Article

CLINICAL: Glaucoma

How Low Does It Need To Go?

The science and art behind tolerable IOP

An active and healthy 72-year-old female returned to our clinic for repeat VF testing, due to moderate glaucomatous VF damage, which was affecting her inferior nasal VFs OU. Upon repeat testing, these defects now showed repeatable and correlating deepening/widening with good reliability OU. Also, the patient reported good adherence with her current prostaglandin q.h.s. OU and fixed combination b.i.d. OU topical therapy, without adverse effects and consistent mid-upper teen IOP readings — an improvement from pretreatment low 20 IOP levels. Pachymetry showed average-thin thickness measurements OU (525µ), gonioscopy revealed a visible ciliary body in all four quadrants with 1-2+ trabecular meshwork pigment, and the clinical exam showed pseudophakia OU, with otherwise normal ocular health. The patient worriedly asked, “How low does my eye pressure need to be to prevent further progression?”

Here, I briefly explain the science and the art behind this challenging question and the treatment approach I took with this specific patient.

THE SCIENCE

Just as a patient’s “normal” IOP is unique to them, based on their race, age and possibly even gender,1 so is their target pressure range. In fact, several population-based studies have shown that the percent of those who progressed after treatment was proportionate to, at least in part, their percent of IOP reduction. (See Figure 1 for a snapshot of key studies that most closely apply to the patient above.)

Figure 1. Key Studies

From these randomly controlled studies and others, Sihota et al. provided recommendations, depending on the patient’s disease stage (see Figure 2).

Figure 2. Initial Recommended Target Pressure Range

THE ART

Based on our patient’s new clinical findings, and these time-tested study results, the patient and I agreed that we needed to reduce her IOP a few more points to stop/slow the VF deterioration. After discussing the treatment options of adding another medication vs. selective laser trabeculoplasty, the patient wanted to continue topical therapy. I had her discontinue the prostaglandin q.h.s. OU and start a fixed-combination of a rho kinase inhibitor and a prostaglandin q.h.s. OU, while continuing her fixed-combination topical therapy b.i.d. OU.

BALANCING ACT

Decreased quality of life is associated with VF deterioration and so is multiple medications.6 Accordingly, and because the patient wanted to stay on topical therapy, we felt it best to keep the regimen as simple (and as similar to her current regimen) as possible. This treatment modification was an agreeable option to maximize adherence and IOP reduction by balancing potential disease progression with patient-centric disease treatment. OM

References:

  1. Hollows FC, Graham PA. Intra-ocular pressure, glaucoma, and glaucoma suspects in a defined population. Br J Ophthalmol. 1966;50(10):570–586.
  2. Öhnell H, Heijl A, Brenner L, Anderson H, Bengtsson B. Structural and Functional Progression in the Early Manifest Glaucoma Trial. Ophthalmology. 2016;123(6):1173–1180.
  3. Musch DC, Gillespie BW, Niziol LM, Lichter PR, Varma R; CIGTS Study Group. Intraocular pressure control and long-term visual field loss in the Collaborative Initial Glaucoma Treatment Study. Ophthalmology. 2011;118(9):1766–1773.
  4. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration. The AGIS Investigators. Am J Ophthalmol. 2000;130(4):429–440.
  5. Sihota R, Angmo D, Ramaswamy D, Dada T. Simplifying "target" intraocular pressure for different stages of primary open-angle glaucoma and primary angle-closure glaucoma. Indian J Ophthalmol. 2018;66(4):495–505.
  6. Quaranta L, Riva I, Gerardi C, Oddone F, Floriani I, Konstas AG. Quality of life in glaucoma: a review of the literature [published correction appears in Adv Ther. 2016 Jun;33(6):982]. Adv Ther. 2016;33(6):959–981.