A new study published in Ophthalmology developed a classification system of visual field (VF) abnormalities in highly myopic eyes with and without glaucoma.
Why did we need this study?
It can be a challenge to distinguish glaucomatous VF loss from nonglaucomatous VF defects in highly myopic eyes due to concurring myopic maculopathy and high myopia-associated optic neuropathy, both of which can mimic glaucomatous perimetric defects.
This study aimed to develop a classification system to describe VF loss patterns in highly myopic eyes without myopic maculopathy.
Tell me about the study.
More than 1,300 highly myopic eyes of 825 participants were included in the study, ranging in age from 18 to 64 years.
The VF classification system consisted of four major types: normal; glaucoma-like defects (paracentral defect, nasal step, partial arcuate defect, arcuate defect); high myopia-related defects (enlarged blind spot, vertical step, partial peripheral rim, non-specific defect); and combined defects (nasal step with enlarged blind spot).
What were the most common fields seen?
Among the 1,302 VF tests, the most frequent result was a normal (74.1%), followed by high myopia-related defects (15%), (specifically an enlarged blind spot [9.5%]), nonspecific defect (5.1%), and vertical step and partial peripheral rim defect (0.4%).
Glaucoma-like defects accounted for 10.8% of defects, and combined defects accounted for 0.1%. Among the eyes with glaucoma-like or combined defects, 26.8% were diagnosed primary open-angle glaucoma.
Any associations between patients who had field defects?
The prevalence of glaucoma-like VF defects and of high myopia-related VF defects were positively associated with older age and longer axial length.
The take home.
The authors state that this new classification system provides a tool for clinicians to distinguish glaucomatous VF loss from nonglaucomatous VF defects in highly myopic eyes and may also facilitate comparison of findings among clinical trials and epidemiologic studies.