Interventional procedure overview of nerve graft for corneal denervation
Closed for comments This consultation ended on at Request commenting lead permission
Summary of key evidence on allograft: acellular nerve allograft with orbital nerves as donor for corneal denervation
Study 8 Sweeney AR (2020)
Due to the similarity in authors, technique, and recruitment centres, this study may include 2 people who are also described in Leyngold (2019). However, this is not explicitly stated.
Study type | Single arm, multicentre, non-randomised, before-and-after study |
|---|---|
Country | USA |
Recruitment period | Not reported |
Study population and number | n=17 eyes in 17 people People with neurotrophic keratitis who had corneal neurotisation |
Age and sex | Mean 42.6 years (range 4 to 69 years); 53% female |
Patient selection criteria | Not reported |
Technique | Acellular nerve allograft, end-to-end or end-to-side coapted to either the ipsilateral or contralateral supraorbital or infraorbital nerves. All surgeons approximated the donor nerve fascicles to the limbus without corneoscleral tunnelling. Further description is provided in Leyngold (2019). |
Follow up | Mean 17.7 months |
Conflict of interest/source of funding | Conflict of interest: the authors declared no conflict of interest. Source of funding: supported in part by an unrestricted departmental grant from Research Prevent Blindness, Inc. |
Analysis
Follow up issues: Follow up ranged from 7 to 31 months.
Study design issues: This single arm, multicentre, non-randomised, before-and-after study assessed the outcomes of corneal neurotisation using an acellular nerve allograft for people with neurotrophic keratitis. Outcomes included corneal sensation (as measured by Cochet-Bonnet aesthesiometry), BCVA, and time until maximum corneal sensation. These outcomes were also assessed in subgroups stratified by coaptation technique, donor nerve, and ipsilateral vs. contralateral donor nerve.
Statistical analysis included statistical summaries and 2-sample t-tests assuming equal variance. Statistical significance was set at p<0.05. The authors do not report adjustment for multiple comparisons.
Study population issues: The cause of corneal anaesthesia was prior infection in 8 people, trigeminal nerve palsy in 8 people (6 of which were secondary to intracranial surgery) and ocular trauma in 1 person. Pre-existing eye conditions included corneal scars in 8 people, amblyopia in 2 people, optic neuropathy in 2 people, cataract/uveitis in 1 person, and proliferative diabetic neuropathy in 1 person.
Key efficacy findings
Corneal sensation
Number of people analysed: 17 eyes in 17 people
Follow up at time of assessment: Unclear, the mean final follow up was 17.7 months
There was a statistically significant increase in mean corneal sensation from 3.6 mm (SD 8.4 mm) before surgery to 44.2 mm (SD 16.2 mm) after surgery (p<0.01).
The time to first gain of corneal sensation occurred at a mean of 3.7 months (SD 2.7 months).
The time to maximum gain of corneal sensation occurred at a mean of 6.6 months (SD 3.5 months)
There were no statistically significant differences in time to first gain of corneal sensation, time of maximum gain of corneal sensation, or before-after surgery improvement in corneal sensation when comparing end-to-end vs. end-to-side coaptation, supraorbital vs. infraorbital, and ipsilateral vs. contralateral donor nerve sites
BCVA
Number of people analysed: 17 eyes in 17 people
Follow up at time of assessment: Unclear, the mean final follow up was 17.7 months
There was no statistically significant change in BCVA from 20/500 before surgery to 20/300 after surgery (p=0.22; BCVA measurements were converted into LogMAR for analysis).
The authors state that visual acuity gains were limited by pre-existing conditions.
Key safety findings
No complications reported.
Study 9 Leyngold IM (2019)
Due to the similarity in authors, technique, and recruitment centres, this study may include 2 people who are also described in Sweeney (2020). However, this is not explicitly stated.
Study type | Single arm, multicentre, non-randomised, retrospective, case series |
|---|---|
Country | USA |
Recruitment period | Not reported |
Study population and number | n=7 eyes in 7 people People with neurotrophic keratitis who had corneal neurotisation with nerve allograft. |
Age and sex | Mean 46 years (range 6 to 75); 57% male |
Patient selection criteria | Not reported |
Technique | Acellular nerve allograft, end-to-end or end-to-side coapted to either the ipsilateral or contralateral supraorbital, supratrochlear, or infraorbital nerves. Nerve fascicles were tunnelled in the subconjunctival space to the corneoscleral limbus. |
Follow up | Mean 6 months (range 3 to 10 months) |
Conflict of interest/source of funding | Conflict of interest: the authors declared no conflict of interest. Source of funding: not reported. |
Analysis
Study design issues: This single arm, multicentre, non-randomised, retrospective, case series reported early results with a novel corneal neurotisation procedure using an acellular nerve allograft for people with neurotrophic keratitis. Outcomes included corneal sensation (as measured by Cochet-Bonnet aesthesiometry), BCVA, and an assessment of epithelial defects.
No statistical analysis was performed.
Study population issues: The cause of neurotrophic keratitis included vestibular schwannoma in 1 person, retinal laser and ocular surgery in 2 people (1 also had diabetes), agenesis of the trigeminal nerve in 1 person, central trigeminal injury in 1 person, and herpes zoster ophthalmicus in 2 people (1 also had diabetes).
Multiple comorbidities were reported, including amblyopia (1 person), cerebral palsy (1), cardiomyopathy (1), coronary artery disease (1), diabetes (2), glaucoma (1), Goldenhar syndrome (1), hypertension (1), proliferative diabetic retinopathy (1), rhegmatogenous retinal detachment (1), smoking (2), thyroid eye disease (1), tractional retinal detachment (1), and ulcerative colitis (1).
Key efficacy findings
Number of people analysed: 7 eyes in 7 people
Follow up at time of assessment: 3 to 10 months
All people had improved corneal sensation after neurotisation, 6 of 7 had improved BCVA, and of the 5 people who had an epithelial defect before surgery, all were resolved after surgery.
Person | Follow up (months) | Epithelial defect | Corneal sensation (mm) | BCVA | |||
Before surgery | After surgery | Before surgery | After surgery | Before surgery | After surgery | ||
1 | 10 | No | No | 23 | 30 | 20/150 | 20/40 |
2 | 10 | Yes | No | 0 | 34 | HM | HM |
3 | 6 | Yes | No | None* | Improved* | LP | CF at 5 ft |
4 | 4 | Yes | No | None* | Improved* | HM | CF at 3 ft |
5 | 6 | No | No | 13 | 60 | 20/70 | 20/20 |
6 | 4 | Yes | No | 10 | 50 | HM | 20/200 |
7 | 3 | Yes | No | 0 | 4 | 20/40 | 20/30 |
*For those people uncooperative with measurement, presence of corneal sensibility is reported as either "none" or "improved" by testing the cornea with a wisp of cotton.
Abbreviations: BCVA, best-corrected visual acuity; CF, counting fingers; HM, hand motion; LP, light perception.
Key safety findings
Number of people analysed: 7 eyes in 7 people
Follow up at time of assessment: 3 to 10 months
Dry eye symptoms, n=2
Synaesthesia, n=1
Resolved over 7 months.
Bulbar conjunctival hyperesthesia, n=2
Recurrent corneal epithelial defect, n=1
Treated with oral prednisone and healed in 1 week.
How are you taking part in this consultation?
You will not be able to change how you comment later.
You must be signed in to answer questions