Combining a minimally invasive glaucoma surgery (MIGS) implant with cataract surgery markedly slows visual field loss compared with cataract surgery alone.
This is according to an analysis of data from the HORIZON trial published in Ophthalmology Glaucoma.
In a post hoc analysis, researchers observed that patients who received a Hydrus Microstent experienced a 44.6% reduction in the mean rate of mean deviation decline over five years.
Standalone cataract surgery showed a progression rate of -0.55 dB/year, whereas eyes with the microstent progressed at a slower rate of -0.30 dB/year.
This multicentre study was conducted by investigators from the UK, US and Canada.
Using a Bayesian hierarchical model, they analysed data from 517 eyes, allowing them to isolate true rates of change by filtering out noise and learning effects in the perimetry data.
The study found that the visual field preservation benefit was not due to early postoperative intraocular pressure (IOP) spikes or irregular mean treated clinic pressures. Instead, the difference was mainly driven by stabilised mean and peak pressure metrics.
The authors said: ‘Taken together, these results support that the [Hydrus Microstent] helps preserve [visual field] by better controlling IOP independently of pressure drops. Our findings highlight the importance of evaluating how interventions impact disease progression, not just IOP alone.’
They suggest the microstent provides vital protection against pressure fluctuations that are often undetectable during routine exams or when patients miss appointments.
Study limitations include the original HORIZON trial not being designed to detect differences in visual field progression, the difficulty of separating the effects of individual IOP parameters due to correlations between metrics, and the lack of a prospective trial focused solely on this aspect.
The authors recommend future research use time-varying models to assess the impact of short-term washout periods and inter-visit pressure variations.
They also propose exploring baseline predictors of treatment success to help clinicians refine patient selection for minimally invasive glaucoma surgery.
