manual debridement vs phototherapeutic keratectomy in the treatment of corneal basement membrane dystrophy

Conditions: Epithelial Basement Membrane Dystrophy

Summary: of the few comparisons made in the existing literature, the results of ptk are comparable to those documented for manual debridement (md). however, the shorter length of follow-up in patients with md may have underestimated the associated complications. our study, therefore, aims to offer a comparison between these two techniques to clarify the choice of effective treatment with a good safety profile.

epithelial basement membrane dystrophy (ebmd) affects the anterior cornea, impacting about 2% of the population. ebmd is characterized by alterations and duplications of the basement membrane, a tissue layer that connects the epithelium to the underlying eye tissue. dysfunction of the basement membrane prevents proper adhesion of the overlying epithelium, leading to recurrent corneal erosions. additionally, tissue protrusions infiltrate the epithelium, creating surface irregularities that cause symptoms like blurred vision and irregular corneal topographies. this abnormal proliferation results in microcysts and corneal irregularities resembling fingerprints and maps. these surface irregularities can be observed in optical coherence tomography (oct) images showing epithelial thickening. non-invasive medical treatments are the first line of therapy, including lubricating drops and hypertonic solutions to protect the ocular surface and promote epithelial adhesion. for corneal erosions, soft contact lenses are used to aid healing. surgical interventions such as manual debridement and phototherapeutic keratectomy (ptk) are required in refractory cases. these are also indicated for patients preparing for cataract surgery to optimize preoperative corneal measurements and postoperative optical outcomes. manual debridement (md), a technique since 1952, involves scraping off the irregular epithelium to allow a new layer to form. some surgeons use 20% ethanol on the cornea before scraping with a blade or sponge, preserving the basement membrane. this method is simple, cost-effective, and has an 85% success rate in treating recurrent corneal erosions. however, recurrence rates are up to 24%, with the first recurrence typically within six months. corneal opacities can form between 7 and 41 days post-procedure. over the past two decades, ptk has become increasingly used for anterior corneal pathologies, including ebmd. ptk uses a 193nm excimer laser to break molecular bonds between cells on the epithelial surface. it is considered a more reliable, safe, and precise alternative to manual debridement, completely obliterating the basement membrane and potentially reducing recurrence rates. success rates without recurrence range from 46% to 100%, with minimal complications. unlike manual debridement, ptk may induce a hyperopic shift, which stabilizes within a year. corneal erosions and pain recur at about 13% over an average of 9.7 months. comparative studies between these two methods are scarce, and more data is needed to favor one technique over the other. limited comparisons suggest ptk results are comparable to manual debridement, though shorter follow-ups in md patients may underestimate associated complications. our study aims to compare these techniques to describe the efficacy and safety of both treatments.

Eligibility criteria:
inclusion criteria: * patient over 18 years of age; * ability to give free and informed consent * at least 1-year follow-up possible * patients with bilateral basal membrane corneal dystrophy who are symptomatic (recurrent corneal erosions, visual disturbances) and are candidates for bilateral surgery. exclusion criteria: * patient under 18 years of age; * history of ocular infection with herpes simplex virus.