A Phase 2 interventional study of N-acetyl cysteine (NAC) 10% solution and N-acetyl cysteine (NAC) 20% solution in Fuchs Endothelial Corneal Dystrophy, sponsored by Massachusetts Eye and Ear Infirmary. Recruiting at 1 site in United States. Open to participants aged 21 Years and older. Per ClinicalTrials.gov, last updated 2026-09-02.
Sponsored by Massachusetts Eye and Ear Infirmary · Phase 2, Interventional, and Treatment
This protocol will investigate whether topical application of N-acetyl cysteine (NAC) eye drops decreases oxidative stress and confers cytoprotection in patients with FECD.
Fuchs Endothelial Corneal Dystrophy (FECD) is the most common corneal endothelial disorder and has been estimated to affect approximately 4% of the US population over the age of 40. Corneal transplantation is currently the primary treatment modality available to treat FECD, and there are no medical therapies that treat the disease or stall its progression. Therefore, there is an unmet need to identify pharmacotherapeutic interventions that would prevent the endothelial cell loss in early through late stages of FECD, as well as after corneal transplantation, aiding in the survival of the corneal grafts.
The investigators know that cell loss in FECD is caused by increased oxidative stress in the CEC and aqueous humor of FECD. The investigators have in vitro and in vivo data showing that the processes involved in the development of FECD can be arrested with administration of N-acetyl cysteine (NAC). Currently topical solutions of NAC are already used in ophthalmology for application in keratoconjunctivitis sicca (using 20% weight/volume solution or 10%), meibomian gland dysfunction (using 5%) and Sjögren's dry eye syndrome (also using 5%).
This is a single center, double-blind, placebo-controlled, randomized trial. Adult participants with advanced FECD and cataracts who qualify for the standard treatment (combined Descemet Membrane Endothelial Keratoplasty (DMEK) and cataract surgery) will be enrolled at Massachusetts Eye and Ear.
After meeting eligibility criteria and completing informed consent, 30 eyes from up to 30 participants with advanced FECD and cataracts with indication for combined DMEK and cataract surgery will be initially enrolled. (NOTE: Some participants may be enrolled twice if they elect to have both eyes treated within the study.) Eyes will be randomized 1:1 to NAC 10% and the placebo, Visine Tears Dry Eye Relief artificial tears ophthalmic solution. Each participant will self-administer 1 drop of study drug four times a day in the planned operative eye for 28 days prior to planned surgery.
After interim analysis of the study with 30 eyes, if a significant difference in the primary endpoint between NAC 10% and placebo is not found, an additional 15 eyes from up to 15 participants will be enrolled and assigned to 20% NAC.
Prior to and after using the study medication, participants will complete patient-reported visual disability questionnaires and have corneal measurements and images taken. Participants additionally will complete a tolerability and medication adherence questionnaire after using the study medication.
In the operating room, a standard incision will be made to collect the fluid from the anterior part of the eye and replaced with a salt solution or viscous agent routinely used during the surgery. This procedure is routinely performed during this type of surgery, however, some of the aqueous fluid will be collected and analyzed rather than being discarded. Additionally, corneal tissue which is normally removed during corneal transplantation surgery and discarded will be kept for further research on FECD.
92 studies on the registry are indexed under Fuchs' Endothelial Dystrophy; 27 are open to participants now.
This study's planned enrollment of 45 is close to the median of 50 across 62 interventional studies indexed under Fuchs' Endothelial Dystrophy.
Browse Fuchs' Endothelial Dystrophy studies →Massachusetts Eye and Ear Infirmary is the lead sponsor of 100 studies on the registry; 23 are open to participants now.
Of its 13 completed or terminated interventional studies of FDA-regulated products, 7 (54%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data.
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Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Subjects in this group will be treated with eye drops containing a 10% solution of N-acetyl cysteine. Topical NAC is a well-tolerated medication that has many applications in ophthalmology including dry eye disease and meibomian gland dysfunction.
