Systematic Review Targets the Eye Findings That Shape Care in Non-Functioning Pituitary Adenoma
Non-functioning pituitary adenomas account for roughly 30% to 40% of pituitary tumours, and their clinical impact often begins where the optic chiasm lies closest to the expanding sellar mass. When the optic pathway is compressed, patients can develop visual field loss, reduced visual acuity, and impaired colour vision long before endocrine effects become obvious. In that setting, ophthalmic testing is not a courtesy check. It is central to treatment planning, surgical timing, and post-treatment surveillance.
A new systematic review protocol in BMJ Open sets out to map how eye assessments are being used before and after treatment in adults with radiologically confirmed non-functioning pituitary adenomas involving the optic pathway. The goal is straightforward but clinically important: bring order to a monitoring process that currently varies widely across centres. Different hospitals use different tests, different follow-up schedules, and different frameworks for judging improvement or deterioration. The lack of international consensus leaves clinicians with uneven evidence when deciding which visual measures deserve the most weight.
One sentence captures the practical problem: patients with the same tumour anatomy may undergo very different visual surveillance depending on where they are treated.
Optic Pathway Involvement Makes Ophthalmic Assessment a Core Treatment Tool
The protocol focuses on adults with radiologically confirmed tumours and documented optic pathway involvement, which is the subgroup in whom vision-related outcomes are most likely to influence management. Compression of the optic chiasm can produce field defects that may be subtle at first and functionally disabling later. Visual acuity can remain relatively preserved even as peripheral loss progresses, so single-test strategies can miss clinically meaningful change. Colour vision impairment adds another layer, particularly when optic nerve dysfunction is evolving or partially recovering after intervention.
This is why surveillance matters before and after treatment. Pre-treatment assessment helps define the degree of compromise and establishes the baseline against which recovery can be judged. After surgery or other intervention, serial testing can reveal whether the optic apparatus is improving, stabilising, or continuing to deteriorate. In pituitary disease, those distinctions affect more than documentation; they can shape the urgency of re-intervention, radiation planning, and long-term monitoring.
The planned review will examine which ophthalmic assessments have been used, when they were performed, and how consistently they were reported. That includes the practical problem of comparing studies that may not have used the same visual endpoints or the same follow-up intervals. Without a common structure, the literature becomes difficult to apply at the bedside, even when individual studies appear informative.
Broad Search Strategy and Strict Study Selection Aim to Capture the Full Evidence Base
The review team plans searches across Ovid MEDLINE, Ovid Embase, CENTRAL, Scopus, Web of Science, and grey literature sources from inception. That approach is designed to capture both published and less visible evidence, which matters in a field where ophthalmic testing may be embedded within surgical or endocrine series rather than reported as a primary outcome. Eligible studies will include randomized and non-randomized designs, as long as they involve adults aged 18 years or older and document ophthalmic assessments in the setting of optic pathway involvement.
Case series with fewer than 10 participants will be excluded. The threshold is sensible for a review intended to inform practice rather than gather anecdotal signals, since very small series can overstate benefit or obscure variability in outcome measurement. Two reviewers will independently screen titles, abstracts, and full texts in duplicate. They will also extract data in duplicate, which reduces avoidable error when the evidence base spans multiple study designs and reporting styles.
Study quality will not be treated as a one-size-fits-all exercise. The protocol specifies design-specific risk-of-bias tools, including the Risk-of-Bias Tool for Randomised Trials, the Risk of Bias in Non-randomised Studies of Interventions, Joanna Briggs Institute checklists, and the Appraisal tool for Cross-Sectional Studies. That mixed-method appraisal strategy reflects the likely diversity of the evidence base. Ophthalmic surveillance in pituitary disease is unlikely to be represented by one uniform trial format, so the assessment plan needs to be flexible enough to handle controlled studies, observational cohorts, and cross-sectional reports without flattening them into the same quality category.
What the Review Can Clarify About Visual Recovery and Residual Deficit
The value of this project lies in standardising expectations around what should be measured, and when. In pituitary adenoma care, visual recovery after treatment is often discussed in broad terms, yet the underlying measurements may differ substantially from one study to another. A patient may show improvement in one domain and persistent loss in another. If the published literature mixes acuity, field testing, colour discrimination, and follow-up timing without a clear framework, clinicians are left with fragmented evidence.
This protocol is positioned to identify those gaps. It may reveal whether certain ophthalmic tests are consistently reported, whether some are rarely used despite clinical relevance, and whether post-treatment surveillance is reported more rigorously than pre-treatment assessment. It may also expose how often studies provide enough detail to link visual change with anatomical optic pathway involvement rather than with tumour size alone. For a disorder where decompression can produce partial recovery but not complete normalization, the granularity of measurement matters.
The review will not generate new patient-level outcomes, and it will not settle treatment controversies on its own. What it can do is define the current measurement habits of the field, which is often the first step toward a more usable evidence base. If the literature shows wide heterogeneity in ophthalmic surveillance, future work can move toward consensus-based testing pathways instead of repeated reinvention at each centre.
Registered Before Analysis Begins
The protocol was prospectively registered with PROSPERO under CRD420261337096, a detail that adds transparency to the planned methods and reduces the risk of selective post hoc changes. No ethical approval is required because the project synthesises previously published data. Findings will be submitted for peer-reviewed publication and presented at national and international conferences.
The most immediate limitation is already visible: a systematic review can only be as coherent as the studies it inherits. If ophthalmic assessments have been inconsistently defined across the literature, even a carefully executed synthesis may end with variability rather than certainty. The next question is whether the published evidence is rich enough to support any practical standard for timing, test choice, and follow-up after treatment of non-functioning pituitary adenomas with optic pathway involvement.