Canaloplasty in Pigmentary Glaucoma: Long-Term Outcomes and Proposal of a New Hypothesis on Its Intraocular Pressure Lowering Mechanism

Pigment dispersion syndrome and pigmentary glaucoma: overview and racial disparities

Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are two stages within the same ophthalmic disease spectrum, which are known to be affected by race. The prevalence of PDS is underestimated, largely due to its minor clinical symptoms. Although the prevalence of PG is low, the visual impairment associated with PG is extremely severe. The prevalence of PDS-PG is four or more times higher in Caucasians than in Blacks or Asians, and the "classic" PDS in Caucasians has long been used as a benchmark diagnostic criterion. Following extensive research focused on African Americans and Asians, the standard for diagnosing PDS-PG was refined. At the same time, the pathogenesis of PDS is not the same in different races. Hence, the effectiveness of preventive treatment and the need for treatment may not be equivalent in different races. The rate of conversion of PDS to PG is nearly 1/3 in Caucasians and higher in blacks and Asians, requiring more aggressive treatment and monitoring. We systematically searched a PubMed database from inception to March 2022 to provide an overview of research progress in various aspects of PDS-PG. Specifically, this paper considers the effects of race on disease prevalence, clinical manifestation, diagnostic criteria, disease mechanism, hereditary traits, treatment, and prevention to provide an accurate and comprehensive guide for the diagnosis and treatment of PDS-PG in various races.

Pigment dispersion syndrome: A brief overview

BACKGROUND

Pigment dispersion syndrome (PDS) is characterized by dispersion of pigment in the anterior chamber structures and can present with deposits on the central corneal endothelium or Krukenberg spindle, iris trans-illumination spoke-like defects, and increased pigmentation in the iridocorneal angle. It is more common in myopic patients with a predominance in young males in the third to fifth decade of life that affects about 1-2% of the population. PDS is a risk factor and can give lead to a rise in intraocular pressure (IOP) and secondary glaucoma. Pigmentary glaucoma (PG) can develop from PDS in the presence of elevated IOP coupled with glaucomatous optic neuropathy, retinal nerve fiber thinning, and/or visual field defects. PDS and PG have the same clinical features, representing different levels of severity on the same clinical spectrum.

RELEVANCE FOR PATIENTS

Early diagnosis, appropriate management, and follow-up of patients with PDS are important to prevent vision deterioration or blindness due to glaucomatous optic neuropathy.

Canaloplasty in the spotlight: surgical alternatives and future perspectives

The modern glaucoma surgeon is faced with many surgical alternatives for the management of glaucoma. In recent years, numerous techniques that make Schlemm's canal (SC) more accessible for surgery by being less invasive and surgically less challenging were introduced. Since its first introduction, canaloplasty has become a well-established method of glaucoma surgery. The aim of this paper was to present an overview of canaloplasty and its modifications, and to highlight their strong points and potential drawbacks based on available data on the effectiveness of each technique. Furthermore, it offered an overview of the development of canaloplasty over time and the clinical aspects that should be considered in patient selection. Abbreviations: ABiC = Canaloplasty ab interno, AH = aqueous humour, CSD = Canaloplasty with suprachoroidal drainage, IOP = intraocular pressure, MIGS = minimally invasive glaucoma surgery, OAG = open angle glaucoma, PEXG = pseudoexfoliation glaucoma, SC = Schlemm's canal, TDM = trabeculo-Descemet's membrane.