A 61 year old male attended glaucoma clinic and complained of fluctuating vision throughout the day, describing it as especially hazy in the morning time.

His previous ocular history was significant for bilateral radial keratotomies (RK) performed in 1986 for high myopia, left eye amblyopia and bilateral primary open angle closure glaucoma (POAG).  The patient was intolerant to several IOP lowering drops, and at the time of presentation he was taking Xalatan to both eyes nightly and brimonidine twice daily to the right eye. 

On presentation, his visual acuity (VA) was 6/9.5 unaided right eye  and 6/24 in the left eye. Sixteen deep RK incisions were observed in both eyes. His IOP was 21mmHg right eye and 19mmHg left eye on GAT. His angles were non-occludable on gonioscopy bilaterally and on examination of his optic discs his CDR was right eye:0.9 and left eye:0.3.

Anterior segment topography demonstrated fluctuating flat keratometry (K1) and steep keratometry (K2) values throughout the day. 

He underwent bilateral selective laser trabeculoplasties (SLT) in order to lower IOP and reduce vision fluctuations secondary to IOP changes, however one month post laser he reported no improvement in visual fluctuations in his right eye despite attaining a satisfactory IOP post SLT (right eye: 16mmHg, left eye:14mmHg).

Six months later, his IOP was uncontrolled in the right eye (26mmHg) and he had a visually significant posterior subcapsular cataract. 24-2 Humphrey visual field testing also revealed significant glaucoma field progression (inferior nasal step and superior arcuate defects). Optical coherence tomography of the optic disc also revealed a thin retinal nerve fibre layer and  ganglion cell layer in the right eye. 

He underwent combined surgery of right Preserflo Ab Externo Microshunt with Mitomycin C alongside right phacoemulsification and intraocular lens implantation procedures  

One day later he complained of a right painful, red eye alongside reduced visual acuity. On examination right eye IOP was 45mmHg. He received 500mg intravenous acetazolamide and underwent a RE anterior chamber paracentesis, following which his RE IOP was 15mmHg. The following morning IOP in the right eye was 30mmHg and he was admitted to hospital, whereby  capsular material that was blocking the Preserflo implant was identified and flushed. 

One day post later, his vision was 6/24 unaided in the right eye, IOP was 4mmHg and he had a diffuse, functioning bleb. OCT macula showed that the CMO had resolved. 

The patient did not experienced any subjective day-time visual fluctuations in his right eye post-operatively. 

This case highlights the diagnostic challenges of diagnosing and assessing glaucomatous progerssion in a patient with fluctuating vision secondary to RK, as well as reporting on complications of minimally invasive glaucoma surgery.