Abstract
To investigate the retinal nerve fibre layer (RNFL) changes after an acute attack of phacomorphic angle closure. This prospective study involved ten cases of phacomorphic angle closure that underwent cataract extraction and intraocular lens insertion after intraocular pressure lowering. Apart from visual acuity and intraocular pressure (IOP), RNFL thickness and vertical cup disc ratio (VCDR) were measured by optical coherence tomography (OCT) at 3–9 months post attack. Humphrey visual field assessment was performed at 9 months post attack. All cases had mean phacomorphic duration of <5 days. Postoperatively, best correct Snellen visual acuity was 0.4 ± 0.2 and IOP at 9 months was 11.0 ± 3.1 mmHg. There was no difference in VCDR and RNFL between the attack and contralateral eye at 3 months post attack (both p = 0.4). At 9 months post attack, there was significant thinning in the average (p = 0.01), superior (p = 0.01), and inferior (p = 0.006) RNFL. There was no significant difference in the pattern standard deviation (PSD) between the two eyes on the Humphrey visual field nor was there any correlation between PSD severity and RNFL thinning (all p > 0.2. Patients with <5 days duration of phacomorphic angle closure are likely to have reasonable postoperative vision. An acute episode of phacomorphic angle closure can trigger an accelerated RNFL thinning despite normal IOP and open angles, most noticeable in the superior and inferior quadrants, occurring between 3 and 9 months post attack. Glaucomatous optic neuropathy in the attack eye was evident by OCT but not by visual field assessment at the same time interval.
Highlights
Phacomorphic angle closure is a secondary angle closure caused by a swollen and mature cataract obstructing the drainage angle, leading to an acute elevation of intraocular pressure (IOP) and potential glaucomatous optic neuropathy (GON) if not treated timely
There was no significant difference in the pattern standard deviation (PSD) between the two eyes on the Humphrey visual field nor was there any correlation between PSD
optical coherence tomography (OCT) for retinal nerve fibre layer (RNFL) has been used to evaluate the damage after a single episode of acute primary angle closure and to offer a more objective supplement to the information provided by Humphrey visual field assessments
Summary
Phacomorphic angle closure is a secondary angle closure caused by a swollen and mature cataract obstructing the drainage angle, leading to an acute elevation of intraocular pressure (IOP) and potential glaucomatous optic neuropathy (GON) if not treated timely. The initial aim of treatment of phacomorphic angle closure is to lower the IOP with combinations of topical anti-glaucoma medications, systemic acetazolamide, intravenous mannitol and or argon laser iridoplasty (ALPI) [1]. All of these treatments have been established to be effective initial treatments with no evidence showing superiority of one over the other at the moment. The term phacomorphic glaucoma is used if there resultant GON [1] which has been previously quantified and reported using visual field (VF) assessments or clinical cup-disc ratio monitoring Both of these parameters are variable and not entirely objective especially when phacomorphic angle closure often affects an elderly population where dementia and neglect are common [2]. The use of optical coherence tomography (OCT) for retinal nerve fibre layer (RNFL) and optic nerve head analyses is non-invasive, requires minimal patient cooperation, and provides objective and early assessment of GON in patients with phacomorphic angle closure
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