BostonSight’s Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) device was the subject of a recent clinical investigation evaluating its use as a therapeutic intervention for neurotrophic keratitis (NK).
Presented during the 2026 Association for Research in Vision and Ophthalmology (ARVO) annual meeting, the findings offer statistically significant potential for this patient base.
Let’s start with the basics: tell me about PROSE.
What it is: This is an FDA-cleared (Class II), customized, non-surgical scleral lens device treatment for restoring visual/physiological function in any ectasia and ocular surface disease (OSD; see here).More specifically: The device is:
- Constructed with a removable, nickel-sized transparent dome
- Composed of gas permeable plastic that enables oxygen to reach the eye’s surface
- Filled with a preservative-free saline solution (prior to insertion) for constant lubrication to the cornea
And how does it work, exactly?
The prosthetic device is placed under the eyelid (on the sclera) and passes over the cornea—without making contact—to create a smooth surface over the distorted, damaged, or diseased cornea.
A couple of notes:
- Prior to insertion, the space between the device and cornea is filled with a preservative-free saline solution for constant lubrication to the ocular surface.
- This device is applied on a patient’s eye in the morning and removed at night, before they go to bed
The treatment duration: Typically involves 5-to-10-day-long visits, frequent follow-ups over the first 6 months, and annual fit evaluations afterward.
So what’s the end-game goal with this?
Two key outcomes: For the PROSE device to protect the cornea, while also providing the ocular surface tissue valuable healing time—not to mention pain relief for patients.
See here for how the device differs from a scleral lens (hint: customization is key).
And where does this new research fit in?
While PROSE has already demonstrated therapeutic benefits for OSD patients, their use for NK across Mackie Stages had not yet been evaluated … until now.
Also, a quick refresh: The Mackie classification system grades NK into progressive stages (based on severity):
- Stage 0: Altered or reduced corneal sensation prior to any appearance of ocular surface damage
- Stage 1: Mild epithelial changes (such as punctate keratopathy)
- Stage 2: Persistent epithelial defects with smooth, rolled edges
- Stage 3: Severe corneal ulceration, stromal forming, and perforation risk
Got it. Now talk about the study.
Investigators in this retrospective observational analysis reviewed 87 eyes (of 87 patients; mean age 46.4 ± 22.9 years; 53 female; 46 right eye ) with NK across the following Mackie stages:
- Stage 0 (n = 8)
- Stage 1 (n = 57)
- Stage 2 (n = 17)
- Stage 3 (n = 5)
The evaluation period: November 2008 to September 2023
And what was analyzed?
Investigators used paired T-tests and Wilcoxon rank tests to evaluate the change in visual function before and after patients underwent PROSE treatment (significant set at p < 0.05).
The functional outcomes:
- Visual acuity (VA) improvement within 6 months
- Mackie stage improvement within 6 months
Next up: the data.
For starters: The average length of follow-up was 4.07 years.
Across the entire cohort of 87 eyes, “statistically significant improvements” were observed:
- Mean Mackie stage improved from 1.22 ± 0.69 at baseline to 0.55 ± 0.54 after PROSE (p<0.001).
- Mean logMAR VA improved from 0.88 to 0.58 (p<0.001)—a Snellen equivalent shift from roughly 20/152 to 20/76.
Tell me more.
A sub-analysis also found a statistically significant improvement in mean Mackie stage in baseline:
- Stage 1 (0.58 ± 0.50, p <0.001)
- Stage 2 (0.71 ± 0.69, p < 0.001)
And baseline Stage 3 patients demonstrated improvement in mean Mackie stage (0.6 ± 0.55) that “approached statistical significance (p = 0.053),” according to investigators.
What else did this sub-analysis discover?
VA outcomes, with mixed results for all three Mackie stages. Case in point: A significant improvement was observed in patients with:
- Mackie Stage 1 (0.77 to 0.49, p-value <0.001)
- Mackie Stage 2 (1.17 to 0.80, p value < 0.001)
Conversely, the Mackie Stage 3 group had a “slight worsening of VA” that was not statistically significant (1.23 to 1.25, p=0.86).
Post-PROSE initiation, how long did it take to achieve the lowest Mackie stage?
The average time was 31.18 days.
Also worth noting: Nearly all (90.9%) of baseline Stage 2 or 3 cases achieved epithelial defect resolution in a mean of 32 days.
How very interesting … so what did researchers conclude?
First: Mackie Stage and logMAR VA were statistically significantly decreased following PROSE treatment among eyes with NK.
And, in addition to that initial finding: Patients with Mackie Stage 1 and 2 NK may be more sensitive to changes linked with PROSE treatment.
Any recommendations for future research?
Indeed—but before we note those, it’s imperative to address a few of the study’s limitations:
- This was a retrospective observation chart review in which there was no external control group to establish causation.
- The endpoint for the lowest Mackie stage at the 6-month mark doesn’t enable a fixed, pre-specified interval.
- Patients were not randomized, as researchers selected who received PROSE, creating the potential for bias.
- The analysis was conducted by clinicians associated with BostonSight, also potentially introducing bias to the results.
- Each of the patient groups varied in size, with just five eyes included with Mackie Stage 3.
Moving forward: Investigators advised that a longitudinal prospective study is needed to further evaluate PROSE for NK—and dive even deeper into the treatment’s benefits for this patient group.
Noted. And in the meantime?
Check out prior research on the impact of PROSE treatment for other forms of OSD.