Mean deviation is a useful summary metric in glaucoma, but it conceals the variable that matters most for premium IOL candidacy: where the damage sits.
Macular involvement in early glaucoma
Glaucomatous damage to the macula is not a late event. It is present early. Frequency-domain optical coherence tomography of the retinal nerve fibre layer and ganglion cell complex shows that early glaucomatous damage frequently involves the macular region, with greater thinning in the inferior retina corresponding to defects in the upper visual field, close to fixation.¹ The macula is more vulnerable, not less, in early disease.
Why the 24-2 is not enough
When 10-2 visual field testing is performed alongside the standard 24-2, defects in the central 10 degrees are detected in nearly as many hemifields as the 24-2 reveals, including in eyes with normal 24-2 fields.² The 24-2 alone is not sensitive enough to clear an eye for premium optics. Patients with paracentral defects in the central 10 degrees may have entirely normal mean deviation summaries on standard testing.
This is why premium IOL candidacy in glaucoma cannot be decided on global metrics. A paracentral defect inside the central 10 degrees moves a patient out of candidacy whatever the mean deviation, whatever the medication regimen, and whatever the patient’s motivation. In published series of premium IOL outcomes in glaucoma, eligibility is typically restricted to mild pre-perimetric disease with no central involvement.³
The location of the defect matters more than its depth. Central visual function changes the conversation completely.
References
- Hood DC, Raza AS, de Moraes CG, Liebmann JM, Ritch R. Glaucomatous damage of the macula. Prog Retin Eye Res. 2013;32:1-21.
- Traynis I, De Moraes CG, Raza AS, Liebmann JM, Ritch R, Hood DC. Prevalence and nature of early glaucomatous defects in the central 10° of the visual field. JAMA Ophthalmol. 2014;132(3):291-297.
- Ferguson TJ, Wilson CW, Shafer BM, Berdahl JP, Terveen DC. Clinical outcomes of a non-diffractive extended depth-of-focus IOL in eyes with mild glaucoma. Clin Ophthalmol. 2023;17:861-868.
Related Topics
- Premium IOLs in the Glaucoma Patient: Where I Say Yes, Where I Refer
- Why Glaucoma Is Not Always a Contraindication to Premium IOLs
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- Why Central Visual Field Loss Changes Premium Lens Decisions
- MIGS and Premium IOLs: Can You Have Both?
- Why a 10-2 Visual Field Matters Before Premium Lens Surgery
- When I Refuse Premium IOLs in Glaucoma Patients
- Diffractive vs Non-Diffractive Lenses in Glaucoma Eyes
