG r = 0.43, p = 0.016. In PACG, ROP2 and ROP3 correlated with the foveal choroid thickness: r = 0.46, p = 0.019 and r = 0.47, p = 0.009, respectively. At the same time, ROP3 was associated with peak IOP (r = –0.402, p = 0.025); the correlation of peak IOP with its fluctuations amounted to 0.7 (p < 0.001).Conclusion. SD-OCT is more informative than SAP in determining the progression of the initial primary glaucoma. The combination of these two methods 1.5 times increases the possibility of detecting progression in comparison with the isolated use of SD-OCT. The choroid thickness, associated with the IOP fluctuations, plays an important role in the progression of PACG.