Some of the most urgent calls 20/20 Onsite takes come from study teams outside ophthalmology. A drug shows a possible ocular signal, FDA asks for ocular safety data, and a site built for infusions or lung function testing suddenly needs slit lamp exams. There is no single ophthalmic assessment schedule for every drug with potential ocular toxicity. Monitoring depends on the drug's mechanism, nonclinical and clinical findings, therapeutic class, and FDA feedback. FDA-approved drugs with established ocular toxicity offer clear examples, often pairing visual acuity and slit lamp exams at baseline with follow-ups tied to dosing. Protocols may add optical coherence tomography (OCT), intraocular pressure (IOP), or fundus imaging when the risk reaches past the cornea. This guide walks through what FDA labels for these drugs require, which exams fit which risks, and how to get them done at your sites without slowing enrollment.
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The clearest public examples of what FDA may expect come from the labeling of approved drugs with established ocular toxicity. Antibody-drug conjugates (ADCs) with a boxed ocular warning spell it out in detail. Three current labels show the pattern:
These exams do more than document risk. On the Blenrep label, the exam grade decides whether a dose is given, held, or reduced. Blenrep is also available only through a Risk Evaluation and Mitigation Strategy (REMS) because of its ocular risk.
The pattern extends across the drug class. A 2024 review in Current Ophthalmology Reports found that 3 of 11 FDA-approved ADCs have been linked to corneal pseudomicrocysts, with incidence ranging from 41% to 100% of patients. For a sponsor developing a drug in a similar class, these labels are a useful reference point for what FDA may ask for during development. They are not a guaranteed requirement for every program.
Start with where in the eye the risk sits. Corneal and ocular surface risk typically involves slit lamp exams and visual acuity, as the ADC labels show. Retinal or optic nerve risk often involves imaging, and pressure-related risk often involves IOP measurement. The table below is a starting point, and the final selection depends on the drug's mechanism, nonclinical and clinical findings, therapeutic class, and FDA feedback.
Matching Ophthalmic Assessments to Ocular Risk
| Risk Area | Example Findings | Core Assessments | When It Is Typically Included |
|---|---|---|---|
| Cornea and ocular surface | Keratopathy, corneal epithelial changes, dry eye, blurred vision | BCVA, slit lamp exam of the anterior segment | Baseline and before dosing, as on the labeled ADCs |
| Retina and macula | Retinal or macular changes | OCT, dilated fundus exam, fundus imaging, BCVA | When class data or nonclinical findings point to retinal risk |
| Optic nerve | Optic nerve changes, visual field loss | Dilated fundus exam, fundus imaging, OCT of the optic nerve, visual fields | When class data or a regulator raises optic nerve concerns |
| Intraocular pressure | IOP elevation | Tonometry, slit lamp exam | When the mechanism or early data suggest pressure effects |
| General ocular safety | Unexpected ocular adverse events | BCVA, slit lamp exam, IOP, dilated fundus exam | At baseline, so later findings have a comparison point |
Baseline matters as much as the follow-up schedule. If baseline exams use a different chart, device, or technician than follow-ups, a real safety signal can be hard to separate from measurement noise. Our guide to BCVA, OCT, and IOP testing in clinical trials covers how each method is standardized. The same thinking applies outside oncology, as our review of GLP-1 clinical trial eye safety shows.
Oncology, respiratory, and Phase 1 units are built for their own therapeutic area, not for slit lamp exams or retinal imaging. When an ocular requirement lands, those sites need calibrated equipment, certified technicians, and protocol-specific procedures, often on short notice. That is usually the point where 20/20 Onsite gets the call. Three programs show what that looked like.
"When the ocular requirement comes after the protocol is written, the hardest part isn't the exam itself. It's getting every site to perform it the same way, on the same schedule as dosing, starting next week."
An ocular safety plan works when it defines the risk, the exams, the timing, and the people who perform them before the first dose. Work through these steps with your clinical and operations teams.
