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Woo-Jin Kim, Kyung-Nam Kim, Chang-Sik Kim; Relationship between preoperative IOP and progression of the RNFL thinning after glaucoma surgery. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2711.
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Several studies reported that the rate of visual field deterioration and retinal nerve fiber layer (RNFL) thinning after glaucoma surgery were slower than before surgery. However, we experienced patients showing significantly decreased RNFL thickness for a few months after surgery, despite well-controlled intraocular pressure (IOP). Therefore, the purpose of this study is to determine the clinical factors affecting changes in RNFL thickness in the early postoperative period after glaucoma surgery.
The medical records of 60 eyes of 60 patients, who underwent trabeculectomy or Ahmed glaucoma valve implantation for uncontrolled IOP, were reviewed retrospectively. Patients with optic neuropathy other than glaucoma, macular disease, or progressive retinopathy were excluded. The RNFL thickness was measured using spectral domain optical coherence tomography, before and 3–6 months after surgery. Changes in RNFL thickness and associated clinical factors were analyzed.
The mean age of the patients was 55.4 ± 13.6 years. The IOP decreased from 37.4 ± 10.8 mmHg to 14.8 ± 3.5 mmHg. The RNFL thickness was significantly decreased from 75.6 ± 17.7 μm to 70.2 ± 15.8 μm (p<0.001). The change in RNFL thickness was significantly correlated with preoperative IOP (r = 0.689, p<0.001). There was no significant correlation between preoperative IOP and RNFL thickness changes in patients with preoperative IOP < 36.5 mmHg, which was the median IOP before surgery (r = 0.175, p=0.354). However, in patients with preoperative IOP > 36.5 mmHg, the RNFL thickness change was significantly associated with the preoperative IOP (r = 0.519, p=0.003).
A significant decrease in RNFL thickness was detected, although IOP was well-controlled for a few months after glaucoma surgery. A higher preoperative IOP was associated with greater reduction in RNFL thickness.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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