Primary Open Angle Glaucoma and Post-LASIK Keratectasia

The patient presented herein is a 52-year-old woman suffering from primary open angle glaucoma (POAG) in both eyes. She has no history of systemic disorders and is not on any systemic medications. She underwent laser in situ keratomileusis (LASIK) 9 years ago for refractive error of -5.50-3.00×180 in both eyes, and was diagnosed with glaucoma 7 years afterwards. Her ocular examination when I saw her for the first time two years ago was as follows. Best corrected visual acuity (BCVA) was 6/10 and 3/10 in the right and left eyes with -4.00-1.00×30 and -13.00-5.50×180 respectively while wearing rigid gas permeable (RGP) contact lenses. Slitlamp examination revealed a LASIK flap and signs of corneal ectasia in the left eye, mild nuclear sclerosis changes were evident in both eyes and other slitlamp findings were unremarkable. Orbscan images (Orbscan II, Bausch & Lomb, Salt Lake City, USA) are shown in figure 1. Gonioscopy revealed widely open anterior chamber angles with no synechiae. Intraocular pressure (IOP) by Goldmann applanation tonometry (GAT) was 10 and 12 mmHg in the right and left eyes respectively while receiving latanoprost (once daily), timolol (twice daily) and dorzolamide (twice daily) in both eyes. Central corneal thickness (CCT) measured 431 and 322 microns in her right and left eyes respectively. Fundus examination revealed average-sized discs with vertical cup to disc ratios of 0.9 and 0.8 in the right and left eyes respectively, together with inferior rim loss; the macula, vessels and periphery were unremarkable. Baseline automated perimetry (Humphrey Field Analyzer II, Humphrey Systems, Carl Zeiss Meditec Inc., Dublin, USA) is shown in figure 2. Considering that target IOP had been achieved, I suggested that she be followed closely with medications. She was observed for two years, but on her last examination I noticed suspicious progression of cupping and visual field defects especially in her left eye. The follow-up visual field and Stratus OCT (Carl Zeiss Meditec, Dublin, USA) scans of the peripapillary nerve fiber layer are shown in figures 3 and 4. At this time, IOP was measured by the ocular response analyzer (ORA) (Reichert Ophthalmic Instruments, Buffalo, USA) which