What clinical trials have tested honey-derived treatments for refractive errors or retinal diseases?

1. What trials have actually tested honey in the eye: surface disease, not refraction or retina

Clinical research described in the assembled sources focuses on ocular surface disorders: randomized/crossover pilot trials of 16% Manuka honey eye drops (Optimel) for contact‑lens related dry eye and MGD; open‑label pilot studies assessing antibacterial honey’s effect on eyelid/conjunctival flora; and a double‑blind clinical trial that tested topical honey drops as adjuvant therapy in vernal keratoconjunctivitis ^{[1] [6] [5] [3]}. Systematic reviews and meta-analyses pool trials of honey for dry eye disease but conclude protocols and honey types were heterogeneous, and pooled endpoints often showed no significant difference vs controls on some measures (tear breakup time, OSDI, Schirmer) ^[2].

2. No clinical trials for refractive error correction

Available sources do not report any clinical trials testing honey-derived treatments to correct refractive errors such as myopia, hyperopia, or presbyopia. Some non‑trial reports and a case/case‑series style article mention exploratory combinations (e.g., honey with bilberry extract or Ayurvedic formulas) aimed at myopia/presbyopia, but these are not described as controlled clinical trials that demonstrate refractive correction ^[7]. In short: clinical trial evidence for honey as a treatment to change refractive error is not found in the current reporting (p1_s1; available sources do not mention randomized trials for refraction).

3. No clinical trials for retinal diseases in the provided literature

The provided systematic reviews and reviews of honey/propolis therapies emphasise laboratory and animal work and say translation to retinal therapy is largely preclinical; clinical study designs are “primarily animal and in vitro,” with an urgent need for human translation ^[8]. Retinal clinical-trial listings (for AMD, DME, inherited retinal disease) in the retinal‑specialist press do not include honey-based retinal therapeutics ^{[9] [10]}. Therefore, human clinical trials of honey-derived agents for primary retinal diseases are not documented in the supplied sources (p2_s1; available sources do not mention clinical retinal trials of honey).

4. What the trials actually found (surface‑eye highlights and limitations)

A double‑blind trial of honey eye drops as adjunctive treatment in VKC reported reductions in redness and limbal papillae and suggested potential steroid-sparing benefits ^{[5] [3]}. Manuka‑honey based products (Optimel) have been studied in prospective randomized or crossover pilot trials for contact‑lens dry eye and MGD with reported symptom improvement and some objective sign changes; these products are commercially cleared/CE‑marked for some indications in Australia/Europe ^{[1] [4]}. Systematic review/meta-analysis of honey for dry eye concluded studies were heterogeneous in honey type, dose and controls, and found no consistent significant difference on several pooled objective endpoints (tear breakup time, OSDI, Schirmer, corneal staining) ^[2]. That heterogeneity and small sample sizes limit confidence in generalizing benefits ^[2].

5. Safety and caveats flagged by clinicians and reviews

Clinicians warn about variable honey preparations, potential stinging/redness with raw or unregulated products, and the importance of quality-controlled, sterilized pharmaceutical formulations ^{[11] [1]}. Reviews note practical formulation issues—osmolarity, pH, sterilization—and seasonal batch variability of honey that can affect bioactive composition; these factors complicate trial design and regulatory acceptance ^{[12] [8]}. Professional commentary stresses rigorous randomized, masked designs and suitable placebos are needed to demonstrate clinical efficacy beyond anecdote and marketing ^[13].

6. How to read the landscape: practical takeaways

If you are looking for clinical trial evidence that honey can correct refractive errors or treat retinal disease, the sources show there are no such human trials documented—research to date concentrates on ocular surface disorders and preclinical retinal/propolis work ^{[7] [8] [3]}. For dry eye/MGD and certain inflammatory surface disorders there is early clinical data—some randomized and double‑blind trials—supporting symptom or sign improvement with specific, pharmaceutical‑grade honey products, but meta-analyses highlight inconsistent endpoints and heterogeneity in methods ^{[1] [5] [2]}.

If you want, I can compile a concise list of the specific trials cited (trial design, honey type/concentration, main outcomes) from these sources and flag which are randomized, masked, or open‑label.