Drug: N-acetyl cysteine (NAC) 10% solution
Subjects in this group will be treated with eye drops containing a 20% solution of N-acetyl cysteine. Topical NAC is a well-tolerated medication that has many applications in ophthalmology including dry eye disease and meibomian gland dysfunction.
Drug: N-acetyl cysteine (NAC) 20% solution
Subjects in this group will be treated with a placebo (Visine Tears Dry Eye Relief artificial tears ophthalmic solution.)
Drug: Visine Dry Eye Relief eye drops
N-acetyl cysteine is a sterile, unpreserved eye drop containing 10% (100 mg/mL) of acetylcysteine.
Also known as: acetylcysteine
N-acetyl cysteine is a sterile, unpreserved eye drop containing 20% (200 mg/mL) of acetylcysteine.
Also known as: acetylcysteine
Visine Tears Dry Eye Relief artificial tears ophthalmic solution
Level of H2O2 in the aqueous humor
The primary endpoint is the level of H2O2 in the aqueous humor obtained at time of DMEK surgery.
Time frame: DMEK Surgery occurs 28 to 42 days after participant enrollment
Assessment of safety of NAC eye drops in patients with FECD by documenting the number and severity of adverse events.
Safety assessment will be ongoing for the entire 28 days that study participants take study drug (prior to surgery) and in all post surgical follow-up visits. Assessment will be based on the number and severity of adverse events, with specific scrutiny for evidence of severe ocular adverse reactions such as ocular chemosis, severe injection, presence or worsening of corneal epithelial staining and/or epithelial defects.
Time frame: Ongoing safety assessment will occur starting on the first day when subjects receive the study drug, through the pre-operative visit, surgery and post-surgical follow-up visits, a period of approximately 6-7 weeks.
Assessment of tolerability of N-acetyl cysteine drops in patients with FECD by documenting participants' reports of irritation, burning, itchiness or redness in their eyes while taking the study drug
Participants will be asked to fill out a tolerability and medication adherence questionnaire where they will rate the irritation, burning, itchiness and redness they experience after using the medication on a scale of 1 to 100.
Time frame: Tolerability will be assessed after participants have taken study drug for 28 days or earlier, if the participants report difficulties tolerating the drug.
Change in patient-reported visual disability after NAC administration
Change in patient-reported visual disability will be obtained using the previously validated questionnaire, V-FUCHS instrument 10 before and after the study drug is administered. Participants will be asked how often they experience specific visual difficulties selecting from the following choices: never, rarely, sometimes, most of the time or all of the time. Participants will also be asked how much difficulty they have performing certain visual tasks. Options for the answers are: No difficulty, a little difficulty, moderate difficulty, a lot of difficulty or extreme difficulty.
Time frame: Assessed when subject starts study drug and again, 21 to 28 days later.
Change in central corneal thickness after NAC administration
Change in central corneal thickness as measured by CCT; decrease by \>30 µm before and after NAC drop administration period.
Time frame: Assessed when subject starts study drug and again, 21 to 28 days later.
Change in corneal endothelial cell counts after NAC administration
Change in the number of corneal endothelial cells as determined by HRT3 with Rostock Corneal Module (Heidelberg Engineering, Heidelberg, Germany) before and after NAC drop administration period. If central counts are unattainable due to end-stage of FECD, then peripheral counts will be obtained.
Time frame: Assessed when subject starts study drug and again, 21 to 28 days later.
Changes in corneal tomography after NAC administration
Corneal tomography is a three-dimensional imaging technique that characterizes the anterior/posterior corneal surfaces. Participants will have corneal tomography twice: first before they start the study drug, and then again, 28 to 42 days later when the drug treatment has concluded. Change in corneal tomography imaging will be assessed qualitatively.
Time frame: Assessed when subject starts study drug and again, 21 to 28 days later.
Started Sep 2020 (actual). Primary completion is estimated for Apr 2027, 79 months after the start.
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Studies of the drug tested here: Acetylcysteine
Fuchs' Endothelial Dystrophy →
Massachusetts Eye and Ear Infirmary →