In the case of a 32-year-old African man with a positive history for glaucoma, the patient had an 8-year history of untreated visual loss and ultimately lost all vision in the right eye.
IOP was 24 and 18 mm Hg, respectively, in the right and left eyes. Central corneal thicknesses were low, and slit lamp evaluation and gonioscopy were unremarkable. The right optic nerve was excavated completely and cupped. The left eye has a glaucomatous disc but no visual field loss, according to Dr. Pasquale.
IOP in this case was not markedly elevated and there was no secondary form of glaucoma apparent. In such a case, Dr. Pasquale underscored the importance of patient education about glaucoma and determination of the status of his children.
“The misconception is that patients in their 20s, 30s, and 40s are unlikely to have glaucoma, but in this population, glaucoma is likely and it is important to detect it,” he said.
Dr. Pasquale cited a study (Bokman et al. PLoS One. 2014; 9(12):e115942), conducted in a Haitian population in south Florida, in which 21% of the participants aged 20 to 40 years either had an IOP of 24 mm Hg or higher or a cup-to-disc ratio over 0.7—indicating that glaucoma is developing in this population one or two decades earlier than in their Caucasian counterparts.
He also described the case of a 12-year-old African-American girl with IOP of 12 mm Hg, normal central corneal thickness and visual fields, and physiologic cupping. Her 34-year-old mother had moderate stage POAG, IOP no higher than 21 mm Hg, and optic nerves similar to her daughter, except for erosion of the superior and inferior neural retinal rims bilaterally.
“With the strong genetic predisposition to glaucoma in this population, we need to find the involved genes,” Dr. Pasquale said.
He also hypothesized there are likely pathophysiologic differences in glaucomatous optic neuropathy between African-American and Caucasian patients.
A study (Skaat et al. Ophthalmology. 2016;123:1476-1483) that sought to determine those differences in patients with optic disc hemorrhages and peripapillary atrophy between the races postulated that because disc hemorrhage is an independent risk factor for OAG, it must be more common in African-Americans than in Caucasians.
The evaluation of about 10,000 disc photographs from both racial groups with and without glaucoma showed, ironically, that African race was associated with reduced risk of disc hemorrhage, and the reason was unclear.
However, Dr. Pasquale noted the importance of this observation because it suggested that the retinal hemodynamics differs in patients of African heritage compared with Caucasians.