The delivery model should match each site. A site with certified ophthalmic staff can keep exams in-house. A site without them can bring in a Mobile Clinic Suite, host a Mobile Vision Pod, or have a Mobile Vision Clinic come to participants. Our guide to designing ocular assessment endpoints covers how to write those specifications into the protocol.
Talk to an Ophthalmic Trial Specialist to map your ocular safety plan to your sites.
For drugs with established ocular toxicity, FDA labeling shows what monitoring can look like: scheduled exams, often tied to dosing, performed by eye care professionals. Building that into the protocol early costs less than adding it after sites are active. 20/20 Onsite delivers BCVA, slit lamp biomicroscopy, IOP, OCT, visual fields, and fundus photography at the point of need (assessments can be customized with our equipment as needed), alongside each site's existing capacity.
Schedule a Consultation to plan ocular safety assessments for your next study.
Plan Ocular Safety Monitoring Before First Dose
Talk with 20/20 Onsite about the ophthalmic exams, schedule, and delivery model your study needs.
Schedule a ConsultationThere is no single schedule that applies to every drug with potential ocular toxicity. FDA-approved drugs with established ocular toxicity offer clear examples: their labels pair visual acuity, often BCVA, and a slit lamp exam of the anterior segment with follow-ups tied to dosing, performed by an eye care professional. Protocols may add OCT, fundus imaging, IOP, or visual fields when the risk involves the retina, optic nerve, or eye pressure. The final mix depends on the drug's mechanism, nonclinical and clinical findings, therapeutic class, and FDA feedback.
Which Drugs Carry FDA Boxed Warnings for Ocular Toxicity?Several ADCs carry a boxed warning for ocular toxicity, including Blenrep (belantamab mafodotin-blmf), Elahere (mirvetuximab soravtansine-gynx), and Tivdak (tisotumab vedotin-tftv). Each label requires ophthalmic exams with visual acuity and a slit lamp exam before treatment and during dosing. Blenrep is also available only through a REMS because of its ocular risk.
How Often Should Ophthalmic Exams Happen During a Trial With Ocular Toxicity Risk?Exam frequency varies by drug and by the size of the risk, and on labeled drugs it often follows the dosing schedule. On current labels, Blenrep requires an exam before each dose, Tivdak before every cycle for the first nine cycles, and Elahere every other cycle for the first 8 cycles. All three also call for exams whenever new symptoms appear. Set the schedule in the protocol with clear windows, so exams land close to dosing at every site.
Who Can Perform Ocular Safety Exams at Non-Ophthalmic Trial Sites?A specialized ophthalmic trial partner can perform them when a site lacks eye care staff or equipment. 20/20 Onsite is dedicated exclusively to ophthalmic assessments for clinical research. It delivers them through Mobile Vision Clinics, Mobile Vision Pods, and Mobile Clinic Suites, or alongside a site's existing capacity. Talk to an Ophthalmic Trial Specialist to check fit for your sites.
What Happens When FDA Adds Ophthalmic Assessments Mid-Trial?Each affected site needs calibrated equipment, certified technicians, and procedures aligned to the amended protocol, often within existing visit windows. When FDA added ophthalmic assessments midway through four trials, 20/20 Onsite brought 65 sites to full operation in 8 weeks. Our article on why eye exams matter in non-ophthalmic trials covers how to prepare before that happens.
How Is Ocular Toxicity Graded During Treatment?Grading depends on the drug and the protocol. On the Blenrep label, the overall grade reflects the worst finding in the worst affected eye, based on either the corneal exam or a change in BCVA. That grade then drives whether the next dose is given, held, or reduced, so consistent exam technique across sites directly affects dosing decisions.
Do Non-Oncology Trials Need Ocular Safety Monitoring?Some do, when a drug class has a suspected ocular signal or a regulator requests ocular safety data. In one Phase 3 chronic cough trial, FDA mandated an ocular substudy at respiratory sites that had no ophthalmic resources. Metabolic programs such as GLP-1 trials have also drawn attention to eye safety, which our GLP-1 ocular safety monitoring article covers.