Recent research on BioTissue’s cryopreserved amniotic membrane (CAM) device evaluated whether its application could improve collagen cross-linking (CXL) recovery among patients diagnosed with progressive keratoconus.
The results from this study were presented by Melanne Rosetta, OD, during the 2025 American Academy of Optometry (AAO) annual meeting in Boston, Massachusetts.
Let’s begin with a look at amniotic membranes.
As part of the placenta—with natural biologic actions—amniotic membrane tissue has biological properties that aid ocular surface repair.
In the context of BioTissue’s CAM device: The amniotic membrane tissue is provided by FDA-regulated tissue banks after undergoing rigorous quality control testing.
Tell me more about BioTissue’s device.
Its name: Prokera Slim
What it is: A self-retained, FDA-cleared therapeutic device made from amniotic membrane
Its indications: Include anti-inflammation and anti-scarring as well as promoting damaged eye surface healing associated with ocular surface disease (OSD).
- Specifically: The sutureless graft is designed to:
- Provide rapid symptom relief
- Reduce OSD-associated inflammation and scarring to rehabilitate corneal tissue
- Maintain patient comfort
- (Potentially) mitigate harmful side effects
And how does it do this?
The combination medical device is delivered through a self-contained conformer ring (akin to a large contact lens) that ensures its well-centered placement.
- The treatment period: Ranges from 3 to 5 days—based on a condition's severity—and may involve applying tape to a patient’s eyes (to partially close their lids after Prokera insertion).
- See here for safety instructions
- Following treatment: A follow-up visit may be required to check on the treatment’s progress and gauge the device’s potential removal from the eye.
So what conditions can it be used for?
OSD-related conditions—such as keratoconus—as well as:
- Recurrent corneal erosion (RCE)
- Epithelial basement membrane (EBMD)
- Persistent epithelial defects
- Keratitis
- Corneal scarring
- Chemical burns
Alrighty, now let’s talk new research.
Investigators conducted a single-center, retrospective, non-randomized, comparative study with the following setup:
- The participants: 46 patients (62 eyes) diagnosed with progressive keratoconus
- Ages: 29.6 ± 9.5 years
- BCVA: 0.37 ± 0.32 logMAR
- Kmax: 59.8 ± 9.6 D
- Central corneal thickness (CCT): 459 ± 42 μm
- The design: All patients underwent epi-off CXL using the Dresden protocol and then received either:
- A bandage contact lens (BCL; Air Optix Night & Day, Alcon)
- n = 39 (46 eyes)
- CAM (Prokera Slim)
- n = 42 (62 eyes)
- Postop: Moxifloxacin and prednisolone were dosed four times a day (QID) for 1 week before tapering
- A bandage contact lens (BCL; Air Optix Night & Day, Alcon)
- The timeframe: Patients were assessed before surgery as well as postoperatively at:
- 1 week
- 1 month
- 3 months
- 6 months
And what were they evaluated for?
Outcomes such as:
- Best-corrected visual acuity (BCVA)
- Maximum keratometry (Kmax)
- Complete re-epithelization
- Complications
Next up: the findings.
First, take note: A total of 14 patients received treatment with the control (BCL) in one eye and Prokera in the other eye.
- Also: For both groups, vision initially became worse before getting better (as expected) following Prokera/the BCL, according to study presenter Melanne Rosetta, OD, of Omni Eye Services and center director at Kremer Eye Center in Iselin, New Jersey.
At 6 months post-treatment, a “significantly greater proportion” of eyes in the Prokera-treated group returned to baseline compared to the control (BCL) group.
- The numbers: 85.7% versus 64.9%, p < 0.05)
And for the other timepoints, how many returned to their preop BCVA (or better) after treatment?
That varied by group. Here’s a month-by-month look for the Prokera group (versus control):
- After 1 week: 28.1% (versus 20.8% for control)
- After 1 month: 58.3% (versus 39.1% for control)
- After 3 months: 78.6% (versus 67.6% for control)
Also in the Prokera group: BCVA “significantly improved” from baseline at the 3- and 6-month postoperative mark (p < 0.05).
- Comparatively: The control group exhibited no significant improvement—at any postop time point.
Any epithelial defect development between the groups?
Investigators noted the presence of an epithelial defect at 1 week postop was comparable to that seen in the control group.
- The numbers: 69.6% (control) versus 66.1% (Prokera), p = 0.71
Similarly, the Kmax value changes were also comparable between both groups for each recorded timepoint— “with no significant difference in recovery to baseline.”
Anything observed in one group over the other?
Yes … three complications developed in the control group.
- Infiltrative keratitis
- This patient had surgery done on their other eye with Prokera and healed without complication but declined Prokera for their second eye
- Treatment for this included moxifloxacin and prednisolone
- Infectious keratitis
- Persistent epithelial defect
- This 17-year-old patient had no underlying health conditions, so the lengthy healing duration left investigators with questions
- Prokera was used on their second eye, which healed with no complications
Let’s talk limitations.
A few were noted, including the study’s retrospective design (and lack of randomization among patients’ eyes).
Plus, both treatment groups included results from two eyes for patients who underwent bilateral surgery.
- Why that matters: It reduced statistical validity by increasing correlation between the data points.
What else to know?
Despite the study’s design, investigators noted that including all eyes meeting the inclusion criteria increased the sample size and statistical power.
And so—since keratoconus is typically asymmetrical and using this approach mimicked routine clinical practice—it was considered appropriate for this retrospective study design, they concluded.
Noted. So, taking all of this into consideration—what were the takeaways?
Based on their findings, investigators determined that the use of Prokera following epi-off CXL “led to a significantly faster return of baseline visual acuity” as well as reduced postop complications.
And for the future?
From an optometric perspective: Dr. Rosetta noted Prokera utilization as a prime example for how comanagement with ophthalmologists can work—particuarly when it comes to managing progressive keratoconus patients, from CXL to postoperative care.
- As for additional research on Prokera: She added that a larger prospective trial grading the amount of corneal haze on an anterior-segment optical coherence tomography (Antec OCT) may offer insights as to whether Prokera could help haze results faster.
The American Academy of Optometry (AAO) annual meeting is taking place Oct. 8-11, 2025, in Boston, Massachusetts.